A373-10-880 Issue R
Page 22
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Operation
4.5
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 you have pumped condensable vapours, you can (if necessary) decontaminate the oil; use the procedure in
4.6
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 (
, item 12). If the oil is cloudy or discoloured,
continue with the procedure at
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.
4.7
Unattended operation
The pump is designed for unattended operation under the normal operating conditions specified in
However, we recommend that you check the pump at a regular interval of not more than 14 days; check the pump
more frequently if you pump high volumes of gas or if you operate the pump with the gas-ballast control open.
Single-phase motors are cooled by internal fans. These motors have a thermal overload device. When the motor is
too hot, the thermal overload device switches off the pump. The thermal overload device has an automatic reset;
when the motor cools down, the device resets and the motor will restart.
When you check 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.
4.8
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 this, use a gas-ballast control
valve (refer to
).
We recommend, as described in the procedure below, that you decontaminate the oil before you shut down the
pump; this will prevent damage to the pump by the contaminates in the oil.
1. Refer to
and decontaminate the oil, as required.
2. Close the vacuum system isolation-valve (if not already closed).
3. Close gas-ballast (that is, turn the gas-ballast control clockwise).
4. Switch off the electrical supply to the pump.
