Edwards GXS Series Instruction Manual page 36

CAUTION:
The dry pumping systems have a maximum continuous exhaust line pressure limit.
Operation above the limit may damage the pumping mechanism.
The medium duty dry pumping systems have an exhaust pressure sensor which will
initiate warnings and alarms when the pump is operated for at least 20 seconds
above the limits given in
run with a warning present, however an alarm will cause the pump to stop.
The light duty dry pumping systems do not have an exhaust pressure sensor. The
maximum continuous exhaust line pressure of these dry pumping systems should not
exceed 0.4 barg.
For all pumps, it is the user's responsibility to provide an exhaust system with
sufficient conductance to ensure the exhaust pressure limit is not normally exceeded.
CAUTION:
Use a catchpot to prevent the drainage of condensate back into the dry pumping
system. Condensate that drains back into the dry pumping system could damage the
pump.
Do not reuse any O-ring or O-ring assembly and do not allow debris to get into the dry
pumping system during installation.
When connecting the dry pumping system to the vacuum system, take note of the
following:
▪ To get the best pumping speed, ensure that the pipeline which connects the
vacuum system to the dry pumping system is the minimum length possible and has
an internal diameter not less than the system inlet port.
▪ Ensure that all components in the vacuum pipeline have a maximum pressure
rating which is greater than the highest pressure that can be generated in the dry
pumping system.
▪ Incorporate flexible pipelines in the vacuum pipeline to reduce the transmission of
vibration and to prevent the loading of coupling joints. We recommend using our
braided flexible pipelines. The pipelines should be rated for 110 °C.
▪ Adequately support vacuum/exhaust pipelines to prevent the transmission of
stress to pipeline coupling joints.
▪ Incorporate a pressure gauge in the inlet pipeline to determine that the dry
pumping system operates correctly.
▪ The dry pumping system inlet must be able to be isolated from the atmosphere
and the vacuum system if pumping or producing corrosive chemicals.
▪ The outlet of the exhaust pipe can have a check valve fitted which prevents the
suck‑back of exhaust vapours after the dry pumping system is shut down. The
check valve also provides additional attenuation of the pulses in exhaust pressure.
▪ For all GXS750 dry pumping systems, there is a limit to the length of NW50 pipeline
that can be used between the pump exhaust connection and the facility exhaust.
For GXS750 dry pumping systems with a check valve, the length of the pipeline is
limited to 1 metre. For GXS750 dry pumping systems without a check valve, the
length is limited to 3 metres. If these lengths are exceeded, GXS750 pump will trip
out due to high exhaust pressure. If the distance to the facility exhaust is greater
M58800880_H - Installation
Table: Pump protection
Page 32
sensors. The pump will continue to