Gas Installation Manual
2000/3000/4000 Series
WARNING
READ AND UNDERSTAND ALL SAFETY PRECAUTIONS
AND WARNINGS MENTIONED IN THIS MANUAL.
IMPROPER OPERATION OR MAINTENANCE
PROCEDURE COULD RESULT IN A SERIOUS ACCIDENT
OR DAMAGE TO THE EQUIPMENT CAUSING INJURY OR
DEATH.
NON-COMPLIANCE
WITH
THESE
INSTRUCTIONS MAY INVALIDATE THE GUARANTEE
OFFERED WITH THE ENGINE.
MAKE QUITE CERTAIN THE ENGINE CANNOT BE
STARTED IN ANY WAY BEFORE UNDERTAKING ANY
MAINTENANCE PARTICULARLY IN THE CASE OF
AUTOMATICALLY STARTING GENERATING SETS.
Gas Installation, October 1997
INTRODUCTION
THE PURPOSE OF THIS INSTALLATION MANUAL IS TO PROVIDE THE USER WITH
SOUND GENERAL INFORMATION FOR INSTALLING AN ENGINE/GENERATING SET
WITHIN AN ENGINE ROOM FACILITY. IT IS FOR GUIDANCE AND ASSISTANCE IN THE
APPLICATION OF AN ENGINE WITH RECOMMENDATIONS FOR CORRECT AND SAFE
PROCEDURE. PERKINS ENGINES LIMITED CANNOT ACCEPT ANY LIABILITY
WHATSOEVER FOR PROBLEMS ARISING AS A RESULT OF FOLLOWING
RECOMMENDATIONS IN THIS MANUAL.
It is essential that all relevant safety precautions are adhered to both with regards to machinery
and personal protection. Safety symbols refer to Safety Precautions insert.
The information contained within the manual is based on such information as was available
at the time of going to print. In line with Perkins Engines (Stafford) Limited policy of continual
development and improvement, information may change at any time without notice. The user
should therefore ensure that before commencing any work, he has the latest information
available.
Users are respectfully advised that it is their responsibility to employ competent persons to
carry out any installation work in the interests of good practice and safety.
It is essential that the utmost care is taken with the application, installation and operation of any
gas engine due to their potentially dangerous nature.
Careful reference should also be made to other Perkins Engines Limited literature, in particular
the Product Information Folder and Engine Operation Manuals.
Should you require further assistance in installing the engine/generating set, the following
persons may be contacted:2000 & 3000 Series
4000 Series
- Applications Manager
- Service Manager
Perkins Engines (Shrewsbury) Ltd
Lancaster Road
Shrewsbury
Shropshire
SY1 3NX
England
Tel: (01743) 212000
Fax: (01743) 212700
Perkins Engines (Stafford) Ltd
Tixall Road
Stafford
ST16 3UB
England
Tel: (01785) 223141
Fax: (01785) 215110
Publication TSL4200
Published by the Technical Publications Department, Stafford.
© 1997 Perkins Engines (Stafford) Limited.
Gas Installation, October 1997
1
CONTENTS
DESCRIPTION
INTRODUCTION
CONTENTS
SAFETY PRECAUTIONS
COMMISSIONING & SIGN OFF PROCEDURE
ENGINE COOLING
LIFTING EQUIPMENT FOR ENGINES
Page
1
3-5
INSERT
7-8
9 - 11
12 - 13
MOUNTING OF ENGINE & DRIVEN UNIT
ENGINE MOUNTINGS
UNDERBASE ENGINE BEARERS
TYPE OF FOUNDATIONS
SUBSOIL-SITE
FIXED CONCRETE BLOCK
INSTALLATION PROCEDURE ON CONCRETE BLOCK
GROUTING
TRENCHES
CONCRETE RAFT
FLOATING CONCRETE BLOCK
RIGID MOUNTINGS
FLEXIBLE MOUNTINGS
ANTI-VIBRATION MOUNTINGS
ALIGNMENT PROCEDURES
14
14
14
14
15
15 - 16
17
18
18
18
18 - 19
20
21 - 22
23 - 24
25 - 29
TORQUE SETTINGS
30 - 31
ENGINE ROOM LAYOUT
INSTALLATION GUIDELINES
INITIAL CONSIDERATIONS
TYPICAL ENGINE ROOM LAYOUT
VENTILATION - ENGINE ROOM
DUCTING AGAINST PREVAILING WIND
VENTILATION - TROPICAL CONDITIONS
FORCED VENTILATION - REMOTE MOUNTED RADIATOR
ALTERNATOR/ENGINE RADIATED HEAT
TYPICAL MULTIPLE ENGINE INSTALLATION
32
32
33
34
35 - 37
38
39
40 - 41
42 - 43
44 - 45
COOLING SYSTEMS
RADIATOR
FAN PERFORMANCE
REMOTE MOUNTED RADIATOR
FILLING THE COOLING SYSTEM
DRAINING THE COOLING SYSTEM
Gas Installation, October 1997
46
46
46
47
48
48
3
CONTENTS
Page
49 - 50
51
51 - 52
53
53
53
54 - 57
BREAK TANK - WATER MIXING
HEAT EXCHANGER COOLING
TWO SECTION RADIATOR (CHARGE COOLED ENGINES)
COOLANT
ANTIFREEZE PROTECTION
WATER TREATMENT
CO-GEN HEAT/POWERSETS
CIRCULATION DIAGRAMS
4006/8TESI (MINNOX) ENGINE COGEN UNIT
COOLING CIRCUIT
4012/16TESI (MINNOX) ENGINE COGEN UNIT
COOLING CIRCUIT
4012/16TESI COGEN UNIT DISN IGNITION/GAS
SYSTEM DIAGRAM
4012/16 TESI FRESH & RAW WATER CIRCULATION
WITH RADIATOR (DOUBLE CORE)
TP385
INSERT
TP386
INSERT
TP387
INSERT
TP384
INSERT
EXHAUST SYSTEM
BACK PRESSURE - LIMITATION
INSTALLATION
FLEXIBLE ELEMENT
EXPANSION
EXHAUST OUTLET POSITION
MULTIPLE EXHAUST OUTLETS
CONDENSATE DRAIN
LAGGING
EXHAUST SYSTEMS GAS EMISSION & CATALYSTS
BACK PRESSURE - CALCULATIONS
NOISE ATTENUATION - EXHAUST
59
59
59
60
61
61
62
62
62
63 - 69
64
68
ENGINE BREATHER
BREATHER INSTALLATION & CLOSED CIRCUIT
70
70 - 71
FUEL SUPPLY SYSTEMS
FUEL SYSTEMS & SAFETY EQUIPMENT
GAS SPECIFICATION
GAS SYSTEMS
72
72 - 73
74
75 - 81
LUBRICATING OIL SYSTEMS
LUBRICATING OIL RECOMMENDATIONS
STANDARD LUBRICATING OIL SYSTEM
EXTENDED RUNNING OIL SYSTEM
82
82
82
82
4
Gas Installation, October 1997
CONTENTS
SOUND INSULATION
NOISE LEVEL
NOISE SOURCE
RECOMMENDATIONS TO CONTAIN NOISE
''FREE'' & ''SEMI-REVERBERENT'' FIELD
SOUNDPROOF CANOPY OVER ENGINE
MULTIPLE ENGINE NOISE LEVEL
Page
83
83
83
83
84
84
85 - 86
AIR INTAKE
AIR RESTRICTION INDICATOR
REMOTE MOUNTED AIR CLEANER
87
87
88
TORSIONAL VIBRATION
CRITICAL SPEED
CRITICAL SPEED - CORRECTIVE METHODS
TORSIONAL ANALYSIS DATA
GENERATING SET TORSIONAL ANALYSIS
89
89
89
90
90
DERATING
DERATING ENGINE
91
91
STARTING, STOPPING & PROTECTION SYSTEMS
GAS ENGINE START & STOP SEQUENCE
AIR STARTING / BATTERIES
BATTERY CHARGING ALTERNATOR
BATTERY CHARGER
STARTING AIDS
STARTING LOADS
STOPPING
PROTECTION SYSTEM
GOVERNOR WIRING
OVERALL DIMENSIONS AND WEIGHTS
Gas Installation, October 1997
92
92 - 93
94 - 96
96
96
96
97
97
97
98
99 - 100
5
COMMISSIONING AND SIGN OFF PROCEDURE
CUSTOMER
SITE
ALTITUDE (m)
ENGINE TYPE
No
POWER (kW)
PERFORMANCE RELATED PARAMETERS (at maximum site load)
TEMPERATURES:
UNITS
Turbine inlet temperatures.
Turbine outlet temperatures.
Air filters inlet temperatures.
Charge air temperatures to charge cooler.
Charge air temperatures from charge cooler.
Ambient (external).
°C
°C
°C
°C
°C
°C
Water into radiator (heat exchanger).
Water into engine oil coolers.
°C
°C
Water temperatures to charge coolers.
Water temperatures from charge coolers.
°C
°C
Cooling air temperature onto fans.
°C
Oil temperature to bearings.
°C
Gas temperature before meter.
°C
Fuel temperature to engine.
°C
PRESSURES:
Boost pressure before charge cooler.
Boost pressure inlet manifold.
mmHg
mmHg
Exhaust back pressure after turbochargers.
mmHg
Canopy depression/pressure.
mmHg
Barometric pressure.
Air filter depression.
(if filtration is non standard or air ducted)
mmHg
mmHg
mmHg
Lubricant oil pressure to bearings.
kpa
Water pressure (out of engine) C.H.P. systems.
Water pressure into pump.
Water pressure after pump.
kpa
kpa
kpa
Fuel pressure (in engine rail-diesel).
kpa
FLOWS
Water flow from pumps (engine jacket circuit).
(Perkins thermostats to be fully open)
L/min
Water flow through charge cooler.
L/min
Air flow through radiator (if cooling suspect).
m3/sec
Crankcase pressure (particularly where “modified” breathers are used).
mmWg
Gas Installation, October 1997
7
COMMISSIONING AND SIGN OFF PROCEDURE
ENGINE PARAMETERS
Emissions
NOx
ppm
Mainly Gas
CO
ppm
Engines
HC
ppm
O2 (Full load and no load)
%
CO2 (If it is possible)
%
Ignition timing (gas).
Mixture screw position (gas).
‘A’ Bank
‘B’ Bank
Gas pressure before gas pressure regulator. (Full and no load)
Gas pressure after gas pressure regulator. (Full and no load)
Gas pressure before meter.
Gas calorific value on site.
(If not available sample must be obtained).
Exhaust shade (diesel).
Head of fuel (diesel).
Governing:
Actuator position at full load.
Gain
Stability
Load acceptance:
% Load applied.
Cold engine
Hot engine
Ramp time to full load (where applicable).
Cooling down times.
Stability. (Gas engine).
°BTDC
mm
mm
mm
mmWG
mmWG
mmWG
MJ/m3
BOSCH
m
%
sec
sec
r/min
or
kWe
GENERAL
Visual inspection (vibration, leaks, etc.). (measured if necessary)
Air circulation (cooling, stagnant areas).
Lubricant oil supplier and grade.
Fuel oil supplier and grade.
Water treatment (coolant).
Gas supplier or area of origination.
Reset power stops to suit site conditions (to prevent overload:- gas and diesel).
8
Customer Signature
Name
PE(ST)L/O.E.M.
Name
Gas Installation, October 1997
ENGINE COOLING CIRCUITS
Fig. 1 - 2006TSI (IN-LINE)
Fig. 1
Gas Installation, October 1997
978.2
9
ENGINE COOLING CIRCUITS
Fig. 2 - 3012SI ('V' FORM)
Fig. 2
10
980.2
Gas Installation, October 1997
ENGINE COOLING CIRCUITS
Fig. 3 - 3008SI ('V' FORM)
Fig. 3
Gas Installation, October 1997
981.2
11
LIFTING EQUIPMENT FOR ENGINES
When lifting engines or generating sets,
special lifting equipment is required. It is
recommended that a spreader lifting beam of
the correct lifting load capacity is used and
that chains, hooks, shackles, eyebolts etc are
checked that they are well within their safe
working loads. The load should be secure,
stable and balanced when lifting, therefore
an assessment of the position of its centre of
gravity must be determined to ensure that the
lifting point is over it.
The lifting chains etc must be firmly secured
to the load by means of hooks etc on to the
purpose-designed lifting points, and that the
rated included angle is not exceeded.
In order to accommodate the chains for lifting
it may be necessary to have to remove engine
components such as air filters etc to prevent
damage, but this should be avoided where
the chains can be made to clear by nondetrimental means.
NOTE: When lifting with chains at an angle
the load on the lifting eye is increased (45° =
40% increase).
LIFTING
EQUIPMENT
SHOULD BE USED BY TRAINED
PERSONNEL ONLY. GENERATING
SETS MUST BE LIFTED USING THE
LIFTING LUGS ON THE BASEFRAME
AND A SPREADER LIFTING BEAM. THE
ENGINE LIFTING BRACKETS AND
ALTERNATOR LIFTING LUGS MUST NOT
BE USED.
ENGINE
LIFTING
BRACKET
Fig. 4
765.2
ENGINE
LIFTING
BRACKET
Fig. 5
766.2
WARNING
12
UNDERBASE
LIFTING
BAR
Fig. 6
767.2
Gas Installation, October 1997
LIFTING EQUIPMENT FOR ENGINES
Fig. 7 Lifting points for Engines
Fig. 7
Gas Installation, October 1997
982.2
13
MOUNTING OF ENGINE & DRIVEN UNIT
When mounting an engine and driven unit the
utmost consideration must be given to the
type of engine mountings and foundation,
which must be strong enough to support the
weight of the unit and the stresses produced
when the unit is operating.
ENGINE MOUNTINGS
The type of mountings depend upon the type
of installation in which the engine is to be
used and the final drive arrangement. The
engine can be fitted with either rigid or flexible
mountings, depending on the type of
foundation or application. Flexible mountings
are normally supplied in matched sets and
are used to isolate engine vibrations and
noise (see pages 21-22). If the engine is
flexibly mounted, the exhaust and fuel pipe
connections must also be flexible.
The engine should be aligned to the driven
unit within the specified recommendations,
using shims between the engine and driven
unit mounting feet and the underbase/bearers.
The dimensions of the shims (or packing
pieces) should not be less than the mating
area of the engine and driven unit mounting
feet. At least two fitted bolts (minimum quality
8.8 steel) must be used both in the engine and
driven unit mounting feet. Where it is not
possible to use a fitted bolt, the mounting feet
should be dowelled to the underbase/bearers
using one dowel in each foot at diagonal
corners.
NOTE: For alignment procedure and
tolerances see pages 25-29.
UNDERBASE/ENGINE BEARERS
The simplest form of mounting is to rigidly bolt
the engine and driven unit directly to an
underbase or bearers. It is essential that all
mounting pads on the underbase or bearers
are flat, square and parallel to each other.
The underbase or bearers should be designed
so that the mounting pads will not distort in
any way and have sufficient rigidity to prevent
deflection due to the weight of the engine and
driven unit, vibrations and various stresses
when the engine is running.
TYPE OF FOUNDATIONS
The engine floor/foundation where the
underbase/bearers are fixed is of great
importance as it must:
i) support the static weight of the units and
withstand any stresses or vibrations when
the engine is running,
ii) be sufficiently rigid and stable so that
there will be no distortion which would
affect the alignment of the engine and
driven unit,
iii) absorb vibrations originating from the
running units and prevent them being
transmitted to the surrounding floor and
walls etc. (see Figs. 8 & 9).
14
Gas Installation, October 1997
MOUNTING OF ENGINE & DRIVEN UNIT
SUBSOIL-SITE
The site subsoil must have a bearing strength
capable of supporting the weight of the
complete set plus the concrete foundation on
which it will stand.
If the bearing strength of the subsoil is in
doubt advice should be taken from a qualified
civil engineer to enable the type and size of
concrete foundations to be determined.
It may not be possible to reach solid subsoil,
hard clay, compacted sand and gravel or
rock, without excavating to an unreasonable
depth. In such a situation, the load must be
spread over a large area on a concrete raft,
the design of which should be entrusted to a
qualified civil engineer in conjunction with
Perkins Engines (Stafford) Ltd Application
Department.
FIXED CONCRETE BLOCK
The fixed concrete block is a proven method
and preferred in some circumstances. In this
case the engine set bedplate is tightly bolted
to the concrete block.
The recommended plan size of the fixed
concrete block as illustrated in Fig.8 is to
allow between 300/450 mm surround on all
sides of the set. The surface of the block is
usually proud of the normal floor line by 'h'
between 100/230 mm and forms a plinth.
The depth of the concrete block is calculated
as follows:
D=
W
dxBxL
D = Depth of concrete block in feet (metre)
W = Total weight of generating set in Ibs (kg)
d = Density of concrete in Ib/ft3 (kg/m3)
NOTE: Use 150 Ib/ft3 and 2403.8 kg/m3 if
accurate figures are not known.
B = Breadth of concrete block in feet (metre)
L = Length of concrete block in feet (metre)
After determining the depth of concrete
required for the weight and stability of the
running set, the subsoil has to be checked to
see if it will carry the total weight (set plus
concrete block) and withstand the forces
involved.
