The Usage Method Of Pipeline Centrifugal Pump

May 04, 2025

1. The actual head of a pipeline centrifugal 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, and the smaller the pipe diameter, the greater the resistance, resulting in loss.

The larger the head, the lower the pipe diameter, the actual head of the pump will not increase, but will decrease, resulting in 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.

2. High head water pumps are used for low head pumping. Some pipeline centrifugal pump users believe that the lower the pumping head, the lower the motor load. Under this misconception, when choosing a water pump, the head of the pump is often chosen to be very high. In fact, for centrifugal water pumps, once the pump model is determined, the power consumption is directly proportional to the actual flow rate of the pump. The flow rate of the water pump will decrease with the increase of the head, so the higher the head, the smaller the flow rate, and the lower the power consumption. On the contrary, the lower the head, the greater the flow rate, and the more power is consumed

3. If there are too many bends on the inlet pipeline of a centrifugal pump, 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.

4. 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.

5. The inlet of the pipeline centrifugal pump is directly connected to the elbow, which will cause uneven distribution of water flow when it enters the impeller through the elbow. When the diameter of the inlet pipe is larger than that of the water pump inlet, an eccentric variable diameter pipe should be installed. The flat part of the eccentric variable diameter pipe should be installed on top, and the inclined part should be installed on the bottom. Otherwise, the air will gather, the water output will decrease or the water cannot be pumped out, and there will be collision sounds. If the diameter of the inlet pipe is equal to that of the water pump inlet, a straight pipe should be added between the water pump inlet and the elbow, and the length of the straight pipe should not be less than 2-3 times the diameter of the water pipe.

6. If the outlet of the pipeline centrifugal pump is above the normal water level of the outlet tank, although it increases the pump head, it reduces the flow rate. If due to terrain conditions, the outlet must be higher than the water level of the outlet pool, then elbows and short pipes should be installed at the pipe mouth to make the water pipe siphon and reduce the height of the outlet.

7. When installing a bottom valve, if the bottom section of the inlet pipe is not vertical and installed in this way, the valve cannot close on its own, causing water leakage. The correct installation method is to install a bottom valve on the inlet pipe, preferably with the bottom section vertical. If vertical installation is not possible due to terrain conditions, the angle between the axis of the water pipe and the horizontal plane should be at least 60 °.

Precautions for installation of inlet position of pipeline centrifugal pump inlet pipe

(1) The distance between the inlet of the centrifugal pump inlet pipe and the bottom and wall of the inlet pool is less than the diameter of the inlet. If there is sediment and other pollutants at the bottom of the pool, and the distance between the inlet and the bottom of the pool is less than 1.5 times the diameter, it will cause poor water intake or suction of sediment and debris during pumping, which will clog the water gate.

(2) When the water inlet of the inlet pipe is not deep enough, it will cause vortices on the water surface around the inlet pipe, affecting the water intake and reducing the water output.

Installing a pipeline centrifugal pump inlet directly connected to the elbow will result in uneven distribution of water flow entering the impeller through the elbow. When the diameter of the inlet pipe is larger than that of the water pump inlet, an eccentric variable diameter pipe should be installed. The eccentric variable diameter pipe should be installed flat on top and slanted on the bottom. Otherwise, the air will gather, the water output will decrease or the water cannot be pumped out, and there will be collision sounds. If the diameter of the inlet pipe is equal to that of the water pump inlet, a straight pipe should be added between the water pump inlet and the elbow, and the length of the straight pipe should not be less than 2-3 times the diameter of the water pipe.

There are many bends on the inlet pipeline of the centrifugal pump: If too many bends are used on the inlet pipeline, it will increase local water flow resistance, and the bends should turn in the vertical direction, not in the horizontal direction, to avoid air accumulation.

When installing the inlet pipeline of a centrifugal pump in a pipeline, the horizontal section should be horizontal or upward curved: this will cause air to accumulate in 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.