To Pump Condensable Vapours; To Decontaminate The Oil; Unattended Operation; Shut-Down - Edwards E2M28 Instruction Manual

A373-10-880 Issue T
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 pumping condensable vapours, decontaminate the oil, if necessary, using 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
continue with the procedure at
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, Edwards recommends 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.
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 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.
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 Section
Edwards recommends, as described in the procedure below, decontaminating the oil before shutting down the pump.
This will prevent damage to the pump by the contaminates in the oil.
1. Refer to Section 4.6 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.
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(Figure
Step 2 below.
7.5.15).
Edwards and the Edwards logo are trademarks of Edwards Limited.
1, item 12). If the oil is cloudy or discoloured,
© Edwards Limited 2014. All rights reserved.
Section 4.6.
Section 2.1.