Centrifugal pump is one of the most commonly used pumps in water delivery, the floor elevation in the pump room depends on the installation height of the pump, the correct calculation of the maximum allowable installation height of the pump, so that the pump station can not only safe water supply, but also save civil construction cost, has very important significance.
In order to avoid cavitation, the installation height of the centrifugal pump needs to be carefully checked and calculated.Schematic diagram of water pump inlet side device is as follows:
The allowable geometric installation height of the pump is related to various conditions, and the formula is as follows:
In the formula:
[Hg] -- allowable geometric installation height of pump, m;(the calculated results can be used in design, and the actual installation height should be lower than the allowable installation height)
pe -- suction surface pressure, Pa;(is the atmospheric pressure of the water suction surface, the higher the altitude, the lower the pressure)
pv -- saturated vapor pressure, Pa;(the higher the water temperature, the higher the saturated vapor pressure.)
ρ - density of fluid, kg/m3;
g -- acceleration of gravity, 9.81m/s2;
[NPSHr] -- allowable cavitation allowance of water pump, m;(related to pump performance, provided by pump manufacturer)
hw -- head loss in suction line, m.(related to suction pipe design, determined by the designer)
As can be seen from the above equation:
The higher the altitude, the higher the water temperature, the larger the allowable cavitation allowance, the greater the water head loss in the inlet pipe, and the smaller the allowable geometric installation height.
The atmosphere at different altitudes and the corresponding water head height are shown in the following table:
Water head height corresponding to saturated vapor pressure of water at different temperatures is shown in the following table:
