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Priming Pump Malfunction
1. If pumping does not generate pressure, then the inlet check valve has probably failed,
and requires replacement.
2. If the system pressurizes and depressurizes in conjunction with the downward and
upward strokes of the pump, then the outlet check valve has failed completely. This
should be disassembled and inspected for dirt or damage to valve seat and seal. After
inspection, clean all parts carefully, replace as required, and re-assemble correctly.
3. If the pump handle rises during normal system pressurization, then the outlet check
valve is leaking. Inspect as above.
Do not continue to pressurize if pump handle rises, as this can
damage the inlet check valve.
Cannot Reach Maximum Pressure
If maximum pressure cannot be reached, even after the screw press has been turned fully
in, and the checks above have been made:
1. Ensure that the screw press is FULLY OUT, and the priming pump is used for initial
pressurization.
2. If the DUT has a large internal volume or there is air in the system, then re-prime
(Refer to Chapter 3), increasing the initial pressurization with the priming pump from
100 psi/7 bar to at least 200 psi/14 bar.
Pressure Falls Away
Large, sudden changes in pressure will cause the system temperature to rise or fall, which
can cause instrument readings to change as the fluid in the system expands or contracts,
thus increasing or decreasing the pressure. Allow a few minutes to determine if the
system pressure is continuing to fall away, or is stabilizing.
Storage and Transportation
1. With the test port plugged, open the reservoir valve and turn screw press fully in,
close reservoir valve.
2. Remove spokes from hub, and store in tool-roll.
3. Remove screw-in handle from pump arm, and store in tool roll.
4. If fluid is to remain in the reservoir, ensure that the tester is kept level at all times to
avoid spills. If not, drain the reservoir as described in Chapter 5, Reserve Assembly.
5. Re-fit instrument lid, ensuring that the hinges are correctly engaged, and secure with
toggle clips at the sides.
Caution
Hydraulic Comparison Test Pump
Storage and Transportation
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