Free chlorine
< 0.2 mg/l
8 °dH (degrees German hardness) = 1.4mmol/l
= 10 °e (degrees English hardness)
= 14 °f (degrees French hardness)
If there is the danger of frost, you may use a water Drystar mixture of up to 50%.
DS water can be used for cooling the pump, if the pH value corresponds to the range indicated
above.
7.5 Connecting purge gas
The pump must be operated with purge gas. The purge gas is distributed in the pump via
flow restrictors as follows:
▪
to the shaft-seal on the low vacuum side
▪
into the pumping chamber (balance line)
▪
to the shaft-seal on the high vacuum side.
The flow restrictors ensure that the gas flow to the shaft-seal on the high vacuum side
becomes very low at ultimate pressure.
The purge gas on the shaft-seals provides an air cushion under the shaft-seals and thus
prevents premature wear.
Use of the correct shaft-seal purge and gas-ballast requirements depend on your application.
If in doubt about your application setting, contact Edwards.
▪
Connect an inert gas supply to the gas system. An upstream supply pressure of 4 to 10
bar(g) is required. Ensure that your gas system can maintain pressure whilst flowing up
to 62 SLM of purge gas.
▪
Adjust the regulator on the gas panel to 2.2 bar(g).
▪
The purge supply should be maintained whenever the pump is operational, to ensure
the process seals operate correctly and that the oil boxes are adequately protected
from process media.
▪
Be aware that the purge supplies are not automatically controlled, therefore it could be
possible to pressurise the pump or system if purge is left on with a closed system.
▪
Atmospheric gas-ballast can be adjusted or shut off completely, depending on your
application, using the manual needle valve.
WARNING: LEAKAGE OF GAS
The atmospheric shaft-seal between the gearbox and atmosphere is a PTFE dynamic seal,
which may, under wear-out conditions, lead to small leakage of gearbox gas. Ensure that
purge gas is supplied continuously to the main pump shaft-seals to prevent process gas
entering the gearbox which could otherwise leak from the atmospheric shaft-seal.
Leakage of purge gas to atmosphere should also be considered; ensure the pump is in a
well ventilated area.
Page 29
A41802880_C - Installation
