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Maintenance
A705-61-880 Issue M
5.16 Fault finding
Refer to Table 16 for fault finding.
Table 16 - Fault finding
Symptom Check Actions
The pump suddenly stops. Is there a hydraulic lock in the
pump ?
Switch off and drain the fluid from
the pump. If necessary, turn the
pump by hand.
Has the shut-down thermal snap-
switch operated to stop the pump
because the pump is operating at too
high a temperature ?
Check that there is a sufficient flow
of cooling-water through the pump:
check that the cooling-water supply
is on, is at the correct pressure and
is of the correct temperature.
Has the cooling-water supply been
interrupted, or has it failed ?
If your cooling-water supply is on and
is at the correct pressure and
temperature, the cooling jacket may
be blocked: clean the cooling jacket
(refer to Section 5.9).
Has the pump seized because the
shut-down thermal snap-switch is
faulty ?
Check the operating temperature of
the pump (at the position shown in
Figure 1, item 3). If the operating
temperature is > 100 °C (212 °F),
there has been insufficient cooling-
water flow through the pump and
the thermal snap-switch is faulty:
contact your supplier or Edwards
for advice.
Has the pump seized due to
deposits ?
Switch off the pump and contact
your supplier or Edwards.
The pump operates at too high a
temperature or the pump
temperature is unstable.
Is the cooling-water flow
inadequate, is the flow variable, or
is the flow being interrupted ?
Before you restart the pump, check
for correct cooling-water flow
(see above).
The pump continues to operate at a
high temperature which may result
in seizure.
Is the interstage relief valve stuck in
the open position ?
Inspect the interstage relief valve
and overhaul it or replace it if
necessary (refer to Section 5.10).
The pump only achieves an ultimate
pump-inlet pressure of 30 to 50 mbar
(3 x 10
3
to 5 x 10
3
Pa, 22 to 37 Torr).
Is the interstage relief valve stuck in
the open position ?
See above.
The pump-motor trips out due to
excessive electrical current
consumption when the GV250 pump
is operating with pump-inlet
pressure in the range 300 to
1000 mbar (3.0 x 10
4
to 1 x 10
5
Pa,
225 to 750 Torr), or when the GV400
pump is operating with pump-inlet
pressure in the range 200 to
1000 mbar (2.0 x 10
4
to 1 x 10
5
Pa,
150 to 750 Torr)
Is the interstage relief valve stuck in
the closed position ?
Inspect the valve and if necessary
replace it: refer to Section 5.10.
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