Gas Installation, October 1997
15
MOUNTING OF ENGINE & DRIVEN UNIT
Fig. 8
Fig. 9
16
768.2
769.2
Gas Installation, October 1997
MOUNTING OF ENGINE & DRIVEN UNIT
INSTALLATION PROCEDURE ON
CONCRETE BLOCK
When the concrete block is being poured
pockets must be incorporated for the Holding
Down Bolts, ie Hook type or equivalent. At
each holding down bolt position removable
wooden boxes are placed. The size of box is
to match the size of the the bolt used in the
installation. When the concrete is reasonably
firm the boxes are removed.
Ensure that the top surface of the concrete
block is level and reasonably smooth and
free from blemishes.
After removing the Holding Down bolt
boxes leave for 5/7 days to dry out before
positioning the set.
Fig. 9 illustrates the method using the common
'hook bolt'.
The depth 'd' should be a little more than the
length of the bolt 'L'. This is so that the bolt can
be dropped into the hole for the concrete and
allow the set to be rolled into position without
obstruction from the bolts.
Pour and pack the concrete into the bolt hole
pockets to within 50 mm of the top. This is to
allow for the final grout.
Leave 2/3 days for the concrete to set then
tighten the holding down bolts.
At this stage check the engine/driven unit
alignment to ensure that the bedplate has not
distorted. If alignment has been affected
carefully slacken the holding down bolts and
shim as necessary. Re-tighten aIl bolts and
re-check alignment. If O.K. carry on to next
stage.
NOTE: It is not necessary to check crankweb
deflections.
WARNING
USE CORRECT
LIFTING
EQUIPMENT. DO NOT WORK ALONE.
ALWAYS WEAR PROTECTIVE GEAR.
When lifting the engine/alternator set into
position it is essential that correct lifting
equipment is used having a tested safe
working load well above the weight of the
complete set to be lifted. Use the lifting facilities
provided where possible and observe safety
precautions regarding suspended loads etc.
When the set is in position pull the bolts up
through the holes in the main bedplate. Fit the
washers and nut until approximately a thread
length, equivalent to the nut thickness, stands
proud of the nut
At each holding down position fit a steel
packing plate across the hole and on each
side of the bolt.
Check that the bedplate is level without sag or
twist. If necessary add shims between the
bedplate and packing plate.
Gas Installation, October 1997
17
MOUNTING OF ENGINE & DRIVEN UNIT
GROUTING
The recommended grout mix is as follows:
1-Part best quality cement
2-Parts clean sharp sand
Grouting mixture is packed into the top of the
holding down bolt pockets, around the bolts
and packing pieces, etc., and between the
underside flange of the bedplate and the top
of the concrete block. See Fig. 9.
Leave for 5/7 days to dry out and set.
Check holding bolts and tighten if
necessary.
When the set has run for 50/75 hours after the
completion of the installation the holding down
bolts should be checked and tightened as
necessary.
TRENCHES
When designing the foundation block various
other areas should be taken into account.
Trenches, particularly for heavy duty electrical
cables need to be considered, bearing in
mind provision for drainage to prevent the
trench filling up with water.
On the larger generating sets these cables
have a large bending radius. It may be
necessary to cut away part of the concrete
block so that a smooth sweep can be made.
See Fig. 8.
CONCRETE RAFT
This type of foundation distributes the set
weight plus the weight of the concrete raft
over a larger floor area than the fixed concrete
block. The unit loading on the subsoil is
minimised and a reduced depth of concrete
can be used.
With the sub-soil of hard clay or compacted
sand and gravel a concrete thickness of
between 380/450mm is typical, but if
reinforced by steel bars or steel mesh this
would be satisfactory for even the largest of
the 4000 series engines. (See Fixed Concrete
Block).
Instead of pre-fitted 'hook bolts' the concrete
may be drilled to take suitably sized
'Rawlbolts' or similar fastenings.
18
FLOATING CONCRETE BLOCK
The floating block is an effective alternative to
the fixed concrete block. The concrete mix,
holding down bolt pockets, surface finish and
installation of the set is the same. The block is
pre-cast using a wooden mould.
To isolate and float the block a matting of
water resistant cork-like material or similar
proprietary material is placed on the surface
of the sub-soil at the bottom of the pit and the
concrete block lowered on to it. The matting
should be adequate to support the weight of
the set plus concrete block. (See Fixed
Concrete Block).
An air gap of approximately 25mm should be
maintained along all four sides of the block.
The gap at floor level must be sealed with a
non-setting mastic or similar material to keep
out dirt and water but still allow flexibility. See
Fig. 11.
This method isolates the machinery and block
and substantially reduces the transmission of
the vibration to the surrounding floor, walls
etc.
All services to the engine, fuel, air and water
pipes, exhaust system and electric cables
must be fitted with a flexible length or
connection to prevent fractures and possible
transmission of harmful vibrations.
Transmission of vibration may culminate as
noise at a point remote from the engine.
Gas Installation, October 1997
MOUNTING OF ENGINE & DRIVEN UNIT
Fig. 10
770.2
Fig. 11
771.2
Gas Installation, October 1997
19
MOUNTING OF ENGINE & DRIVEN UNIT
RIGID MOUNTINGS
A typical application where rigid mountings
are used is an engine/alternator mounted on
an underbase as shown in Fig. 12. In this
case an alternator is the driven unit but could
also be a water pump or compressor.
Fig. 12
20
772.2
Gas Installation, October 1997
MOUNTING OF ENGINE & DRIVEN UNIT
FLEXIBLE MOUNTING (USED WITH
UNDERBASE)
To reduce the noise level, and absorb any
vibrations being transmitted to the installation
foundations, the above underbase is fitted
with flexible mountings. See Fig. 13.
The flexible mountings are positioned so as
to give even load distribution, which is
determined by calculating the total weight of
the set and its centre of gravity, and disposing
the mountings equally about the centre of
gravity of the unit:
Total bending moment
WxL=
(W1 x L1) + (W2 x L2)
(W1 x L1) + (W2 x L2)
. L=
Total Weight W
. .
L1 and L2 Should be determined by the
installer from a datum point to find L (See Fig
13).
Fig. 13
Gas Installation, October 1997
773.4
21
MOUNTING OF ENGINE & DRIVEN UNIT
FLEXIBLE MOUNTINGS (ENGINE
BEARERS)
In the case where there is no underbase and
the engine/alternator are to be flexibly mounted
directly to the engine bearers as shown see
Fig. 14. It is important to use a specific type of
flexible mounting to ensure that the mountings
are correctly loaded and are suitable for
restricting movement, torsional vibration &
engine torque. This type of mounting is not
recommended where the radiator is fixed to
the engine bearers but can be used for remote
mounted radiator installations.
Normally four mountings are used on most
engine/flywheel housing mounted alternator
sets but engine weight distribution may be
unsuitable for standard flexible mountings. It
is not good practice to use additional flexible
mounts to provide 6-point system without first
checking their suitability.
If the engine is fitted with an open coupled
driven unit and the complete unit is to be
flexibly mounted then the unit should be
mounted on side channels and the flexible
mountings fitted on the underside of the side
channels.
L1 and L2 Should be determined by the
installer from a datum point to find L3 (see
Fig. 14).
NOTE: Where the driven equipment is not
supplied with the engine, Perkins Engines
(Stafford) Ltd, should be contacted for flexible
mounting
and
mounting
bracket
recommendations.
Generally engine flexible mounts have a
height adjustment to enable alignment of the
engine output flange to the alternator shaft to
be carried out accurately. Initially height
adjustment should be carried out by inserting
shims between the engine bearer and the
flexible mountings. The final height adjustment
being carried out on the flexible mounting
adjusting nut.
Total bending moment
= WL = (W1 x L1) + (W2 x L2) + (W3 x L3)
= WL = W x L1 + W x L2 + W x L3
3
3
3
= WL = W (L1 + L2 + L3)
3
. 3L - (L1 + L2) = L3
. .
Fig. 14
22
774.3
Gas Installation, October 1997
MOUNTING OF ENGINE & DRIVEN UNIT
ANTI-VIBRATION MOUNTINGS (2, 3 & 4000
SERIES)
Large concrete blocks with the accompanying
holding down bolt methods are expensive
and not always possible. A cheaper practical
solution is to install the complete set on antivibration mountings, providing that the
foundation can withstand the weight and
loading involved.
This type of mounting is available in many
similar designs but the typical industrial
requirement falls into the two categories as
follows:
i) Rubber or steel spring or both - without
adjustment. See Fig. 15 and 16.
ii) Steel spring in compression - with
adjustment. See Fig. 17.
NOTE: For the 4012/16 Series engines it is
imperative that the type shown in Fig. 16 and
17 (ie without or with adjustment of the Christie
and Grey design or equivalent) must be used.
The most frequent application is where engine
and driven unit are solidly mounted on a
common steel bedplate connected together
with a flexible coupling or spring drive plate.
The anti-vibration mountings are placed
between the underside of the bedplate, or
wings built out from the bedplate, and the floor
surface.
The concrete floor surface must be level and
reasonably smooth. It must be capable of
supporting the generating set. The dynamic
loads are relatively small and will have little or
no effect on the foundation.
Mountings, with or without adjustment, can
readily be selected to absorb up to 90% of the
forces and reduce the amplitude of the
vibrations transmitted by the running set. No
harmful vibrations will be transmitted to the
building structure or other equipment, if the
correct mounting and foundation are used.
The total weight of the set should be equally
distributed on each mounting so that a common
mounting can be used. The requirement will
be 4, 6 or 8 mountings depending on the size
of the set and the grade of mounting selected.
Gas Installation, October 1997
The adjustable mounting has the advantage
that, if the floor level and/or the loading is
uneven, adjustment can be made to each
mounting so that the loading and deflection
can be corrected at each mounting position. It
is also a safeguard against distortion of the
underbase.
There are many reputable suppliers of AntiVibration mountings and to obtain the most
economical and effective mounting for a
particular installation quotations should be
obtained from more than one supplier. If
necessary they will supply installation
drawings and in the case of adjustable mounts,
the method and degree of adjustment.
It is recommended that the anti-vibration
mountings are bolted to the floor.
If other running machinery is sited nearby
then vibrations from these units could be
picked up by the stationary generating set.
These vibrations could have a harmful effect
on the engine bearings and particularly on the
alternator shaft with its ball or roller bearings.
The above mentioned anti-vibration
mountings now work in reverse and protect
the stationary engine from external vibrations.
23
MOUNTING OF ENGINE & DRIVEN UNIT
ANTI-VIBRATION MOUNTS - MOBILE
UNITS
If the set is a mobile unit that will be towed by
a vehicle special attention must be paid to the
A.V. mounting selection.
When towed over rough ground the set will
bounce up and down. With ordinary mountings
the rubber that is normally in compression will
be subjected to repeated extension and
compression and the elements will fail. To
prevent this the mounting should incorporate
steel rebound washers which will limit
deflection to safe limits. The suppliers will
advise the correct type to use.
24
Fig. 15
775.2
Fig. 16
776.2
Fig. 17
777.2
Gas Installation, October 1997
MOUNTING OF ENGINE & DRIVEN UNIT
ENGINES FITTED WITH CLOSE COUPLED
ALTERNATORS
It is essential that the flywheel counterbore
(dia 'A') is concentric to the flywheel housing
counterbore (dia 'B') to a maximum eccentricity
of 0.13mm (0.05''), to comply with S.A.E.
standard S.A.E. J162a and S.A.E. J1033 (see
Fig. 18).
The engine should be offered up to the
baseframe and located by bolts through the
engine feet and baseframe mounting holes.
These bolts should not be tightened up at this
stage.
Next the distance (depth) between the
rearmost machined face of the flywheel
housing and face F (Fig. 18) of the flywheel
(dimension 'X') should be measured by means
of a straight edge and rule.
Two bearing alternators should now have the
flexible coupling, and single bearing
alternators the drive plate fitted to the driven
shaft. These should be knocked on just far
enough so that dimension X (Fig. 19) =
dimension X (Fig. 18).
The alternator should now be offered up to the
engine so that both drive disc and housing
spigot engage at the same time.
Firstly the bolts retaining alternator to flywheel
housing should be started and tightened up
straight away. Then the drive disc to flywheel
bolts started and tightened to the correct
torque. Finally check with feeler gauges the
gap between engine and driven unit feet and
baseframe mounting pads, insert shims where
necessary, and tighten up the securing bolts
to the correct torque.
Gas Installation, October 1997
25
MOUNTING OF ENGINE & DRIVEN UNIT
Check that the faces ''E'' and ''F'', are parallel
and concentric with one another to within a
maximum runout of 0.005'' (0.13mm).
FLYWHEEL
FLYWHEEL
HOUSING
Fig. 18
778.2
FLYWHEEL
DRIVE FLANGE
ALTERNATOR FRAME
CORNER OF DRIVE
FLANGE CHAMFERED
TO ENSURE GOOD FIT
INTO FLYWHEEL
RECESS
Fig. 19
26
FLEXIBLE DRIVE PLATES (SINGLE BEARING)
FLEXIBLE COUPLING (TWO BEARINGS)
779.3
Gas Installation, October 1997
MOUNTING OF ENGINE & DRIVEN UNIT
ENGINES FITTED WITH OPEN COUPLED
DRIVEN UNITS
It is essential that the flywheel counterbore
(dia 'A') is concentric with the flywheel housing
counterbore (dia 'B') to a maximum eccentricity
of 0.13 mm (0.005''), to comply with S.A.E.
standard S.A.E. J162a and S.A.E. J1033 (see
Fig 18).
Firstly the engine and then the driven unit
should be offered up to the baseframe, and
located by bolts through the mounting feet
and baseframe mounting holes. These bolts
should not be tightened up at this stage.
The driven shaft and flywheel should be
checked for alignment by fitting dial test
indicators as shown in Fig. 18. In practice
most people would prefer to check with one
dial test indicator at a time, starting with
indicator 2.
Alignment should be checked by rotating the
driven shaft and observing the readings on
the d.t.i.
Corrections to misalignment should be made
as follows:-
FLYWHEEL
INDICATOR 1
INDICATOR 2
DRIVEN SHAFT
FACE E
FACE H
Fig. 20
919.2
(a) Radial misalignment as indicated by
indicator 2.
The object here is to get the flywheel and
driven flange flat and parallel to each other.
Radial misalignment has two components,
horizontal and vertical. The horizontal
component will be shown by the d.t.i. readings
at three o'clock and nine o'clock, and is
corrected by moving the tail of the driven unit
towards the negative (widest gap). The vertical
component will be shown by the d.t.i. readings
at 12 o'clock and 6 o'clock. If there is a negative
reading at 12 o'clock, then the tail of the driven
unit is low, and should be shimmed until the
reading is correct. If there is a negative reading
at 6 o'clock, then the tail of the driven unit is
high, and shims should be inserted at the front
mounting point until a correct reading is
observed.
Gas Installation, October 1997
27
MOUNTING OF ENGINE & DRIVEN UNIT
(b) Axial misalignment as indicated by
indicator 1.
This is to ensure that the flywheel and driven
shaft are on the same axis (or centre line).
Once again, this has two components,
horizontal and vertical. The horizontal
components will be shown by the d.t.i. readings
at three o'clock and nine o'clock. This is
corrected by moving the complete machine
towards the negative reading. The vertical
component will be shown by the d.t.i. readings
at 12 o'clock and 6 o'clock. If there is a negative
reading at 12 o'clock, then the driven unit is
too low, and should be packed up with shims
equally at both front and near. If there is a
negative reading at 6 o'clock, then the engine
is too low, and should be packed up with
shims at both front and rear.
Finally, both radial and axial alignment should
be rechecked and adjusted if necessary. This
should be repeated until the alignment is
observed to be correct, i.e. do not make an
adjustment and presume that the alignment
has been corrected always make a final check.
The installation alignment should always be
as accurate as possible, to allow for foundation
movement.
NOTE: Conical misalignment is a function of
Radial and axial misalignment and is not
directly checked.
ALLOWABLE INSTALLATION
MISALIGNMENT
ENGINE
SERIES
HOLSET
RB
COUPLING
SIZE
AXIAL
RADIAL
CONICAL
mm
mm
°
LIMIT ON
DISTORTION
W
2000
0.73
1.5
1
0.5
0.73 = 204 W
3000
1.15
1.5
1.5
0.5
1.15 = 224 W
4000
2.15
3.86 - 5.5
0.45
0.6
0.3
0.3
0.1
0.1
2.15 = 369 W
3.86 - 5.5 = 369/465 W
28
Gas Installation, October 1997
MOUNTING OF ENGINE & DRIVEN UNIT
MAINTENANCE
All rubber elements should be inspected after
12 months of initial running. Then further
change of elements should not need to be
carried out until 20K hours running or 3 years
is completed. Obvious wear or misalignment
must result in inspection of the coupling.
CRANKSHAFT END FLOAT
When aligning the driven equipment to the
engine flywheel it is vital that the crankshaft
end float is not taken up all one way thus
putting undue pressure on the thrust bearing.
Such a situation could lead to serious
consequences as soon as the engine is
started.
After the assembly of single and two-bearing
alternators, etc. the end float must be checked
and should lie between the limits given below.
Engine
2000
3000
4006/8
4012/16
End Float of Crankshaft when
New.
