Instruction manual

VHS-4, VHS-6 and VHS-250 Diffusion Pumps
D R A F T 6 / 1 8 / 1 3
47
Inlet pressure surges Incorrect heater voltage. Check and correct voltage.
Fluid outgassing. Condition pump fluid by
operating pump for a few hours.
Leak in system ahead of
pump inlet.
Check and correct.
High chamber contamination Forepressure too high. Check for leak in foreline, poor
mechanical pump performance,
breakdown of pump fluid, and
incorrect valve operation.
Prolonged operation at high
throughput at pressure above
10
−3
Torr (1.33x10
-3
mbar).
Review operating procedures.
Improper system operation
air-release procedures.
Review operating procedures
Pump will not start Safety circuits and/or protective
devices prevent contactor from
staying closed.
Check utilities, flow switches,
interlocks, and thermostat
operation.
Table 4-1 Troubleshooting (Continued)
Symptom Probable Cause Repair Action