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May 11, 2022 View:

What Are The Commonly Used Performance Parameters In The Rotary Lobe Pump

The following performance parameters are commonly used in lobe pumps.

1、Flow Q

Flow rate is the amount of liquid (volume or mass) that the pump delivers out per unit time.

The volumetric flow is expressed in Q in units such as: m3/s, m3/h, l/s, etc.

The mass flow rate is expressed in Qm, in units such as: t/h, kg/s, etc.

The relationship between mass flow and volume flow is as follows


where Density of the liquid (kg/m3, t/m3), clear water at room temperature = 1000 kg/m3.

2、Head H

The head is the value added of the energy per unit weight of liquid pumped by the pump from the pump inlet (pump inlet flange) to the pump outlet (pump outlet flange). It is also the effective energy gained by a newton of liquid through the pump. Its unit is Nm/N = m, i.e. the height of the column of liquid pumped by the pump, customarily abbreviated as metres.

3. Speed n

The speed is the number of revolutions per unit time of the pump shaft and is expressed by the symbol n in r/min.

4、Cavitation allowance

The NPSH cavitation margin, also known as the net positive suction head, is the main parameter indicating cavitation performance. The cavitation margin was once expressed domestically as h.

5. Power and efficiency

The power of the pump usually refers to the input power, i.e. the power transmitted from the prime mover to the pump shaft, so also known as shaft power, expressed in P.

The effective power of the pump, also known as the output power, is expressed in Pe. Diaphragm pump it is the effective energy obtained in the pump per unit of time from the liquid conveyed out of the pump.

Because the head is the effective energy obtained from the pump per unit of heavy liquid output, the product of the head and mass flow and gravitational acceleration is the effective energy obtained from the liquid output in the pump per unit of time, i.e. the effective power of the pump.


where Density of the liquid conveyed by the pump (kg/m3).

The heaviness of the liquid conveyed by the pump (N/m3).

Q flow rate of the pump (m3/s).

H pump head (m).

g acceleration of gravity (m/s2).

The difference between the shaft power P and the effective power Pe is the lost power in the pump, the size of which is measured by the efficiency of the pump. The efficiency of the pump is the ratio of the effective power and the shaft power, expressed in terms of

Zhejiang Ace Pump Technology Co., Ltd. is a large comprehensive pump company integrating the design, development, production and sales of lobe pumps, rotary lobe pumps and rubber lobe pumps. The company has been focusing on the technical research, production and manufacturing of various pumps, and is committed to providing customers with applicable pump handling system solutions.