0.13 mm to 0.33 mm
0.1 mm to 0.3 mm
0.13 mm to 0.48 mm
0.13 mm to 0.51 mm
Under no circumstances must the weight of
the alternator be overhung from the flywheel
housing.
There is a limit on the amount of weight that
can be supported by specific engines,
therefore it is important that the type of single
bearing alternator to be fitted to a particular
engine is submitted to Perkins Engines
(Stafford) Ltd for approval.
A torsional vibration analysis will also be
required to assure compatibility between the
engine and alternator.
ENGINE
SERIES
MAXIMUM WEIGHT
OF ALL ROTATING
COMPONENTS (kg)
2006
NOT QUOTED
3008
3012
4006
4008
4012
4016
NOT QUOTED
NOT QUOTED
1000
1000
1700
1700
Using a pinch bar at the free end or the
flywheel end of the engine the crankshaft can
be moved backwards and forwards. The
movement - END FLOAT - can be checked on
a suitably fixed clock gauge.
OVERHUNG WEIGHT OF SINGLE
BEARING ALTERNATOR
A single bearing alternator is bolted to the
engine flywheel housing, and the rotor is
supported at the rear by a single bearing
housed in the alternator frame. The front of the
rotor is bolted to the engine flywheel and is
supported on the engine crankshaft rear
bearing.
It is essential that consideration be given not
only to the weight of the rotor to be supported
by the engine crankshaft, but also that the
weight of the alternator be carried on the
alternator feet.
Gas Installation, October 1997
29
TORQUE SETTINGS
IT IS ESSENTIAL THAT THE CORRECT LENGTH OF
SCREW OR BOLT IS USED. INSUFFICIENT THREAD MAY RESULT
IN THE THREAD BEING STRIPPED, WHEREAS TOO LONG A THREAD MAY RESULT
IN BOTTOMING IN A BLIND HOLE, OR CATCHING ON ADJACENT COMPONENTS.
WARNING
NOTE: * Bolt heads and threads must be lubricated with clean engine oil.
**Cylinder head bolts to be lubricated under the heads, under the washers and on the
threads with P.B.C. (Poly-Butyl-Cuprysil) grease. Important: See Section R13 in the
Operation Manual before fitting. All other bolt threads only to be lubricated with clean engine
oil. care mustbe taken not to oil the heads and faces.
TORQUE SETTINGS
Cylinder Head Group
**Cylinder head bolt (early type)
**Cylinder head bolt (later (waisted) type)
Rocker shaft bolt/nut
Rocker adjuster nut inlet/exhaust
Rocker adjuster nut pump/injector
Rocker box bolt
Air manifold bolt
Exhaust manifold bolt
Turbocharger V-band clamp
M24
M24
M16
M12
M14
M10
M10
M10
M8
lb.ft
550
530
90
35
50
35
35
50
8
Nm
750
723
120
50
70
50
50
70
11
Crankcase and Crankshaft Groups
*Main bearing bolt
Lateral capscrews, main bearing tie bars (4008 only)
Bolts sump to crankcase
Connecting rod bolt (must be
New bolts
fitted with dry threads
Reused bolts
Viscous damper bolts
Viscous damper bolts
Flywheel bolt
Front drive adaptor bolts
Balance weight bolt
Front crankshaft pulley bolt
Oil transfer block 4006/8 ONLY
Piston cooling jet bolt
Flywheel housing bolt
M24
M16
M10
M16
M16
M16
M12
M16
M16
M16
M16
M10
M10
M10
550
200
30
200
200
250
120
250
250
250
250
20
20
35
750
270
41
285
270
340
160
340
340
340
340
27
27
50
Lubricating Oil Pump
Bolts, pump housing to gearcase plate
Thin nut gear to drive shaft
M10
M24
35
170
50
230
Camshaft group
Camshaft gear screw
Camshaft thrust plate screw
Camshaft follower housing capscrew
Camshaft follower housing bolt
Idler gear hub bolts
M12
M10
M10
M10
M10
110
35
50
35
35
149
50
70
50
50
30
Gas Installation, October 1997
TORQUE SETTINGS
Water Pump
Water pump gear nut
Water header to oil cooler bolts
Water pump to gearcase bolts
Raw water pump gear securing nut
(non lubricated thread)
M24
M10
M10
lbf.ft
170
35
35
Nm
230
50
50
M35
180
250
Engine Feet
M12
70
95
Governor
Control shaft mounting plate bolt
M10
35
50
1
35
65
50
90
3
15
20
M10
M27
2BA
M5
50
150
6
6
70
203
8
8
Flexible Coupling (Holset)
Flexible coupling cover screw
M12 or 1/2" UNC 47
Coupling driving flange screws (coupling size 2.15) M12 or 1/2" UNC 47
Coupling driving flange screws (coupling size 3.86) M16 or 5/8" UNC 114
64
64
155
Fan
Fan driven pulley taper lock bush screws 4006 series
Fan driven pulley taper lock bush screws 4008 series
Alternator
Drive pulley taper lock bush screw
/2" BSW
/8" BSW
5
/8" BSW
Fuel Pump/Injectors
Injector capscrew clamp to cylinder head
injector nozzle nut to holder
Fuel pump control linkage screw
Fuel pump control arm capscrew
GENERAL TORQUE LOADINGS
The following torque loadings are general for metric coarse threads and for grade 8.8 steel, but
do not supersede the figures quoted above.
Thread
M5
M6
M8
M10
M12
M16
M20
M24
lbf.ft
5
8.62
20.5
41
72
180
351
606
Nm
7
12
28
56
98
244
476
822
GENERAL NOTE:
M10 - 12.9 Steel
68
92
TIGHTENING TORQUES
These are based on 85% of the proof loads designated in BS3692.
Gas Installation, October 1997
31
ENGINE ROOM LAYOUT
INSTALLATION
4.
USE CORRECT
LIFTING
EQUIPMENT. DO NOT WORK ALONE.
PERSONAL PROTECTIVE EQUIPMENT
MUST BE WORN.
5.
When installing the engine and components
in the restricted confines of an engine room
care must be taken that easy access is
provided for carrying out routine servicing.
7.
WARNING
a. Installation and removal of various
components:
- Cylinder heads
- Coolant pump
- Oil sump
- Timing Case
- Starter and alternator
- Flexible mountings
- Camshaft
b. Maintenance, inspection and
replacement of parts:
- Lubricating oil filter
- Air cleaner
- Fuel filter
- Lubricating oil filler
- Crankcase breather
- Dipstick
- Radiator filler cap and access for
filling
- Rocker covers
6.
8.
9.
10.
11.
12.
13.
Install a fire extinguishing system in the
engine room.
Locate batteries in a separate vented
compartment or box, with access for
routine maintenance, keeping length of
starter cables as short as possible.
Make provision for draining the oil sump
and fit a drip tray underneath.
Check that the entrance into engine room
is large enough to allow for the engine/
alternator set to enter and be removed.
Provide adequate lighting and power
points.
Lifting beam in roof for maintenance.
Provision for draining engine cooling
system.
All rotating shafts are adequately guarded
for safety purposes.
Provide natural ventilation to allow any
gas leaks to rise safely through the roof to
atmosphere.
Methane detector (shuts down engine).
INSTALLATION GUIDELINES
1. Avoid plastic and other unsuitable
materials for fuel piping and connections
including metallic braided flexible pipes
which can corrode or chafe and leak fuel.
2. Keep fuel lines away from hot exhaust
pipes.
3. Insulate 'dry' exhaust systems, using heat
shields, lagging and muffs over flexible
sections, and keep piping well away from
woodwork.
NOTE: Dry engine exhaust manifolds must
not be lagged. (Refer to Exhaust Section).
32
Gas Installation, October 1997
ENGINE ROOM LAYOUT
INITIAL CONSIDERATIONS
When initially deciding on the size of the
engine room the following aspects should be
considered:(1) Sufficient space available to
accommodate power unit, load bearing
capacity of the floor suitable for weight of
power unit, and that the ventilation
facilities in the building are adequate to
cater for supplying air for engine cooling
& aspiration.
(2) Access to fuel supply, cooling water, and
that the exhaust emission from the engine
can be dispersed to atmosphere without
exceeding the maximum back pressure.
(3) That suitable air intake filters and exhaust
silencer can be accommodated within
the engine room without effecting the
engine performance otherwise the engine
may need to be derated or the filters and
silencer repositioned outside the room.
(4) If an existing building is to be used, that
openings in the wall for intake and outlet
louvre panels can be made without
affecting the structural strength of the
building.
(5) Mechanical noises from the engine,
together with exhaust outlet noise can be
insulated by fitting attenuating panels etc.
especially when operating in a residential
area.
Colour Coding
Water
Oils
Gases
Electrical Services
Waste Water Drainage
Condensate
Primary Cooling
Hot Water Supply
Grass Green
Brown
Yellow Ochre
Orange
Black
Grass Green
Grass Green
Grass Green
Gas Installation, October 1997
33
ENGINE ROOM LAYOUT
TYPICAL WATER COOLED ENGINE
ROOM LAYOUT (4000 SERIES)
A typical water cooled engine room layout is
shown in Fig. 21, using a single generating
set installation as an example.
It is essential that the hot air from the radiator
is ducted outside the engine room and not
allowed to recirculate in order to keep the
engine room temperature as low as possible
for the engine to give the required performance
(see page 35 onwards).
Since the generating set is mounted on AntiVibration mountings it is essential that the
exhaust silencer should be supported from
the roof, and that flexible bellows be fitted to
isolate the engine from the exhaust.
The same comments apply for the hot air
outlet ducting and any other engine/alternator
connections, must be of the flexible type, ie
fuel pipes and electrical connections.
Fig. 21
34
983.2
Gas Installation, October 1997
ENGINE ROOM LAYOUT
VENTILATION - ENGINE ROOM
When a set with an integrally mounted radiator
is installed in an engine room, the basic
principal is to extract hot air from the room and
induce air at the ambient temperature outside
the engine room with minimum re-circulation.
Fig. 22 illustrates the most suitable position of
the engine in relation to the walls of the
building. The object is to get cool air in at the
lowest possible point, push it though the
radiator matrix and then out of the building.
It is unsatisfactory to position the set so that
the radiator is adjacent to the opening in the
wall. When in operation some hot air will
recirculate back into the radiator fan via the
gap between the radiator and the wall.
This will lead to inefficient cooling and could
result in overheating problems. The outlet
opening in the wall should have a FREE
FLOW AREA about 25% larger than the
frontal area of the radiator matrix and be of the
same rectangular shape.
A sheet metal or plastic duct is fixed to the
opening frame using a flexible connection to
the radiator duct flange. The flexible section is
particularly necessary when the set is
mounted on a floating concrete block or antivibration mountings.
The inlet air opening should also have a
FREE FLOW AREA at Ieast 25% larger than
the radiator matrix.
With the design of inlet and outlet openings it
must be remembered that the radiator fan has
a limited total allowable external resistance ie. “inlet to fan plus outlet from radiator”:- this
must not be exceeded or cooling air flow will
be reduced.
The inlet and outlet openings will usually be
fitted with a mesh grille, louvres, noise
attenuating panels or inside and outside
ducting. Whatever is fitted will promote
resistance to air flow and it may be necessary
to further increase the opening area.
NOTE: It is recommended that the engine fan
is motor driven, rather than by the engine,
which eliminates the power loss of the belt
drive.
Fig. 22
Gas Installation, October 1997
787.2
35
ENGINE ROOM LAYOUT
Example:
For a radiator matrix frontal area of 1.44 m2 the
air outlet/inlet opening in the wall should have
an area of 1.80m2, if a grille is fitted then the
opening should be increased to give 2.25 m2
(See Fig. 23).
Fig. 23
36
788.2
Gas Installation, October 1997
ENGINE ROOM LAYOUT
The large quantity of air moved by the radiator
fan is usually sufficient to adequately ventilate
the engine room.
As shown in Fig. 22 the cool incoming air is
drawn over the alternator which takes its own
cooling air from this flow, across the engine
air intake filter and the engine. The radiator
fan then pushes air through the radiator matrix
to outside. There must be no obstruction to air
flow immediately in front of the radiator outlet
and to deflectors, etc.
This is the best possible ventilation system
but, in practice, the best is not always possible.
Fig. 24 shows the air inlet position high in the
wall. This is acceptable if ducting directs the
air to the end of the alternator and has the
advantage of preventing heated air from
collecting near the ceiling.
Fig. 25 shows the air inlet position high in the
wall and at right angles to the fan air flow. This
is wrong and should not be considered. With
this arrangement the cooling air will bypass
the alternator and the engine air intake filter
with a resulting increase in operating
temperatures unless load is reduced.
Where a high engine room temperature cannot
be avoided then the temperature of the
induction air into the engine air filters must be
checked and the load reduced, or the
generating set derated. (See page 90).
Alternatively the engine air filter(s) could be
moved to an area of cool air and connected to
the engine air intake manifold(s) with pipe(s)
of suitable diameter. The pressure drop
through the pipe(s) and new air filter element(s)
should not exceed 18mm Hg. Deration of
power output may then be avoided.
If the radiator is matched for temperature
conditions i.e. up to 38°C ambient, a change
of fan speed may be possible to make the
radiator performance satisfactory up to 45°C
or 52°C ambient. It is normally necessary to
have a 52°C capacity radiator supplied for
operation in temperature above 38°C ambient.
If problems are experienced with radiator
performance then Perkins Engines (Stafford)
Ltd Applications Dept. should be contacted,
since modification of the installation may result
in an economical solution.
Gas Installation, October 1997
Fig. 24
789.2
Fig. 25
790.2
37
ENGINE ROOM LAYOUT
DUCTING AGAINST PREVAILING WIND
In positioning the air outlet opening attention
must be paid to the direction of the prevailing
wind.
All Perkins Engines (Stafford) Ltd radiators
have “pusher” fans which force air through the
radiator matrix and out through the opening in
the wall.
If the prevailing wind is blowing into the
opening additional resistance will be put on
the fan with a resulting reduction in cooling air
flow. Therefore, if possible. the opening should
be in a wall not affected by the prevailing
wind.
If the above condition is not possible other
methods may be considered, as follows :(i) Outside ducting with the outlet being at
90° to the cooling air flow
(ii) A deflector panel
See Figs. 26 and 27
Fig. 27
38
Fig. 26
791.2
792.3
Gas Installation, October 1997
ENGINE ROOM LAYOUT
VENTILATION - TROPICAL CONDITIONS
To cater for tropical conditions it is quite
common practice for the engine room to have
open sides, or consisting only of a roof with
supporting columns, See Fig. 28.
This type of cover is not suitable for protection
against driven rain, dust or sand.
Where multiple engines are installed in an
open sided building it is imperative that
partitions are fitted to prevent the prevailing
wind blowing the radiated heat from one
engine onto the next and so on. Allow access
for engine maintenance (see Fig. 29) or only
enclose the side facing the prevailing wind.
Fig. 28
793.2
Fig. 29
794.2
Gas Installation, October 1997
39
ENGINE ROOM LAYOUT
FORCED VENTILATION - ENGINE ROOM
(Remote Cogen)
When a remote mounted radiator is fitted (see
pages 46 onwards) the ventilation of the
engine room must be considered.
First - the exhaust system in the engine room
must be efficiently lagged so that the radiated
heat is minimal.
For the best forced ventilation system it is
usual to use two electric motor driven fans.
One fan pushing the air into the room and
being mounted in the wall next to the generator
end of the set.
The other fan is an extractor fan, taking hot air
out of the engine room. This fan would be
mounted in the wall next to and above the
engine. See Fig. 30.
On the inlet air side ducting is necessary if the
cooling air is not reaching the alternator,
engine and radiator. The duct directs the air to
the alternator and across the engine to the
extractor fan.
If a duct is not fitted when the inlet fan is at the
high level the incoming cooling air will bypass
the generating set and be extracted by the
extractor fan without cooling the set.
If a large air intake opening can be
accommodated and correctly positioned then
the fan pushing air into the room can be
deleted.
The extractor fan will require adequate suction
to overcome the resistance to air flow through
the inlet and outlet louvres and ducts if fitted.
Fig. 30
40
It is recommended that the general
temperature in the engine room is maintained
at a maximum of 25°C. Where the ambient
temperature exceeds this figure then a
temperature rise of no more than 8°C should
be maintained above the temperature of the
incoming air.
Where the outside temperature is cold, say
10°C the temperature rise in the engine room
could be as much as 28°C.
The quantity of the air required can be
calculated from the following:
795.2
Gas Installation, October 1997
ENGINE ROOM LAYOUT
The temperature rise in the engine room is the
most useful factor in calculating the required
air flow. The volume of air required to give a
pre-determined temperature rise is based on
the following:Airflow required
for cooling =
Total Radiated Heat
W x constant x temp. rise
m3/min =
RT
kW(th)
W
kW (th)
W x 0.0167 x RT °C
Air flow for ventilation will be the total air flow
for cooling plus the air flow for combustion.
Example:- Engine Only
Based on 1 hour rating and a 16°C rise above
the incoming air temperature.
