Instruction manual

Oct 04 Issue H
GV Dry Vacuum Pumps
PAGE
41
41
MAINTENANCE
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
o
C (212
o
F), there has been insufficient
cooling-water flow through the pump and
the thermal snap-switch is faulty: contact
your supplier or BOC Edwards for advice.
Has the pump seized due to
deposits ?
Switch off the pump and contact your
supplier or BOC 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
5x 10
3
Pa, 22 to 37 torr).
Is the interstage relief valve
stuck in the open position ?
See above.
Table 15 - Fault finding (Sheet 1 of 2)