Precautions for Installing Self-priming Pump Inlet Pipe

When installing the water inlet pipe of the self-priming pump, it is necessary to pay attention to the fact that the large-diameter self-priming pump is equipped with a small water pipe to deliver water. When installing the water inlet pipe of the self-priming pump, it is upwards. The bottom section of the water inlet pipe with the bottom valve of the self-priming pump is not vertical, the position of the water inlet of the self-priming pump water inlet pipe is wrong, the outlet pipe is above the normal water level of the outlet pool, and the high-lift self-priming pump works at a low head.

1. Large diameter self-priming pump with small water pipe for water delivery

Some users think that doing so can increase the actual head of the self-priming pump, which is equal to the total head minus the loss head. After the pump model is determined, the total head is certain.

The head loss mainly comes from pipeline resistance. The smaller the pipe diameter, the greater the resistance, and the head loss will also increase. After the pipe diameter is reduced, the actual head of the self-priming pump will not increase but will decrease. The efficiency of the self-priming pump is reduced. When the small-diameter water pump is used for pumping water in a large water pipe, the actual head of the pump will not be reduced, and the resistance of the pipeline will decrease, and the loss of the head will also decrease, and the actual head will increase.

There are also some novices who think that when the small-diameter pump uses a large water pipe to pump water, the motor load will increase. They think that after the pipe diameter increases, the pressure of the water in the outlet pipe on the pump impeller will increase, which will greatly increase the motor load. The size of the liquid pressure is related to the height of the head, and has nothing to do with the size of the cross-sectional area of the water pipe.

As long as the head is constant, the size of the impeller of the self-priming pump will not change, and the pressure acting on the impeller is constant no matter how large the pipe diameter is. After the pipe diameter increases, the resistance of the water flow will decrease, and the flow rate will increase, and the power consumption will increase appropriately. As long as it is within the rated range, the self-priming pump can work normally no matter how the pipe diameter increases, and the loss of the pipe can be reduced and the efficiency will be improved.

2. When installing the water inlet pipe of the self-priming pump, it will be upturned

Doing so will cause air to accumulate in the water inlet pipe, and the vacuum degree of the water pipe and the self-priming pump will decrease, and the water suction head will also decrease, and the water output will decrease. The correct method is to tilt towards the water source and not tilt upward.

3. There are many elbows used on the water inlet pipe of the self-priming pump

If too many elbows are used on the water inlet pipe, the local water flow resistance will be increased. And the elbow should turn in the vertical direction, and should not turn in the horizontal direction to avoid air accumulation.

4. The section below the water inlet pipe with the bottom valve of the self-priming pump is not vertical

If the valve is installed in this way and cannot be closed by itself, it will cause water leakage. The correct installation method is that the section below the inlet pipe with the bottom valve is vertical. If vertical installation is not possible due to terrain conditions, the angle between the axis of the water pipe and the horizontal plane must be more than 60 degrees.

5. The position of the water inlet of the self-priming pump inlet pipe is wrong

The distance between the water inlet of the self-priming pump water inlet pipe and the bottom of the water inlet pool and the wall is smaller than the diameter of the water inlet. If there is dirt such as mud and sand on the bottom of the pool, if the distance between the water inlet and the bottom of the pool is less than 1.5 times the diameter, it will cause poor water intake during pumping or suck in mud and sand debris to block the water inlet.

When the water inlet depth of the water inlet pipe is insufficient, this will cause the water surface around the water inlet pipe to generate eddies, and the water inlet will be affected, and the water output will be reduced. The correct method is: the water inlet depth of small and medium-sized water pumps should not be lower than 300mm-600mm, and the depth of large-scale water pumps should not be less than 600mm-1000mm.