The RUVAC WS and RUVAC WSU are Roots pumps driven by a canned motor.
The WSU types have a pressure balance line between the discharge and intake flanges.
The RUVAC WS and WSU are lubricated with mineral oil or perfluorized polyether (PFPE) in the case of the PFPE models. Apart from the lubricant the mineral oil and PFPE models are identical in type.
Only the RUVAC WS/WSU PFPE can be used for pumping greater than atmospheric concentrations of oxygen or very aggressive or hazardous gases.
Principle of Operation
Roots pumps - also known as Roots blowers - contain in their pump casing (1/3) two symmetrical impellers (1/4) rotating in opposite directions. The impellers have roughly the cross section of a figure „8“ and are synchronised by a toothed gearing so that they move past each other and the casing without contact but with a small clearance.
In impeller positions I and II, the volume in the intake flange is increased. When the impellers rotate further to position III, part of the volume is sealed off from the intake side.
In position IV, this volume is opened to the discharge side, and gas at backing pressure (higher than the intake pressure) flows in. The inflowing gas compresses the gas volume pumped from the intake side. As the impellers rotate further, the compressed gas is ejected via the discharge flange.
This process occurs twice per complete revolution of each of the two impellers.
Due to the non-contacting rotation in the pumping chamber, Roots pumps can be operated at high speeds (standard n = 3,000 rpm at a mains frequency of 50 Hz). Thus a relatively high pumping speed is attained with small pumps.
The pressure differential and compression ratio between the intake and discharge sides are limited on Roots pumps. If the allowable pressure differential is exceeded, the pump overheats.
In practice, the maximum attainable pressure differential is significant only in the rough vacuum range (p > 10 mbar), whereas for pressures in the fine vacuum range (p < 1 mbar) the attainable compression ratio is decisive.
RUVAC pumps from the WS/WSU range have been specifically designed for operation in the rough and fine vacuum ranges. They are thus either used in connection with backing pumps or in closed gas cycles. The pump’s power consumption depends not only on the pumping chamber volume and the rotational speed of the pump, but also on the pressure differential between the discharge and intake flanges.
Unit is fully rebuilt and comes with a FULL 12-MONTH WARRANTY!
AJVS can Repair and Service your Leybold / Oerlikon WS-501 Vacuum Booster. Please visit our Service Page for more information.