B344-21-880 Issue N
Page 48 © Edwards Limited 2007. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Maintenance
5.12 Fault finding
Table 4 - Fault finding
Symptom Check Action
Poor ultimate pressure Is there a leak in the system,
virtual or real ?
Locate and seal the leak.
Is the system dirty ? Clean the system.
Is the pump fluid contaminated ? Inspect the fluid and replace if
necessary.
Is the heat input low or high ? Check the supply voltage. Check the
heater for power rating, electrical
continuity, burnt out element, poor
thermal contact.
Is there inadequate cooling ? Check the cooling-water pressure.
Check the cooling-coils for obstructions
and back pressure.
Is the backing pressure high ? Check for a leak in the backing pipeline,
poor rotary pump performance, thermal
breakdown of the pump fluid.
Is your vacuum gauge incorrectly
calibrated ?
Check and rectify.
Inlet pressure surges Is the heater input incorrect ? Check and rectify.
Is the pump fluid outgassing ? Inspect the pump fluid and replace if
necessary.
Is there a leak in the system
ahead of the inlet to the Diffstak ?
Check and rectify.
Is there trapped volume in the
system ?
Check and rectify.
Are the ‘O’ ring seals excessively
lubricated ?
Check and rectify.
Is there excessive fluid charge ? Drain off, as necessary.
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