HP-HT Laboratory - Operations and Safety Manual
8 March, 2016
SCHOOL OF ENGINEERING
HPHT LABORATORY
SUPPLEMENTARY SAFETY INFORMATION
TO BE READ IN CONJUNCTION WITH SCHOOL SAFETY
HANDBOOK
AUGUST 2014
Co-ordinator:
Dr A. R. Akisanya
Tel. 2989
Resident Technician:
Mr M. Gourlay
Tel. 2810
Technical Resources Officer (TRO)
Mr G Cordiner
Tel. 2788
Document approved for issue by Dr A.R. Akisanya
Signature:_______________________________ Date:__________________
Aberdeen University
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HP-HT Laboratory - Operations and Safety Manual
8 March, 2016
High Pressure - High Temperature Laboratory
Operations and Safety Manual
The HP-HT laboratory is situated in room LG021 of the Fraser Noble Building. It houses
three heated high pressure cylinders capable of operation up to 250C and 200 MPa. Two of
the cylinders are equipped with 10 tonne servo-controlled mechanical test machines. An
associated hydraulic pump unit is housed in the pump room off the Materials Laboratory
(LG017) and its hydraulic pipe-work runs along the wall of this room.
1 Responsibilities
The co-ordinator of the HP-HT laboratory has overall responsibility for the operation of the
laboratory. The co-ordinator is responsible for the safety, operational rules, authorisation of
access, authorisation of installations, calibration, maintenance, certification, modifications
and work priorities in this laboratory.
The co-ordinator may nominate a deputy from time to time to authorise activities in his/her
absence.
Technical staff of the School, under the supervision of the Technical Resource Officer (TRO),
work under and report to the co-ordinator. The resident technician has delegated
responsibility to ensure compliance with the safety and operating procedures as laid down by
the co-ordinator.
The TRO will organise annual third party inspections for insurance purposes but it remains
the co-ordinators responsibility to ensure any inspections are undertaken.
2 Access
Although there should be no unsafe conditions inside, entry to the laboratory is restricted to
authorised persons only. The laboratory co-ordinator is responsible for authorisation of
access.
Only authorised personnel are permitted to switch on or operate the equipment.
A list of authorised workers will be posted inside the laboratory.
Authorised staff are likely to include academic staff, university technicians, major equipment
suppliers, postgraduate researchers and postgraduate students. In all cases they must be
adequately trained to operate specific items of equipment. In the case of students, their
competence should have been demonstrated to their supervisor, who must also be one of the
authorised operators.
Undergraduate project students will only be allowed to operate the equipment under
supervision and will not normally become authorised users.
Access to laboratory space is also subject to the various School rules and reference must be
made to the School Safety Handbook.
The safety screens will be closed whenever a system is pressurised or the heating pump is
running. There will be no access beyond the screens in these circumstances. Access behind
the screens in any circumstances will require the approval of an authorised user. School
guidelines prohibit lone working or work outside normal hours. Where the system is in
operation and a check of function is necessary out with normal hours, approval must first be
sought from the co-ordinator. In this situation the protective screens must remain closed and
access to the equipment behind them prohibited.
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3 Physical protection
The principal hazards result from the use of fluids at high pressure and high temperature, up
to 250C and 200 MPa. The heating system also contains hotter fluid (up to 300C) at modest
pressure driven by a circulating pump. Other hazards can arise from slippery floors and
objects dropped from the cylinder towers during maintenance or experimental set up. The
Risk Analysis for this area is attached as Appendix 1.
There is very little risk while observing or operating the system from the console with the
screens closed.
The safety screens must be kept closed at all times when the heating system or the high
pressure system is in operation.
Personal protective equipment is available in the laboratory in the form of hard hats, goggles,
insulated gloves and lab-coats, and should be used when appropriate.
Wearing safety goggles and insulated gloves will be normal practice when opening and
closing the vessels following tests involving heated fluid.
Always use the steps provided to load/unload the chambers or when carrying out
maintenance, never use tables or chairs.
Wearing a protective helmet will be normal practice when opening one of the taller vessels
following a test, or when working below anyone using tools on an access ladder to adjust or
set up equipment in the test chamber.
Individual risk assessments must be carried out and approved by the co-ordinator before any
new work can commence. These risk assessments will be in addition to Appendix 1 which is a
generalised risk assessment for the laboratory. Consideration must be given to the effect high
pressure and temperature may have on any materials and chemicals used in the process.
