2 Design and function
The SRV300 is single-stage, oil-sealed rotary vane pump. The anti-suck back valve, gas
ballast valve, exhaust filter, oil return circuit and oil cooling oil are integrated functional
elements. The pump is 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 change periodically with the
rotation of the rotor.
As the rotor rotates, the intake portion of the pumping chamber expands and sucks gas
through the intake port. The gas passes through the dirt trap and the open anti-suck back
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. When the compressed gas pressure is higher than the exhaust 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
transfer. 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.
Oil trapped in the exhaust filters is returned to the inlet chamber via an oil return
transfer. 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 case
(pressure above or equal to atmospheric pressure) and the intake port (pressure below
atmospheric pressure).
A fan running on the pump shaft generates the necessary cooling air. The oil cools
down through a radiator. Water cooled pumps with an oil-water heat exchanger and
thermostatic valve are also available (as specific variants).
By opening the gas ballast valve, 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 vapor tolerance specified in the Technical Data) when pumping condensable gases or
vapors.
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