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The Reason Of Head Reduced

- May 30, 2018 -

The Reason Of Head Reduced

  1. Impeller Flow channel blockage

If the impeller part of the flow channel block, it will affect the impeller's work, resulting in reduced outlet pressure. Therefore, it is necessary to check the removal of foreign objects. In order to prevent this problem from occurring again, a filter device may be added before the pump inlet if necessary.

2.Internal leakage

When the gap between the rotating part and the stationary part of the pump exceeds the design range, internal leakage will occur, which is reflected in the drop of the pump discharge pressure, such as the gap between the impeller ring and the interstage gap of the multi-stage pump. At this time, a corresponding inspection and inspection shall be carried out to repair or replace parts that cause excessive clearance.

3.Cavitation at suction 

If the suction pressure of the pump is too samll, below the saturated vapor pressure of the pumped medium, cavitation will form. In this case, check whether the inlet piping system is blocked or the opening of the inlet valve is too small, or increase the liquid level of the suction tank.

4.Speed Reduce

The important factors affecting the pump lift are the outer diameter of the impeller and the speed of the pump. Under the same conditions, the head of the pump is proportional to the quadratic speed of the speed. It can be seen that the influence of speed on the lift is very large, sometimes because For some reason outside the pump speed will be reduced, it will reduce the pump head accordingly. At this time, the pump speed should be checked. If the actual speed is not enough, check the reason and solve it properly.

5.Operating point offset to large flow low head

Generally, the centrifugal pump has a continuous downward performance curve, and the flow gradually increases as the head decreases. During the operation process, the back pressure of the pump is reduced for some reason, and the working point of the pump passively shifts to a low head and a large flow point along with the device curve. This will result in a reduction in the head. Actually, this is due to external factors such as the device. The resulting change does not have a special relationship with the pump itself. At this time, simply increase the pump back pressure, such as closing a little outlet valve, etc. to solve the problem.

6.Motor reversal

The motor's steering to be opposite to the actual request of the pump as the wrong wiring. In general, the steering of the pump must be observed first. If the steering is reversed, any two wires on the terminal of the motor should be exchanged.