A UTC Fire & Security Company
The Design and Construction
of Fire Fighting Monitors
Fixed and Mobile, Manual and Remote Control, Water and Foam
Introduction
Monitors spend most of their lives static and
lifeless. But when a fire is detected they can
often be the only practical way of applying
foam or water to the fire.
While simple in principle, monitors are
sophisticated pieces of engineering made to
deliver a specific performance after long
periods of inactivity. Like many engineering
challenges the design of a monitor can take
many forms depending on the specific
hazard it is intended to protect and the
mechanism and method of operation the
designer uses to achieve the final layout.
When designing a monitor the manufacturer
must balance performance, operational life
and ease of use against cost.
The installation of fixed monitors, or the
provision of mobile or portable monitors, is
usually the outcome of a careful analysis of
the fire risk and the realisation that without
planning in advance fighting any subsequent
fire will present difficulties. It is essential
therefore, that monitors are robust and will
have a long service life, even under adverse
conditions.
2
Applications
Fixed monitors are found wherever there are substantial
Class B fire risks while mobile or portable monitors are
often used to protect multiple risks by moving the
monitors around the site.
Nearly all industrial fire hazards are candidates for
monitor protection, but some of the more common
applications are:
• Refineries
• Fuel distribution depots
• Chemical plants
• Warehouses
• Helicopter landing pads
• Aircraft hangars
• Loading jetties
• Process plants
• Industrial process areas
• Shipping
• Vehicle-mounted
Fixed or mobile?
While many monitors are permanently fixed to pipework
and designed to protect specific installations, it is
sometimes more convenient to mount monitors on
trailers that can be moved from hazard to hazard. In
addition, smaller monitors can be designed to be moved
by hand and placed on the ground to provide a rapid
response in the event of a fire. However, mobile
monitors require a water supply, usually provided by
hoses or portable pumps.
The jet reaction force for a portable monitor can vary
from a few kg, for a small ground monitor, to over a
tonne for a larger trailer-mounted unit. Any portable
monitor must be secured so that it cannot move once the
full water flow and pressure is applied.
Small, hand-wheel portable monitors are specifically
designed to be easy to manoeuvre and carried over
rough terrain. To resist the jet reaction forces portable
ground monitors are provided with a method of
stabilising them on soft ground.
Larger monitors are usually mounted on trailers. In
addition, the trailer is often fitted with outriggers to
provide stability. Water tanks on the trailer can be filled
to provide additional weight for stability. Extra tanks can
also be specified to provide foam concentrate.
Angus monitor with optional foam induction system anchored on
soft ground with bipod mechanism
Angus trailer-mounted monitors with self-inducing foam cannons
Trailer-mounted monitors provide a useful addition to the armoury of equipment a fire service can draw on should a
large fire occur. The mobile monitor can be used to protect locations inadequately covered by fixed monitors or provide
cooling to equipment adjacent to the fire.
3
Monitor Design
Design is always a compromise
Bearings
The layout of the pipes that make up a monitor must
serve several functions. They must contain the water
while allowing the jet to be moved in both the
horizontal and vertical planes; they must be strong
enough to resist the pressure and reaction forces
generated by the water; and they must be robust
enough to allow the mounting of additional items such
levers, gearboxes, hydraulic actuators and nozzles. All of
this must be achieved with a design that is cost effective,
has an acceptable pressure loss, will resist corrosion and
is not too heavy. Like many engineering designs a typical
monitor is a compromise between cost, weight and
performance.
The normal practice is to
support the two parts of
a monitor, where it
moves in the horizontal
or vertical plane, using a
double ball race. A shaft
seal is positioned
between the ball races
and the waterway to
retain the water under
pressure. Plugs are
machined into the outer
casing to allow the ball
bearings to be inserted
during the
manufacturing process
and can be fitted with
grease nipples to allow
lubrication during
manufacture or
maintenance.
Pressure losses
If too much water is forced around too many tight bends
at too high a speed there will be an unacceptable
pressure loss between the monitor inlet flange and the
nozzle. The result will be that the water or foam jet will
not travel as far as it could. Some designs use a very
compact layout forcing water to turn 90° bends and
splitting the water into two paths which meet again at
the outlet. While the dual path waterway layout is
compact its pressure losses can be unacceptable where
the supply pressure is limited.
Monitor type
Pressure loss at
1000 l/min
Typical nozzle
throw
Single waterway
fabricated
stainless steel
0.2 bar (3.0 psi)
38 m
Single waterway
cast bronze
0.3 bar (4.5 psi)
37 m
Dual path waterway 1.0 bar (15 psi)
cast aluminium
33 m
In addition, the turbulence created when the two water
streams meet usually adversely affects the nozzle
performance and limits its range still further.
Waterways manufactured from cast bronze usually have
tighter bends than those manufactured from steel since
it is difficult to fabricate tight bends in steel tube. As a
result, stainless steel monitors generally have a lower
pressure loss than the equivalent cast bronze monitor
while the dual waterway designs have the highest
pressure losses of all.
Water takes on a spin when negotiating the bends in a
single or dual waterway pipe. By the time it has
negotiated both the horizontal and vertical joint bends
the spin generated can cause a reduction in throw. The
spinning water expands the jet stream creating greater
friction as it passes through the air. To reduce the spin
cast bronze or iron waterway monitors often have vanes
or blades cast into the tube to reduce the spin in the
water stream.
4
Sharp bends and merging flows
cause turbulence
Some designs include a second seal to prevent dirt and
dust entering the bearing assembly. However, this can
cause difficulties since the bearing chamber becomes a
sealed space with no room for expansion.
Like most engineering designs the layout of the bearings
is a compromise. The wider apart they are the lower the
forces on each bearing race. However, widening the
bearing spacing also increases the overall size of the unit.
To resist the loads steel balls are used. These are normally
a high grade stainless steel such as SS316. When the
monitor body is bronze the steel balls rest in tracks
machined into the casting. However, when the monitor is
fabricated from stainless steel pipe and the bearing
tracks are incorporated into the fabrication it is essential
to select a material for the steel balls that does not react
with the steel of the bearing races or the balls may “pick
up” causing the bearing to seize.
