A371-32-880 Issue C
Page 18 © Edwards Limited 2007. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Operation
4.7 Unattended operation
The pump is designed for unattended operation under the normal operating conditions specified in Section 2.
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.
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 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 Section 7.4.5).
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 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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