Safety information relating to any chemicals must be kept within the laboratory. The risk
assessment should also identify the need for specialised protective clothing to be used when
handling chemicals.
4 Procedures
There must be a robust written procedure for starting and using each item of specialised
equipment installed in the HP-HT laboratory. Existing procedures are appendixed to this
document.
All procedures must be consistent with this operations manual, and are to be read in the light
of this manual.
All procedures and laboratory installations or modifications should be consistent with the
High Pressure Safety Code published by the High Pressure Technology Association.
Simultaneous operation of the three systems is feasible, but set-up and maintenance of any
system is not practicable while one of the vessels is pressurised, or the heating pump is
running, as this would require the safety screens to be opened.
Existing written procedures for the HP-HT system, the servo-hydraulic test machine and the
servo-electric test machine are appended to this document.
The equipment, pumps and mains power supplies will normally be switched off at night
unless planned overnight running is intended following normal School procedures. This
precaution is purely for the peace of mind of the security staff, although both the major
equipment suppliers have indicated that it would be better to leave the equipment permanently
switched on.
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5 Emergency procedures.
The HP-HT system is protected by inter-linked emergency stop buttons.
The Instron test machines each have an individual emergency stop button nearby, and a
software emergency stop on the operator's computer screen.
It is not necessary to switch off the electrical power at the isolator which is located inside the
safety screen, even in the event of a fire.
In the event of a genuine fire alarm or fire, the laboratory should be evacuated immediately.
In principle, the equipment could be left running as it has its own protection against
operational failure. It may be prudent to shut it down, by standard procedures or by using the
emergency stop buttons, depending on the perceived level of risk to personnel, equipment or
specimens.
In the case of pre-planned fire alarms, evacuation will be as normal but the equipment may be
left running if this is the sensible course of action.
In the event of mains electrical power failure, attended or unattended, all the major equipment
will restart in a safe condition when power is restored. The main exceptions to this are the
two water chillers which require to be manually started.
Fire extinguishers are located immediately outside the laboratory door, in LG017
There are no fire extinguishers in the HP-HT laboratory.
6 Maintenance
The co-ordinator is responsible for ensuring that any maintenance is carried out in accordance
with the manufacturers instructions. Day to day care and maintenance will be carried out by
the resident technician. Assistance is available from the electronic and mechanical workshops
if required. Certain specialized equipment such as the water chillers may require external
contractors to carry out the work.
7 Modifications
No modifications will be undertaken without the approval of the co-ordinator. Any re-design
must meet the pressure and temperature requirements of the system. After modification the
system must be re-commissioned and tested.
8 Appendixes
Appendix 1: Risk Assessment
Appendix 2: Pressure Vessel start up and control procedure.
Appendix 3: Servo-hydraulic mechanical test machine control procedure.
Appendix 4: Servo-electric mechanical test machine control procedure.
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Appendix 1: High Pressure - High Temperature Laboratory
Risk Assessment
1. Summary
The laboratory contains three test rigs which include chambers designed to operate at
pressures up to 200 MPa and 250C. Two of the vessels are equipped with engineering test
machines capable of applying a 100 kN load to specimens within the chambers. Risks arising
from operation of this equipment have been categorised under the following headings:

High pressure

Hot fluid

Access at heights

Access to hot chambers

Toppling of test rigs

Slipping on oily floors

Working environment
2. High Pressure
The vessels will contain only liquid and not gas, minimising the stored energy of the systems.
Explosion of the vessels themselves is not regarded as a possibility, but the failure of smaller
components such as pipe fittings, electrical lead-throughs or pipe runs must be considered. A
failed pipe joint can lead to pipe-whip if the pipes are not adequately supported.
The vessels are protected in use by screening designed and operated in accordance with the
guidelines of the High Pressure Technology Association, (Ref. 1) to protect personnel from
flying fragments in the event of a burst. The 3mm steel panels and 10 mm polycarbonate
viewing windows have been designed by Dr. D.S. Thompson using the methods detailed in
the HSE report, "Pressure test safety" (Ref. 3).
The pressure vessels themselves and all their associated pumps and pipe-work have been
designed and manufactured by a reputable supplier, Stansted Fluid Power, who are members
of the High Pressure Technology Association.
