Gas Purges - Edwards GXS Series Instruction Manual

3.4.2 Gas purges

WARNING:
If inert gas purges to dilute dangerous gases to a safe level are to be used, ensure that
the pump is shut down if inert gas supply fails.
Switch on the inert gas purge to remove air from the pump and the exhaust pipeline
before the process starts. Switch off the purge flow at the end of the process only after
the remaining flammable gases or vapours have been purged from the exhaust pipeline.
If liquids that produce flammable vapours could be present in the pump foreline, then
the inert gas purge to the dry pumping system should be left on all the time this liquid is
present. Flammable liquids could be present in the foreline as a result of condensation
or may be carried over from the process.
When calculating the flow rate of inert gas required for dilution, consider the maximum
flow rate for the flammable gases/vapours that could occur. For example, if a mass flow
controller is being used to supply flammable gases to the process, assume a flow rate for
flammable gases that could arise if the mass flow controller is fully open.
Continually measure the inert gas flow rate. If the flow rate falls below that required,
then the flow of flammable gases or vapours to the pump must be stopped.
M58800880_H - Installation
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