INCREASED
TURBULENCE
NOZZLE
NO VEINS
VANES
TURBULENCE
TIGHT BENDS
SWEEPING BENDS
Flow straightners in pipe reduce water stream turbulence and rotation
Ball Bearings
Nozzle flow
at 7 bar
Total reaction
force at tip
Typical side force on
monitor handle with
5° of misalignment
in the horizontal plane
2,000 l/min
140 kg
6 kg
4,000 l/min
240 kg
11 kg
6,000 l/min
310 kg
14 kg
8,000 l/min
425 kg
19 kg
Shaft Seal
Fitting Plugs
for Bearing
Insertion
Misalignment is more common in fabricated monitors.
Unless great care is taken during the welding, and special
techniques and jigs are used, the welded pipes can easily
distort.
A worm and wheel gearbox drive is generally used for
control in the vertical and horizontal planes for monitors
where the flow is 3,000 l/min or more.
Gearbox actuation
Reaction forces
It is important to arrange the layout of a monitor so that
the thrust or reaction force caused by the water leaving
the nozzle or foam cannon is directed through the pivot
point in both the horizontal and vertical planes.
Control of the vertical and horizontal movement using a
worm and wheel gearbox is recommended for two
reasons. Firstly, it is easy for the operator to set the
monitor in position. The handle loads are low and
control is precise. Secondly, a worm and wheel gearbox,
if correctly designed, will resist any out of alignment
forces.
Provided the worm drive angle is less than 20° it is
possible for the worm to drive the wheel, but it is
impossible for the wheel to drive the worm due to
friction in the gearing. The mechanism is therefore
intrinsically safe and any out-of-balance forces in the
monitor cannot move it off target.
Out-of-balance forces cause the monitor to rotate or move out
of alignment
If the monitor is distorted and the reaction force does
not pass through the pivot there will be a sideways or
vertical force on the monitor. If the out-of-line force is
not restrained the monitor will tip up or down or spin in
the horizontal plane. The consequences of this can be
serious. If the monitor is spinning, often the only way to
stop it may be to turn off the water at its base. If over 80
kg of monitor body is spinning at 2 or 3 revolutions per
second it can be dangerous to climb underneath the
spinning body to turn off the water! It could also
damage or bend the pipework or other structures.
The forces exerted by the jet are considerable and even a
minor misalignment can result in a large side load. If at
the same time there is a side wind acting on the monitor
it is possible for the load on the handle to be too much
for the operator to manage.
Non-reversible worm drive makes it easy to steer and holds the monitor
in position
5
Construction
The materials most commonly used are steel in the form
of fabricated tube or cast bronze, but aluminium and
cast steel or iron are also available.
Fabricated steel
High quality steel monitors are normally fabricated from
grade SS316 stainless steel tube, although some are
fabricated from the lower grade SS304 to reduce cost but
these suffer corrosion problems in coastal areas and
should not be used with seawater. Steel monitors usually
have a larger footprint and are physically higher than
cast units because of the limits imposed when bending
the tube. It is impossible, when bending steel tube, to
achieve the tight bend radius possible with a cast unit.
However, the larger radius bends have the advantage
that the water pressure losses are lower with fabricated
stainless steel monitors when compared to cast bronze.
Typical performance comparison
Material
Nominal
pipe size
Flow at 7 bar Pressure
inlet pressure
loss
Cast bronze
80mm (3”)
4,000 l/min
3.5 bar
Stainless steel
80mm (3”)
6,000 l/min
0.9 bar
However, when comparing stainless steel with bronze
monitors with similar flow rates bronze units are
substantially heavier.
Typical performance comparison at similar flow rate
Material
Cast bronze
Stainless steel
Nominal
pipe size
Flow at 7 bar
inlet pressure
Weight
90mm (31/2”)
6,500 l/min
76 kg
80mm (3”)
6,000 l/min
35 kg
Low cost monitors or monitors intended for applications
where corrosion is not a problem can be fabricated from
mild steel tube. The steel is sometimes galvanised to
provide some protection against corrosion, although a
painted finish is often used to reduce cost.
Fabricated steel monitors present additional challenges
during manufacture. When the monitor is to be moved
using a gearbox, or a geared drive using hydraulic or
electric motors, it is necessary to join together thin wall
tube and robust cast or machined components of widely
differing thicknesses. This can lead to distortion and
stresses during the manufacturing process unless the
fabricator is experienced or sophisticated jigs are used.
Where a monitor is made from mild or stainless steel
tube it is important to ensure the ball bearings used in
the joints are compatible with the grade of steel used or
the bearing may fail under load.
Cast bronze
While cast bronze monitors are heavier and generate
slightly greater pressure losses for a given nominal pipe
diameter they are usually more compact and robust than
fabricated steel units. However, there is a wide range of
materials which are called “bronze” and it is important to
determine the specification of the material used when
judging strength and corrosion resistance.
Nearly all cast bronze monitors use double race bearings
incorporating steel balls for the horizontal and vertical
joints. If the bearing is carefully designed to spread the
load, and if the bronze is hard enough, it is usual to allow
steel balls to run in grooves machined directly into the
bronze casting. This layout has the advantage of simplicity
and will provide a long life if correctly maintained.
A standard published by FM Global calls for monitors to
have free movement in their bearings when subjected to a
pressure of 35 bar, having previously been subjected to a
static pressure of 58 bar. The end load on a bearing in a
150mm (6”) monitor subjected to this pressure is over
10,000 kg or 10 tonnes! To prevent the steel balls denting
the bronze bearing face it is usually necessary to
incorporate steel bearing surfaces inside the bronze castings
to withstand the test load. This can lead to extra cost and
corrosion problems in the long-term where the steel meets
the bronze. In practice, monitors are rarely subjected to
pressures greater than 16 bar. As a result, many
manufacturers prefer to design to the UL standard or the
new European EU standard.
