2XZ rotary vane vacuum pump
2XZ rotary vane vacuum pump
2XZ rotary vane vacuum pump
2XZ rotary vane vacuum pump
2XZ rotary vane vacuum pump
2XZ rotary vane vacuum pump
2XZ rotary vane vacuum pump
2XZ rotary vane vacuum pump
2XZ rotary vane vacuum pump
2XZ rotary vane vacuum pump
2XZ rotary vane vacuum pump
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2XZ Series Double Stage Rotary Vane Vacuum Pump Overview

Suzhou Doctor Pump Co.,Ltd
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2XZ Series Rotary Vane Vacuum Pump Structure

2XZ series rotary vane vacuum pump is double stage high speed oil sealed rotary vane vacuum pump.

Rotors are eccentrically mounted within the cylindrical housing of the pump casing 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 pump casing wall throughout rotation. Thus the inlet port and outlet port on the pump casing 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 vacuum pump. Double stage vacuum pump is the arrangement of two single stage vacuum 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 series rotary vane vacuum 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,s o 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 vapor condensation in the 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 will drop, and the temperature of the pump will rise when the gas-ballast valve is open .

2XZ series rotary vane vacuum pump has the outstanding advantages of small size, light weight, low noise and easy to start, etc. Besides, the vacuum pump can also be equipped with NRV to prevent oil from sucking back to chamber.

Fig. 1 Section view of the pump

 2XZ rotary vane vacuum pump section view

1. Inlet port     2.Filter net     3. Oil baffle 

4.“O”ring        5. Spring             6. Vane      

7. Rotor       8. Pump casing     9. Oil box  

10. Vacuum oil     11. Exhaust valve plate     

12. Screw plug for oil drain        13. Oil glass    

14. Screw plug for oil filling    15. Gas-ballast valve

16. Mist reducer   17. Outlet port        18.Handle  

2XZ rotary vane vacuum pump section view

2XZ Series Rotary Vane Vacuum Pump Usage

  1. Vacuum pump is one of the basic equipment to suction air ina sealed vessel. 2XZ series rotary vane vacuum pumpcan be used either independently and can also be served as backing pump for roots booster pump, diffusion pump and molecular pump. It can be used for electric vacuum devices manufacturing, thermos bottle manufacturing, vacuum welding, printing, plastics, refrigeration equipment repair, instrumentation matching, etc. It is more suitable for laboratory use because of its advantages like small size, light weight and quiet operation, etc .

  2. 2XZ series rotary vane vacuum pump is allowed to work continuously for long timeunder the condition that atmospheric temperature of 5℃-40℃ and intake pressure below 1300Pa. While the pumped gas contain relative humidity more than 90%, gas-ballast valve should be opened.

  3. With the inlet port widely opened to atmosphere, the vacuum pump is not allowed to work more than one minute.

  4. 2XZ series rotary vane vacuumpump 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.


2XZ Series Rotary Vane Vacuum Pump Specifications







Capacity (L/S)






Max vacuum (Pa)



Power (kw)






Inlet diam






Net weight (kg)







2XZ Series Rotary Vane Vacuum Pump Installation

  1. The vacuum pump should beinstalled on a dry, airy and clean place.

  2. The vacuum pumpis with a handleand rubber foot, except for transportation, it needs to be placed in a smooth place.

  3. To wire the electricity,pleasenote the direction of rotation. If you see from the motor fan side, impeller rotation should be clockwise. For test running, you can use your hand to rotate shaft or motor fan, so the oil inside the pump can be discharged.

  4. The diameter of the pipeline should not be smaller than that of the inlet port of the pump. The pipelineshould be short and should have as few bends as possible in order to reduce the loss of pumping speed. Meanwhileleakage of the pipeline should be noticed. If rubber pipe is adopted, the pipe should preferably be de-sulfurized.

  5. When the vacuum pump is started with the inlet port widely opened to atmosphere, little amount of oil mist will be dischargedout. If you worry about itsworking, you can use plastic pipe to lead it away or install oil mist reducer.

  6. This vacuum pump is equipped with NRV to prevent oil from sucking back to chamberwhen it stops running. Therefore it is not necessary to installa electromagnetic valve on the inlet port.


2XZ Series Rotary Vane Vacuum Pump Operating Instructions

  1. Oil checking. If oil is too low, exhaust valve can not be sealed and vacuum degree be effected.If oil is too high, spraying of oil may be happened while the pump is started with its inlet port widely opened to atmosphere. It is quite normal to lift oil lever when the pump is rotating. After filling oil, screw the plug. The oil should be filtered filling in order to prevent it from mixing with impurities to clog oil hole.

  2. The vacuum pump can be started with inlet port widely open to atmosphere of under any degree of vacuum. If electromagnetic valve is installedon the inlet port, it should be started simultaneouslywith the pump.

  3. When thevacuumpump is operated under higher temperature, the oil temperature will be raised and the viscosity of oil will be lowered, the saturated vapor pressure will be increased, this will cause ultimate vacuum dropping, especially the total ultimate pressure measured by thermo couple gauge. Good ventilation for radiating heat or substitution of better quality oil will improve ultimate vacuum.

  4. To check ultimate vacuum of the pump, a column of mercury gauge should be used.Under the condition that the a column of mercury gauge is directlyconnected to the inlet port of the pump and pump temperature is stable and the gauge itself is checked, the pump will attain to its ultimate vacuum when it runs within 30 minutes (for reference only). The ultimate pressure is related to oil, vacuum gauge, it might differs.

  5. If the pumped gas contains more condensable vapor (its relative humidity is higher),let the pump run 20-40 minutes with gas-ballast valve widely opened, then close the valve. Before stopping the pump, open the gas-ballast valve, let the pump run empty 30 minutes so the pump can have a longer service life.

