Explanation On The Installation Height Of Agricultural Centrifugal Pump

The reason why the agricultural centrifugal pump can send water out is due to the effect of centrifugal force. Before the pump works, the pump body and the water inlet pipe must be filled with water to form a vacuum state. When the impeller rotates rapidly, the blades make the water rotate rapidly, and the rotating water flies away from the impeller under the effect of centrifugal force. After being thrown, the central part of the impeller forms a vacuum area. The water from the water source is pressed into the water inlet pipe through the pipe network under the action of atmospheric pressure (or water pressure). The circulation is endless like this, just can realize continuous pumping. It is worth mentioning here that the agricultural centrifugal pump must be filled with water in the pump casing before starting, otherwise, the pump body will not be able to absorb liquid, causing the pump body to heat up, vibrate, and not come out of the water, and "idling" occurs, Cause damage to the water pump (referred to as "air binding") and cause equipment accidents.

Electric Water Pump manufacturers show you the installation height Hg:

The suction vacuum height Hs refers to the maximum vacuum degree that can be achieved by the pressure p1 at the pump inlet

The actual suction vacuum height Hs is not a value calculated according to the formula, but a value measured by the pump manufacturer's test. This value is attached to the pump sample for users to check. It should be noted that the Hs value given in the pump sample is the value when clean water is used as the working medium, the operating condition is 20°C and the pressure is 1.013×105Pa. When the operating conditions and working medium are different, conversion is required.

(1) Transport clean water, but the operating conditions are different from the test conditions and can be converted according to the following formula

Hs1=Hs+(Ha-10.33)-(Hυ-0.24)

(2) Transporting other liquids When the conditions of the transported liquid and the villain are different from the test conditions, two steps of conversion are required: convert Hs1 detected from the pump sample according to the above formula; convert Hs1 into H’s according to the following formula

NPSH Δh

As for the oil pump, the NPSH Δh is used to calculate the installation height, that is, the NPSH Δh is checked from the oil pump sample, and its value is also measured with 20°C water. If you transport other liquids, proofreading is also required, and you can check the relevant books in detail.

From a safety point of view, the actual installation height of the pump should be less than the calculation value. When the calculated Hg is a negative value, it means that the suction port of the pump should be below the liquid level of the storage tank.