All the vessels have been proof tested at Stansted to 150% of working pressure, i.e. to 300
MPa. Each installed system is protected by a burst disc chosen to match the maximum
working pressure. To test the integrity of all the installed pipe-work at Aberdeen, the burst
discs were replaced by blanks and the systems pressurised to 10% above normal working
pressure, i.e. to 220 MPa, after which the burst discs were replaced. All these tests were
witnessed by Dr. D.S. Thompson.
The materials used to manufacture all the major high pressure components are covered by
certificates of compliance with material standards.
Contact between exposed flesh and a high pressure fluid jet is in itself a hazard, but only
within approximately 150 mm of the source. The blast screening will also guard against this
hazard, and in any case the operating position is some two metres beyond the screens.
The fluids used in the high pressure chamber must be selected for their suitability for
operation at the intended test pressure. In particular, they must not freeze at the intended
pressure. Water containing soluble oil is suitable, as is diesel oil. Hydro-carbon oil should be
suitable, particularly at elevated temperatures, but individual choices should be checked. It is
also more convenient to use a fluid which does not boil within the expected temperature
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range. The vessels have been commissioned largely using silicone oil which is satisfactory in
respect of both freezing and boiling and is non toxic and non flammable.
Pressure freezing of the fluid must be avoided completely. The pressure is measured by a
gauge mounted near the pump and by a transducer which displays its output on the console.
Both are connected in accordance with standards (Ref 1) to minimise errors due to freezing in
the pressure lines to the instruments. A manual valve will allow emergency pressure release
if freezing is inadvertently permitted.
Corrosive fluids are envisaged and the vessels have corrosion resistant steel liners. They are
designed on a leak-before-burst basis and the pressure control equipment will shut down in
the event of a fractured liner, with the outer vessel maintaining pressure integrity.
Appropriate chemical exposure hazards should be considered when selecting corrosive fluid
additives.
3. Hot fluid
The worst hazard in this laboratory is likely to result from the high temperature of any leaking
fluid or jet, and this hazard will not be diminished by distance or by an indirect trajectory
taken by the jet. The screening is therefore full height from floor to ceiling, using sliding
doors on double track mounted over the bund wall. The vessels will not be operated with the
screens open.
If any of the vessels is to remain in operation while test preparation or other work is
performed at another machine, screening between the two systems will have to be provided
but this issue has not yet been addressed.
4. Access at heights
Access to the test chambers to set up specimens is above head height. A mobile step-ladder
with hand rails and guard rail to the platform has been procured for this purpose. The
platform height is 1013 mm and so does not constitute a danger in its own right. Protective
helmets should be worn when tools are being used at the top of the steps.
5. Access to HP-HT chambers
The vessels cannot be opened while under pressure. Vessels should not be opened while hot
fluid remains inside and a panel warning light indicates when it is safe to open the vessel..
The chamber and specimens are likely to remain hot for some time, and there may be drops of
hot fluid trapped in corners even after draining. Protective gloves and goggles are provided
for handling specimens in circumstances when they cannot be allowed to cool.
The vessels are opened and closed by hydraulic rams. The controls require two hands to
operate them, so that hands cannot be trapped in the chamber. The rams will not operate if
the breech screw is not correctly aligned. The vessels continue to be held in the raised
position, even if the hydraulic pump is switched off.
6. Toppling of test rigs
Two of the test rigs are nearly four metres tall and weigh 1.5 tonnes or more. They have been
designed against an industrial toppling criterion which requires 12 rotation from the vertical
before they become unstable.
To meet concerns, however, the tall towers have been secured to each other and to the ceiling.
The third tower, which is much shorter, is secured to the floor.
All the towers include a crane to permit dismounting and removal of a pressure vessel liner if
necessary and the extra security of the fastenings will further ensure their safety in this event.
7. Slipping on floors
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Fluid leakage could present a slip hazard and the area occupied by the test rigs has been
surrounded by a 100 mm high bund wall to contain spills and leaks. A contrasting floor
colour either side of the bund visually emphasises the potential trip hazard and the region
within the bund is not a traffic area.
The floor coverings have been chosen with attack from hot oil in mind, although there is
nothing on the market which is guaranteed to cope with the conditions in the vessels. Leaked
fluid is not likely to remain at the peak temperature for long enough to damage the floor.