Air ventilation =
41
1.2 x 0.0167 x 16
= 128
= 167 m3/min
+ Combustion air
+39
- Rise in Temp: °C
- Total radiated Heat
- Density of air - at the fan inlet:
kg/m3
DENSITY OF AIR
TEMPERATURES
°C
kg/m3
0
1.30
5
1.27
10
1.25
15
1.23
20
1.20
25
1.18
30
1.16
35
1.15
40
1.13
45
1.11
50
1.09
55
1.08
AT
VARIOUS
The total heat to be dissipated is the heat
radiated from the engine, generator and any
other source of heat in the engine room .The
radiated heat can be found in tabular form on
pages 42 and 43.
Values for combustion air can be found in the
Product Information Manual under the
appropriate engine data.
Gas Installation, October 1997
41
ENGINE ROOM LAYOUT
ENGINE AND ALTERNATOR RADIANT HEAT TO THE ENGINE ROOM (kWt)
One hour rating and 25°C ambient temperature
Engine
Alternator speed (r/min)
1000 1200 1500 1800
Engine speed (r/min)
1000 1200 1500 1800
4006 (Minnox) 200 LC
-
18
27
-
-
44
54
-
4006 (Minnox) 140 LC
-
-
24
-
-
-
27
-
4006 (Minnox) 140 HC
-
-
26
-
-
-
49
-
4008 (Minnox) 200 LC
-
-
-
-
-
-
-
-
4008 (Minnox) 140 HC
-
-
32
-
-
-
51
-
4008 (Minnox) 90 HC
-
-
32
-
-
-
52
-
The above figures are used to calculate ventilation calcs as heat given off engine & alternator
can alter ventilation.
2006
-
-
-
-
-
-
37
42
3008
-
-
-
-
-
-
46
51
3012
-
-
-
-
-
-
63
77
Warning:- None of the above figures should be used for heat recovery purposes.
Engine specific data sheets are available from PE(ST)L Applications.
42
Gas Installation, October 1997
ENGINE ROOM LAYOUT
ENGINE AND ALTERNATOR RADIANT HEAT TO THE ENGINE ROOM (kWt)
One hour rating and 25°C ambient temperature
Engine
Alternator speed (r/min)
1000 1200 1500 1800
Engine speed (r/min)
1000 1200 1500 1800
4012TESI
(MINNOX)
-
-
36
-
-
-
136
-
4012TESI
(MINNOX) 140 HC
-
-
38
-
-
-
58
-
4012TESI
(MINNOX) 90 HC
-
-
38
-
-
-
111
-
4016TESI
(MINNOX) 200 LC
-
-
47
-
-
-
96
-
4016TESI
(MINNOX) 140 LC
-
-
47
-
-
-
96
-
4016TESI
(MINNOX) 140 HC
-
-
47
-
-
-
118
-
Warning:- None of the above figures should be used for heat recovery purposes.
Engine specific data sheets are available from PE(ST)L Applications.
Gas Installation, October 1997
43
ENGINE ROOM LAYOUT
TYPICAL
MULTIPLE
ENGINE
INSTALLATION
Generally multiple engine installations follow
on the same lines as for a single unit
installation, each unit having its own
independent foundation and exhaust system
as shown in Fig. 31.
WARNING
THE EXHAUST GAS
FROM A MULTIPLE
ENGINE INSTALLATION MUST NOT BE
COMBINED INTO A COMMON EXHAUST
SYSTEM AS THIS CAN BE VERY
DANGEROUS AND COULD CAUSE
ENGINE DAMAGE.
TYPICAL
MULTIPLE
ENGINE
INSTALLATION
WITH
REMOTE
RADIATOR
Since actual installations can vary the engine
room will need to be ventilated by fitting electric
motor driven wall mounted intake and
extractor fans to dissipate the radiated heat
from the engine and alternator (see table on
pages 42 & 43).
Starter batteries should be positioned as near
to the starter motor as possible otherwise the
size of the cable may need to be increased.
It is essential that the common fuel and cooling
systems can be isolated to allow the removal
of one unit whilst the remaining units are still
operating.
The exhaust silencer must be supported from
the roof, and the support brackets should
allow for expansion of the piping. A length of
flexible pipe or bellows should be fitted
between the engine exhaust outlet and the
rigid pipe work, especially if the generating
set is mounted on anti-vibration mountings.
The exhaust system must be as short as
possible and the number of bends kept to a
minimum so as not to exceed the appropriate
engine back pressure recommendations.
Where conditions would cause the back
pressure to be in excess of the above
recommendation then the size of the exhaust
piping should be increased to suit.
THE EXHAUST SHOULD NEVER GO INTO
A DISUSED CHIMNEY UNLESS THE
CHIMNEY HAS BEEN CHECKED FOR
GAS LEAKS.
Ducting should be fitted between the radiator
and the opening in the engine room wall to
direct the air flow from the engine room. The
Iength of the ducting should be kept to a
minimum to prevent back pressure exceeding
Perkins
Engines
(Stafford)
Ltd
recommendations, these vary between
engines (see Product Information Manual).
44
Gas Installation, October 1997
ENGINE ROOM LAYOUT
Fig. 31
Gas Installation, October 1997
984.2
45
COOLING SYSTEMS
WARNING
ALL EXPOSED
ROTATING PARTS
AND BELT DRIVES MUST BE FITTED
WITH GUARDS.
GENERAL OBSERVATIONS
The most common system is the utilisation of
a jacket water pump to force coolant through
the engine oil cooler, engine water jackets,
cylinder heads and through a water cooled
exhaust manifold.
The hot water from the engine then enters the
header tank of a radiator, passes through the
radiator tubes and out to the suction side of
the pump. A pressure of 0.5 - 0.7 bar is
maintained in the system. Water passing
through the radiator is cooled by pushing air
through the matrix by an engine driven fan
(see appropriate Engine Water Circulation
Diagram).
4000 Series engines fitted with turbochargers
have charge cooling to enable them to comply
with specified exhaust emissions using lean
burn technology.
When the charge air is cooled by secondary
coolant an additional water pump is fitted to
the engine or electric driven pump is fitted to
circulate secondary coolant through an engine
mounted charge air cooler, where the air is
cooled before entering the engine air intake
manifolds (see appropriate Water
Circulation Diagram).
Customers who obtain their own radiator
should make sure it is designed to the
temperature of the cooling air into the radiator
fan and not to the outside ambient temperature.
FAN PERFORMANCE
The fan performance must take into account
the fact that, in an engine room installation,
there will be resistance to the air flow to the fan
in addition to that through the radiator matrix.
Extra resistance will be at the air intake in the
engine room wall and air outlet after the
radiator.
With radiators and fans the air flow to cool the
engine on 110% load or standby - whichever
is the greatest - is more than adequate against
the radiator matrix resistance only.
Further resistance can be applied until the air
flow is reduced to the safe minimum to cool
the engine. This extra resistance can be
determined and is known as “The total
allowable external resistance on the fan” ie
“inlet to fan plus outlet from radiator”
See the Product Information Manual.
RADIATORS
Perkins Engines Ltd can supply a radiator
suitably matched to each engine type in the
range.
Even when an engine is correctly installed in
the engine room the temperature of the cooling
air at the suction side of the radiator fan is
greater than the outside ambient temperature.
This is due to the radiated heat from the
engine, driven unit and exhaust system
warming up the engine room air. The radiators
are designed to take this increase into account.
46
Gas Installation, October 1997
COOLING SYSTEMS
REMOTE
MOUNTED
RADIATOR
TURBOCHARGED ENGINES
In some installations by reason of space
limitation, environment, etc., it may be
necessary for the radiator to be mounted on
an upper floor or horizontally away from the
engine. Fig. 32 illustrates a typical installation.
The radiators supplied by Perkins Engines
Ltd. can all be modified so that the radiator,
fan and drive motor form an integral unit. This
type of modification is completed at the works
of the manufacturer.
The opening in the wall for the air outlet and
duct are sized as for the set mounted radiator.
See in Fig. 24. However, as the radiator will
now be solidly mounted the flexible duct
section will not be required.
Water pipes to and from the engine will
incorporate a flexible length if the set is on
flexible mountings.
To complete the water system a make-up
tank should be fitted so that daily topping-up
is not necessary. Calculations should be
made to allow for the normal radiator system
which is pressurised from 0.5 to 0.7 bar The
pressure cap and relief valve are removed
from the radiator top header tank and fitted to
the make-up tank to maintain a pressurised
system. The radiator top header must be
sealed.
The capacity of the make-up tank should be
large enough to hold the necessary make-up
water with space to allow for the expansion of
the water in the system. The expansion space
is usually calculated as 5 to 6% of the volume
of the water in the total system.
Gas Installation, October 1997
REMOTE MOUNTED RADIATORS
Under certain conditions, remote mounted
radiators may experience excessive noise
and vibration in the pipework between engine
and radiator, during the warm up period. This
is caused by ''cold slugs'' of coolant entering
the engine due to the large volume of coolant
external to the water pump and thermostat.
This problem may be avoided, by removing
the standard (engine mounted) thermostat
and bypass, and replacing them with an "Amot"
type thermostat (or equivalent), fitted in the
pipework between engine and radiator.
In general if the volume of external
pipework exceeds 50% of the engine
cooling jacket volume, then an external
thermostat as described above should be
considered.
Each installation should be considered with
reference to its individual characteristics, and
so we would strongly recommend that a full
installation drawing showing all the pipework
be submitted to our Applications Department,
for advice on a suitable location for the external
thermostat for charge cooler circuit.
47
COOLING SYSTEMS
WARNING
THE GATE VALVES
MUST ALWAYS BE
OPEN WHEN THE ENGINE IS RUNNING.
FILLING THE COOLING SYSTEM
THE COOLING
SYSTEM IS
PRESSURISED - DO NOT REMOVE THE
FILLER CAP FROM THE MAKE-UP TANK
WHILE THE ENGINE IS HOT. PERSONAL
PROTECTIVE EQUIPMENT MUST BE
WORN.
WARNING
The tank filler tube is extended into the tank
for sufficient length to allow for the air space.
On filling the system add water until the level
stabilizes at the bottom of the tube.
A small hole 3 mm dia: must be drilled in the
filler tube just below the top so that pressures
will be balanced when expansion occurs.
The height limit to which the radiator can be
mounted above the engine is Iimited by the
pressure to which the water pump seal can
stay on its seat against the static head when
the engine is stationary.
The radiator top header should be no more
than 7 metres above the engine water pump
with the pressurised make-up tank no more
than 0.5 meters higher.
In aIl systems with remote radiators, with and
without break tanks, heat exchangers etc.,
the water pipe diameters should at least equal
the diameter of the fittings at the engine water
pump inlet and top water outlet pipe.
Depending on the length of the pipe run to
and from the engine and radiator number of
bends, valves, pipe fittings, etc., the pipe size
should be increased so that additional
resistance to flow is no more than 75 mbar.
Earlier 4000 series engines fitted with water
cooled exhaust manifolds (but without vent
pipes) will need bleeding to remove air locks.
48
Fig. 32
985.2
DRAINING THE COOLING SYSTEMS
When draining the engine cooling system it is
recommended that the external pipework fitted
between the engine and radiator/make-up
tank must be isolated by fitting gate valves so
as not to drain the whole system and lose the
anti-freeze, as indicated in Fig. 32.
Gas Installation, October 1997
COOLING SYSTEMS
BREAK TANK - WATER MIXING
The height limitation of the radiator can be
overcome by introducing a break tank into the
system to break the pressure head put on the
engine by the radiator.
The system is un-pressurised and there is a
good deal of water loss by evaporation from
the open tank.
When sizing the tank this volume must be
allowed for in addition to the volume required
for satisfactory cooling. When the depth of
water in the tank has been determined add a
further 150 mm to the open top edge of the
tank to retain splashing when the engine is
running.
WARNING
IF THE ENGINE
RUNS A NORMAL
DAY SHIFT DAILY INSPECTION OF THE
WATER LEVEL MUST BE CARRIED OUT.
Fig. 33 illustrates the system and a typical
tank is shown. When the engine is not running
and the system is static all the water in the
radiator and pipes will run back into the tank.
Fig. 33
Gas Installation, October 1997
799.2
49
COOLING SYSTEMS
WARNING
THE GATE VALVES MUST ALWAYS BE OPEN WHEN THE ENGINE
IS RUNNING.
The baffle plate which forms the ‘weir’ is positioned to split the tank into equal sections. The
height of the ‘weir’ from the bottom of the tank is equal to the depth of water required for
satisfactory cooling. (See schedule below).
The bottom corners of the weir plate are chamfered - aprox. 40 mm x 45° - to assist in mixing
and stabilizing the water level.
The dimensions recommended for sizing the tank should be worked to. The plan size given
enables suction pipes to be positioned (see Fig. 33) so the aeration and vortexing will be
minimal.
For Perkins Engines (Stafford) Ltd. engines the volume of water for satisfactory cooling and the
suggested plan size of the tank is as follows:-
Power Output up to
For Satisfactory Cooling
Volume of Water
Plan Size of Tank
300 kWb
600 kWb
1000 kWb
1500 kWb
2000 kWb
650/750 litres
1350/1450 litre
2250/2350 litre
3500/3600 litre
4800/5000 litre
0.9 metres sq.
1.2 metres sq.
1.5 metres sq.
1.7 metres sq.
2.0 metres sq.
The electric motor driven water pump in the radiator circuit should have an output matching the
engine driven water pump. The pressure head that the electric motor driven pump will have to
deliver against will be that caused by the pipes and fittings ‘to’ and ‘from’ the radiator plus the
pressure drop through the radiator and engine.
The tank is usually situated adjacent to the engine with the bottom of the tank positioned above
the floor line so that the water outlet from the engine rises slightly to the position where it enters
the tank.
On engine start-up the radiator and pipes are empty of water. The engine driven water pump
draws water from the secondary side of the tank, pushes it through the engine and discharges
the warmer water into the primary side of the tank.
To ensure quick warm-up of the engine, a thermostatic switch in the primary circuit will control
the starting of the electric motor driven water pump and radiator fan.
When the water in the primary side reaches 70/75°C the thermostat switch operates and starts
up the electric motor driven water pump and radiator fan. Hot water is drawn from the primary
side, pushed up to and through the radiator and returned to the secondary side of the tank.
The water will find its own level in each side of the tank, ie on either side of the weir. It will be
necessary to adjust the water flow from each pump by throttling so that the water level in each
side of the tank is just below the weir. If the levels cannot be stabilised it is recommended that
any slight flow over the weir is from the secondary side to the primary side.
50
Gas Installation, October 1997
COOLING SYSTEMS
HEAT EXCHANGER COOLING (SEE
COGEN SECTION)
With the exchanger cooling two separate water
systems are used:Jacket Water Circuit
The jacket water is circulated round the engine
oil cooler and engine jacket. The hot water
from the engine is piped to the heat exchanger
where it flows round the outside of the tubes in
the heat exchanger. The cooled water returns
to the suction side of the engine driven water
pump. An engine mounted header and
aeration tank is incorporated in the system.
TWO SECTION RADIATOR - CHARGE
COOLED ENGINES
Water-to-Air Charge Coolers
A two section radiator system is often used to
replace a heat exchanger system where there
is no external source of water or where the
size of the radiator is too large to be
accommodated in an engine room. (See
Appropriate Engine Water Circulation
diagram).
The charge air section in the radiator is fitted
between the conventional engine water
section and the fan.
To remote cool a charge cooled engine with a
heat exchanger and cooling tower, can be
very expensive. An economical compromise
could be a remote radiator with two sections.
One section to cool the High temperature
cooling water circuit of the engine and the
other to cool the Low temperature cooling
water circuit of the water cooled charge cooler.
The sections are cooled by air flow from a
single fan. Fig. 34 illustrates.
Gas Installation, October 1997
It must be accepted that, with this method, the
Low temperature circuit wiII not be cooled to a
temperature lower than 8°C/9°C above the air
temperature put through the radiator matrix by
the radiator fan.
e g. Air temp. into fan 35°C.
Water temperature out of radiator = 35°C + 8°/
9°C = 43°/44°
It will be seen that, depending on ambient
temperatures, there could be some power
output deration. See appropriate derating
information in the Product Information
Manual.
The installation of the radiator will follow the
same pattern as outlined in Fig. 32.
The “HIGH” and “LOW” temperature circuits
(see Fig. 34) will each have a separate
pressurised make-up/vent system.
The Low temperature circuit may require an
electric motor driven water circulating pump,
replacing the engine driven raw water pump,
should this not be suitable.
If the radiator installed height exceeds the
figure of 7 metres above the engine water
pump as indicated in Fig. 33 a break tank
system will be required in the engine cooling
circuit.
A break tank will not be necessary in the
charge cooling circuit unless the radiator
section in this circuit is more than 15 metres
above the charge coolers fitted on the engine.
51
COOLING SYSTEMS
For naturally aspirated engines charge cooler
circuits are NOT required.
THE GATE VALVES
MUST ALWAYS BE
OPEN WHEN THE ENGINE IS RUNNING.
WARNING
Fig. 34
52
986.2
Gas Installation, October 1997
COOLING SYSTEMS
COOLANT
WARNING
ALWAYS STOP THE
ENGINE
AND
ALLOW THE PRESSURISED SYSTEM
TO COOL BEFORE REMOVING THE
FILLER CAP. PERSONAL PROTECTIVE
EQUIPMENT MUST BE WORN TO AVOID
SKIN CONTACT WITH ANTIFREEZE.
