Complete line of Roots vacuum pumps

Roots vacuum pumps product display

ZJ Roots vacuum pumpsComplete line of Roots vacuum pumps

Product parameters

Model ZJ-150~ZJ-1200 ZJP- 70~ZJP- 2500
Pumping speed(L/s) 150~1200  70~ 2500
Ultimate pressure
1stage piston pump as backing pump 5×10-2
2 stage piston pump as backing pump 1×10-1
Max. allowable diff. pressure(Pa) 8×103~5×103 4×103~ 2. 7×103
Motor rotary speed(RPM) 3000
Suitable motor power(kW) 2.2~11  1.1~ 22
Flange size Inlet(mm) 100~250 80~ 320
outlet(mm) 100~ 200  80~ 320
Cooling water consumption(L/h) 120~150  120~ 200
Allowable temperature(℃) 100
Vacuum pump oil 100#
Weight(without motor)(kg) 195~ 860 110~ 1350


A vacuum pump is realized by means of a pair of leaf-shaped rotors synchronously and counter-rotating in the pump chamber to move the gas.
Roots pump (is a vacuum pump without internal compression, usually compression ratio is very low, so high, medium vacuum pump need front pump.

The product description

Roots vacuum pump refers to the mechanical vacuum pump with a pair of synchronous high-speed rotary sole rotor, which can not be pumped alone. The front stage needs to be equipped with oil seal and water ring, etc., which can be directly discharged into the atmosphere.

Its structure and working principle are similar to roots blower. When working, its suction port is connected with the vacuum container or the main pump of the vacuum system. The rotor of this vacuum pump is not in contact with the rotor and the rotor is not in contact with the pump shell. The clearance of the schematic diagram is generally 0.1~0.8 mm. You don’t need oil. The rotor profile includes arc, involute and cycloid. The capacity utilization rate of involute rotor pump is high and the machining accuracy is easy to be guaranteed. The speed of roots vacuum pump can be up to 3450~4100 RPM; The pumping rate is 30~10000 l/s (1 l =10-3 m 3); Ultimate vacuum: 6.5 10-2 pa for single stage and 1 10-3 pa for double stage.

The ultimate vacuum of roots pump depends not only on the pump structure and manufacturing precision, but also on the ultimate vacuum of the front pump. In order to improve the ultimate vacuum pump, the roots pump can be used in series. Roots pump works similar to roots blower. Due to the continuous rotation of the rotor, the pumped gas is sucked into the space v0 between the rotor and the pump housing from the air inlet, and then discharged through the exhaust port. Since the v0 space is fully enclosed after inspiration, the gas in the pump chamber is not compressed or expanded. However, when the top of the rotor turns around the edge of the exhaust port and the v0 space is connected with the exhaust side, due to the high gas pressure on the exhaust side, a part of the gas rushes back to the v0 space, making the gas pressure suddenly increase. As the rotor continues to rotate, gas is expelled from the pump. Roots pump in the pump chamber, there are two “8” shaped rotor perpendicular to each other mounted on a pair of parallel shaft, driven by a pair of gear ratio of 1 for each other reverse synchronous rotation movement. Between the rotor, the rotor and the pump shell wall, maintain a certain gap, can achieve high speed operation.

Roots pumps are ideal for low and medium vacuum applications, typically used for:

Coating and semiconductor industry,
Chemistry and technology,
Research and development.


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