Nitrogen Purge (Epx N Series Pumps) - Edwards EPX HiVac Series Instruction Manual

A419-00-880 Issue F
Remove the blanking plugs from the outlet(s)
suitable clamp and seals to connect the outlet(s) to your exhaust pipeline. Take note of the following when you
connect the exhaust pipeline:
If your exhaust pipeline incorporates any shut-off valves, you must be able to prevent operation of the pump
when any of the valves are closed (that is, the pipeline is restricted or blocked). If the EPX (Twin) pump
operates when the pipeline is restricted or blocked, the pump will not operate correctly and may be severely
damaged.
You should not incorporate a check valve in the exhaust line of the EPX (Twin) pump. If you do, the EPX
(Twin) pump may not operate properly and may become damaged. If an exhaust check valve is unavoidable
then you must ensure that the pump is at atmospheric pressure (for example by use of a foreline purge)
before you start the pump. This applies to all EPX (Twin) pump variants.
Incorporate flexible bellows in the exhaust pipeline to reduce the transmission of vibration and to prevent
the loading of coupling-joints. If you use flexible bellows, you must ensure that you use bellows which have a
maximum pressure rating which is greater than the highest pressure that can be generated in your system,
and which can withstand the maximum temperatures that can be generated by your process conditions, for
example, braided flexible bellows may be used for this purpose.
The exhaust pipeline must be a minimum diameter of NW25 throughout.
3.6

Nitrogen purge (EPX N series pumps)

The EPX pump should not be used to pump pyrophoric gases or explosive mixtures.
Dilute flammable gases to less than 25% of the LEL (Lower Explosive Limit) before the pump inlet.
The responsibility for ensuring the correct dilution of the pumped gas lies with the operator.
The flow switch is set to 12 slm and therefore provides an indication that a flow in excess of 12 slm
is present, but gives no guarantee that there is sufficient flow to prevent condensation or to
provide sufficient dilution of the process gas to safe levels.
The flow switch is not a guaranteed interlock. To ensure dilution of the process gas to safe levels,
the system installer must fit appropriate interlocked hardware to ensure correct nitrogen purge
flow and monitoring.
The following instructions apply to EPX N series pumps. They are not applicable to EPX L series pumps.
A 1/4 inch compression fitting is provided on the pump, marked 'N
nitrogen purge inlet connection using 1/4 inch OD tube, (refer to
Ensure that the nitrogen supply is stable to guarantee that the nitrogen purge flow is maintained. The nitrogen purge
gas should comply with the specifications detailed in
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(Figure 2, item 8 [there are two outlets on the EPX Twin]), use a
WARNING
WARNING
WARNING
WARNING
Inlet'. Connect the nitrogen purge supply to the
2
Figure
Table 10.
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Edwards and the Edwards logo are trademarks of Edwards Limited.
6, item 4).