If operating a CDX pump with an oil temperature (measured on the end cover) higher than 95 °C (203 °F), use
a nitrogen shaft-seals purge. If not, the shaft-seals may be damaged during operation.
Use a rigid metal (such as stainless steel) pipeline with an outside diameter of ¼ inch for the nitrogen or compressed
dry air supply. If an acoustic enclosure will be fitted, ensure that the pipeline will not obstruct the enclosure.
Edwards recommends installing an automatically operated isolation valve in the gas supply pipeline configured so
that:
z The shaft-seals purge gas supply is on whenever the pump is on.
z The shaft-seals purge gas supply remains on for a period of at least 30 minutes after the pump is stopped.
Refer to Figure 1, 2 or 3, detail C and use the following procedure to connect the shaft-seals purge gas supply:
1. Remove the red blanking cap from the shaft-seals purge inlet (25)
2. Connect the gas supply pipeline to the inlet.
3.15 Connect the pump inlet and outlet
Note: If the CDX pump is part of an ATEX system, refer to the ATEX system instruction manual for further
information when connecting the pump inlet and outlet.
Where there is a risk that corrosive or dangerous condensates may form inside the pumping system, Edwards
recommends fitting suitable heaters to the inlet and outlet pipelines. If necessary, contact Edwards or the
supplier for advice.
3.15.1 Connect the pump to the process system
Note: Flame arrestors are available as accessories: refer to Section 7.4.
When connecting the pump to the process system:
z Support process pipelines to stop the transmission of stress to pipeline joints.
z The pump must be able to be isolated from the atmosphere and process system if pumping or producing
dangerous chemicals.
z To g e t t h e b es t p u m pi n g s p e e d , e n s u r e t h a t t h e p i p e l i n e which connects the process system to the pump is as
short as possible and has an internal diameter not less than the pump inlet.
If pumping flammable and explosive gases, use a CDX flame-proof pump (use a pump with integral
flame arrestors, or fit external flame arrestors) and ensure that the system can provide adequate
gas ballast and/or inlet purge to dilute the gases to safe levels. If not, there may be a danger of fire
or explosion.
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