SOGEVACpumps are designed for pumping of inert gases in the range of
medium vacuum, between atmospheric pressure and end pressure of the
pump. When removing condensable vapors, a gas ballast valve must be
installed or opened.
1.1 Principle of operation
The SOGEVAC Neo D are 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) and by an oil pump. On part of the oil
is taken from the oil casing and flows via the oil filter 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.
A fan running on the motor shaft generates the necessary cooling air.
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 vapor tolerance specified in the Technical Data) when pumping
condensable gases or vapors. There are different types of gas ballast:
- standard manual gas ballast closed, small flow & standard flow,
- EM 24 V DC gas ballast available upon request,
- permanent, available upon request,
