Misunderstanding in the use of centrifugal pump

1 high lift pump for low lift pumping

A lot of machine hand think pump head is lower, the motor load is smaller. Under the misleading understanding of this error, the purchase of a pump, the pump will be a high lift pump. In fact, for the centrifugal pump, when the pump model is determined, the size of its power consumption is proportional to the actual flow of the pump. And the pump flow will increase with the increase of head and reduce, and thus the higher the head, the smaller the flow, the smaller the power consumption. Conversely, the lower the head, the greater the flow, the greater the power consumption. Therefore, in order to prevent motor overload, the general requirements of the actual pumping water pump lift shall not be less than 60% of the calibration head. Therefore, when the high head is used for pumping low head, the motor is easy to overload and heat, and the motor can be burnt out when the time is serious. If the emergency use, it must be in the outlet pipe on the one for the regulation of water gate (or wood object blocking, small water outlet) to reduce the flow, to prevent motor overload. Pay attention to the temperature rise of the motor, if the motor overheating, should be promptly closed or shut down water outlet flow. It is also easy to misunderstand, some hand that blocking the outlet, forced to reduce the flow will increase the load of the motor. In fact, on the contrary, the formal power outlet pipe centrifugal pump unit is provided with a drainage valve, in order to reduce the unit motor load at startup, first close the valve, the motor starts gradually after the valve is the truth.

2 large diameter pumps with small water pipes pumping

A lot of machine hand that can improve the actual head, in fact, the actual pump head = total head loss. 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. In the same way, when the small tubular pump water pump with a large water pipe, it will not reduce the actual head of the pump, but will be reduced by the resistance of the pipeline to reduce the loss of head, so that the actual head has increased. Also that the small diameter pump with organic hand pumping pipe, will greatly increase the motor load, they think the diameter increases, the pressure of the water outlet pipe of the pump impeller is large, so it will greatly increase the motor load. As everyone knows, the size of the liquid pressure is only related to the height of the head, while the size of the water pipe section is not related. As long as the head, the pump impeller size constant, no matter how large the diameter, the role of pressure on the impeller is a certain. Just after the diameter increases, the flow resistance will be reduced, and the flow is increased, the power consumption is also increased. But as long as the rated head range, regardless of how the diameter of the pump can increase the normal work, and can also reduce the pipeline loss, improve the efficiency of the pump.

3 installation of water pipes, horizontal section or upward

In this way, the water can be gathered in the water pipe, and the vacuum degree of the water pipe and the water pump is reduced, the water suction head of the water pump is reduced, and the water discharge quantity is reduced. The correct approach is: the horizontal section should be slightly inclined to the direction of the water level, should not, not up.

4 the water inlet pipe is used on the elbow.

If the water pipe on the use of the elbow, will increase the local flow resistance. And the elbow should be in the vertical direction, not allowed to turn in the horizontal direction, so as not to gather the air.

5 water inlet and the elbow is directly connected

This causes the water to flow through the uneven distribution of the elbow into the impeller. When the inlet diameter is greater than the pump inlet, eccentric reducer should be installed. Eccentric adjustable tube mounted on a flat part to the above, the inclined part installed in the following. Otherwise, the air, the amount of water is reduced or no water pumping, and there is an impact sound, etc.. If the water inlet pipe and the water inlet of the water pump is equal to the diameter, between the water inlet of the water pump and the elbow with straight pipe, straight pipe length of not less than 3 times the pipe diameter of 2 ~.

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

Such as this installation, the valve can not be closed, resulting in leakage. The correct installation method is: a water inlet pipe valve, the next best is vertical. If the topographic conditions are not limited to the vertical installation, the water pipe line and the horizontal plane angle should be more than 60 degrees.

The water inlet of the water inlet pipe 7 position is wrong

(1) the water inlet of the water inlet pipe from the bottom of the pool and the pool wall distance is less than the diameter of the inlet. If the bottom sediment and dirt, water from the bottom of the distance is less than 1.5 times the diameter of the pumping water, will cause the poor in sediment or debris, blocking the water inlet.

(2) the water inlet of the water inlet pipe into the water depth is not enough, it will cause the inlet swirl around the surface of the water, the water reducing effect, water. The correct installation method is: small and medium-sized water pump into the water depth shall not be less than 300 ~ 600mm, large pump shall not be less than 600 ~ 1000mm.

The 8 water outlet in the above normal water pool

If the outlet in the pool above the normal water level, although the increase of the pump head, but reduces the flow. 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.