Edwards Vapour Diffusion Vacuum Pump Diffstak 160/700C

Allow the Diffstak pump to cool and open it to atmospheric pressure.

Switch on the pump heater for a maximum time of two minutes to warm the pump fluid.

Ensure the pump fluid is not vaporised.

Disconnect the Diffstak from the electrical supplies and detach it from your vacuum system.

Remove the drain-plug and allow the fluid to drain from the pump.

Visually check the interior of the pump for discolouration or charred fluid.

Is the Diffstak boiler operating at a higher than normal temperature?

Allow the pump to cool and open it to atmospheric pressure

Remove the dipstick and 'O' ring

Check the fluid-level on the dipstick

Is the fluid-level below the notch mark?

Removal of Damaged Position Indicators

Refer to Figure 27 and loosen the clamp screw (7) on the valve open position indicator (6).

Slide the valve open position indicator down the dovetail groove (3) and out of the cylinder.

Loosen the clamp screw (7) on the valve closed position indicator (1).

Slide the valve closed position indicator down the dovetail groove (3) and out of the cylinder.

Installation of New Position Indicators

Ensure that the dovetail groove is clean.

Slide the new valve closed position indicator (1) into the dovetail groove (3) and ensure correct orientation as shown in Figure 27.

Adjust the position indicator until the gap (2) between the position indicator and the valve actuator is correct.

Isolate the Diffstak from the electrical supply

Remove the retaining screws and detach the cover from the terminal-box

Disconnect the incoming supply cables at the terminal-block

Disconnect the earth (ground) cable

Disconnect the two cables to the heaters

Remove the nut from the radiation shield/heater assembly securing stud

Release the radiation shield together with the terminal-block

WARNING: Remove all traces of the cleaning solution before you operate the pump.

Select the cleaning solution suitable for the type of pump fluid used

Ensure the jet assembly is vapour de-greased

Pump Interior Inspection and Cleaning

Inspect the pump interior for solid deposits of pump fluid around the base

Is there a solid deposit of pump fluid around the base?

Use an ultrasonic cleaning bath to remove solid deposits, if present

Wash the interior of the pump and the pump interior components with the selected cleaning solution