8. Working environment
The laboratory is fully ventilated and air coolers have been installed to offset the effect of the
hot chambers. During commissioning, the existing ventilation system has proved to be
inadequate. Steps have been taken to prevent emission of oil fumes and to eliminate oil
leakage. If the problem persists, additional ventilation will be installed with a fume-hood
over the heater.
9. Safe working practice
All laboratory operations will be subject to a statement of safe working practice, which will
be based on Ref. 1 and 2.
The equipment will not be operated without the screening in place. As these are not
interlocked with the controls, it is the operator's responsibility to ensure they are closed before
a test commences.
The equipment will only be operated by personnel who have been adequately briefed and
authorised. Undergraduate students will normally operate the equipment only under close
supervision.
Extended maintenance work will not take place on a vessel which is in use, nor while an
adjacent vessel is in use.
Experimental set-up will take place when an adjacent vessel is pressurised only when an
adequate screening arrangement has been installed.
10. References
1. High Pressure Safety Code, High Pressure Technology Association, 1975 (reprinted 1988)
2. Safety in Pressure Testing, 2nd Ed 1992 (reprinted 1998), HSE Books, HMSO
3. Pressure Test Safety, Saville G, Richardson S M, Skillerne de Bristowe B J, HSE Report
168/1998, HMSO 1998
Dr. David Thompson
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Appendix 2: HP-HT LABORATORY PRESSURE VESSEL CONTROL SEQUENCE
Preliminary steps:
1. Switch on 3-phase electrical supply at rear wall.
2. Check that air pressure is shown on regulator – do not adjust or turn off.
3. Switch on heater unit and set controller in the corner of the laboratory if heating required.
4. If no lights on panel, switch on at hp pump unit behind the vessel. Normally left on.
5. Check fluid levels in heater and process tank.
6. Confirm process fluid is suitable for use at intended test pressure and temperature.
7. Switch on water coolers if they are required, ie if working above 100ºC.
Main control panel sequence:
1. Confirm three small green lights at top of panel.
2. Set key-switch to local control – “LOC”.
3. Identify red “STOP” button and emergency shut down button.
The red light will illuminate if a fault arises or an action is inhibited.
4. Set desired pressure (MPa) and temperature (ºC) values using potentiometers.
5. Press white “DRAIN VESSEL” button – listen for air blast and gurgling.
6. Wait for steady orange light. (Light flashes during programmed time delay.)
7. Open and close breech nut on pressure vessel – close firmly (clockwise).
8. Orange light flashes and blue light flickers to prompt for next step.
9. Ensure safety screens are in place to protect against burst and hot leaks.
10. Press blue “PRE-FILL” button.
11. Blue button illuminates while pump runs until flow switch in top of vessel activated.
12. Wait until fluid in vessel reaches set temperature (ºC). Orange light flashes long-short until
temperature within limits, when the small green temperature light comes on. Note that there
are two temperature channels which are scanned sequentially:
Channel 1 (no light showing) shows the heating jacket temperature;
Channel 2 (small orange light glows) shows the process fluid temperature.
13. Green light blinks to prompt next step when set temperature is reached (if small green light
on!).
14. Confirm correct target pressure is set (MPa).
Press the green ”PRESSURISE” button to pressurise the vessel.
15. The vessel will now follow the pressure set using the potentiometer, up or down.
16. Press the “DECOMPRESS” button to release the pressure in the vessel. The vessel is not
drained and the temperature could now be altered and the vessel then re-pressurised. Because
the vent is open, heating the vessel will not cause any pressure rise due to thermal expansion.
17. On completion of tests, drain the vessel by pressing the white “DRAIN” button. A time delay
allows for deflation and if a red light appears, wait a while and try again. Listen for air blast
and gurgling noises. Repeat until gurgle. Use water cooling if fluid above 100ºC. Confirm
that the process fluid has returned to its original level.
18. The procedure can now be repeated from step 6 if required.
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Appendix 3: Start-up procedure for the
Instron 8802 Hydraulic Actuator in the HP-HT laboratory (Vessel 3).