Flanges and material strength
While some monitors used in Europe are fitted with PN16
European standard flanges, most monitors are supplied
with US ANSI flanges. ANSI flanges come in two basic types,
flat faced (FF) and raised face (RF). The full designation also
indicates the maximum working pressure for the flange.
For example a ANSI 4” 150 RF flange is a raised face flange
to fit a 4” (100mm) nominal diameter pipe and designed to
be operated at a maximum operating pressure of 150 psi
(10 bar). Because a raised face flange, when tightened up,
exerts a greater force on the gasket contact area than a flat
faced flange, raised face flanges can be used at greater
pressures than flat faced. However, if the material used for
the flange is not strong enough the flange will distort
when bolted up. Therefore, when selecting a material for a
monitor the style of flange and the working pressure
needed must be taken into account.
In general steel monitors use steel flanges. These can always
be raised face since steel is strong enough not to distort at
pressures used in fire fighting. However, leaded bronze or
gunmetal, with its superior corrosion resistance, is relatively
soft and cannot always be used for a raised face flange
which in turn can limit its pressure rating.
Brass tube
Brass tube is the weakest of all fabrication materials used
for monitors and it is limited in size because it is not
strong enough to resist the reaction forces from a large
water jet. In addition, it is impractical to operate the
monitor using a gearbox because of the difficulties of
attaching the gearbox mechanism to the tube. As a result
it is only used for small, hand-operated units.
6
Flat Face
Raised Face
Raised Face (soft material)
Soft materials are unsuitable for raised face flanges
One solution is to increase the thickness of a bronze
flange to give it sufficient strength to be machined as a
raised face flange and bolted up to the recommended
torque.
Materials
To resist heat and have sufficient strength monitors are
made from different metals.
While the basic materials, namely iron, aluminium and
copper, can be used in their natural state it is more
common to create alloys or variants of the basic metal to
improve their strength, corrosion resistance and their
ability to be cast or formed.
Iron is cheap and easy to cast. However, it is heavy and
can be brittle if the carbon content is too high.
Corrosion is a problem and it is normal practice to
increase the wall thickness of components to allow for
corrosion, which adds more weight.
Aluminium is light and easy to cast. However, its
strength is low. Corrosion is a major problem and
components made from aluminium must be protected by
anodising (a chemical process which puts a hard layer of
Aluminium Oxide on the surface) or painting. Both
processes, if applied well, provide a hard coating which
separates the water from the metal. However, once the
surface coating is scratched corrosion sets in quickly and
cannot be reversed.
Copper does not have the strength necessary for
monitors. It is also soft, which can lead to damage if the
monitor is knocked. Copper is also too soft to work as a
flange material. Corrosion resistance to salt water is poor.
Material
Grey cast iron
Mild steel strip
Stainless steel (SS316)
Aluminium (casting grade – with Copper)
Copper (annealed)
Brass (Copper with Zinc)
Bronze (Copper with Tin)
Leaded Brass (Copper with Zinc and Lead)
Gunmetal or Marine Brass
High performance Bronze (Nickel Aluminium Bronze)
BS EN 1982
Copper
Cu
Zinc
Zn
Brass (Copper & Zinc) is popular for small, low cost,
monitors but suffers from many of the same problems as
Copper.
Bronze comes in many forms and is the most popular
material for manufacturing long lasting cast monitors.
Simple Bronze is made from a mixture of Copper and Tin.
However, while it is easy to cast and machine, it can be
weaker and harder than Brass.
Nickel Aluminium Bronze is much stronger and an
ideal material. However, it is expensive to cast and costly
to machine. UK standards AB1-C and AB2-C for
Aluminium Bronze (AB2 contains extra Iron and 5%
Nickel) have been superseded by European specifications
CC331G and CC332G. Nickel Aluminium Bronze is
generally used for marine propellers, hubs and valves in
permanent contact with sea water and subject to
continuous abrasion. These conditions do not generally
apply to monitors.
Gunmetal, with its added Lead, has excellent corrosion
resistance but is not as strong as Aluminium Bronze. It is,
however, easy to machine. In the UK two grades of
Gunmetal are in common use, LG2 and LG4. Both these
designations are now renamed as CC491K and CC492K.
Bronze standards in common use
European standard BS EN 1982 is the new European
standard for Copper alloy and Bronze specifications. It
replaces the UK standard BS1400 and other national
standards such as UNI in Italy. US specifications for
Bronzes do not match European standards. However, for
most of the European Bronzes in common use there is a
close match with the US ASTM standard bronzes.
