Edwards Vapour Diffusion Vacuum Pump Diffstak 63/150P

Isolate the Diffstak from the electrical supply

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

Disconnect the incoming electrical supply cables and the earth (ground) cable at the terminal-block

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

Lower the complete radiation shield and heater assembly

Disconnect the electrical connections at the heater and remove the heater

Replace the defective heater(s)

Reconnect the heater electrical supply cables to the terminal-block

Coat the thread of the radiation shield/heater assembly securing stud with an anti-seize compound

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

Drain the pump fluid as detailed in Section 5.4.

Disconnect the following connections

Remove the pump from the system.

Remove the valve-plate from the shaft (refer to Sections 5.5.2 and Section 5.5.3).

Examine the valve-plate seal and the 'O' rings on the valve-shaft for wear or damage.

Isolate the pump from the electrical supply

Wipe the radiation shield with a soft cloth

Use a suitable cleaning solution if necessary

Disconnect the pneumatic pipelines from the Diffstak

Remove the socket-head screws securing the valve-plate to the shaft

Valve-shaft removal for Diffstak 63/150P and 100/300P pumps

Detach the red safety cover from the pneumatic actuator

Remove the three screws retaining the actuator to the boss on the valve-body

Carefully withdraw the valve-shaft (complete with actuator) from the valve-body

Valve-shaft removal for Diffstak 160/700P pumps

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