Gas Purges; Shut Down Procedure; Manual Reset - Edwards RV3 Instruction Manual

A652-18-880 Issue C
6.2

Gas purges

If you use inert gas purges to dilute dangerous gases to a safe level, ensure that the rotary vacuum
pump is shut down if an inert gas supply fails.
You must obey the instructions and take note of the precautions given below, to ensure that the
pumped gases do not enter their flammable ranges.
You must obey the instructions within this manual. Failure to do so will compromise the ATEX
compliance and may cause harm, injury or death to persons.
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 any remaining flammable gases or vapours have been purged
from the pump and exhaust pipeline.
If liquids that produce flammable vapours could be present in the pump foreline, then the inert gas purge to the
vacuum pump 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 you calculate 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 used to supply flammable gases
to the process, you should assume a flow rate for flammable gases that could arise if the mass flow controller is fully
open.
Continually measure the inert gas purge flow rate: if the flow rate falls below that required, you must stop the flow
of flammable gases or vapours into the pump.
6.3

Shut down procedure

On the E1M/40/80/175 and 275 pumps, the gas ballast control will be open while purging the system with inert gas
or clean air. If for any reason the pump is switched off, the system pressure will increase due to the drive shaft
direction reversal.
Close the vacuum system isolation-valve (if not already closed).
Switch off the electrical supply to the pump.
Close the cooling water supply (E1M/E2M175/275).
6.4

Manual reset

The pump must not be able to restart automatically after a fault condition until the fault has been cleared.
Your control must incorporate a manual reset device, which you must use to restart the system after a fault condition
has occurred.
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