Troubleshooting

Table 4-1 Troubleshooting (Cont’d)

Fault	Probable Cause	Corrective Action
Poor ultimate	Contaminated pump fluid	Examine and clean pump;
pressure		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.

	Excessive or too cold cooling water	Check temperature. Adjust 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.

	Low heat input	Check heaters.

	Low fluid level	Add fluid.

	Malfunctioning pump assembly.	Check and repair or
	Improperly located jets. Damaged	replace.
	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	Forepressure too high	Check for leak in foreline, poor
contamination		mechanical pump performance,
		breakdown of pump fluid, and
		incorrect valve operation.

	Prolonged operation at high	Review procedures.
	throughput at pressure above10-3Torr
	Improper system operation and	Review procedures.
	air release procedures

Pump will not start	Safety circuits and/or protective
	prevent contactor from
	staying closed

Check utilities, flow devices switches, interlocks. Check thermostat operation.

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