ENGINE COOLING SYSTEM
The cooling system of an engine contains
many different materials e.g. cast iron,
aluminium, copper, solder, rubber (various
types). To maintain these materials in good
condition and free of corrosion it is essential
to use a very good quality coolant.
UNTREATED WATER IS NOT SUITABLE
in order to combat corrosion of the cooling
system it is necessary that the water is treated
with a suitable additive that gives the
necessary protection.
WATER QUALITY
The water that is mixed with the additive must
have the following characteristics:
Chlorides less than 80 PPMV (parts per million
by volume)
Sulphates less than 80 PPMV
Total hardness less than 200 PPMV
pH of water between 7 to 7.5 (i.e. neutral to
slightly alkaline)
Under no circumstances should an additive
containing nitrites, borates, phosphates,
chromates, nitrates, or silicates be used, as
these materials are not compatible with the
materials used i the cooling system.
When mixing the anti-freeze with the water
always follow the manufacturer's
recommendation, which is to add the antifreeze to the water to the correct concentration
before adding to the engine cooling system.
Mixing water to anti-freeze can lead to the
information of a gel in the mixture, due to over
concentration, which can lead to blockage of
water passages and subsequent loss of water
flow causing overheating.
MAINTENANCE OF COOLANT
The water/anti-freeze mixture should be
regularly replaced in operating engines once
a year.
In engine used for standby duty it is essential
to maintain the water/anti-freeze mixture at
the correct alkalinity level i.e. the pH should
not increase above 7.5. A hydrometer only
shows the proportion of ethylene glycol, and
is not a measure of protection against
corrosion.
WARNING
FAILURE TO
FOLLOW
THE
ABOVE RECOMMENDATIONS MAY
RESULT IN ENGINE DAMAGE AND WILL
INVALIDATE THE ENGINE WARRANTY.
ADDITIVES TO WATER
Due to the complexity of the cooling system it
is necessary to use an additive that contains
a balanced package of corrosion inhibitors.
To achieve the required solution a 50/50 mix
of Shell Safe Premium antifreeze wit water
should be used at all times, even in areas
where frost is unlikely.
This mixture will give frost protection down to
-35°C. In areas where Shell Safe Premium is
unobtainable contact Perkins Engines
(Stafford) Ltd for advice on an alternative.
Gas Installation, October 1997
53
COOLING SYSTEMS
INSTALLATION REQUIREMENTS
FOR GAS ENGINES IN COGENERATION/
COMBINED HEAT AND POWER SETS
1.1 CONCEPT
In a CHP set a gas engine drives a generator
and heat from the engine cooling system and
exhaust system is made available to heat a
building or provide heat for an industrial
process. If the engine can be operated on full
power and the electricity and heat available
can be continuously used very high overall
thermal efficiencies i.e. 90%, can be achieved.
Since the power available to heat is
approximately 60% and to electricity 30%, the
sizing of the CHP set should be matched to
the heat demand of the building. To keep the
engine operating at full load with variable
electrical demand for the building, the
generator is put on line with the mains and
surplus electricity is sold to the local electricity
grid.
From the viewpoint of the gas engine supplier,
CHP sets are more complex than conventional
generating sets, and there is a shared
responsibility with the CHP set builder for
satisfactory specification and installation of a
number of features especially in the cooling
system.
Since a gas engine is capable of very long
engine life, to overhaul, the installation
services for that engine must be satisfactory
as originally installed and must match the
longevity of the engine. Secondly,
deterioration by fouling of heat exchanger/s
etc. must be detected and action taken to
avoid distress to the engine.
To meet the generally accepted practice with
CHP sets, the engines are supplied without
coolant pumps and thermostats, but water
jacketed exhaust manifolds are fitted. Attention
has been paid to providing flanged interfaces
for the coolant connections on the engine,
wherever possible without major alteration.
See the engine arrangement drawings for full
definition.
54
1.2 COOLING CIRCUIT
A typical cooling circuit is shown on Fig. 35.
Coolant leaves the engine block and passes
through the water jacketed exhaust manifold
before flowing through a heat exchanger and
then returning to the engine inlet. Typically
the secondary water that flows through the
same heat exchanger then passes into the
exhaust gas heat exchanger to extract further
heat from the exhaust gases. It should be
possible to extract sufficient heat from the
exhaust for the temperature of the gases
leaving the heat exchanger to fall below 100°C
when a condensing boiler is fitted. Provision
must be made for collecting and disposing of
the condensate (approx. 1 litre condensate
produced for each cubic metre of gas burnt).
An electrically driven water pump is used to
obtain a flow as specified in this data against
the combined pressure drop of the engine
and the two heat exchangers. The electric
pump is also required to maintain circulation
when the engine is stopped - see Control of
Operating Temperatures. A thermostat is
required to allow the engine to warm through
quickly - it may take several hours to warm the
building. Similarly in warm ambients the
building may require very little heat, in which
case the engine needs to maintain normal
temperatures while only small flows pass
through the main heat exchanger.
Gas Installation, October 1997
COOLING SYSTEMS
2.0 PERKINS REQUIREMENTS FOR THE COOLING SYSTEM
2.1 The primary cooling system, which includes the engine, shall preferably be filled with
a 50/50 glycol/water anti-freeze mix. Alternatively, if there is no danger of freezing, plain water
can be used in conjunction with Perkins inhibitor. This is sold in bottles, Perkins part number
OE 45350, (not for 4000 series).
The engines have dis-similar metals in the cooling system and corrosion will occur if untreated
water is used. The anti-freeze mix is also fully effective in preventing cavitation erosion in the
engine.
Sizing of heat exchangers in the primary circuit must take account of the effect of glycol mixes
on heat dissipation. This can vary dependent on the heat exchanger design.
2.2 The electric water circulation pump will normally be chosen from units used in central
heating systems. A typical manufacturer is Grundfos. Sizing will depend on the overall
pressure drop through the engine and external heat exchangers. The required flows for the
engines are listed below and the pressure drops through the engine only are given.
2006SI
3008
3012
4006
4008
4012
4016
Flow rate (l/min)
1500 rpm
1800 rpm
320
264
345
415
432
520
456
462
918
942
Pressure drop (kPa)
140
185
45
64
44
63
54
55
70
77
(1800 rpm not in production yet as a rule for 4000 Series engines).
2.4 CONTROL OF OPERATING TEMPERATURES
The engine should operate within a normal temperature range at all times. This range is 7895°C.
CHP sets will normally be used as an adjunct to a boiler, and it is usually arranged that the
boiler has adequate capacity to provide the full heat requirement, when the CHP set is stopped
for maintenance. In those cases where CHP set and boiler are normally operated together, the
CHP set should be placed ahead of the boiler in the circuit, so that it can handle the cooler
water.
2.4.1 THERMOSTAT
It is Perkins policy always to have a thermostat in the circuit to safeguard the engine against
running too cold. This is particularly important when the CHP set is first started and the building
is cold. Following the current convention, a thermostat remote from the engine is used, which
reacts to the combined heat input of the engine and exhaust heat exchanger. Thermostat must
be fitted to charge cooler and jacket water circuits.
Suitable thermostats can be obtained from Amot Controls, Bury St Edmunds, Suffolk, UK.
Perkins has selected basic sizes, temperature range and bleed hole size. The set builder can
choose to have a flanged or threaded connections.
Gas Installation, October 1997
55
COOLING SYSTEMS
The temperature range reference is '185'
Begin to open
Fully open
2000/3000
82°C
91°C
4000
82°C
90°C
The bleed hole size is 3mm; this is selected to
assist in initial fill of the system without air
locks; Amot reference D1.
The thermostats selected for the three engine
sizes are:
2006-SI
3008-SI
2B F C E - 185 - 01 - D1 - AA
3012-SI
The 4000 series standard fitting thermostat.
The F and E refer to a flanged connection
C
is cast iron housing
185 is temperature setting (as above)
D1 is bleed hole size
AA is standard build
2.4.2 CONTROL OF HIGH OPERATING
TEMPERATURES
Two alternatives exist to safeguard the engine
when the heat load is smaller than the full heat
output from the engine.
*
If the engine must be maintained at full
load to supply sufficient electricity, a 'heat
dump' i.e. a radiator, must be
incorporated, to be progressively
switched in by a thermostat. This radiator
must have sufficient capacity to cool the
engine on its own in the maximum
ambient temperature. See Fig. 32.
*
If the engine loading can be controlled to
match engine heat output to the space
heating requirements, a 'heat dump' is
not essential, but the safety of the engine
is controlled by customer supplied
temperature sensors and circuitry. Two
systems are currently used:
As the water temperature at the sensor,
(normally at the outlet from the exhaust
heat exchanger) is exceeded, the engine
is shutdown. Coolant flow is maintained
by the electric pump and heat is gradually
dissipated to the secondary circuit
through the main heat exchanger.
56
-
At a preset lower temperature the engine
is restarted and full load applied. The
engine duty cycle is therefore a
continuous sequence of full load and
stop. Since the engine is started so
frequently, it is common to use an
induction motor in place of the main
generator. The engine is therefore started
from the mains by the induction motor
and this is then used to generate electricity.
Preferred by Perkins are systems in which
the power is modulated in several steps
down to 50% i.e. as the sensed water
temperature rises due to reduced demand
from the space heaters, control circuits
progressively reduce engine power by
changes in generator load.
At less than 50% power demand the
engine should be stopped, with the electric
pump maintaining coolant flow, until it
cools to preset temperature, when the
engine will be restarted and loaded at
50%. Continuous operation at light load
is not advocated and could lead to cylinder
bore glazing.
Gas Installation, October 1997
COOLING SYSTEMS
CHP - SET UP C/COOLING
Fig. 35
Gas Installation, October 1997
987.2
57
EXHAUST SYSTEM
ALL EXPOSED HOT
SURFACES
SHOULD BE FITTED WITH GUARDS OR
LAGGED.
WARNING
The primary function of the exhaust system is
to pipe the exhaust gases from the engine
manifold(s) and discharge them, at a
controlled noise level, outside the engine
room, at a height sufficient to ensure proper
dispersal.
BACK PRESSURE
Engines give optimum performance when
the resistance to exhaust gas flow is below a
certain limit. Starting at the engine exhaust
outlet flange the total exhaust system should
not impose back pressure on the engine
greater than that recommended.
Excessive back pressure will cause a lack of
complete combustion and deterioration in the
scavenging of the cylinders. The result will be
loss in power output, high exhaust temperature
and the formation of soot. The soot, if oily,
could also affect the turbine of a turbocharger.
The oily soot would build up on the turbine
blades, harden and, as pieces of carbon break
off, the turbine wheel would become
unbalanced and cause problems.
INSTALLATION
The exhaust system should be planned at the
outset of the installation. The main objectives
must be to:i) Ensure that the back pressure of the
complete system is below the maximum
limit laid down by the engine
manufacturer. (e.g. 40 mm/Hg / 54 mbar).
ii) Keep weight off the engine manifold(s)
and turbocharger(s) by supporting the
system.
iii) Allow for thermal expansion and
contraction.
iv) Provide flexibility if the engine set is on
anti-vibration mountings.
v) Reduce exhaust noise.
vi) Minimum length.
vii) Exhaust ventilation to help during purging
i.e. long exhaust systems.
A typical installation is shown in Fig. 36.
If the engine is on Anti-Vibration mountings or
similar, there will be lateral movement of the
engine exhaust outlet flange when the engine
starts and stops. A flexible pipe should
therefore be fitted as near to the outlet flange
as is practically possible (See Fig. 36).
Maximum Back Pressure
Back pressure figures vary between naturally
aspirated and turbo-charged engines and also
from manufacturer to manufacturer.
The maximum exhaust back pressure
figures can be found in the Product
Information Manual.
Gas Installation, October 1997
59
EXHAUST SYSTEM
FLEXIBLE ELEMENT
Flexible Pipe
The flexible pipe is constructed by winding
and interlocking formed metal strip, including
packing in the process.
It is intended to be used with a slight deviation
from straight as the flexibility is by relative
movement at the ends of the pipe at right
angles to the longitudinal axis. It should never
be used to form bends as it will lock rigidly
with no flexibility or freedom for expansion.
When installing make sure the bellows are
not extended on “free length”. It is better to
install with, say, a 3mm compression.
If the exhaust system is long then it should be
divided into lengths with one end of each
Iength fixed and the other end having a
bellows unit. The tail pipe after a final silencer
should be ten times the bore in length.
Flexible Bellows
The flexible bellows have some degree of
lateral flexibility and a fair amount of axial
movement to take up expansion and
contraction. (See Fig. 37).
With exhaust outlet bores up to 150mm
diameter one unit is usually adequate but two
can be bolted together to double the movement
possible.
Fig. 36
60
805.2
Gas Installation, October 1997
EXHAUST SYSTEM
EXPANSION
The expansion of one metre of pipe per rise in
temperature of 100°C is 1.17mm.
5 metres of pipe having a temperature rise
from 27°C to 600°C will expand (5.73 x 1.17 x
5) = 33.5mm.
This expansion figure shows, by its size, how
important it is to properly plan the exhaust run
if long life is required.
EXHAUST OUTLET POSITION
The exhaust outlet outside the engine room
must be in such a position that there is no
possibility of hot gas entering the cooled air
inlet opening. If possible the outlet should be
in the same wall as the hot air outlet from the
radiator. See Fig. 36.
If the exhaust outlet terminates vertically a
rain shield must be fitted. Usually the outlet
pipe goes horizontally through the wall with
the underside of the pipe cut away at an
angle. If directing the exhaust straight out
causes a directional noise problem then a
horizontally fitted right angled bend would
probably be a simple solution.
Gas Installation, October 1997
Fig. 37
806.2
61
EXHAUST SYSTEM
MULTIPLE EXHAUST OUTLETS
If more than one engine is being installed the
exhaust from the engines must not be taken
into the same flue. Each engine must have
its own separate system and individual
outlet.
The reason is that if one engine is stationary
when others are running, exhaust gases with
condensate and carbon will be forced into the
exhaust system of the stationary engine and
then into the engine cylinders. Obviously this
would cause problems.
It may be considered that a flap valve in each
exhaust Iine near to the flue could be the
solution. The exhaust carries carbon and soot
deposits which will cause the flap valve to
leak. The leak will not be known about until
the engine is in trouble. The best policy is to
provide separate outlets.
Do not terminate the exhaust outlet into an
existing chimney or flue that is used for another
purpose. The pulsations in the exhaust could
upset the up-draught and create problems
with other equipment that relies on the updraught. There is also the risk of explosion
due to unburnt gases. Fan assisted exhaust
systems should be fitted to ensure purge can
be achieved.
CONDENSATE DRAIN
ln all exhaust systems there is condensate
due to gases cooling and differential
temperature between the gases and metal
pipes, etc.
If this is ignored condensate could run into the
engine, depending on manifold configuration,
and bring associated problems.
The exhaust system usually runs vertically
from the engine outlet and it is advisable to fit
a drain pocket at the bottom bend. A small
hole min. 20mm giving a permanent drain
would clear the condensate but would allow
a small amount of exhaust gases to be blown
into the engine room when the engine is
running. If this is not acceptable then a
permanent open drain pipe should be taken
to the outside of the engine room (See Fig.
36).
62
Fig. 38
807.2
LAGGING
The amount of heat radiated from the exhaust
system can create problems with the radiator
cooling and ventilation and may lead to a
larger radiator, pusher fan and extractor fan.
These are costly items and the cheapest and
most practical solution is to lag the exhaust
system that is inside the engine room. Heat
insulating wrappers which clip around the
pipe are suitable, 25mm to 50mm is the usual
thickness and can be obtained in suitable
lengths from specialist suppliers. See Fig. 38.
Where pipe flanges or flexible bellows are to
be lagged clip-on muffs can be used. The
muffs are easily fitted and will not prevent
flexible units from doing their intended job.
A - CLIP-ON INSULATION WRAPPER
B - CLIP-ON INSULATION MUFF
NOTE: Do not lag exhaust manifolds or
turbochargers, to do so would lead to operating
deficiencies and very quickly cause failure of
parts due to thermal stress.
Gas Installation, October 1997
EXHAUST SYSTEM
EXHAUST SILENCERS
Silencers are used, as the name implies, to
reduce the noise level emissions at the
exhaust pipe outlet. In general terms the
silencer should be installed near the engine
exhaust outlet flange or at the end of the
system.
If the engine or generating set has acoustic
treatment to reduce noise levels it is also
necessary to ensure that the exhaust silencers
are capable or reducing exhaust noise to the
same (or below) noise level being achieved
by the acoustic treatment. See page 64
onwards.
There are various types of silencer available
as detailed below from different
manufacturers.
i) The first type is a re-active type silencer
which has a series of baffles and
perforated tubes and attenuates a high
degree of noise in the lower frequency
bands. To a lesser degree noise in the
high frequency bands is also absorbed.
This type of silencer is referred to as a
primary silencer.
ii) The second type is a triple-chamber type.
In the first two chambers initial low
restriction expansion and diffusion of the
hot gas takes place with some attenuation
of low frequency noise.
In the third chamber attenuation of the
higher frequencies is achieved by the
absorption principle.
This again is referred to as a primary
silencer.
iii) The third type is what is known as a
“straight through” silencer and works on
the absorption principle. The silencer
consists of an outer case with a perforated
centre tube. The annular space between
case and tube is packed with heat resisting
fibre glass, or similar material.