Symbols
Fe + C + Si
Fe + C
Fe + Cr + Ni + Mo
Al + Cu
Cu
Cu + Zn
Cu + Sn
Cu + Zn + Pb
Cu + Zn + Sn + Pb
Cu + Al + Fe + Ni
Lead
Pb
Tin
Sn
Tensile strength
275 MPa
300 – 500 MPa
480 – 600 MPa
250 – 360 MPa
210 MPa
285 – 400 MPa
250 – 310 MPa
215 - 400 MPa
200 – 250 MPa
300 – 750 MPa
Aluminium
Al
Iron
Fe
Nickel
Ni
Manganese
Mn
Alloy Type
BS 1400
(old)
High Tensile Brass
HTB3-C
CC762S
63.0%
25.0%
5.0%
3.0%
4.0%
High Tensile Brass
HTB1-C
CC765S
61.0%
35.0%
1.0%
1.0%
2.0%
Copper Tin Nickel
CT2-C
CC484K
86.0%
Leaded Gunmetal
LG1-C
CC490K
84.0%
8.0%
5.0%
12.0%
3.0%
2.0%
Leaded Gunmetal
LG2-C
CC491K
85.0%
5.0%
5.0%
5.0%
Leaded Gunmetal
LG4-C
CC492K
88.0%
2.0%
3.0%
7.0%
Leaded Bronze
LB4-C
CC494K
86.0%
9.0%
5.0%
Leaded Bronze
LB2-C
CC495K
80.0%
10.0%
10.0%
Leaded Bronze
LB1-C
CC496K
78.0%
15.0%
7.0%
Leaded Bronze
LB5-C
CC497K
75.0%
20.0%
5.0%
Aluminium Bronze
AB1-C
CC331G
88.0%
10.0%
2.0%
Aluminium Bronze
AB2-C
CC333G
80.0%
10.0%
5.0%
7
Materials
Country
Leaded Gunmetal
Europe
USA
Italy
Aluminium Bronze
USA
Europe
Designation
Copper
Cu
Zinc
Zn
Lead
Pb
Tin
Sn
CC491K (formerly BS LG2)
ASTM B30 C83 600
UNI 7013
85.0%
85.0%
83.0%
5.0%
5.0%
4.0%
5.0%
5.0%
6.0%
5.0%
5.0%
7.0%
ASTM B30-C95 800/500
CC333G (formerly BS AB2)
78.2%
80.0%
Aluminium
Al
Iron
Fe
Nickel
Ni
Manganese
Mn
9.4%
10.0%
5.5%
5.0%
5.5%
5.0%
1.4%
Note: the percentages of different materials shown in the table are all subject to tolerances. For example, the quantity of Zinc in the European standard
leaded Gunmetal, CC491K, is shown as 5% but can be anywhere between 4% and 6%. This means that materials which are shown as having slightly
different compositions can be identical in practice when the tolerance bands are taken into account.
When specifying a material for monitor production it is necessary to trade off the excellent corrosion protection of the
Lead in Gunmetal against the extra cost and strength of Aluminium Bronze.
Steel
Mild or ???? steel is used in the form of tube for low cost
monitors. Like Aluminium it must be protected against
corrosion by painting or galvanising. Like Aluminium,
once the coating has been damaged, corrosion spreads
quickly. While the material is low cost it presents technical
difficulties when being welded as distortion can occur
where there are rapid changes in section (typically where
the thin wall section joins a bearing housing).
International standard
Grade
SS301
SS302
SS304
SS305
SS309
SS310
SS315
SS316
SS317
SS320
SS321
SS403
SS409
SS410
SS420
430
434
Cr
18%
18%
18%
23%
25%
17%
17%
18%
17%
18%
13%
12%
12%
13%
17%
17%
Constituents
Ni
17%
9%
10%
12%
14%
20%
10%
12%
13%
12%
10%
Mo
7%
1.5%
2.5%
3.5%
2.5%
Stainless Steel, next to Bronze, is the most popular
material for fabrication of both small and large monitors.
SS316 is generally considered the best grade of Stainless
Steel for monitors since it combines excellent corrosion
resistance with good welding and fabrication features.
However, to save cost some manufacturers use SS304.
Corrosion resistance
Applications
*
**
**
**
**
**
****
****
*****
****
**
**
**
**
**
***
**
Springs, structural and wear parts
Kitchen sinks, water tubing
Food processing equipment
Spun parts
Heat exchangers
Heated and electrical parts
Sections and dying plant
Monitors and process plant
Thick section process plant
Thick section chemical plant
Heater elements and aircraft parts
Turbine blades
Exhaust parts
Gas turbine parts
Kitchen knives
Decorative houseware
Car trim, wiper blades
* Low corrosion resistance ***** Extremely high corrosion resistance
International material standards
Most countries with an industrial base have standards for
materials which specify their composition and
performance. The most common standards in use are the
US ASTM standards and the European EN standards.
However, many other countries have standards including
Italy, Germany, India and Japan.
Comparing materials from one standard to another is
often difficult. However, the US ASTM B62 (also known
as leaded red brass) is equivalent to EN 1982 CC491K (the
old BS1400 alloy LG2) and the Indian specification IS:318
– LTB2. In Europe SS316 stainless steel for sheet and rod
is equivalent to the American ASTM A497.
Applications in chemically hazardous areas
Bronze is preferred by most users, particularly if the
monitor is used for sea water or in coastal salt laden
atmospheres, but other materials have advantages when
other chemicals are present.
8
If Hydrogen Sulphide is present Bronze can blacken and
corrode. Hydrogen Sulphide can be a by product of
Methane and Propane production. For these applications
stainless steel is the preferred material.
Salt (Sodium Chloride) and water (H2O) can combine,
especially with heat from strong sunlight or processes, to
form Hydrogen Chloride. Hydrogen Chloride is also used
in chemical plants for pH control and cleaning. Hydrogen
Chloride attacks steel, including stainless steels such as
SS316. Where Hydrogen Chloride is present Bronze
monitors are preferred.
Salt also attacks Aluminium or light alloy and while
Aluminium is a good material for monitor production, as
it is light and low cost its resistance to salt corrosion is
poor. Over a period of time salt will turn the metal
surface to a white powder if it is not protected and the
monitor regularly flushed with clean water after use and
kept out of salt laden atmospheres.
Remote Actuation
In many applications it is necessary to operate a monitor
remotely. To do this motors are fitted to move the
monitor body in the horizontal and vertical planes. In
addition, if the monitor is fitted with an adjustable
nozzle this will also need to be moved with a motor or
actuator. Remote control monitors will often need to
meet the standards for operation in an area subject to
explosive gases such as ATEX in Europe or NEC in the
USA. Some applications require a master panel and slave
panel arrangement, while others require feed back to
show the operator where the monitor is pointing so that
it can be operated even when smoke obscures the view.
Disadvantages:
• Can be expensive if explosion proof motors necessary
• Secondary panels in an explosion area need to be
contained in explosion proof casings
MAIN
UP
RIGHT
DOWN
NOZZLE
VALVE
OPEN
Hydraulic drive
POWER ON
FAULT
MONITOR
LEFT
FULL
TAG
FAULT
UP
Hydraulic motors have the advantage of low cost,
simplicity and are usually explosion proof.
