1. high lift pumps for low lift pumping

Many machine hands believe that the lower the pumping lift, the smaller the load of the motor. Under the misguidance of this mistake, the pump's lift is often chosen when the pump is selected. In fact, for centrifugal pumps, when the model of the pump is determined, the power consumption is proportional to the actual flow of the pump. And the flow of the pump will decrease with the increase of the lift, thus the higher the lift, the smaller the flow and the smaller the consumption power. On the other hand, the lower the lift, the greater the flow, the greater the power consumed. Therefore, in order to prevent the motor overload, it is generally required that the pump's actual pumping use lift should not be less than 60% of the calibrated lift. So when the high lift is used for low lift pumping, the motor is easy to overload and heat, and the motor can be burned down when it is serious. If emergency is used, we must install a gate valve for regulating the output of water, or block small outlet with wood and so on, so as to reduce flow and prevent motor overload. Pay attention to the temperature rise of the motor. If the motor is overheated, the flow or shutdown of the water outlet should be closed in time. This is also easy to misunderstand, some of the hands think that plugging out of the outlet, forced to reduce the flow of flow, will increase the motor load. In fact, on the contrary, the outlet pipe of the regular high power centrifugal pump irrigation and drainage unit is equipped with gate valves. In order to reduce the motor load during start-up, the gate valve should be closed first, then the gate valve will be opened gradually after the motor starts.

2. large caliber pumps with small water pipe pumping

Many machine hands think this can improve the actual lift, in fact, the actual head of the pump = the total lift to the loss lift. When the pump type is determined, the total lift is certain; lift loss mainly comes from the pipeline resistance, smaller diameter obviously the greater the resistance, so the lift loss is bigger, so reducing the diameter of the pump, the actual head can only be increased, it will reduce, resulting in the decline in pump efficiency. Similarly, when the small diameter pump pumps with large water pipes, it will not reduce the actual lift of the pump, but it will reduce the loss lift and reduce the actual lift of the pump because of the reduction of the resistance of the pipeline. Also the organic hand thinks that when the small tube pump pumps with large water pipes, it will increase the load of the motor greatly. They think that after the diameter increases, the pressure of the water in the outlet pipe will increase to the impeller of the pump, which will greatly increase the load of the motor. It is not known that the size of the liquid pressure is only related to the height of the head, but has nothing to do with the section size of the water pipe. As long as the lift is certain, the impeller size of the pump is constant, no matter how large the diameter of the pipe is, the pressure on the impeller is certain. Only when the diameter of the pipe increases, the flow resistance will decrease, and the flow rate increases, and the power consumption will be increased appropriately. But as long as the rated head is in range, no matter how the diameter increases, the pump can work normally, and it can also reduce the pipeline loss and improve the efficiency of the pump.

3. when the inlet pipe is installed, the horizontal section is horizontal or upwards.

In this way, the air in the inlet pipe will be gathered, the vacuum of the water pipe and water pump will be reduced, and the water suction lift of the pump is reduced and the water output is reduced. The correct way is that the horizontal section should be slightly inclined to the direction of water source, not to be horizontal, and not to rise up.

4. more elbow used in the inlet pipe

If the elbow used in the inlet pipe is more, it will increase the resistance of local flow. And the elbow should turn in the vertical direction, not allowed to turn in the horizontal direction, so as not to gather the air.

5. the water intake of the pump is directly connected with the elbow

This will make the flow unevenly when the water flow through the elbow into the impeller. When the diameter of the inlet pipe is larger than the water inlet of the pump, the eccentric variable diameter tube should be installed. The flat part of the eccentric variable diameter tube should be mounted on it, and the slope part is installed below. Otherwise, the air is gathered, the amount of water is reduced or the water is not pumped up, and there is a sound of impact. If the inlet pipe is equal to the diameter of the water inlet of the pump, the pipe should be added between the inlet of the pump and the elbow. The length of the straight pipe should not be less than 2~3 times the diameter of the pipe.

6. equipped with bottom valve inlet pipe the next section is not vertical alcohol pump

In this way, the valve can not be closed by itself, causing water leakage. The correct installation method is: a water inlet pipe valve, the next best is vertical. The angle between the axis of the water pipe and the horizontal plane should be 60° if the terrain is not installed vertically, the angle between the axis of the pipe and the horizontal plane should be above.

7. the inlet position of the inlet pipe is incorrect

(1) the distance from the inlet of the inlet pipe to the bottom of the tank and the wall of the pool is less than the diameter of the inlet. If there are sediment and other pollutants at the bottom of the pool, the distance between the inlet and the bottom of the tank is less than 1.5 times that of the diameter. It will cause inflow of water or suction of the sediment and the clogging of the intake.

(2) when the inlet depth of the inlet of the inlet pipe is not enough, this will cause a whirlpool around the water of the inlet pipe, affecting the influent and reducing the amount of water. The correct installation method is that the water intake depth of the small and medium water pumps should not be less than 300 ~ 600mm, and the large water pump should not be less than 600 ~ 1000mm.

8. the outlet pipe is above the normal water level of the water pool

If the outlet is above the normal water level of the pool, the pump lift is increased, but the flow rate is reduced. As a result of terrain conditions, the water outlet must be high out of the water level of the water, should be installed in the elbow and the short pipe, the pipe become siphon, reduce the height of the outlet.

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