How to calculate the reasonable installation height of the water pump? After reading it, you will know everything

Centrifugal pumps are one of the most commonly used pumps for transporting water. The elevation of the pump floor depends on the installation height of the pump. The correct calculation of the maximum allowable installation height of the pump is of great significance to ensure safe water supply and save civil construction cost.

In order to avoid the occurrence of cavitation, the installation height of the centrifugal pump needs to be carefully checked and calculated. The schematic diagram of the inlet side device of the pump is as follows:

The allowable geometric mounting height of the pump is related to various conditions, and its formula is as follows:

[Hg]- Allowable geometric mounting height of pump, m; (Calculation results for design use, the actual installation height should be lower than the allowable installation height)

Pe - suction surface pressure, Pa; (Atmospheric pressure at the inlet surface, the higher the altitude, the lower the pressure)

Pv - saturated steam pressure, Pa; (Related to water temperature, the higher the water temperature, the higher the saturated steam pressure)

ρ - fluid density, kg/m3;

G - acceleration of gravity, 9.81m/s2;

[NPSHr]- Allowable cavitation margin of the pump, m; (Related to pump performance, provided by pump manufacturers)

Hw- Suction pipe head loss, m.(Related to suction pipe design, determined by designer)

As can be seen from the above formula:

The higher the altitude, the higher the water temperature, the greater the allowable cavitation margin, the greater the head loss of the inlet pipe, and the smaller the allowable geometric installation height.

The atmospheric and corresponding water head heights at different altitudes are shown in the following table:

The water head height corresponding to the saturated steam pressure of water at different temperatures is shown in the following table:

For example, the NPSHr of a brand VISO125X100-315-55/2 water pump is 3.29m. 500 meters above sea level, the highest water temperature in summer is 40℃. If the suction pipe head loss is 1m, the geometric installation height [Hg] of the pump during local operation is calculated as follows:

Assuming that the water intake pressure is the local atmospheric pressure, the water head is 9.7m according to the atmospheric pressure at an altitude of 500m in the table.

When the water temperature is 40℃, the saturated steam pressure head of water is 0.752m.

Calculation :(Hg)= 1.9.7-0.752-3.29 =4.658