FULL
POWER ON
MONITOR
DOWN
LEFT
RIGHT
NOZZLE
FOG
CLOSE
Optional secondary control
station housed in explosion
proof enclosure
FOG
Advantages:
• No need to use limit switches on the motors. When
they reach the limit of travel they will simply circulate
the hydraulic fluid without damage
• Reliable, low cost and easy to maintain
• Option of a water driven hydraulic power pack means
the system does not need an electrical supply
1500m
Hydraulic/electric systems
For some applications hydraulic/electric systems are
preferred. In these the monitor is moved using hydraulic
motors but the hydraulic power is provided by individual
hydraulic power packs mounted at the base of the
monitor. The power packs are generally explosion proof.
Hydraulic
control panel
with electric
driven
hydraulic
power pack
Hydraulic
control panel
with water
driven
hydraulic
power pack
MAIN
UP
OPEN
TAG
UP
200m
FULL
Disadvantages:
• No facility for a secondary panel
• No facility for position indicators
POWER ON
MONITOR
DOWN
LEFT
• General limited to 300 m maximum distance between
the monitor and control panel
RIGHT
DOWN
FAULT
Water
POWER ON
FAULT
MONITOR
LEFT
FULL
RIGHT
NOZZLE
NOZZLE
VALVE
FOG
CLOSE
Optional secondary control
station housed in explosion
proof enclosure
FOG
1500m
The advantages of this arrangement are that it combines
the benefits of using hydraulic motors with the benefits
of electrical control panels, retaining the option of a
slave panel and no distance limitations between the
master panel and the monitor.
Electric drive
Distance limitations
Electric motors must have a mechanism to stop the
current when they reach the limit of travel or they may
burn out. Modern positioning encoders and electronic
controls are replacing the more traditional overload
protection devices.
There is a limit to the distance it is practical to run
hydraulic pipes. If the distance is too long there can be
problems with friction in the pipes. If the pipe size is
increased in diameter to reduce friction the cost
increases, and there can be problems with air in the
pipes. Both air and friction will cause the movement of
the monitor to be sluggish or erratic.
Advantages:
• Possible to have a master and slave panel arrangement
• Built in encoders will show monitor position if required
• Distance between the monitor and master panel is not
limited
Alternatively an electrical supply can be run almost any
distance. Generally a Zone 1 explosion rated multi core
electrical cable is cheaper than the equivalent multi tube
hydraulic pipe.
Hydraulic pipe Electric cable
Maximum practical distance 300 to 400 m
between panel and monitor
1,500 m
9
Remote Actuation
Nozzle and Cannon Design
Explosion proof panels
Two types of nozzle are generally fitted to monitors.
Fog/Jet nozzles which can be adjusted to give either a
straight jet or a wide spray water or non-aspirated foam
fan, and foam cannons or nozzles specifically designed for
throwing aspirated foam by entraining a quantity of air
into the stream.
It is normal to mount the
master electrical panel in
a safe area with the
secondary panel, near
the monitor, contained
in a explosion proof
enclosure. Where the
panel is hydraulic it is
necessary, if it is
positioned in the risk
area, to ensure both the
hydraulic power pack
and the panel are
explosion rated.
TAG
FAULT
UP
DOWN
LEFT
FULL
POWER ON
MONITOR
RIGHT
NOZZLE
FOG
Where it is not considered good practice to have an
electrical supply to the monitor it is possible to use water
pressure to power a Pelton wheel driven hydraulic pump.
In this way it is possible to install a remotely controlled
monitor which is totally independent of an electrical
supply and intrinsically safe for zone 1 areas.
Position indicators
Some systems require the position of the monitor, its
direction and elevation to be indicated on the master
control panel. This can be useful when the area is
obscured by smoke as they allow the operator to point
the monitor at a specific target even though it cannot be
seen.
Most electrically driven monitor designs can be fitted
with encoders on the horizontal and vertical movements
which send a low voltage signal (intrinsically safe) back
to the control panel where the position is shown on a
dial.
X
Manual override
Many specifications require the ability to manually
operate the monitor in both the horizontal and vertical
planes in the event of a complete power failure.
However, the addition of hand wheels also adds to the
cost and complexity of the system.
10
Fog/Jet Nozzles are generally manufactured from brass,
bronze or aluminium. The simplest designs are adjusted by
hand while hydraulic or electrical actuation is employed
for remote control monitors. The design is simple in
principle and uses a plunger in the nozzle stream to force
the water into a straight stream when the outer casing is
extended, and into a wide jet when retracted. It is normal
to use either water or foam solution in a Fog/Jet nozzle.
However, the degree of air entrapment in a foam stream is
limited to the small amount of air that is trapped in the
stream once it leaves the nozzle, which limits the foam
expansion that can be achieved and reduces the stability
of the foam once loaded.
Throw Calculations
Foam cannons are usually not adjustable and will only
provide a straight jet. To generate expanded foam an
orifice in the pipe entrance is used to generate a low
pressure area and draw air into the foam stream. Foam
expansion ratios of up to 8:1 are common.
Cannons are traditionally manufactured from stainless
steel (SS316) for the expansion tube and bronze for the
tube base. The design and shape of pipe end is critical
for generating a coherent and tightly packed foam
stream. If the foam stream diverges, not only does it pick
up more air and expand, but its range will be less.
CURVED LIP CAUSES JET SPREAD
SHARP LIP MAINTAINS JET LINEARITY
Self-inducing nozzles and cannons
For some applications it is convenient to fit the nozzle or
branchpipe with an orifice and pick up tube which, when
the water is flowing through the nozzle, will suck up
foam concentrate from a container. Foam pick-up tubes
should not be placed more than 4 to 6m from the nozzle
or the efficiency of the inductor mechanism will be
impaired and the foam mix may be affected. The energy
needed to pick up the foam will have a small but
noticeable negative effect on the maximum throw.
Distance travelled
The distance a jet of water or foam solution will travel is,
in theory, simple to calculate. If the flow of water
through the monitor, typically in litres/minute, is known
and this is divided by the cross sectional area of the
nozzle, the speed of the jet can be calculated. If it is
assumed that there is no atmospheric drag then the
optimal angle for the jet is 45°. This is easier to
understand by taking the two extremes. If the jet were
to be pointed straight up (90º) it would not travel any
distance horizontally and would fall back to ground
where it started. If the jet were fired horizontally (0º) it
would hit the ground almost immediately and once
again travel no distance. Half way between 90º and 0º,
or 45º, gives the maximum distance that can, in theory,
be travelled horizontally before gravity pulls the jet
down to the ground. For a monitor flow of 6,000 l/min
with an effective nozzle orifice diameter of 6 cm, the exit
velocity from the nozzle is 35 m/sec. If the nozzle is at an
angle of 45º the vertical and horizontal components of
the velocity are 25 m/sec. Gravity will slow the jet by 9.8
m/sec for every second the jet is in the air. Therefore, the
time that will elapse before the vertical jet stream hits
the ground is just under 5 seconds (2.5 seconds upwards
and 2.5 seconds downwards). During this time the jet will
travel horizontally for 5 seconds at 25 m/sec or a
theoretical distance of 125 m before hitting the ground.
However, in real-life air resistance and other dynamic
effects make the actual distance much shorter, typically
80 m, or 50% to 60% of the theoretical distance
achievable.
theoretical throw
actual throw
50%
60%
100%
Air resistance
The major influence on jet travel is air resistance. As the
water jet leaves the nozzle it breaks up into droplets,
each one of which behaves as a small ball travelling
through the air. The smaller the droplets, the wider the
spread of the jet, the greater the air resistance and the
shorter the throw. Not only is there resistance through
the air but the jet is subject to wind, either from the side
or head on. Even a small air movement will make a
significant difference to the spread of the jet and the
throw of a nozzle.
Air resistance increases as a square of the water droplet
speed. Therefore, the jet slows at a greater rate when it
first leaves the nozzle than when it is close to hitting the
ground at the end of its travel. Because of this effect the
optimum angle for achieving the maximum throw or
distance is not 45° but nearer 32°.
Water jet and self-inducing foam cannon mounted on a single monitor
body. Linked change over valves direct the water flow to the jet or the
cannon
11
Throw Calculations
Water, Foam & Powder
Foam in the jet stream
Water
Foam, especially aerated foam from an aspirating cannon
increases the area of the jet stream and therefore the
theoretical air resistance. However, in practice it can have
the opposite effect. Modern protein-based foam (FP or
AR-FFFP), is cohesive and sticks to itself, increases the
droplet size. This has the effect of binding or coalescing
the foam stream into a “rope” helping the jet to punch
through the air with reduced surface area and therefore
reduced resistance. As a general rule a modern FP or ARFFFP protein-based foam in the jet stream, provided it is
not expanded above 10:1, can increase the maximum jet
throw by around 5%.
Where the primary function of a monitor is cooling, dust
control or water jetting the only considerations are
whether the water is potable, brackish or seawater. If salt
is present then a bronze or SS316 stainless steel monitor
is required. Mild steel and light alloy will be quickly
attacked by salt, severely reducing the working life of
the product, leading to high maintenance and unreliable
operation.
However, synthetic based foam like AFFFS can have the
opposite effect. The detergent bubbles slip and slide over
one another and have no cohesive effect on the jet. This
results in a jet more likely to spread out, increasing wind
resistance. In addition, synthetic foam is often seen
falling short with wider levels of dropout between the
monitor and the target, resulting in less foam reaching
its destination. High performance ARAFFFS with their
polymer additives help detergent foams behave more
like protein based products.
Depending on the application either a fog/jet nozzle or a
simple water cannon for maximum throw is adequate for
water alone.
Distance or foam quality?
It is possible to design a foam cannon that will maximise
the distance the jet will travel. However, it is important
to ensure that the foam quality generated is good
enough to extinguish a fire. Unfortunately cannons that
generate foam with the best expansion ratios and
drainage times are not the same designs that will throw
the longest distances. It is essential when comparing
cannons and monitors to ensure that distance claims are
backed up with foam quality tests. Distance alone is
almost always achieved at the expense of foam quality,
in some cases to the point where the foam delivered will
be inadequate for effective fire fighting.
How far will the jet travel?
Unfortunately there are so many conflicting effects that
come into play that it is difficult to predict with any
degree of accuracy how far a given combination of
monitor, nozzle and foam will throw or what height the
jet will clear. Not only are there the effects of nozzle
design but wind, foam type, self-inducing pressure losses
and the general condition of the equipment will all
affect the distance travelled. Figures given in data sheets
must of necessity be taken as an approximate guide to
the best that can be achieved under ideal circumstances.
Where cooling is the objective it is important to ensure
that the correct quantity of water can reach the hazard
after taking into account obstructions.
Foam
The majority of monitors are used to place foam on to a
fire or fire hazard. The monitor design, its throw and jet
height are critical to ensure the foam can reach its target
while still maintaining adequate quality in terms of
drainage time and expansion ratio.
Modern FP, ARFFFP or ARFFF foams are preferred since
they enhance the throw of the jet and minimise dropout
and wastage. They also minimise fuel pick up from
forceful plunging and provide superior burnback
resistance with longer post-fire security.
Most monitors are designed to produce their optimum
performance using only one manufacturer’s foam. Where
the monitor producer does not manufacture foam then it
can be difficult to determine performance in the field.
Powder
The use of fire fighting powders is particularly useful
where pressurised gas and liquid leaks may occur.
Because of the nature of these hazards it is essential to
choose the correct powder. For powder applications
specialist assistance is recommended from the
manufacturer at an early stage in the specification of the
monitor and powder cannon but Monex is the discerning
choice by many leading class B, C, E fire professionals.
Allowances need to be made for prevailing conditions
during use that can reduce the distance travelled
through no fault of the monitor, nozzle, induction
system or foam concentrate being used.
