Edwards Vapour Diffusion Vacuum Pump Diffstak 250/2000C

Refer to Section 7.2 for Item Numbers of the position indicator spares kits.

Refer to Figure 27 for visual guidance.

Removal of Damaged Position Indicators

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

Select the duty type of the pump

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 using the dipstick.

Is the fluid-level below the notch mark?

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

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

Check if the interior is badly discoloured or coated with charred fluid

If the pump fluid has deteriorated, clean the pump as detailed in Section 5.5

If the fluid is in satisfactory condition, refill the pump as detailed in Section 3.9 and refit it to the system

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

Choose the cleaning solution suitable for the type of pump fluid used.

Ensure all traces of the cleaning solution are removed before operating the pump.

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 deposits if present.

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

Wash again with acetone to remove all traces of the solution.