2XZ Series Double Stage Rotary Vane Vacuum Pumps

2XZ series rotary vane vacuum pump is double stage high speed oil sealed rotary vane vacuum pump (hereinafter referred it as "the pump" for short). Its pumping principle is same as that of 2X type pump. Rotors are eccentrically mounted within the cylindrical housing of the stators and vanes are fitted freely inside the respective slots of the rotor.
When the rotor rotates at high speed, vanes in the rotor slot are urged outwards by centrifugal force as well as by spring force so as to keep close contact at their tips with the stator wall throughout rotation. Thus the inlet port and outlet port on the stator are separated by them. The volume of the space leading to the inlet port expands progressively and periodically with gas filling the space through inlet pipe, meanwhile the volume of the space leading to the outlet port diminishes progressively and periodically to compress the gas previously sucked.
By means of gas pressure and oil pressure exhaust valve on the outlet port is opened to expel gas out of the pump through the valve, then vacuum is obtained at the intake side of the pump. Fig 1 shows the working principle of a single stage pump. Double stage pump is the arrangement of two single stage pumps in series. When the intake pressure is higher, both stages of the pump may exhaust simultaneously, while at lower suction pressure gas is first expelled out from first stage to second stage, then from second stage exhausts to the open air.
2XZ type pump is equipped with gas-ballast valve. Its function is to fill the exhaust space with certain amount of air, when the valve is open, so to reduce the proportion of the partial pressure of vapor in the total discharge pressure.
As the partial pressure of vapor is lower than that of the saturated vapor pressure corresponding to the working temperature of the pump, vapor can be discharged from the pump with the filled air in order to avoid condensation of vapor in the pump oil and to prevent oil from emulsifying by the condensed vapor so as to prolong the useful lift of oil. However the ultimate vacuum of the pump shall drop, and the temperature of the pump shall rise when the gas-ballast valve is open.
2XZ type pump has the outstanding advantages of small size, light weight, low noise and easy to star etc. Besides, devices to prevent oil from sucking back and leakage of oil from axle sealing to contaminate environment are also provided.


Characteristics
Simple voice, simple structure, high efficiency
Extreme high vacuum, pumping speed large
Use gas ballast valve, can be able to pump condensable gas, such as water vapor
Pressure oil circulating system
Automatic fuel oil returning check valve
Applications
The pump is one of the basic equipment to exhaust a sealed vessel. It can be used either independently and can also be served as fore-pump for booster pump diffusion pump and molecular pump or as holding pump for a vacuum system and as a pre pump for titanium pump.
The pump is allowed to work continuously for long time under the condition that atmospheric temperature of 5ºC-40ºC and intake pressure below 1300Pa. While the pumped gas contain relative humidity more than 90%, gas-ballast valve should be opened.
With the inlet port widely opened to atmosphere, the pump is not allowed to work more than one minute.
The pump is not suitable for pumping over-oxidized, poison, explosive and corrosive gas, gas containing particulate dust as well as gases which react chemically with the pump.
It can be used for electric vacuum devices and thermos manufacturing, vacuum welding, printing, plastics, refrigeration equipment repair, medical analysis device industry, solar energy industry, electric light source industry, vacuum furnace industry and scientific research unit, instrumentation, etc. It is more suitable for laboratory use because of its advantages like small size, light weight and quiet operation etc.