Instruction manual

Issue H Oct 04
PAGE
24
GV Dry Vacuum Pumps
OPERATION
24
4.3 Check the purge pressures and flows
Do the following checks immediately after pump
start and regularly during pump operation:
1. Check that the pressure of your shaft-seals
purge air or nitrogen supply is correct and
adjust if necessary (refer to Section 2.7).
2. If fitted, check that the pressure of your gas-
ballast nitrogen supply is correct and adjust if
necessary.
3. If necessary, open the gas-ballast flow valve
(Figure 1, item 10) to achieve the required gas-
ballast flow into the pump.
WARNING
Ensure that you do not touch the
pump-body when you adjust the gas-
ballast flow valve. During operation,
parts of the pump can become hot.
4.4 Shut down the pump
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.
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 or close to atmospheric
pressure 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 supply
(if fitted).
CAUTION
Purge the pump before you shut it down. If you do
not, process vapours may condense in the pump
and corrode or damage it.