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Operation
M588-00-880 Issue E
4.4 Manual shut down
If the pump is stopped without the gas purge cycle on processes that have condensable or solid by-products then
the pump may not restart.
For applications pumping liquids or condensable gases: if the pump is switched off straight after process then
liquids may remain trapped in the pump. These liquids can corrode the pump mechanism whilst the dry pumping
system is switched off for extended periods and may prevent the pump from starting again. For these
applications Edwards recommend carrying out a Smart Stop with Stop Time set to the maximum 3600 seconds.
Once the pump has stopped, seal the inlet and exhaust to prevent migration of liquid/condensable back into the
pump mechanism.
The GXS dry pumping system has two manual shut down modes: Fast and Auto.
In Fast shut down mode, no gas purges are introduced and the pump stops quickly. This method of shut down is not
recommended.
In Auto shut down mode, a purge gas cycle is introduced and the pump shuts down gradually over a time period. This
is the recommended shut down mode and is the default mode on the dry pumping system.
Smart Stop is an additional sequence that allows the user to define the time period for the gradual shut down and to
configure a setpoint temperature. If Smart Stop is enabled, the pump will perform a Smart Stop when the user selects
Auto shut down.
Refer to Table 22 for stop sequences.
If the dry pumping system is shut down and not isolated from the electrical supply, do not
disconnect the Pump Display Terminal or release control from the Pump Display Terminal or front
panel. This may result in the dry pumping system being started by another Module.
Do not remove the inlet connections until the pump has been allowed to stop rotating and the
power has been isolated. The pump can take up to three minutes to completely stop.
Table 22 - Stop sequences
Sequence Description
Stop with inlet purge Inlet purge gas valve opened (medium duty pumps only).
Inlet isolation valve closed (if fitted).
Pump runs for 15 minutes before stopping.
All gas purge valves closed before pump stops.
Smart Stop Inlet purge gas valve opened (medium duty pumps only).
Inlet isolation valve closed (if fitted).
Pump speed is ramped down over configurable shut down time.
All purge gas valves closed before pump stops.
Pump stops after configurable shut down time or after a configurable time period
after the pump temperature is below a configurable setpoint.
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