3.
Close the gas-ballast control.
4.
Open the vacuum system isolation-valve and pump down to ultimate vacuum.
5.5 To pump condensable vapours
Use gas-ballast (open the gas-ballast control) when there is a high proportion of
condensable vapours in the process gases:
1.
Close the vacuum system isolation-valve.
2.
Turn the gas-ballast control anti-clockwise to fully open and operate the pump for
30 minutes to warm the oil, this will help to prevent vapour condensation in the
pump.
3.
Open the vacuum system isolation-valve and continue to operate the pump with
the gas-ballast control open.
After pumping condensible vapours, decontaminate the oil (if necessary), use the
procedure in
To decontaminate the oil on page 25
.
5.6 To decontaminate the oil
The oil in the pump should be clear. If the oil is cloudy or discoloured, it is contaminated
with process vapours.
1.
Look at the condition of the oil in the oil sight-glass (
). If the oil is cloudy or discoloured, continue with the procedure
at step 2 below.
2.
Close the vacuum system isolation-valve.
3.
Turn the gas-ballast control fully anti-clockwise.
4.
Operate the pump until the oil is clear.
5.7 Unattended operation
The pump is designed for unattended operation under the normal operating conditions
specified in
Operating and storage conditions on page 12
. However, we recommend you
to checking the pump at a regular interval of not more than 14 days, check the pump
more frequently if pumping high volumes of gas or if operating the pump with the gas-
ballast control open.
The motor is protected by an overload device which isolates the pump from the
electrical supply when critical temperature or current levels are exceeded. The overload
device resets automatically when the motor has cooled. When checking the pump, make
sure that the pump is not going through a repetitive cycle of thermal overload failures
and automatic resets. If necessary, reduce the thermal load from the pumped gases, to
prevent overheating of the pump.
5.8 Shut-down
Note:
If the gas-ballast control is open and the motor is switched off for any reason, the pump
drive shaft may rotate in the reverse direction, causing a system pressure rise. To prevent
Page 25
A37132880_F - Operation
Summary of Contents for A37104902
Page 43: ...Page 41 A37132880_F Service...
Page 44: ...edwardsvacuum com...
