B344-21-880 Issue N
Page 42 © Edwards Limited 2007. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Maintenance
5. To refit a pneumatically-actuated valve:
z On Diffstak 63/150P and 100/300P pumps: Assemble as in step 4. Secure the actuator to the boss on the
valve-body with the retaining screws. Fit the safety cover.
z On Diffstak 160/700P pumps: Assemble as in step 4. Connect the pneumatic cylinder to the link arm and
secure the pin with the grub screw. Fit the switch mounting bracket and secure with the retaining screws;
ensure that the microswitch operating lever is positioned correctly. Fit the safety cover.
z On Diffstak 250/2000P pumps: Assemble as in step 4. Connect the pneumatic cylinder at the pivot-pin
mounting and secure the microswitch mounting bracket to the boss on the valve-body; ensure that the
microswitch operating lever is positioned correctly. Fit the safety cover.
6. Refit the baffle.
7. Inspect all of the ‘O’ rings; replace any that are damaged or that have undergone thermal set. Use a dry,
lint-free cloth or paper to clean the undamaged ‘O’ rings. Ensure that all ‘O’ rings are dust-free before
reassembly.
8. Reconnect the Diffstak pump to your vacuum system. Fill the pump with fluid as detailed in Section 3.9.
9. Reconnect the electrical supply and the cooling-water pipelines. For P-model pumps, reconnect the pneumatic
pipelines.
10. Test the installation to ensure that the Diffstak pump operates correctly.
5.6 Clean the radiation shield
Keep the radiation shield which surrounds the Diffstak boiler clean to maintain thermal efficiency.
To clean the external surface of the radiation shield:
1. Isolate the pump from the electrical supply.
2. Allow the pump to cool:
z On Diffstak 250/2000 pumps: Allow the pump to cool for at least 45 minutes.
z On Diffstak 63/150, 100/300 and 160/700 pumps: Allow the pump to cool for at least 20 minutes.
3. Wipe the radiation shield with a soft cloth (and use a suitable cleaning solution if necessary).
If you then need to clean the internal surface of the radiation shield:
1. Remove the heater assembly.
2. Remove the radiation shield.
3. Clean the radiation shield.
4. Refit the radiation shield and then the heater assembly.
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