1、 Matching of pipeline part of pipeline centrifugal pump

Some pipeline centrifugal pump users think that this can improve the actual head, in fact, the actual head of the pump=total head~loss head. When the pump model is determined, the total head is certain; The loss head mainly comes from the pipeline resistance. The smaller the pipe diameter is, the greater the resistance is. Therefore, the greater the loss head is. After reducing the pipe diameter, the actual head of the pump will not increase, but will decrease, leading to a decline in pump efficiency. Similarly, when a small diameter pump uses a large water pipe to pump water, the actual head of the pump will not be reduced, but the loss head will be reduced due to the reduction of pipeline resistance, so that the actual head will be increased.

They also think that when small diameter pumps pump water with large pipes, the motor load will be greatly increased. They think that when the pipe diameter increases, the water in the outlet pipe will have a greater pressure on the pump impeller, which will greatly increase the motor load. As we all know, the liquid pressure is only related to the lift, but not to the sectional area of the water pipe. As long as the head is fixed, the impeller size of the pump remains unchanged. No matter how large the pipe diameter is, the pressure acting on the impeller is fixed. However, when the pipe diameter increases, the flow resistance will decrease, which will increase the flow and power consumption. However, as long as it is within the rated lift range, the pump can work normally no matter how the pipe diameter is increased, and can also reduce the pipeline loss and improve the pump efficiency. 　　

2、 High lift pump for low lift pumping

Some pipeline centrifugal pump users believe that the lower the pumping head, the smaller the motor load. Under the misleading of this wrong understanding, when selecting and purchasing water pumps, the pump head is often selected to be very high. In fact, for centrifugal pumps, when the pump model is determined, the power consumption is proportional to the actual flow of the pump. The flow of the pump will decrease with the increase of the head, so the higher the head, the smaller the flow, and the smaller the power consumption. On the contrary, the lower the head, the greater the flow, and the greater the power consumption. Therefore, in order to prevent motor overload, it is generally required that the actual pumping head of the pump shall not be less than 60% of the calibrated head. Therefore, when the high lift is used for pumping water at the low lift, the motor is easy to overload and generate heat, and in serious cases, the motor can be burned. In case of emergency use, a gate valve (or block the small water outlet with wood, etc.) must be installed on the water outlet pipe to reduce the flow (public number: pump steward) and prevent motor overload. Pay attention to the temperature rise of the motor. If the motor is overheated, turn down the water outlet flow or shut down the machine in time. This is also easy to misunderstand. Some operators think that blocking the water outlet and forcibly reducing the flow will increase the motor load. In fact, on the contrary, the outlet pipe of the normal high-power centrifugal pump irrigation and drainage unit is equipped with a gate valve. In order to reduce the motor load when the unit starts, the gate valve should be closed first, and then gradually opened after the motor starts.

3、 There are many elbows on the inlet pipe of pipeline centrifugal pump

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

4、 When installing the water inlet pipeline, the horizontal section shall be horizontal or upward

This will cause air to collect in the water inlet pipe, reduce the vacuum degree of the water pipe and pump, reduce the suction head of the pump, and reduce the water output. The correct practice is that the horizontal section should be slightly inclined to the water source, not horizontal, and not upward. 　　

5、 The water inlet of pipeline centrifugal pump is directly connected with the elbow

This will cause uneven distribution of water flow when it enters the impeller through the elbow. When the diameter of the water inlet pipe is larger than the water inlet of the pump, the eccentric reducer pipe shall be installed. The plane part of eccentric reducer shall be installed on the top, and the inclined part shall be installed on the bottom. Otherwise, air will gather, water output will decrease or water cannot be pumped, and there will be impact sound. If the diameter of the water inlet pipe is the same as that of the water pump inlet, a straight pipe shall be added between the water pump inlet and the elbow, and the length of the straight pipe shall not be less than 2-3 times the diameter of the water pipe. 　　

6、 The outlet of pipeline centrifugal pump is above the normal water level of the outlet pool

If the outlet is above the normal water level of the outlet pool, the pump head will be increased, but the flow will be reduced. If the water outlet must be higher than the water level of the outlet pool due to the terrain conditions, elbows and short pipes shall be installed at the pipe orifice to make the water pipe siphon and reduce the height of the water outlet. 　

7、 The water inlet position of the water inlet pipe is incorrect

① The distance from the inlet of the inlet pipe to the bottom and wall of the inlet tank is less than the diameter of the inlet. If there is sediment and other pollutants at the bottom of the pool, when the distance from the water inlet to the bottom of the pool is less than 1.5 times the diameter, it will cause the water inflow to be blocked or the sediment and sundries will be sucked in during pumping, and the water inlet will be blocked.

② When the water inlet depth of the water inlet pipe is not enough, it will cause vortex on the water surface around the water inlet pipe, affect the water inlet and reduce the water output. The correct installation method is: the water inlet depth of small and medium-sized pumps shall not be less than 300~600mm, and that of large pumps shall not be less than 600~1000mm.

8、 When the bottom valve is set, the lowest section of the inlet pipe is not vertical

If installed in this way, the valve cannot be closed by itself, causing water leakage. The correct installation method is: the bottom section of the inlet pipe with bottom valve should be vertical. If the vertical installation cannot be carried out due to the terrain conditions, the included angle between the water pipe axis and the horizontal plane shall be more than 60 °.

Pipeline centrifugal pump is the most widely used pump type in various fields. Pharmaceutical users understand the eight misunderstandings of pipeline centrifugal pump and try to avoid the above. Shanghai Sunshine Pump Co., Ltd. is a professional manufacturer of pipeline centrifugal pumps. It has rich production experience and perfect testing equipment, so as to ensure the stability, reliability, long service life and other advantages of product quality.