  6. Oil choose. Pump viscosity affects starting power and ultimate vacuum. Higher viscosity is better for vacuum and the starting power is higher.


2XZ Series Rotary Vane Vacuum Pump Maintenance

  1. Precautions

(1) The pump should always be kept clean to prevent any impurities from entering the pump.

(2) The oil level should always be kept at middle of the sight glass.

(3) Due to the improper storage of the pump, water or any other impurities may enter the pump affecting ultimate vacuum of the pump. Open gas-ballast valve to provide the purification of oil, then observe if the ultimate vacuum changes. In case of that no improvement of ultimate vacuum is observed after several hours, oil should be renewed and even renew the oil twice again if necessary.

Process of renewing of oil:

Let the pump operate about 1/2 hour to raise the temperature of oil as to decrease the oil viscosity, stop the pump and drain out the oil. Restart the pump and let it operate about 10-20 seconds with inlet port widely opened. In this interval slowly fill little amount of clean oil into the pump through the inlet port to replace the original.

(4) Diesel oil, gasoline and other oil of higher saturated vapor pressure are forbidden to mix with the vacuum oil in order to avoid the ultimate vacuum. Generally gauze is used to clean the pump parts. To wash the parts with metal chips, sand and other impurities, gasoline can be employed. Reassembly should be carried out after they are dried.

(5) If the pump should be disassembled in order to clean or to inspect the interior parts, attention should be paid to the disassemble procedure and reassemble to avoid impairment of the parts.


  1. Disassemble Procedure

(1) Drain oil.

(2) Screw out the bolts on inlet flange, take out the inlet pipe. Screw out the bolts on gas-ballast flange, take out the gas-ballast valve.

(3) Take off the oil box.

(4) Take off the split-pin on the oil check valve and the impeller.

(5) Screw-out the tighten bolts of the frame and pump body, take off the pump casing. 

(6) Screw out the pump cover bolts, take off the pump cover and then pull out rotors and vanes.


  1. Assemble Procedure

  • Wipe and clean all partsusing gauze.

  • Put vanes into the respective slots of the rotor,then put the rotor of high stage into pump casing, put the pump cover, pins, screws, keys, shaft on their original place..

  • Repeat the same process once again for lower stage rotor.

  • Put back check valve. The flat surface of valve head should be point to the oil hole. Stop the impeller by hand while rotate the rotor, the oil hole should be alternately closed and opened by the valve,then adjust the max height of opening of the flat surface of the valve head to such a value of 0.8-1.2mm.

  • Put the rest spare parts like exhaust valve and oil baffle.

  • Mount the pump casing, key, shaftand motor on the frame.

  • Enclose the pump casingwith oil box.

  • Insert the inlet pipe and gas-ballast valve and screw on their flanges to fix them.



During assembly, spread clean vacuum oil on the rubbing surfaces of all mating parts.

All parts should be set back to their original positions.

All the screwed parts should be tightened, no loosening is allowed.

All worn out parts should be inspected. Readjust or replace if necessary.

After assembly, observe running condition and measure ultimate vacuum. If the ultimate vacuum does not conform with specified value, adjustment should be made.

At same time with the overhauling of the pump, the pipeline system, valves and motor should also be cleaned and overhauled.


2XZ Series Rotary Vane Vacuum Pump Troubles and Troubleshooting

  1. Ultimate Vacuum

(1) The oil level is too low, exhaust valve can not be sealed and sound of exhausting is loud.

Fill in more oil.

  • The failure may be due to the contamination of the oil by the condensable vapor.

Widely open the gas-ballast valve to purify the oil or renew the oil.

  • Air leak at the joint of pipelines, pipelineitself and  

Take measure to eliminate the leak.

  • Improperly placing of inlet pipelines or gas ballast valve rubber seals.

Readjust or replace of them should be made.

  • Clogging of the oil holes.

Drain oil, dismount the oil box, clear the oil holes.

  • The vacuum system, including containerand pipelines, is seriously contaminated.

Cleaning them .

  • Breaking of vane springs.

Replace them with new spring.

  • Vanes, stator may be worn out.

Check them, replace or readjust.

  • Overheating of the pump, it causes not only the droppingof oil viscosity and rising of the saturated vapor pressure but also causes the cracking of oil.

Improve ventilation and cooling to decrease ambient temperature. If the gas temperature is too high, it should be cooled before sucked into the pump.


  1. Oil splash

Check the oil level, whether it is too high. Are there any oil or impurities to clog the oil separator? Is the oil baffle is right positioned and firmly fixed? Is the gaskets in inlet port or gas ballast valve is sealed?


  1. Oil leakage

Check the oil plug, sight glass and oil box gasket, if they are worn out or improper assembled, if the glass is overheated and deformed, replace them if necessary or lower oil temperature.

If the connecting screws between the pump and supporting frame are not tightened, or oil seal improper assembled or worn out, it will also cause oil leakage, but it will not contaminate the environment. If it’s not severe, the pump still can be used. If it’s severe, oil seals, gaskets should be replaced and reassemble.


  1. Noise

The noise may be caused by breaking of vanes, too much oil, worn out of bearing and deterioration of parts.

Check them and readjust or replace them if necessary.

If vanes are not rightly positioned, it will also cause noise. If temperature is too high, vanes got thermal expansion.


  1. Oil return back to chamber

Check valve is not tightly closed, causing oil level drops fast after pump stops.

Check the variation of oil level by starting and stopping the pump again and again. If check valve worn out or deformed, replace a new check valve.

If oil seals inside pump cover are improperly placed or worn out, replace them.

The pump cover or stator surface is uneven, repair them.


  1. Oil blackened, oil temperature too high, it might because oil seals are not tightened and friction with rotor.

Oil seal should be replaced so as not to damage vanes.


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