rotary vane vacuum pump of pumping rate

For the customers who choose vacuum pumps, the pumping speed matching the working conditions is the first condition to choose vacuum pumps. Of course, we need to understand several pumping speed concepts in order to better choose the vacuum pumps. The pumping rate refers to the volume of the gas discharged by the rotary vane vacuum pump in a unit time. Vacuum pump pumping speed is divided into three definitions: geometric pumping speed, nominal pumping speed and actual pumping speed.water-liquid-ring-vacuum-pump-for-plastic-extruder-machine

I. Geometric Pumping Speed
Geometric pumping speed is the volume of gas pumped out in unit time when the pump operates at rated speed. Geometric pumping speed is the product of the volume of suction chamber Vs at the end of suction and the number of rotors N and z, that is:

Szh = n.Vs.Z = n.A.l.z

Section area of the suction chamber at the end of the suction

L is pump cavity width

2. Nominal pumping speed

Nominal pumping speed is the nameplate pumping rate that we usually see when the pump leaves the factory.high-flow-dry-vacuum-pump-manufacturer

3. Actual pumping speed
The so-called actual pumping speed is the pumping rate measured in the actual operation of the pump. At normal atmospheric pressure, the actual pumping speed should be equal to the nominal pumping speed. Considering the leakage loss in actual operation, the general design geometric pumping speed is 1.1 to 1.25 times the nominal pumping speed.

The actual pumping speed can be understood by using the principle of function, that is to say, the pressure at the pump inlet is equivalent to a function value. In the actual pumping process, the pressure at the pump inlet decreases with the decrease of the pressure at the pump inlet. When the inlet pressure equals the limit pressure, the actual pumping speed becomes zero. Therefore, we can calculate that the volume of the gas returned to the suction chamber through the gap is equal to the volume of the air pumped.Air-cooled-Roots-Vacuum-Pump-Unit-in-Thermal-Power-Plant