Gas Installation, October 1997
The exhaust noise is effectively dissipated by
the packing through the perforations.
Resistance to exhaust gas flow is negligible
and, in calculations for back pressure can, be
taken as a piece of exhaust pipe the same
length and bore size as the silencer.
This type of silencer is usually classed as a
‘secondary’ silencer and is normally at the
end of the pipe system. However, it could be
used as a primary silencer if noise level
standards are not critical.
63
EXHAUST SYSTEM
LOCAL AUTHORITY REGULATIONS NOISE
Local Authorities can, and do, set down noise
limits for the different areas that come within
their jurisdiction.
The combinations and type of silencer to be
used are best recommended by the silencer
manufacturers who should be brought into
design discussions at an early stage.
BACK PRESSURE - EXHAUST SYSTEM CALCULATIONS
The basic engine data required to calculate
the back pressure in an exhaust system is
shown in the Product Information Manual
against each engine type, ie The gas flow by
volume and by weight at the appropriate
temperature for a given engine speed and
power.
64
Gas Installation, October 1997
EXHAUST SYSTEM
HOW TO USE THE INFORMATION
Gas Flow by Volume (m3/min)
With this information the velocity through a
certain pipe or silencer bore can be calculated
using the following formula:Gas
Velocity =
Volume flow (m3/min) = m/s
Area of pipe in m2 x 60
Having calculated the gas velocity and
obtained the gas volume flow from the product
manual for a single exhaust outlet (where
twin outlets are required the volume flow
should be divided by 2) then, by referring to
the silencing equipment suppliers data sheets
you will be able to determine the resistance to
flow through the silencer in mm Hg.
If a suitable system cannot be obtained with
the diameter of pipe suggested it may be that
increasing the silencer bore one size would
be satisfactory. If not, pipe sizes will also have
to be increased. Transition units as shown in
Fig. 39 will be required. Where a single outlet
is preferred to the standard twin outlets, a
single outlet adaptor as shown in Fig. 40 will
be required.
The equivalent length of straight pipe against
various features in the exhaust system are
shown in the following table.
Gas Flow by Mass (kg/s)
Using this data the pressure drop through a
given length of straight exhaust pipe can be
calculated by using the following formula:
P=
L x Q2
D5.33
x 1187 x 109
P = Back pressure (mm Hg)
Q = Gas Flow (kg/s)
L = Total equivalent length * straight pipe (m)
D = Pipe diameter (mm)
* When bends are used in the exhaust system
then pressure loss is expressed in
equivalent straight length of pipe see page
66.
Adding the pressure losses through the
silencers (or silencer) to the pressure loss
through the pipe work will give the total back
pressure incurred by the exhaust system.
THIS MUST NOT EXCEED THE FIGURE
QUOTED IN THE PRODUCT MANUAL
AGAINST THE APPROPRIATE ENGINE
AND RATING.
Gas Installation, October 1997
65
EXHAUST SYSTEM
EQUIVALENT LENGTHS OF STRAIGHT
PIPE
Flexible pipe: 2 x Actual length of
flexible pipe
Exhaust bellows: 2 x Actual length of
bellow
Transition unit: See Fig. 39
Single outlet adaptor: See Fig. 40
90 Degree bend: 15 x Bore of pipe
45 Degree bend: 6 x Bore of pipe
IMPORTANT NOTE: Ensure that if the
diameter or length is expressed in millimetres
you should divide by 1000 after you have
multiplied by the appropriate factor, as the
unit of length in the pressure loss formula is in
metres.
Fig. 39
808.3
Fig. 40
809.2
66
Gas Installation, October 1997
EXHAUST SYSTEM
Equivalent length (L) of pipe to D diameter is determined by calculating as follows:Measure the effective centre line length of one branch pipe from turbo-charger outlet to single
outlet i.e. ι 1 and ι 2 as shown, plus the equivalent length of bends in each plane i.e. 6 x d bend
on ι 1 and 15 x d for bend on ι 2, giving a total equivalent length L to d diameter.
Equivalent length L of pipe D diameter will be:L = ι x (q/Q)2 (D/d)5.33 = ι /4(D/d)5.33
EXAMPLE
4008TAG2 (twin turbo-chargers) at 1500 rpm using the proposed single exhaust system as
follows:
(a) 1 x 127 mm flexible bellows
(b) SE24N single exhaust outlet adaptor (127 mm inlet/254 mm outlet)
(c) 1 metre flexible pipe (254 mm)
(d) 254 mm primary exhaust silencer (Peco-Maxim)
(e) 1 x 45° bend
(f) 3 m straight through silencer
(g) 15 m straight pipe
Gas velocity =
200.9
= 66.04 m/s
0.0507 x 60
Primary silencer pressure loss = 29.9 mm Hg.
Maximum allowable exhaust back pressure - 50 mm Hg. (Product Information Manual).
Exhaust system allowance = 50 - 29.9 = 20.1 mm Hg.
Since the 4008TAG2 is fitted with twin turbo-chargers we consider half of the system as for the
single outlet adaptor.
Check list
Equivalent Lengths of Straight Pipes
(a) 1 Bellows 0.102m (2 x 0.102)
=
0.204 m
(b) Adaptor SE24N effective length
=
0.200 m
''
90° Bend
=
1.905 m
''
45° Bend
=
0.762 m
Total Effective Length at 127 mm (d), ι
=
3.071 m
Equivalent length in 254 mm (D) System
L = ι/4 (D/d)5.33
=
30.88 m
(c) 1 m Flexible Pipe
=
2.00 m
(d) Primary Silencer Allowance Already Deducted
(e) 1 x 45° Bend (6 x 0.254)
=
1.52 m
(f) 3 m Straight Through Silencer
=
3.00 m
(g)10 m Straight Pipe
=
10.00 m
Total equivalent length L
=
47.4 m
From Back Pressure Formulae
P = 47.4 x 1.5292 x 1187 x 109 = 20.0 mm Hg
2545.33
Therefore since this pressure is less than exhaust system allowance of 20.1 mm Hg. the
proposed system will be satisfactory.
Gas Installation, October 1997
67
EXHAUST SYSTEM
NOISE ATTENUATION - EXHAUST
PERSONAL
PROTECTIVE
EQUIPMENT MUST BE WORN WHEN
WORKING NEAR A RUNNING ENGINE.
When resulting value is obtained then this is
paired with the third value at 250 Hz
WARNING
The noise carried by the exhaust gas out of
the exhaust manifold of a running engine is
very loud and objectionable to personnel. It
could prove harmful over a period of time.
The great majority of the harmful noise is in
the frequency range or 63 to 8000 Hz. The
best choice of silencer(s) is the design that
will attenuate most noise within that range.
To assess the value of each type of silencer
described previously, and a combination of
primary and secondary silencers, the
following schedules show the noise
attenuating capacity of these type silencers
when in the exhaust pipe line of a running
engine.
e.g. Hz
63
125
250
dB
79
74
79
.
. . Difference 5 dB
add 1 dB to 79 dB
80
And so on
Difference 1 dB
add 3 dB to 80
83
The exhaust noise of a turbocharged engine
running at 1500 rpm was taken in a semireverberent field and the octave band centre
frequency analysis from 63 to 8000 Hz in
decibels - dB - was as follows:-
Example
Add together dB values for the separate octave
band frequencies take the first pair of figures
eg. at 63 and 125 Hz. the resulting figure has
been adjusted in the following manner.
If the dB values differ by 0 or 1 dB - add 3 dB
to higher values
If the dB values differ by 2 or 3 dB - add 2 dB
to higher values
If the dB values differ by 4 to 9 dB - add 1 dB
to higher values
68
Gas Installation, October 1997
EXHAUST SYSTEM
CATALYST - TO ACHIEVE 1/2 TA LUFT
2000, 3000 Series
Engine which runs at Lamba 1 must use a 3
way ctalyst to reduce levels of CO (Carbon
Monoxide) Nox, HC's (Hydrocarbons) emitted
to the atmosphere.
4000 Series
Engines which operate with excess air like
the 4000 series range (Lambda 1.6) can be
fitted with a 2 way catalyst to reduce CO, HC's
in the atmosphere.
EXHAUST GAS EMISSION & CATALYSTS
The exhaust gas emission levels are as stated
in the Product Information Folder or are
available on request from Perkins Engines
(Stafford) Ltd.
All gas engines these are factory set and the
exhaust emission presently meet certain
national limits. Development work in this area
is continuing seeking to further reduce the
already low levels of emission.
The exhaust emissions do however vary
according to the particular operating
conditions, and the analysis of the gas being
used. Care must therefore be taken to check
the levels of exhaust emissions against the
national or local requirements.
The Minnox gas engines are factory set to
operate on clean natural gas conforming to
the British Natural Gas specification having a
lower calorific value of 34.71 MJ/sm3 (930
BTU/Sft3).
Ensure hole 1/8 BSP is in exhaust elbow for
analysing purposes before installation is
complete, also a hole for O2 sensing for
programming Lambda controller (M18 x 1.5
mm thread with a thin boss) must be fitted if
this option is required for the engine.
Provision is made on the ‘Minnox’ gas engines
for connecting an exhaust gas analyser
(Special Tool No. T6253/242), to check
whether the exhaust emission level and
temperature are within the specified limits.
Should the engine need to be adjusted to give
the specified limits to comply with the national
or local standards, the method to be used is
detailed in the Appropriate Engine
Operation Manual.
Gas Installation, October 1997
69
ENGINE BREATHER
PERSONAL
PROTECTIVE
EQUIPMENT MUST BE WORN WHEN
HANDLING OR CLEANING THE ENGINE
BREATHER/ELEMENT.
WARNING
All engines are fitted with a breathing system
that prevents a build up of pressure in the
crankcase. The build up in pressure is caused
by blow-by from the pistons. The fumes in the
crankcase are vented to atmosphere.
The fumes contain contaminants from the
combustion process and minute globules of
lubricating oil. The fumes will pollute the
atmosphere in the engine room particularly if
the radiator and fan are remote mounted.
Fig. 41
970.2
BREATHER INSTALLATION
It maybe that with the radiator and fan in the
engine room all the fumes could be drawn, or
directed, to the fan intake from an open circuit
breather. All 4000 series and CHP
specification PE(S)L engines are now fitted
with a closed circuit breather for natural gas
applications.
The fumes would deposit oil on the radiator
matrix and particles of dust in the airflow
would tend to stick. In time the radiator and
fan performance would deteriorate and lead
to overheating.
It is far better to pipe the fumes to outside the
building. See Fig. 41.
Key
(Fig. 41)
A. Where there are two breathers they should
be joined together in a downward position to
a single pipe with a slight slope to separating
tank B. (See Fig. 41)
B. Separating tank, with drain tap C, can be
positioned inside or outside the engine room
C. Drain
D. Breather fitted to end of pipe
E. Flexible connection
70
Gas Installation, October 1997
ENGINE BREATHER
BREATHING - POINTS TO WATCH
The breather fumes should never be piped
directly to be digested by the engine air filters.
Harmful contaminants, including acids, would
be circulated around the engine with long
term harmful effects. In some instances the
fumes would have a detrimental effect on the
air filter element.
However, should the engine be fitted with a
crankcase emmission absorber, in which case
the contaminents will have been removed,
then the fumes from the absorber outlet can
be piped into the engine air inlet.
In multi-engine installations, as with the
exhaust system the breather pipe from each
engine must have its own individual run. If
terminating in the same tank the fumes from a
running engine could leak back into the
stationary engine.
The outlet of the breather pipe should not be
sited in a position where fumes could be
drawn into the cooling air inlet stream.
If the engine is on anti-vibration mountings a
flexible section should be fitted in the breather
pipe near the engine.
Fig. 43
Gas Installation, October 1997
Fig. 42
966.2
964.2
71
FUEL SYSTEMS
3.1 INTRODUCTION
To ensure safe and consistent operation of a
gas engine it is important to pay particular
attention to the fuel supply system. In some
locations gas engine installations are the
subject of mandatory requirements and it is
advisable to discuss proposed installations
with the appropriate authorities.
The following section is intended as a guide
to successful installation, it is not intended to
cover every possible hazard. It is the installers
responsibility to consider and avoid possible
hazardous conditions which could be present
on any given installation.
In general these recommendations are based
on the British Gas Code of Practice for Natural
Gas Fuelled Spark Ignition Engines.
Publication IM/17, and The Institution of Gas
Engineers Utilization Procedures IGE/UP/3.
They will also apply to Operation on other
types of hydrocarbon gaseous fuels, i.e.
Landfill, Biomass and Wellhead gases. In
these latter cases however there may be
additional requirements in terms of gas
treatment, dual fuel starting etc, which must
be considered at the installation stage.
3.3 GAS SHUT OFF SYSTEMS
A typical installation to the British gas Code of
Practice is shown in Fig. 50. The requirements
of the code call for a minimum of two
certificated or acceptable shut off devices to
be fitted to the gas supply pipe. In addition the
upstream shut off valve should be preferably
be a fast acting solenoid type linked into both
emergency and normal shutdown systems.
At least one of the safety shut off devices
should be protected from engine vibration by
a length of suitable flexible pipe. It is always
good practice to fit a manual shut off valve, of
a quick acting type upstream of all other control
devices and upstream of any flexible pipe
sections. See paragraph 3.2.
3.4 PIPEWORK
Where possible all pipework should be in
accordance with the Codes of Practice IM/17.
Pipework sizing should be such that pressure
drops are kept to a minimum and no smaller
than the zero pressure regulator inlet fitting
size.
3.2 STANDARD EQUIPMENT
In their basic form Perkins Gas engines will
be supplied with a carburettor and zero
pressure regulator fitted as standard.
The purpose of the carburettor is to mix the
fuel gas and air in the correct ratio and, in
conjunction with the governor, control flow of
the air fuel mixture to the engine cylinders.
The ratio of air to gas mixed by the carburettor
is determined by the difference in pressure of
air and gas supplied to the carburettor. The
carburetion system incorporates a 'power
mixture valve' which regulates gas flow to the
carburettor and facilities adjustment of the full
load fuel air mixture only. The air to gas
pressure differential is maintained by the gas
pressure regulator.
The function of the balance line is to allow the
regulator to sense actual air inlet pressure.
This prevents variations in air fuel ratio due to
air filter restriction changes in service.
72
Gas Installation, October 1997
FUEL SYSTEMS
3.5 SPIT BACK DETECTOR
Spit back is the explosion of the gas/air mixture
in the engine inlet manifold. It is normally a
result of ignition timing errors or malfunction
of the engine inlet valves.
The rapid rise in pressure generated is usually
dissipated adequately through the carburettor
air intake. However, the emission of flame,
which is a characteristic of spit back, if left
unattended, could present a fire hazard. For
this reason it is recommended that on
installations which could run unattended for
long periods a spit back detector be fitted on
the gas supply line adjacent to the carburettor.
The detector usually takes the form of a high
pressure cut out diaphragm switch. This will
detect the pressure pulses resulting from spit
back which are generally less than 10 kPa
peak but only 20-30ms in duration. The switch
connection should be such that both engine
ignition and the gas supply are turned off
simultaneously on detection of spit back.
It should be noted that pressures generated
by spit back will be considerably greater on
pressure charged engines.
3.6 GAS SUPPLY LOW PRESSURE
DETECTOR
When operating on Natural Gas it may be
required by the supply authority to fit protection
against low and fluctuating gas supply
pressures. This is particularly the case if
operation of the engine may cause reduction
in supply pressure to other users. The
requirement for this type of device can be
determined prior to installation by reference
to the relevant regional authority.
Gas Installation, October 1997
3.7 GAS
FILTRATION
AND
PRECONDITIONING
With respect to solid contaminants it is
recommended that gas supplies are filtered to
the same standard as that of the intake air (5
microns maximum partical size).
Filter restriction to gas flow must be sufficiently
low as to ensure that at full engine load the
minimum gas supply pressures can be
maintained at the inlet to the regulator. This
condition must be met with the filter element in
its 'dirty' condition at the end of its service life.
Hydrocarbon liquids must not be allowed to
enter the engine and should be separated
from the gas prior to paticulate filtration. In
some instances, particularly biogas
installations, it may be necessary to
precondition the gas chemically to reduce the
level of harmful constituents such as hydrogen
sulphide and chlorine. In these instances
reference must be made to the appropriate
engine manufacturer.
3.8 SHUTDOWN PROCEDURES
Under emergency stop conditions it is
necessary to shut down both engine ignition
and gas supply simultaneously. Under
conditions of normal shutdown it is beneficial
to shut off the gas supply first. This allows the
engine to consume the fuel downstream of
the shut off valve and prevents gas being
pumped into the exhaust system.
73
FUEL SYSTEMS
GAS SPECIFICATION
Gas engines are factory set to operate on clean natural gas conforming to British natural gas
specifications having a lower calorific value of 34.71 MJ/Nm3 (930 BTU/Sft3).
The difference between high heat value (HHV) and low heat value (LHV) is that (HHV) is the
total amount of heat given off by the gas during combustion and (LHV) is the high heat value
less the amount of heat used to vaporize the water content of the gas by combustion. The
amount of heat lost in vaporizing the water is different for different gases, hence the reason that
the lower calorific value of the gas is chosen as the basis for fuel consumption data.
