Instruction manual

47
High Throughput Diffusion Pumps
DRAFT 12/23/04
Poor Pump or System Performance
Table 15 lists the faults, the probable causes and corrective actions to take if you have a problem with a large diffusion
pump.
Table 15 Troubleshooting Guide
Fault Probable Cause Corrective Action
Poor system pressure Leaks in system, virtual or real Locate and repair
High process gas load Measure gas load, eliminate cause
System dirty Clean system to reduce outgassing
Poor ultimate pressure Contaminated pump fluid Examine and clean pump; replace fluid
Low heat input Check voltage. Check for continuity, burned-out
element, poor thermal contact
Inadequate cooling water flow Check water pressure. Check tubing for obstructions
and backpressure
Cooling water is too cold Check temperature
Cooling water flow is too high Adjust water flow
High forepressure Check for leak in foreline, poor mechanical pump
performance, breakdown of mechanical pump fluid
Water in Quick Cool coil Check and remove cause
Slow pumpdown Low heat input Check heaters
Low fluid level Add fluid
Malfunctioning pump assembly Check and repair or replace
Improperly located jets
Damaged jet system
Inlet pressure surges Incorrect heater input Check and correct
Fluid outgassing Condition fluid by operating the pump for a few hours
Leak in system ahead of pump inlet Check and correct
High chamber
contamination of the
pump fluid
Forepressure too high Check for leak in foreline, poor mechanical pump
performance, breakdown of pump fluid, and
incorrect valve operation
Prolonged operation in overload range Adhere to operating procedures
Cutting over from the backing pump too
early in the pump down cycle
Cut over at a lower chamber pressure
Improper system operation and air
release procedures
Adhere to operating procedures
Pump will not start Safety circuits or protective devices
prevent contactor from staying closed
Check utilities, flow devices switches, interlocks.
Check thermostat operation