EN – 33
EN
Operation
Purges for pumping condensable,
corrosive, and hazardous gases
C1 and C2 Series
Purges
The use of vane pumps may result in pumping gases or vapors which are flammable
or that could contaminate the oil. In this case, these products must be diluted using
purges supplied with dry gases, such as nitrogen to avoid undesirable reactions.
For this purpose, a filtered dry nitrogen supply or other inert gas with the same
characteristics is required:
• condensation point < 72°F/22°C,
• dust < 1μm,
• minimum absolute pressure 2 bar,
• H
2
O concentration < 10 ppb,
• O
2
concentration < 5 ppb.
Oil case purge
The purge dilutes pumped gases with a inert gas.
It makes it possible to limit corrosion in the oil case, condensation and accumulation of
gases in dead spaces of the pump.
Furthermore, the purge allows to flush with gas the pipes and accessories connected at
the exhaust of the pump.
Connect the dry nitrogen supply on the specific connector (1/8 NPT).
Set the nitrogen pressure to approximately 15.4 PSIG (1.1 absolute bar) (
see table
page 34
), and the flowrate so as to satisfy the dilution conditions.
(Caution: do not generate an excess pressure > 7 PSIG (0.5 relative bar).
Purge with gas ballast
Because of the danger present if the gas ballast was to be opened to astmosphere
(C2 series), the manual gas ballast doesn’t operate. Connect the dry nitrogen on the
specific connector (1/8 NPT). The nitrogen flowrate should be adjusted according to
the values from table page
34
.
C2 Series
Use of the bubbler
The bubble device is composed of an air tube with several holes, located at the bottom
of the oil case, which releases bubbles of inert gas in the oil. In this way, the oil is
saturated with neutral gas, which reduces its capacity to dissolve pumped gases. The
bubbles of inert gas released make it possible to eliminate the volatile vapours or acids
condensed in the oil. The bubbler flow also lowers the pumps temperature which slows
corrosion.
Connect the dry nitrogen supply on the specific connector (1/8 NPT).
Setting
The gas flow rate is adapted according to the application and the installation, taking
the following criteria into account (flow 60 to 300 l/h) (
see table page 34
):
• When pumping high quantities of gas, a highly corrosive gas or an easily condensable
gas, it is recommended to use a high nitrogen flow rate.
Caution ! It is assumed that a sufficient quantity of nitrogen is available.
• The pump exhaust circuit must be such that, for discharged flow rates, pressure drops
do not cause an abnormal excess pressure in the oil case.
• The nitrogen flow rate must be such that oil loses have no effect on the operation of
the pump throughout the pumping cycle (the oil level must be above the lower limit
of the sight glass at the end of pumping).
Run the pump at ultimate vacuum for one hour and set the nitrogen flow rate as
follows (at atmospheric pressure and at 60°F/20°C).