Outline Procedure
1. Start up hydraulic pump.
2. Power-up PC.
3. Start FastTrack Console software.
4. Switch on the Instron system.
5. After warm-up, dismiss "Test Event Logger" screen.
6. Select "Live Displays" from the Actuator pull down menu.
7. Restore the load cell calibration.
8. Set and enable sensible load limits - positive tension down and negative compression up!
9. Set and enable sensible position limits - positive downwards and negative upwards!
10. Select hand set button "I" to activate the actuator at low pressure.
11. Select hand set button "II" to activate the actuator at high pressure.
12. Use hand set buttons and thumb wheel to give local control of position.
13. Customise the live displays.
14. Set up test using ramp generator, waveform generator etc by right click on actuator menu.
15. If a limit is triggered:
Carefully drive the system away from the limit
Reset and re-enable the limit
Click on "load protect" icon and disable load protection
Reselect high hydraulic pressure using button "II"
Detailed Procedure
1. Start the correct hydraulic pump in pump room off LG017. Press the green button and hold until
the gauge stabilises at working oil pressure, after approximately 10 seconds.
2. Power up PC, back in the HP-HT laboratory.
3. Double click "FT Console" on Windows Desktop,
or Start Programs C:\Instron\FastTrack2\FTConsole.
4. Power on at 13A wall socket behind the Instron control box.
5. Power on at the main switch on the Instron FastTrack tower, at the top left hand corner of the rear
panel, viewed from the rear.
6. Check that the "Test Event Logger" screen opens and records various events, eg "Watchdog
Failed" while the Instron system is warming up and self-checking. This should end with
"Hydraulics - Actuator Off, Actuator Active" after about one minute.
7. Close the Test Event Logger screen panel (select X in top right hand corner).
8. The icon bar along the top of the screen shows actuator-related icons in the right hand half and
pressure system icons to the left. Right-click on the right-most actuator icon and select the "Live
Displays" item from the pull-down menu.
9. The load cell icon will probably show "R" in a yellow circle to indicate that the calibration should
be restored. Click on this icon, choose the "calibration" tab and select the "Restore Now" button.
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This will be greyed-out if it is not required. The live displays should now show meaningful values
for load and position. The position sensor does not normally require re-calibration.
10. While still on the Load Cell menu, or re-selecting it, choose the "Limits" tab and set suitable load
limits in both directions and enable them.
Even if the settings are correct, they must now be enabled to make them effective.
Remember
positive load is tensile and pulls down
negative load is compressive and pushes up.
The arrows on the icon turn yellow when the limits are active.
11. Click on the "position and limits" icon, select the "limits" tab and set suitable limits in both
directions for the position sensor.  50 mm can be reached but 49 mm may be better as the limit
switch has been known to stick. The actuator itself should be capable of  52.5 mm, as should the
pressure vessel, but the precise relative zero setting of the two systems is difficult to locate.
Remember
"upper limit" positive (tensile) is when travelling down!
"lower limit" negative (compressive) is when travelling up!
Again, both limits must be separately enabled to make them active and the arrows on the icon turn
yellow to reflect this.
12. All the steps above can be carried out with the hand set inactive, ie with red button "0"
illuminated.
Now press hand set button "1" to activate the actuator in low pressure. The Test Event Logger
will confirm this with the message "Hydraulic Filter Blocked" and the arrow keys on the hand set
will light up, allowing local coarse control of position subject to the load and position limits set.
The low pressure setting is normally used as a safe setting for manoeuvring, but it does not
provide enough force to overcome seal friction on our system. The high pressure setting "II" must
be selected to give proper control, but be aware that the full load can be applied and make use of
the load limits to protect yourself, the specimen and the equipment.
Fine local control is obtained by using the thumb wheel on the hand set.
13. If the SFP pressure equipment is powered on, click on the pressure gauge icon at the left hand end
of the toolbar, click "calibration" and press the "Restore Now" button if it is not greyed-out.
14. Set the live displays bar to an appropriate set of outputs for monitoring the intended test. Click on
one of the readings to select it and right-click to access its "properties" for example:
Device
Signal Source
Channel
Type
hpht
sensors
pressure
track
8800(0,1)
sensors
load
track
8800(0,1)
sensors
position
track
8800(0,1)
ramp wavegen
time
elapsed
15. Right click on the actuator symbol to select test functions from the pull down menu, such as the
ramp generator or the waveform generator.
16. If a limit is triggered, "Load Protection" will automatically be enabled and will probably need to
be disabled to continue operation, after re-setting the triggered limit. Load protection is not very
helpful because a higher load is needed to overcome seal friction in this application. Consider
whether the action take on triggering the limit is appropriate. The hand set control button will also
need to be reset to "II" to activate full hydraulic pressure.
