The inlet of the water inlet pipe is incorrectly located

       The distance between the water inlet of the water inlet pipe and the bottom of the water pool and the wall is smaller than the diameter of the water inlet. If there is dirt and other dirt at the bottom of the pool, the distance between the water inlet and the bottom of the pool is less than 1.5 times the diameter, which will cause poor water intake or suction of debris and block the water inlet during pumping.

       When the water inlet of the water inlet pipe is not deep enough, this will cause a vortex on the water surface around the water inlet pipe, which will affect the water inlet and reduce the water output. The correct installation method is: the depth of the small and medium water pump should not be less than 300 ~ 600mm, and the large water pump should not be less than 600 ~ 1000mm.

       The water outlet pipe is above the normal water level of the water outlet. If the water outlet is above the normal water level of the water outlet, the pump head is increased, but the flow is reduced. If the water outlet must be higher than the water level of the water tank due to the terrain conditions, elbows and short pipes should be installed at the nozzle to make the water pipe a siphon type and reduce the height of the outlet.

       The water inlet of the centrifugal pump is directly connected to the elbow, so that the water flow is unevenly distributed when passing through the elbow and entering the impeller. When the diameter of the water inlet pipe is larger than the water inlet of the pump, an eccentric reducer should be installed. The flat part of the eccentric reducer shall be installed on the upper part, and the inclined part shall be installed on the lower part. Otherwise, the air will be collected, the water output will be reduced or the water will not be pumped, and there will be impact sounds. If the diameter of the water inlet pipe and the water inlet of the pump are equal, a straight pipe should be added between the water inlet of the pump and the elbow. The length of the straight pipe must not be less than 2 to 3 times the diameter of the water pipe.

       Many people think that the lower the pumping head, the smaller the motor load. Under the misunderstanding of this misunderstanding, when choosing a centrifugal pump, the pump head is often selected very high. In fact, for centrifugal pumps, when the model of the pump is determined, its power consumption is proportional to the actual flow of the pump. The flow of the pump will decrease with the increase of the head. Therefore, the higher the head, the smaller the flow, and the smaller the power consumption. Conversely, the lower the head, the larger the flow, and the greater the power consumed.

       Therefore, in order to prevent the motor from being overloaded, it is generally required that the actual pumping head of the pump should not be lower than 60% of the nominal head. Therefore, when the high head is used for pumping at too low head, the motor is easily overloaded and generates heat, and the motor can be burned in severe cases. For emergency use, you must install a gate valve on the outlet pipe to adjust the amount of water to reduce the flow and prevent the motor from overloading. Pay attention to the temperature rise of the motor. If it is found that the motor is overheated, the flow of the water outlet should be closed or shut down in time.

       This point is also easy to cause misunderstanding. Some operators believe that blocking the water outlet and forcing a reduction in flow will increase the load on the motor. In fact, the opposite is true. The outlet pipe of a regular high-power centrifugal pump drainage and irrigation unit is equipped with a gate valve. In order to reduce the motor load at the start of the unit, the gate valve should be closed first, and the gate valve should be gradually opened after the motor starts.

       There are many elbows on the water inlet pipeline. If more elbows are used on the water inlet pipeline, local water flow resistance will increase. And the elbow should turn in the vertical direction, and it is not allowed to turn in the horizontal direction to avoid the accumulation of air.

       The bottom section of the inlet pipe equipped with a bottom valve is not vertical. If this is installed, the valve cannot close by itself, causing water leakage. The correct installation method is: the water inlet pipe equipped with a foot valve needs to be installed vertically. If it cannot be installed vertically due to terrain conditions, the angle between the water pipe axis and the horizontal plane should be above 60 °.

       Many operators think that this can improve the actual head. In fact, the actual head of the pump = total head-lost head. After the model of the centrifugal pump is determined, the total head is constant; the lost head mainly comes from the resistance of the pipeline. The smaller the diameter, the greater the resistance, and therefore the larger the lost head. Therefore, after reducing the diameter of the pump, the actual head of the pump is not only unable to Increasing it will decrease it, which will cause the pump efficiency to decrease.

       In the same way, when the large pipe is pumped by the small-diameter pump, the actual head of the pump will not be reduced, but the loss head will be reduced due to the reduction of the resistance of the pipeline, which will increase the actual head. Some people also think that when pumping with a large pipe for a small-diameter water pump, the load on the motor will inevitably be greatly increased. They believe that after the pipe diameter increases, the pressure in the outlet pipe will increase the pressure on the pump impeller, which will greatly increase the motor load.

       As everyone knows, the size of the liquid pressure is only related to the head height, and has nothing to do with the cross-sectional area of the water pipe. As long as the head is fixed, the size of the impeller of the water pump will not change, and the pressure on the impeller will be constant regardless of the diameter of the pipe.

       Only when the pipe diameter increases, the water flow resistance will decrease, and the flow rate will increase, and the power consumption will also increase appropriately. However, as long as it is within the rated head range, the pump can work normally regardless of the increase in pipe diameter, and it can also reduce pipeline losses and improve pump efficiency.

       When installing the water inlet pipe, the horizontal section is leveled or tilted up toward the water source. This will cause air to collect in the water inlet pipe, reduce the vacuum of the water pipe and the pump, reduce the suction head of the pump, and reduce the water output. The correct approach is: its horizontal section should be slightly inclined towards the water source, it should not be horizontal, and it should not be tilted upward.