IF THE ENGINE IS NOT SET TO SUIT THE SITE GAS,
UNECONOMICAL RUNNING, LOSS OF POWER OR DAMAGE MAY
RESULT, WHICH COULD RESULT IN INJURY.
WARNING
In cases where different gases to British Natural Gas are being considered such as wellhead
gas, digester gas, landfill gas, it is essential that a detailed analysis of the proposed gas is
submitted to Perkins Engines (Stafford) Ltd for approval, which may involve resetting or
changing the standard gas equipment.
Limiting Values for British Natural Gas given as a guide only see Operation Manual for more
precise figures.
(1) Methane number must exceed
76
(2) Combustible constituents must exceed
85%
(3) Calorific value (LHV) to exceed
34MJ/Nm3 Ex's 0°C
(912 BTU/Sft3)
(4) Ethane
4.5%
(5) Hydrogen content not to exceed
0.1%
(6) Propane must not exceed
1%
(7) ISO butane content not to exceed
0.2%
(8) Normal butane not to exceed
0.2%
(9) Normal pentane and higher fractions (hexane,
heptane,etc.) The summation must not exceed
0.02%
(10) Gas pressure at inlet to regulators (minimum)
15mbar
(1.5 kPa)
(11) Gas pressure not to exceed without additional
50mbar
pressure regulators
(5 kPa) = 10mbar
(12) Hydrogen sulphide not to exceed
0.01% (100ppm)
There must be no liquid hydrocarbon fractions in the fuel gas, and the supply must be at a
constant pressure.
NOTE: The rating may be reduced if the lower calorific value of the fuel is lower than 34 MJ/Nm3
(912 BTU/Sft3).
WARNING
IT IS ESSENTIAL THAT ALL DERATING FACTORS BE
CONSIDERED, AND THAT, IF NECESSARY THE DERATING
PROCEDURE BE CARRIED OUT, AS DESCRIBED IN THE OPERATION MANUAL.
74
Gas Installation, October 1997
FUEL SYSTEMS
2000 / 3000 SERIES
Fig. 44
988.2
2000 / 3000 SERIES
Fig. 45
Gas Installation, October 1997
989.2
75
FUEL SYSTEMS
2000 / 3000 SERIES
Fig. 46
76
990.2
Gas Installation, October 1997
FUEL SYSTEMS
GAS SYSTEMS
4000 SERIES
NO NAKED FLAMES
OR
SMOKING
SHOULD BE ALLOWED IN THE VICINITY
OF A GAS ENGINE WHETHER
STATIONARY OR OPERATIONAL.
ENSURE THAT THE BUILDING IS
NATURALLY
VENTILATED
TO
PREVENT POCKETS OF GAS FORMING.
WARNING
The standard natural gas system as supplied
on the engine is connected to the supply at the
pressure regulator, and if the gas pressure is
correct, ie 2-4.9 kPa 20-49mbar (8”-20” H20)
for naturally aspirated and 15-50 mbar (1.5 - 5
kPa) (6"-20" H 2o) on the turbocharged
(MINNOX) engines, the engines should
operate satisfactorily.
Fig. 47
814.2
4000 SERIES
Fig. 48
Gas Installation, October 1997
815.2
77
FUEL SYSTEMS
Should the supply pressure not lie within
acceptable limits, then the following action
should be taken:High Pressure Supply
In the UK the normal pressure for natural gas
is approximately 8” H20 (20 mbar). But where
the site pressure is higher than that accepted
by the engine it will be necessary to fit a
suitable gas train to reduce this pressure,
(refer to Perkins Engines (Stafford) Ltd).
The system fitted should conform to whatever
local or national regulations apply.
Low Pressure Supply
NOTE: Consideration must be given to rapid
changes in gas flow.
Should the site pressure be lower than the
engine can accept then the pressure should
be increased by fitting a suitable booster unit
to raise the pressure (refer to Perkins Engines
Ltd Applications Department).
Seek advice on gas supplier and pipework
sizing.
Fig. 49
78
WARNING
IT IS ESSENTIAL
THAT THE GAS
SUPPLY SYSTEM IS NOT SUBJECTED
TO A NEGATIVE PRESSURE UNLESS
SPECIFICALLY DESIGNED FOR THIS
TYPE OF OPERATION.
When the zero pressure regulator is mounted
remote from the engine it is imperative that the
length of the pipe between the zero pressure
regulator and the carburettor mixing unit be
no more than 1.2m long and not less than
50mm bore, and it must be mounted absolutely
horizontal. The gas supply pipe to the zero
pressure regulator should be sized as to
maintain a gas pressure of at least 6” H2O
(15mbar) UNDER ALL LOAD CONDITIONS.
High compression; one regulator.
994.2
Gas Installation, October 1997
FUEL SYSTEMS
PIPE LINE INSTALLATION CORRECT TO
IGE/UP/3
If 5 is fitted fit 7, don't fit 10.
Pipework mounted:
1
Emegency isolation valve (outside
engine room)
2
Vent (when required)
3
Manual isolation valve
4
Filter (when fitted)
5
Gas pressure regulator (when fitted)
6
Low pressure cut off switch
7
High pressure cut off switch
8
1st safety shut off valve
9
2nd safety shut off valve (or see item 12)
10 Non return valve (when required)
11 Flexible
Engine mounted:
12 Alternative position for 2nd safety shut
off valve
13 Gas regulator
14 Spit back protection device
15 Engine manifold
16 Carburettor
17 Inlet manifold
Diagrammatic resprentation of the relative
positions of controls which may be required in
a typical low pressure gas supply to an engine.
Fig. 50
Gas Installation, October 1997
991.2
79
FUEL SYSTEMS
Fig. 51
80
620.2
Gas Installation, October 1997
FUEL SYSTEMS
British Gas Council Code Of Practice (IGE/
UP/3)
Where a gas engine needs to conform to the
British gas code of practice IM17, the gas
system as supplied on the engine is connected
to the gas supply at the manual valve.
NOTE: In the case of the turbocharged
(MINNOX) engines, 2 gas solenoid valves
are required to conform to the British Gas
Council Code of Practice since they do not
accept the carburettor mixing unit as an
automatic valve, which they do in the case of
the Impco type carburettor. (See Fig. 52).
Other Gases (Wellhead Gas, Digester Gas,
Landfill Gas)
When an engine is to operate using other than
British natural gas (see page 74) it is essential
that a detailed analysis of the proposed gas is
submitted to Perkins Engine for approval.
The engine is factory set to operate on clean
British natural gas, using other gases could
result in severe damage to the engine.
Depending on the proposed gas analysis it
may be necessary to have to reset the engine
or change the standard gas equipment.
Ignition System
The 4000 Range Engine ignition system will
need to be connected to a 24V DC battery and
is as described in the Operation Manual.
Fig. 52
Gas Installation, October 1997
646.2
81
LUBRICATING OIL SYSTEMS
WARNING
PERSONAL
PROTECTIVE
EQUIPMENT MUST BE WORN WHEN
FILLING THE SUMP WITH LUBRICATING
OIL.
The lubricating oil used on the engine test is
drained from the sump before the engine is
dispatched, and will give up to 12 months
preservation protection.
It is important that when filling the sump that
lubricating oil of the correct specification is
used, and that it is not contaminated.
LUBRICATING OIL RECOMMENDATIONS
The quantity, grade and type of oil to be used
are stated in the appropriate Engine
Operation Manual.
STANDARD LUBRICATING OIL SYSTEM
The oil in the standard sump must be changed
at regular intervals (see Appropriate Engine
Operation Manual) therefore access to the
dipstick, drain plug and oil filler must be
allowed for routine servicing to be carried out,
and also if necessary for the sump to be
removed.
Fig. 53
82
EXTENDED RUNNING OIL SYSTEM
To extend the servicing interval on unattended
engines to coincide with the normal oil change
interval (see Appropriate Engine Operation
Manual) the sump oil capacity can be
increased by fitting a make-up tank. The makeup tank should be positioned on a stand along
side the set and the outlet connection on the
tank must be at least 0.3 metres above the
inlet connection on the ‘REN’ valve. The
standard oil level in the sump is maintained
by supplying oil from the make-up tank. the oil
flow from the tank being controlled by a ‘REN’
valve. (See Appropriate Engine Operation
Manual).
It is important to prevent losing the oil in the
make-up tank, when changing the sump oil
that an isolating tap is fitted between the tank,
outlet connection and the ‘REN’ valve. The
make-up tank oil level should be checked and
topped up at the same time as the sump oil is
changed. It is also important to maintain the
running max. level.
A typical extended running oil system is shown
in Fig. 53.
298.2
Gas Installation, October 1997
SOUND INSULATION
WARNING
PERSONAL
PROTECTIVE
EQUIPMENT MUST BE WORN WHEN
WORKING IN AN ENGINE ROOM.
NOISE LEVEL
Noise levels are measured in decibels - dB through a frequency range of 31.5 to 16,000
Hz and at each octave band centre frequency
ie 31.5, 63, 125, 250 Hz etc.
The human ear is responsive to noise levels
in the frequency range of 63 to 800 Hz.
The noise level in dB can be weighted A, B, C
and D to suit different requirements. The
accepted norm is the ‘A’ Weighting as such
an overall noise level closely reproduces the
response of the human ear. The most
commonly accepted readings are “Sound
Pressure Level”.
NOISE SOURCE
A running engine produces mechanical noise
- valve gear, fuel pump etc. combustion noise,
noise from vibration, noise from air induction
and from the radiator fan, if fitted.
Usually the radiator fan noise and the air
induction noise is less than the mechanical
noise.
Noise level readings of the engine and fan are
available, if required from Perkins Engines
(Stafford) Ltd (see Product Information
Manual).
Should additional noise reduction be required
this can be achieved by acoustic treatment.
If the acoustic treatment reduces the
mechanical noise levels as quoted in the
above noise level readings then the fan and
induction noise need not be considered.
Providing a canopy around the engine is
relatively economical and gives good results,
from a position 1 metre from the canopy an
overall reduction of 10 dB(A) can be achieved.
Sound attenuating canopies need to be
expertly designed to be effective, and would
advise that companies with acoustic treatment
experience be consulted.
Gas Installation, October 1997
RECOMMENDATIONS TO CONTAIN
NOISE
In an engine room installation where outside
noise levels have to be controlled the following
factors must be considered:i) Building Construction
Outside walls - should be double brick with cavity.
Windows - double glazed with an
approximate gap of 200mm between
panes.
Doors - double door air-lock or single
door with a wall built outside the door as
a noise barrier to absorb and reflect noise
when the door is opened.
ii) Ventilation
The air inlet(s) for engine combustion
and cooling air and the air outlet from the
radiator fan or extractor fan should be
fitted with noise attenuating splitters.
These are proprietary items and should
be discussed with the manufacturer.
Ensure that the splitters do not restrict
airflow thus putting excess resistance on
the fans.
With the amount of cooling air required
on the larger engines the splitters are of
generous proportions and the building
should be adapted so that they fit correctly.
iii) Anti-Vibration Mountings
The engine set mounted on anti-vibration
mountings to prevent vibrations being
transmitted to the walls, other pieces of
equipment, etc. These vibrations often
generate noise. (See Anti-Vibration
Mountings).
iv) Exhaust silencing
(See Exhaust section)
Attention to the foregoing could lead to a
noise attenuation of 30/35 dB(A) from
inside to 1 metre outside the building,
provided that top quality inlet and outlet
attenuators and exhaust silencers are
used.
83
SOUND INSULATION
'FREE' & 'SEMI-REVERBERNENT FIELD'
If the noise “escaping” from the engine room
emerges into a “FREE-FIELD” area then, a
good approximation of the decaying noise
level is that doubling the distance reduces the
noise level by 6 dB(A).
eg. at
1 metre - 70 dB(A)
2
''
- 64''
4
''
- 58''
8
''
- 52''
However, the area around the engine room
may include other buildings or reflective
surfaces to make it into a “Semi-reverberent
field”.
In a “Semi-reverberent field” the decay is
more likely to be approximately 3 dB(A) per
doubling of distance. Once clear of the semireverberent field the figure of 6 dB(A) can be
used in the “FREE-FIELD”.
eg. at
1 metre Semi-reverberant Field 70 dB(A)
2
''
''
- 67''
4
''
''
- 64''
8
''
Free Field
- 58''
With these simple approximations the noise
paths can be assessed at, say, a residential
area 100 metres from the noise source.
SOUND PROOF CANOPY OVER ENGINE
So far the object has been to contain the noise
in the engine room. If the room is unmanned,
or only occasionally worked in for short
periods, this could be acceptable.
Fig. 54
84
If the room is manned and perhaps used for
other purposes then it would be economic to
enclose the engine set in a canopy with inlet
cooling air being directed into the end of the
canopy and the radiator fan (or canopymounted motor driven fans if no radiator fitted)
pushing air through set mounted radiator,
ducting and the outlet splitter.
Lining the canopy with glass-fibre or mineral
rock wool and faced with perforated board
would absorb some mechanical noise. This
is the same principle as used in straight
through exhaust silencer.
Such a canopy would control the noise level
so that working in the engine room would not
cause discomfort to the operators.
An added advantage would be that the area
outside the engine room would be much
quieter. See Fig. 54.
lf a canopy is used the breathing system of an
engine with an open circuit breather should
be modified to take the fumes outside the
canopy and, if necessary, outside the building.
This will prevent the radiator matrix becoming
clogged.
When in an area where the noise level is
important remember it is possible that another
noise source may give a background noise
greater than the engine noise. If there is a
problem make sure that readings are not being
influenced by other noise sources. The engine
installation may not be at fault. Check with
local authority.
816.2
Gas Installation, October 1997
SOUND INSULATION
MULTIPLE ENGINE NOISE LEVEL
In a multiple engine installation using the
same type of engine the maximum noise level
will increase above that for a single engine
installation as shown in the Tech Data for the
respective engine in the Product Information
Manual.
Using a single engine as the datum point the
maximum noise level can be taken from the
Technical Data sheet for the single engine, as
shown in the appropriate engine Product
Information Manual.
From Fig. 56 add the additional noise level
depending on the total number of engines to
the single engine noise level.
Example:
The maximum noise level for a single
4006TAG2 engine running at 1800 rpm is
shown as 111 dB(A) at position 3. When the
total number of engines is 3, the maximum
noise level will be 111+ 4.8 = 115.8 dB(A).
NOTE: If the precise position for each engine
in a multiple engine system is known, a more
accurate evaluation of the maximum noise
level can be made. Generally, this will be
slightly lower than the maximum value
obtained above.
Fig. 55
Gas Installation, October 1997
817.2
85
SOUND INSULATION
Fig. 56
86
942.2
Gas Installation, October 1997
AIR INTAKE
WARNING
ALL EXPOSED AIR
INTAKES
TO
ENGINE MUST BE FITTED WITH
GUARDS.
The air into the engine for combustion must
be clean filtered air at the coolest temperature.
Under normal site conditions the standard
duty type air cleaner will filter out approximately
99% of the fine dust content down to 15 microns.
When the engine is operating in dusty/desert
conditions a heavy duty type air cleaner is
required to give the same filtration of the air
into the engine.
This is achieved by adding a further stage of
filtration to the standard duty air cleaner in the
form of a pre-cleaner. The pre-cleaner by
cyclonic action takes out the heavier dust
particles leaving the fine dust to pass on to the
next stage of filtration (see Fig. 57).
Dry air cleaners are fitted, since they give finer
filtration than the oil bath type.
AIR RESTRICTION INDICATOR
When the air cleaner filter elements are clean
the resistance to air flow is approximately
20mbar. As the restriction increases in service
the restriction indicator will signal by showing
red that the element must be changed for a
new one. (See appropriate Engine Operation
Manual).
Should the temperature of the air intake in the
engine room be higher than ambient
temperature, then the air cleaner must be
arranged via intake ducting/piping to draw the
air from outside the engine room.
Where noise level is also to be taken into
consideration the ducting/piping from the
standard air cleaner(s) mounted on the engine,
should be connected to an intake splitter
mounted in the wall of the engine room.
PRE-CLEANER
(OPTIONAL)
Fig. 57
Gas Installation, October 1997
493.2
87
AIR INTAKE
The additional noise splitter and ducting/
pipework will increase the resistance to air
flow. The additional resistance to air flow plus
the initial restriction of the engine mounted air
cleaner should be kept at 250/300 mm H2O by
increasing the size of the air filters and piping,
so as not to reduce the servicing interval.
(See Maintenance Schedule).
REMOTE MOUNTED AIR CLEANER
Should the engine mounted air cleaner(s)
be replaced by a remote mounted combined
air cleaner/intake splitter, then the total
resistance to air flow should be sized to
give the same as the engine mounted
cleaner(s) ie. 200/250 mm H20.
The weight of the ducting/piping between the
remote mounted air cleaner and the
turbocharger intake should be independently
supported, since this weight must not be
carried on the turbocharger. (See Fig. 58).
A flexible length of piping should be included
in the pipework to isolate the engine vibrations.
(See Fig. 58).