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Appendix 4: Start-up procedure for the
Instron 8802 Electric Actuator in the HP-HT laboratory (Vessel 2).
Outline Procedure
16. Power-up PC.
17. Start FastTrack Console software.
18. Switch on the Instron system.
19. After warm-up, dismiss "Test Event Logger" screen.
20. Select "Live Displays" from the Actuator pull down menu.
21. Restore the load cell calibration.
22. Set and enable sensible load limits - positive tension down and negative compression up!
23. Set and enable sensible position limits - positive downwards and negative upwards!
24. Select hand set button "1" to activate the actuator.
25. Use hand set buttons and thumb wheel to give local control of position.
26. Customise the live displays.
27. Set up test using ramp generator, waveform generator etc by right click on actuator menu.
28. If a limit is triggered:
Carefully drive the system away from the limit
Reset and re-enable the limit
Click on "load protect" icon and disable load protection
Detailed Procedure
17. Power up PC.
18. Double click "FT Console" on Windows Desktop,
or Start Programs C:\Instron\FastTrack2\FTConsole.
19. Power on at 13A wall socket behind the Instron control box.
20. Power on at the main switch on the Instron control box, top right on the front panel.
21. The Instron FastTrack tower which stands to the left of the larger control box is normally
left switched on so it is powered up at step 4. If necessary, its own mains switch is at the
top left hand corner of the rear panel, viewed from the rear.
22. Check that the "Test Event Logger" screen opens and records various events, eg
"Watchdog Failed" while the Instron system is warming up and self-checking. This
should end with "Hydraulics - Actuator Off, Actuator Active" after about one minute.
23. Close the Test Event Logger screen panel (select X in top right hand corner).
24. The icon bar along the top of the screen shows actuator-related icons in the right hand half
and pressure system icons to the left. Right-click on the right-most actuator icon and
select the "Live Displays" item from the pull-down menu.
25. The load cell icon will probably show "R" in a yellow circle to indicate that the calibration
should be restored. Click on this icon, choose the "calibration" tab and select the "Restore
Now" button. This will be greyed-out if it is not required. The live displays should now
show meaningful values for load and position. The position sensor does not normally
require re-calibration.
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26. While still on the Load Cell menu, or re-selecting it, choose the "Limits" tab and set
suitable load limits in both directions and enable them.
Even if the settings are correct, they must now be enabled to make them effective.
Remember
positive load is tensile and pulls down
negative load is compressive and pushes up.
The arrows on the icon turn yellow when the limits are active.
27. Click on the "position and limits" icon, select the "limits" tab and set suitable limits in
both directions for the position sensor.  50 mm can be reached but 49 mm may be
better as the limit switch has been known to stick. The actuator itself should be capable of
 52.5 mm, as should the pressure vessel, but the precise relative zero setting of the two
systems is difficult to locate.
Remember
"upper limit" positive (tensile) is when travelling down!
"lower limit" negative (compressive) is when travelling up!
Again, both limits must be separately enabled to make them active and the arrows on the
icon turn yellow to reflect this.
28. All the steps above can be carried out with the hand set inactive, ie with red button "0"
illuminated.
Now press hand set button "1" to activate the actuator. The Test Event Logger will
confirm this with the message "Hydraulic Filter Blocked" and the arrow keys on the hand
set will light up, allowing local coarse control of position subject to the load and position
limits set.
Fine local control is obtained by using the thumb wheel on the hand set.
29. If the SFP pressure equipment is powered on, click on the pressure gauge icon at the left
hand end of the toolbar, click "calibration" and press the "Restore Now" button if it is not
greyed-out.
30. Set the live displays bar to an appropriate set of outputs for monitoring the intended test.
Click on one of the readings to select it and right-click to access its "properties" for
example:
Device
Signal Source
Channel
Type
hpht
sensors
pressure
track
8800(0,1)
sensors
load
track
8800(0,1)
sensors
position
track
8800(0,1)
ramp wavegen
time
elapsed
31. Right click on the actuator symbol to select test functions from the pull down menu, such
as the ramp generator or the waveform generator.
32. If a limit is triggered, "Load Protection" will automatically be enabled and will probably
need to be disabled to continue operation, after re-setting the triggered limit. Load
protection is not very helpful because a higher load is needed to overcome seal friction in
this application. Consider whether the action take on triggering the limit is appropriate.
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