3.7 Check the direction of motor rotation
CAUTION
Ensure that debris and objects do not fall into the pump inlet when you check the direction
of motor rotation. If this happens, you may damage the pump.
Note: When you switch off the pump, the cooling-fan may stop and then rotate in the reverse direction
for a few revolutions.
1. Watch the cooling-fan from the motor end of the pump, switch on the pump for two or three
seconds, then switch the pump off.
2. The correct direction of rotation of the cooling-fan is clockwise when viewed from the motor
end of the pump and is indicated by the arrow on the coupling-cover (Figure 1, item 3 for
the ESDP12 and Figure 2, item 7 for the ESDP30). If the direction of rotation is incorrect:
• On an ESDP30 3-phase pump, isolate the pump from the electrical supply, swap any
two of the phase-wires in the motor terminal-box, then reconnect the pump to the
electrical supply and repeat step 1 to ensure that the direction of rotation is now correct.
• On ESDP12 and ESDP30 1-phase pumps, do not use the pump; contact your supplier or
Edwards for advice.
3.8 Connect the pump-inlet to the vacuum system
Ensure that debris does not get into the pump when you install it. If the pump is to replace a
pump in an existing system, purge the existing pump with nitrogen for 15 minutes before you
disconnect it. If the existing pump is an oil-sealed pump, we recommend that you dismantle
the pipeline which connects the vacuum system to the pump and clean the pipeline to ensure
that there is no residual oil contamination in the pipeline.
Use standard NW fittings to connect the pump-inlet to your vacuum system: refer to Section 2.1
for the inlet sizes. When you connect to the vacuum system:
• To get the best pumping speed, ensure that the pipeline connected to the pump-inlet has an
internal diameter not less than the inlet-port diameter.
• Incorporate flexible bellows in your system pipelines to reduce the transmission of vibration
and to prevent loading of coupling-joints. The bellows must have a maximum pressure
rating which is greater than the highest pressure that can be generated in your system. We
recommend that you use Edwards flexible bellows.
• Incorporate an inlet isolation-valve in the pipeline from the vacuum system to the pump, so
that you can isolate the vacuum system from the pump when it is switched off and prevent
the suck-back of process gases and debris into the vacuum system.
20 ESDP12 and ESDP30 Scroll Pumps
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