Fluorprotein-Based Foam
Synthetic-Based Foam
Angus Colossus large-capacity aspirating foam monitor
12
Explosion Proof Rating
Many monitors are sited in areas where flammable
liquids or gases are processed, stored or transported.
While there is little risk of explosion when the liquids
and gases are contained, it must be assumed that there is
a risk of explosion if there is a breakdown, an emergency
release or sudden ignition. To allow for this,
specifications normally call for monitor and monitor
control systems to be manufactured to international
explosion proof standards such as ATEX (ATmosphères
EXplosibles) or NEC (National Electrical Code) in the USA.
Therefore, for a monitor used to protect a Zone 1 area,
for example a hydrocarbon loading jetty, the ATEX
approval should read: CE Ex II 2 II EEx d T4.
Note: The ATEX classification system only applies to
equipment containing electrical components or
apparatus which could cause a spark or become hot and
can cause ignition and a subsequent explosion.
Equipment which is only mechanical and cannot cause a
spark or produce sufficient heat to ignite gas cannot be
ATEX approved.
Most fire fighting equipment will be sited in:
“A place in which an explosive atmosphere is likely to
occur in normal operation occasionally.” These are
classed as Zone 1 or Class 1 areas.
ATEX Directive
For gases (and vapours given off by flammable liquids)
this represents a Zone 1 area. (Zone 0 is the continual
presence of flammable gas, Zone 2 is where flammable
gas is not likely to occur).
Equipment for use in these areas is classified into Groups
and Categories.
Zone 1 requires monitors and control equipment to be
Group II approved. (Group I is reserved for mining
equipment).
USA – Hazardous area classifications
Under the US NEC system areas are firstly given a
“Class” location for specific applications. Class 1 covers
flammable gases, vapours or liquids. (Class 2 is dust and
3 fibres). Classes are further subdivided into “Divisions”.
Division 2 is defined as “Where ignitable concentrations
of flammable gases, vapours or liquids are not likely to
exist under normal operating conditions”. (Division 1 is
for flammable gases present some or all of the time
during normal operating conditions).
There is a further classification for the type of gas or
vapour that may be present and their ignition
temperatures. Most industrial systems fall under Groups
C and D.
Equipment is given a Category depending on the Zone in
which it is intended to operate. A Zone 1 environment
requires equipment classified as Category 2G, where G
stands for gas. (There are separate categories for dust
hazards - D).
A typical monitor installed under the US classification
system may be required to operate in a Class 1,
Division 1, area in which gases in Groups C and D may be
present.
The type of protection applied is defined by the CENELEC
(Comité Européen de Normalisation Electrotechnique)
code. Ratings are defined by a letter preceded by EEx. An
explosive or flame proof enclosure for a control panel
intended for a Zone 1 area would be classed as EEx d. In
addition, the maximum surface temperature the
equipment can generate is also added to ensure it
cannot form the source of ignition for any gases present.
The code “T4” indicates a maximum temperature of
135°C which caters for most fire fighting requirements in
industrial areas.
Comparison of ATEX and NEC
The ATEX system was made mandatory in Europe in July
2003 and reflects a more up to date method of working.
It also takes into account a wider range of parameters
than the US system. As a result, ATEX is a more
comprehensive system and is therefore the preferred
system for most international fire fighting specifications.
Comparison of ATEX and NEC zone classifications:
ATEX
NEC (USA)
Zone 0
Division 1
Where ignitable concentrations of flammable gases,
vapours or liquids are present continuously or for long
periods of time under normal operating conditions
Where ignitable concentrations of flammable gases,
vapours or liquids can exist all of the time or some of
the time under normal operating conditions
Zone 1
Where ignitable concentrations of flammable gases,
vapours or liquids are likely to exist under normal
operating conditions
Zone 2
Division 2
Where ignitable concentrations of flammable gases,
vapours or liquids are not likely to exist under normal
operating conditions
Where ignitable concentrations of flammable gases,
vapours or liquids are not likely to exist under normal
operating conditions
13
Titan Range
Angus Fire has been
manufacturing fixed and
portable monitors for over 40
years. The range includes light
alloy, stainless steel and
bronze models ranging in
nominal flow from 1000 to
40,000 l/min. The trailer
mounted fixed range of
monitors is supplemented by a
wide range of fog/jet nozzles
and foam cannons. Selfinducing nozzles and cannons
are also available.
Titan
Angus Fire, the manufacturer
of the unique Monnex®
powder, manufacture
specialist powder nozzles for
selected models.
4,000 - 5,900 l/min
Max throw 80m
Max throw 90m
6,000 Max
Portable / mobile
PMA 18
PMS 27-37
PMB 40
PMB 65
1,800 l/min
2,700 - 3,700 l/min
4,000 l/min
6,500 l/min
Hand lever with
friction locks
LMB/A 30
LMS 30
LMB 40
LMS 45
LMS 60
3,000 l/min
3,000 l/min
4,000 l/min
4,500 l/min
6,000 l/min
GMA 30
GMS 30
GMB 50
GMS 45
GMS 60
3,000 l/min
3,000 l/min
5,000 l/min
4,500 l/min
6,000 l/min
560 SSM
AR-AFFF is increasingly
popular by those committed
to synthetic detergent based
products on the basis of
exceptional Last Fire test
performance.
Hand wheel*
with worm and
wheel gearbox
Hydraulic, electrical and
hydro/electric remote control
options are available on all
monitors together with a wide
range of single and multi way
control panels. Remote
control panels for use in areas
where explosive regulations
apply are also available.
*Chain drive optional
Angus Fire is the worlds
leading manufacturer of fire
fighting foam concentrates.
Angus Fire monitors are
designed to optimise the
performance of Angus Fire
foams, maximising throw and
flow without reducing foam
quality. Modern FP or AR-FFFP
protein-based foams, such as
Angus Fire Tankmaster, are
preferred since they enhance
the throw of the jet and
minimise dropout and
wastage. They also minimise
fuel pick up from forceful
plunging and provide superior
burnback resistance with
longer post fire security.
