BOC Edwards 18B4B, Instruction Manual, Page: 52 / 62

Issue A Feb 04
PAGE
46
18B4B Vapour Booster Pumps
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Fault symptom Possible causes
The pump will not start.
• The electrical supply connections are disconnected.
• The electrical supply thermal overload has tripped.
The pump shuts down.
• The electrical supply connections have become
disconnected.
• The electrical supply thermal overload has tripped.
• One of the thermal snap-switches has operated.
The pump fails to reach ultimate vacuum,
or low-pressure pumping speed is poor.
• There is a leak in your vacuum system.
• There is a leak in the pump.
• The pump fluid is contaminated.
• Your vacuum system is contaminated.
• A heater has failed.
• The guard ring is incorrectly fitted/adjusted.
• The pump has been filled with new pump fluid.
• The cooling-water temperature is too high.
• Your pressure gauge is incorrectly calibrated.
High-pressure pumping speeds are poor.
• The backing pump is too small or is faulty.
• There is a leak in the backing pipeline.
• The fluid-level is incorrect.
• There is a restriction in the pump-outlet.
• The pump interior assembly is installed incorrectly.
• A pump heater has failed.
• The diameter of the backing pipeline is too small or the
backing pipeline is too long.
Pumping is unstable.
• The fluid return to the pump boiler is restricted.
• The pump fluid-level is low.
Table 12 - Fault finding (Sheet 1 of 2)