Fig. 58
88
818.2
Gas Installation, October 1997
TORSIONAL VIBRATION
WARNING
UNDER NO
CIRCUMSTANCES
MUST THE ENGINE BE RUN WHEN
EXCESSIVE VIBRATION OF THE
POWER UNIT IS BEING EXPERIENCED
THE ENGINE MUST BE STOPPED
IMMEDIATELY AND THE CAUSE
INVESTIGATED.
The information below explains the
importance of a T.V. analysis being done long
before the time comes for putting the engine
and driven unit together, this can be done by
PE(ST)L or the generating set manufacturer.
CRITICAL SPEED
When fitting driven equipment to an engine,
particularly single and twin-bearing
alternators, it is very important to investigate
the Torsional Vibration system of the complete
unit. Torsional vibrations occur in any rotating
shaft system.
At certain speeds in the engine running range
these vibrations may be of sufficient magnitude
and frequency to fracture the engine crankshaft
and flywheel bolts, strip teeth off gear wheels,
damage flexible couplings and driven
equipment. The point in the speed range
where any of the above hazards can occur is
called the ‘CRITICAL SPEED’.
The object of the torsional analysis is to locate
the critical speed points from the magnitude
and frequency of the disturbing forces and
ensure that damaging critical speeds are
outside the operating range of the engine and
that all is clear within +10% to -5% of the
synchronous speed.
There may be some critical speeds in the
speed range from starting speed to 95% of
synchronous speed but these could be judged
as “safe” because the critical speed is passed
through in a second or so.
However, if by application the requirement is
an “all speed” range then all critical speeds
have to be controlled within safe limits.
Gas Installation, October 1997
CRITICAL SPEEDS - CORRECTIVE
METHODS
If there is a problem with critical speeds the
position of the critical speed can be moved
and its magnitude reduced in various ways.
The first area to consider modifying would be
the stiffness of the flexible coupling. If it has
rubber elements a different stiffness of rubber
could be selected.
If a spring plate drive or spring type flexible
coupling was used it may be necessary to
change to a different type.
Other solutions could be to change the inertia
of the engine flywheel, fit a torsional vibration
damper or, if one is fitted as standard, remove
it or fit a damper of different inertia and different
damping capabilities. Occasionally, usually
with a single bearing machine application, a
tuning disc is required at the free end of the
crankshaft.
It can be seen that if there is a problem many
avenues can be explored to arrive at a
satisfactory solution. It is very rare that the
alternator shaft has to be modified.
89
TORSIONAL VIBRATION
TORSIONAL ANALYSIS DATA
Perkins Engines (Stafford) Ltd have carried
out a T.V. analysis for all the engine ranges
and models with a number of proprietary single
and two-bearing machines - mostly at 1500
rpm. Analysis at other speeds are not as
numerous.
Upon request Perkins Engines (Stafford) Ltd
will advise if an intended combination has
torsional vibration approval.
If not, and the customer wishes, Perkins
Engines (Stafford) Ltd will do the analysis on
receipt of the necessary details from the
customer.
In the case of alternators the information
required would be as Iisted below.
i) Synchronous speed.
i) Electrical output.
iii) Detail drawing of alternator shaft.
iv) Inertia of armature and exciter.
v) Inertia of cooling fan if fitted and position
on shaft.
vi) Detail of flexible coupling type to be used
or inertia of driver and driven parts,
dynamic stiffness, limits of vibratory torque
and coupling magnifier or damping factor.
or Inertia or spring plate drive for single
bearing machine.
vii) Is alternator driven from FREE END or
FLYWHEEL END of the engine?
Alternative to the aforementioned Perkins
Engines (Stafford) Ltd will supply information
of the engine dynamic system for the customer
to make his own arrangements for the
Torsional Vibration Analysis.
NOTE: SPEED OR DRIVEN EQUIPMENT
CHANGES
It often happens that one engine has been
ordered at, say,1500 rpm; delivered and put in
stock by the customer. When ordered this
engine may have been cleared to be
compatible with a certain coupling and
alternator. If, due to urgency, this engine is
allocated to drive another alternator or at a
speed different to 1500 rpm the new
combination must be re-checked for torsional
vibrations.
Besides the T.V. check the engine could need
new governor springs, a different air filter,
flywheel, turbocharger and the ignition timing
changed. To be absolutely certain contact
Perkins Engines (Stafford) Ltd Applications
Department who will provide the correct
information.
GENERATING
SET
TORSIONAL
ANALYSIS
Where an engine and alternator set has been
supplied a torsional analysis will have been
carried out by Perkins Engines (Stafford) Ltd
to ensure that the engine, flexible coupling,
torsional vibration damper and alternator are
compatible.
90
Gas Installation, October 1997
DERATING
DERATING ENGINE
May be necessary where conditions exceed
site parameters this can include ambient
temp., altitude, c/c inlet temp.
Derating means reducing of the power output
of an engine from its maximum rating at normal
temperature and pressure conditions to allow
for adverse effects of site conditions eg.
altitude and ambient temperature.
The engine is factory set to meet ISO 3046/1
standard conditions:
- Ambient temperature (at the air inlet)
25°C
- Barometric pressure
100 kPa
- Humidity (Non-turbocharged engines)
60%
Conversion figure 100Kpa = 1 bar = 1
Atmosphere = 110 metres
Should the site conditions exceed the above
conditions then the engine must be derated in
accordance with the respective engine
derating procedure.
NOTE: The maximum ambient temperature
is the temperature that can occur during any
day of the year according to records.
Should the actual site conditions be known
before despatch then the engine will be
derated at the factory, and a label attached to
the engine to that effect.
DERATING PROCEDURE
The derating procedure for gas engines is as
described in the respective engine operation
manual, together with the derating charts.
Gas Installation, October 1997
91
STARTING, STOPPING AND PROTECTION SYSTEMS
Fig. 59
92
992.2
Gas Installation, October 1997
STARTING, STOPPING AND PROTECTION SYSTEMS
Fig. 60
Gas Installation, October 1997
993.2
93
STARTING, STOPPING AND PROTECTION SYSTEMS
Starter Cables
The size of the starting cables (battery/starter
and starter/battery) based on a 2m length and
stranded copper wire are:4006/8
4012/16
2000, 3000
2 x 70 mm or 1 x 120mm
2 x 70 mm or 1 x 120mm
Resistance 0.207 OHM (600
AMPS)
AIR STARTING
The air starter motor is operated either
manually or automatically from a compressed
air supply. The working pressure at the starter
motor is 30 bar. The receiver should be sized
to give up to 6 starts under normal starting
conditions down to a minimum pressure of 17
bar.
The size of the receiver is estimated as follows:
The battery(ies) should be mounted as near
to the starter motor(s) as possible, to keep the
cable length short and minimize the voltage
drop.
The chosen position should allow for easy
access for inspection and maintenance, and
isolation from fire hazard and vibrations.
THE FOLLOWING INFORMATION
RELATES TO LEAD ACID BATTERIES
ONLY FOR NICKEL CADMIUM BATTERIES
REFER TO THE MANUFACTURERS
HANDBOOK.
Ar x Ns = Rc
dP
Rc = Receiver capacity
Ns = Number of starts
dP = Differential pressure
Ar = Free air requirement per start
NOTE: (Ar) For the 4006
" " 4008
" " 4012
" " 4016
=
=
=
=
400 litres
500 "
650 "
700 "
Based on the GALI type A25.
The air receiver(s) should meet BS
specification and be fitted with a safety valve,
pressure gauge and manual drain valve.
BATTERIES
WARNING
PERSONAL
PROTECTIVE
EQUIPMENT MUST BE WORN WHEN
TOPPING
UP
OR
CHANGING
ELECTROLYTE IN THE BATTERY, AND
NEVER NEAR A NAKED FLAME.
94
Gas Installation, October 1997
STARTING, STOPPING AND PROTECTION SYSTEMS
Preparing Battery for Service
Where a battery is supplied for the engine
starting circuit, it is dry charged.
Remove the seals from the vent plugs or
break the seal across the vent in the lid and fill
to 5/16” (8mm) above the plates with dilute
sulphuric acid of the following strength:
In temperate climates - with specific gravity
1.270
In tropical climates - with specific gravity 1.240
Battery and capacity
This varies with battery size, but current types
hold 6.7, 20.5 or 13.5 litres per battery. One,
two or four batteries are supplied according to
engine size and climate conditions.
After 10 to 15 minutes the acid level will fall
and it should be restored by adding more
acid. The battery should immediately be place
on a commissioning charge to ensure that the
acid is sufficiently mixed within the battery.
This filling wiIl cause a certain heating of the
battery due to the chemical reaction of the
sulphuric acid on the plates.
Charge at the initial charging rate given on the
instruction label until all celIs are gassing
freely and the specific gravities and voltage
remain constant for at least three successive
hourly readings.
When the initial charge is completed, the
specific gravity may require adjustment. A
fully charged battery should have a specific
gravity of:In temperate climates - 1.270 -1 285
ln tropical climates -1.240 -1.255
If adjustment is necessary continue the
charge to thoroughly mix the electrolyte in
the cells, finally adjust the level of the
electrolyte to 5/16-5/8“ (8-16mm) above the
top of the plates (i.e. level with the top of the
separators). This adjustment should be done
when the battery is standing on open circuit
and several hours after coming of charge.
The temperature of the filling acid should
never exceed 33°C (90°F).
Gas Installation, October 1997
WARNING
WHEN DILUTING
ACID, ALWAYS ADD
ACID TO WATER TO MINIMISE HEATING
AND AVOID ACID BEING EJECTED
FROM THE MIXING VESSEL. HAND AND
EYE PROTECTION MUST BE WORN.
Battery Installation
(i) Polarity check
Make sure that the positive of the battery
is connected to the positive connection of
the system and the negative of the battery
to the negative connection.
WHEN COUPLING THE BATTERIES
IN SERIES TO GIVE A HIGHER
VOLTAGE MAKE SURE THAT THE
POSITIVE OF ONE IS CONNECTED
TO THE NEGATIVE OF THE NEXT
BATTERY.
(ii) Clean connections
Clean the connecting terminals well
before fitting on to the battery. Dirty or
corroded terminals will cause bad contact
to the battery and may result in affecting
the starting current.
If the terminals are corroded, wipe over
the affected parts with a solution of sodium
carbonate or ammonia, dry off and finally
smear over a film of petroleum jelly to
prevent further corrosion. Make sure that
the sodium carbonate solution or
ammonia does not enter the cells.
95
STARTING, STOPPING AND PROTECTION SYSTEMS
(iii) Fitting into Battery Housing. (IF
SUPPLIED)
When fitting the battery, ensure that it is
secure without undue strain. The cables
to the battery must have sufficient length
and be flexible to prevent pulling and
strain on the battery terminals. In clamping
down, ensure that the clamps and bolts
are not overtightened, otherwise the
battery container may be damaged. Bolt
the terminal connections tightly to the
battery posts.
(iv) Inspection
The battery should be so installed that
inspection and topping up is facilitated.
The top of the battery and the surrounding
parts should be kept clean and dry and
free from oil and dirt. The maximum
possible ventilation should be given; this
is particularly important when the battery
is in close proximity to the engine, leading
to high battery temperature.
BATTERY CHARGING ALTERNATOR
DO NOT RUN
ENGINE
WITH
BATTERIES DISCONNECTED AS
DAMAGE TO THE ALTERNATOR MAY
RESULT.
WARNING
BATTERY CHARGER
The battery is normally charged by an engine
driven alternator, which as long as the engine
is running will give sufficient charge to fully
maintain the battery capacity to cater for
standard starting conditions. Under extremely
cold starting conditions it may be necessary
to increase the capacity of the battery.
Engines not fitted with a battery charging
alternator must have a static charger fitted,
output not less than 10 amps.
Where an engine is fitted with both an engine
driven alternator and a static charger a relay
must be fitted to disconnect the static charger
when the engine is running.
STARTING AIDS
Jacket Water Heater(s)
In extreme cold ambient temperature
conditions, besides changing to the correct
grade lubricating oil, the engine may be fitted
with a mains supply jacket water immersion
heater(s). (See Data Sheet in appropriate
engine operation manual for recommended
size of heater(s)). Fitting a jacket water
heater(s) caters for easier starting by keeping
the engine water temperature between 26.737.8°C (80-100°F).
The battery charging alternator and its
regulator operate as a system to maintain the
battery in a charged condition when the set
is running. Operation is such that a flat battery
will be charged in a minimum time and a
healthy battery will be held in that condition
by a trickle charge.
FOR DETAILS OF ENGINE CHARGING
CIRCUITS REFER TO THE ENGINE
OPERATION MANUAL.
96
Gas Installation, October 1997
STARTING, STOPPING AND PROTECTION SYSTEMS
STARTING LOADS
When starting the engine it is recommended
that the drive equipment be unloaded to make
for easier starting of the engine only, and
allow the engine to accelerate up to full speed
and develop the rated power, before applying
the load.
The above conditions are not always possible
on driven equipment such as water pumps,
compressors, stone crushers which could be
on load from start-up. This type of driven
equipment should be fitted with either a
centrifugal clutch which can take-up the drive
when the engine is developing sufficient power
to coincide with the power required.
Load Acceptance
In the case of a generating set the load that
can be applied to the engine in one step at
rated speed is limited. A genset load
acceptance on a gas engine is limited due to
constant air/fuel ratio.
The load acceptance will be stated on request
from the relevant engine manufacturer.
To achieve the above load it is essential that
the engine is kept at its normal working
temperatures by fitting heaters, and that the
correct grade of lubricating oil is being used.
(See Operation Manual).
The following information is requested by
Perkins Engines (Stafford) Ltd in order to
assess specific load requirements.
PROTECTION SYSTEM
To protect the engine from damage that could
be caused by the following:High water temperature
Low lubricating oil pressure
Overspeed
High induction manifold pressure
The engine is fitted with suitable switches
which when a pre-determined setting is
reached operate via a protection panel, an
electrical stopping solenoid which overrides
the normal methods of stopping the engine.
Protection Panel
The protection panel circuitry will, when given
a signal from the protection switches, stop the
engine either by a solenoid connected to the
solenoid valve (gas engines).
The above protection panel is in the form of a
protection module which when required is
incorporated in the various generating set
panels or mounted separately on the engine.
STOPPING
Gas engine stopped by de-energising gas
solenoid valves.
NOTE: THE ENGINE SHOULD BE RUN
FOR 5 MINUTES AT NORMAL SPEED ON
NO LOAD BEFORE STOPPING, TO
ALLOW THE ENGINE TO COOL DOWN
ADEQUATELY.
Gas Installation, October 1997
97
GOVERNOR WIRING
Governor Wiring
Certain additional item associated with the
governor e.g. speed setting potentiometer,
load sharing unit require to be wired using
screened cables.
It is important that the screen on these cables
is connected to the correct point in the
governor circuit. Refer to Maintenance
Manual Section AA for full information.
NOTE: It is essential that the speed setting
potentiometer be mounted in a cool,
vibration free position. It must not be
mounted on the engine.
DURING
COMMISSIONING
OR MAKING ADJUSTMENTS TO THE
SET IT IS ESSENTIAL THAT THE ENGINE
BE EQUIPPED WITH SEPARATE
(INDEPENDENT)
AUTOMATIC
OVERSPEED PROTECTION IN ORDER
TO GUARD AGAINST SEVERE ENGINE
DAMAGE, WITH CONSEQUENT
DANGER TO LIFE AND LIMB OF NEARBY
PERSONNEL.
WARNING
98
Gas Installation, October 1997
OVERALL DIMENSIONS AND WEIGHT
936
927.5
956
645
72
908
64
124
1863.5
220
552
1625
1561
2616
-
3250
4008TESI
2241
mm
956
mm
mm
645
72
mm
mm
908
64
mm
mm
124
1447.5
mm
mm
220
543
mm
mm
1625
1552
mm
mm
mm
KG
2100
ENGINE
4006TESI
A
Gas Installation, October 1997
WEIGHT
DRY
Fig. 61
TYPE OF
NOTE:
FIG. 61 IS INTENDED AS A GUIDE ONLY,
SINCE THE DIMENSIONS SHOWN COULD
ALTER WITHOUT PRIOR NOTICE.
2200
O
N
M
L
K
J
H
G
F
E
D
C
B
8 HOLES O 22
HOUSING SAE 'OO' FLYWHEEL SAE 14
1825
P
mm
BASIC 4006/8TESI MINNOX GAS ENGINE (SINGLE EXHAUST)
758.2
99
OVERALL DIMENSIONS AND WEIGHT
175.5
mm
mm
573
1210
mm
mm
386.4
1778
mm
mm
472
2650.5
mm
mm
399
1000
mm
mm
70
130
mm
mm
235.4 1789.5
mm
mm
646
1868
mm
mm
mm
mm
KG
5665
ENGINE
4012TESI
WEIGHT
A
TYPE OF
DRY
100
2232
K
J
H
G
F
E
D
C
B
6 HOLES O 22
Fig. 62
3874
O
N
M
L
8 HOLES O 22
NOTE:
FIG. 62 IS INTENDED AS A GUIDE ONLY,
SINCE THE DIMENSIONS SHOWN COULD
ALTER WITHOUT PRIOR NOTICE.
3350
T
S
R
P
HOUSING SAE 'OO'
FLYWHEEL SAE 18
BASIC 4012TESI MINNOX GAS ENGINE (TWIN EXHAUST)
754.2
Gas Installation, October 1997