Edwards DRYSTAR GV Series, Instruction Manual

Page: 36 / 58

A705-74-880 Issue K
Page 30 © Edwards Limited 2009. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
OPERATION
4.3 Check the purge pressures and flows
Carry out the following checks immediately after pump start and regularly during pump operation:
Check that the pressure of your shaft-seals purge air or nitrogen supply is correct and adjust if necessary (refer to
Section 2.2 ).
If fitted, check that the pressure of your gas-ballast supply, purge air supply and / or nitrogen supply is correct and
adjust if necessary.
If necessary, open the gas-ballast flow valve ( Figure 1 , item 10) to achieve the required gas-ballast flow into the
pump.
4.4 Pump Shut down
CAUTION
Purge the pump before shut down. If you do not, process vapours may condense in the pump and corrode or
damage it.
Note: If the pump will be shut down for a long time in an environment where the temperature is close to freezing,
we recommend that you drain the cooling-water from the pump to prevent damage to the pump: refer to
Section 6.1 .
Use the following procedure to shut down the pump.
1. Isolate the pump-inlet from the process gases.
2. Refer to Figure 1 . Purge the pump of contaminants: operate the pump with full gas-ballast (that is, with the gas-
ballast flow valve (10) open) for at least 15 minutes. Alternatively, use one of the following methods:

Operate the pump for at least 45 minutes.

Operate the pump at an inlet pressure between 100 mbar and 300 mbar for at least 15 minutes; this is the
recommended method for dusty processes.

Operate the pump with full inlet purge (if fitted) for at least 15 minutes.
3. Close the gas-ballast flow valve (10), or switch off inlet purge (if fitted).
4. Switch off the pump.
5. When the pump has cooled down, turn off the cooling-water supply.
6. Switch off the shaft-seals purge nitrogen or air supply (if fitted).
7. For prolonged shut down it is recommended that the exhaust of the pump is disconnected and sealed to prevent
moisture ingress. Ensure that the exhaust sealing mechanism is removed before re-start.