Knowledge Of Piping For Water Pumps

Mar 03, 2025

Many operators believe that using a large-diameter water pump with a small water pipe to pump water can increase the actual head, but in fact, the actual head of the water pump is equal to the total head minus the loss head. After the model of the water pump is determined, the total head is fixed; The loss of head mainly comes from pipeline resistance. The smaller the pipe diameter, the greater the resistance, resulting in a greater loss of head. Therefore, reducing the pipe diameter not only fails to increase the actual head of the pump, but also reduces it, leading to a decrease in pump efficiency.
Similarly, when a small diameter water pump uses a large water pipe to pump water, the actual head of the pump will not be reduced. Instead, the loss head will be reduced due to the decrease in pipeline resistance, resulting in an increase in the actual head.
Some experts believe that when a small diameter water pump uses a large water pipe to pump water, it will inevitably greatly increase the motor load. They believe that as the pipe diameter increases, the pressure of the water in the outlet pipe on the pump impeller will increase, thus greatly increasing the motor load. Little did they know that the magnitude of liquid pressure is only related to the head, and not to the cross-sectional area of the water pipe.
As long as the head is constant and the impeller size of the water pump remains unchanged, the pressure acting on the impeller remains constant regardless of the diameter of the pipe. However, as the diameter of the pipe increases, the water flow resistance will decrease, resulting in an increase in flow rate and a moderate increase in power consumption. But as long as it is within the rated head range, the water pump can work normally regardless of how the pipe diameter is increased, and it can also reduce pipeline losses and improve pump efficiency.
When installing the inlet pipeline, horizontal or upward tilting of the horizontal section will cause air to accumulate inside the inlet pipeline, reduce the vacuum degree of the water pipe and pump, lower the suction head of the pump, and reduce the water output. The correct approach is that the horizontal section should be slightly inclined towards the direction of the water source, not horizontal, let alone upward.
If more elbows are used on the inlet pipeline, it will increase local water flow resistance. And the elbow should turn in the vertical direction, not in the horizontal direction, to avoid gathering air.