14
1,800 - 3,900 l/min
Automatic
oscillating
gearbox
OMB 36
OMB 40
3,600 l/min
4,000 l/min
Hydraulic drive
(EExd rated)
RHMA 30
Hydraulic drive
with electro/
hydro power
packs
(EExd rated)
Electric drive
(EExd rated)
RHMB 50
RHMS 60
5,000 l/min
6,000 l/min
RHEMA 30
RHEMB 50
RHEMS 60
3,000 l/min
5,000 l/min
6,000 l/min
REMA 30
REHMB 50
REMS 60
3,000 l/min
5,000 l/min
6,000 l/min
3,000 l/min
A
Light alloy body
L
Hand lever and locks
B
Bronze body
M
Monitor
C
Continuous rotation
O
Oscillating movement
CG
Chain drive Gearbox
P
Portable
E
Electrical motors
R
Remote control
G
Worm and wheel gearbox
S
Stainless steel 316 body
H
Hydraulic motors
INCREASED
TURBULENCE
NO VEINS
TURBULENCE
TIGHT BENDS
Double row stainless
steel bearings
Jig welded stainless steel
minimises offset forces
Computer a
reduce flo
n Monitor Range
- 7,900 l/min
throw 95m
8,000 - 9,000 l/min
15,000 - 30,000 l/min
50,000+ l/min
Max throw 100m
Max throw 115m
Max throw 130m
PMS 80
PMS 100 - 300
8,000 l/min
10,000 - 30,000 l/min
LMB 65
LMS 80
LMB 85
6,500 l/min
8,000 l/min
8,500 l/min
GMB 65
GMS 80
GMB 85
GMS 200
GMS 300
6,500 l/min
8,000 l/min
8,500 l/min
20,000 l/min
30,000 l/min
OMB 65
OMB 85
6,500 l/min
8,500 l/min
RHMB 65
RHMS 80
RHMB 85
RHMS 200
RHMS 300
RHMS 500
6,500 l/min
8,000 l/min
8,500 l/min
20,000 l/min
30,000 l/min
50,000 l/min
RHEMB/C 65
RHEMS 80
RHEMB/C 85
RHEMS 200
RHEMS 300
RHEMS 500
6,500 l/min
8,000 l/min
8,500 l/min
20,000 l/min
30,000 l/min
50,000 l/min
REMB 65
REMS 80
REMB 85
REMS 200
REMS 300
6,500 l/min
8,000 l/min
8,500 l/min
20,000 l/min
30,000 l/min
LEO + HYD 80
Alloy
NOZZLE
VANES
TAG
FAULT
UP
aided bends
ow losses
Electro-hydraulic, waterhydraulic and electrical panels
Bronze
Nominal flows and throws shown at 7 bar inlet pressure
with foam and no wind conditions
POWER ON
MONITOR
DOWN
LEFT
FULL
SWEEPING BENDS
Stainless Steel 316
© Angus Fire. Angus Fire reserves the right to modify any specification without prior notice
RIGHT
NOZZLE
FOG
Panels for
hazardous areas
Wide range of fog jet nozzles
and foam cannons
Angus Fire, Thame Park Road, Thame, Oxon, OX9 3RT, UK
Telephone +44 (0)1844 265000 Fax +44 (0)1844 265156
E-mail general.enquirie@kiddeuk.co.uk Web www.angusfire.co.uk
15
Approvals
In common with most fire fighting equipment,
monitors can be approved by third party national
and international accreditation bodies. While some
bodies verify the manufacturers’ specifications,
others test the equipment to their own, clearly
defined standards.
The two most common test standards for fixed fire
protection equipment are FM Global and UL
(Underwriters Laboratories Inc) based in the USA.
Others in common use are Lloyd’s Register/MCA
(Lloyd’s Register plus UK Maritime and Coastguard
Agency), Bureau Veritas (France), ABS (American
Bureau of Shipping), DNV (Det Norsk Veritas –
Norway) and RINA (Registro Italiano Navale). The
latter are approvals based on codes for the
protection of ships but are also often accepted for
land-based systems.
It is expected in the future that fire fighting
equipment that generates foam will need to be
tested by an independent third party test house for
compliance with the EEC Construction Equipment
Directive. The test standards and scope of this
section of the Directive are in the process of being
formulated.
FM standard
FM Global specifies that monitors
should to be tested for movement of
the monitor after high and low
temperature and salt spray tests. In
addition the standard calls for a 58 bar
static pressure test (monitors are not
normally exposed to pressures greater
than 16 bar in operation) and a 35 bar
dynamic test.
FM Global also require the “K” factor of the monitor
to be logged at various flows and the straight water
jet throw distance (using an FM standard jet) to be
measured at a variety of inlet pressures. This is useful
for water jets but has little relevance for foam
applications.
UL standard
Underwriters Laboratories Inc. follows
a similar system to FM with one
important addition. For UL Listing the
quality of the foam generated by the
monitor is measured under various conditions
and must conform to set criteria.
Where monitors are installed for spraying foam the
quality of the foam generated is paramount and
often critical to the successful control and extinction
of a fire. In this respect UL Listing is generally more
comprehensive and relevant to the practical
application than other monitor standards.
Lloyd’s Register, Bureau Veritas, ABS and RINA
Unlike FM Global and UL these
approvals
are, in the main, verifications that the
manufacturers’ specifications are
accurate and that the equipment
performs as stated in their specification
and will meet the minimum marine
equipment performance criteria.
Technical datasheets containing further information are available on request from your local Angus Fire representative or
from our website www.angusfire.co.uk
Angus Fire reserves the right to modify any specification without prior notice.
REF: 6445/1-01/07
© Angus Fire
Printed in England
A UTC Fire & Security Company
THAME PARK ROAD, THAME, OXFORDSHIRE, OX9 3RT, ENGLAND
Tel: +44 (0)1844 265000 Fax: +44 (0)1844 265156
e-mail: general.enquiries@kiddeuk.co.uk Web site: www.angusfire.co.uk