rough vacuum, between atmospheric pressure and end pressure of the pump.
When removing condensable vapours, a gas ballast valve must be installed.
1.1 Principle of operation
The SOGEVAC®SV40 B – SV65 B – SV 100 B – SV120 B ATEX Cat 2 are
single- stage, oil-sealed rotary vane pumps. The anti-suckback valve, gas
ballast valve, exhaust filter, oil return circuit and oil cooling oil are integrated
functional elements. The pumps are driven by a directly flanged motor.
The rotor mounted eccentrically in the pump cylinder has three vanes which
divide the pump chamber into several compartments. The volume of each
changes periodically with the rotation of the rotor. As the rotor rotates, the
intake portion of the pumping chamber expands and sucks gas thru the intake
port. The gas passes through the dirt trap and the open anti-suckback valve
and enters the pump chamber. As the rotor rotates further, the vane
separates part of the pump chamber from the intake port. This part of the
pump chamber is reduced, and the gas is compressed. At slightly above
atmospheric pressure the gas is expelled from the chamber via the exhaust
valve.
Oil injected into the pump chamber serves to seal, lubricate and cool the
pump. The oil entrained with the compressed gas is coarsely trapped in the oil
case by deflection. Then fine filtering occurs in the exhaust filter elements.
The proportion of oil in the exhaust gas is thus reduced below the visibility
threshold (over 99 % entrapment rate).
Oil trapped in the exhaust filters is returned to the inlet chamber via an oil
return line.
To prevent gas flowing at atmospheric pressure from the oil reservoir into the
intake port, the oil return line is controlled by a float valve.
The oil cycle is maintained by the pressure difference existing between the oil
casing (pressure above or equal atmospheric pressure) and the intake port
(pressure below atmospheric pressure). On part of the oil is taken from the oil
casing and flows via the oil filter bypass to the bearing points of the rotor and
to the pump chamber. The other part of oil injected in the pump does not run
through the oil filter bypass.
A fan running on the motor shaft generates the necessary cooling air. The oil
is also fed, thru a cooling coil, or in case of water cooled pumps, flows
through a water oil heat exchanger controlled by a thermostatic valve.
All SOGEVAC®SV40 B – SV65 B – SV 100 B - SV120 B ATEX Cat 2 pumps
are fitted with:
•PT100 temperature sensor
•Oil level switch
•Oil casing pressure transmitter
Pumps depending of their P/N are equipped with a gas ballast device. If
opened, a controlled amount of air so called "gas ballast" is admitted into the
pump chamber. This gas ballast prevents condensation (up to the limit of
water vapour tolerance specified in the Technical Data) when pumping
condensable gases or vapours. There are different types of gas ballast :
- standard manual gas ballast,
- large gas ballast (10 %), available upon request,
- permanent, available upon request, allowing temperature class T4 inside.
The pump temperature class may vary depending of the GB type. Please
