(1) before the start of the pump is not filled with enough water, sometimes it looks like the water has been poured from the bleed hole overflow, but did not turn the pump shaft to the air completely discharged, resulting in a little air left in the water pipe or pump body.
(2) in contact with the water pump inlet of the horizontal application of reverse flow direction, fell more than 0.5% slope, connect one end of the highest import pumps, do not completely level. If the upward tilt, will be retained within the inlet air, reduce water pipes and pumps in the vacuum, the impact of water.
(3) pump packing has been used for long-term wear or packing pressed too loose, discharge gap caused by the large amounts of water from filling with the shaft sleeve, the external air gap into the pump from the inside, affected the water.
(4) due to the long-term potential of the water pipe, the pipe wall corrosion appear holes, water pump works, the water continued to decline, when these holes exposed, the air from the hole into the water inlet pipe.
(5) there is a crack in the water inlet pipe bend pipe, the water inlet pipe and the water pump connection in the small gap, it is possible to make the air into the water inlet pipe.
2, pump speed is too low:
(1) human factors. Some users because of original motor damage, may be accompanied by another motor, resulting in a flow of small, low head or even the consequences of Sheung shui.
(2) mechanical failure of the pump itself. Impeller and pump shaft fastening nut loose or pump shaft deformation and bending, resulting in multi impeller, direct friction with the pump body, or bearing damage, it is possible to reduce the pump speed.
(3) power machine maintenance. Motor due to the winding burn, and loss of magnetism, maintenance of the winding turns, wire diameter, wiring method changes, or the failure of the maintenance of the fault is not completely eliminated factors will make the pump speed change.
3, suction process is too large:
Some of the water is deep, some of the surrounding terrain is relatively flat, while ignoring the pump allows suction process, resulting in less water absorption or not the result of water suction. To know that the vacuum degree of the pump suction mouth is limited, the absolute vacuum suction process is about 10 meters high water column, while the pump can not establish an absolute vacuum. And a large vacuum, easy to make the pump water vapor, the pump work. Therefore, the centrifugal pump has its maximum allowable suction process, generally between 8.5 - 3 meters. The installation of the pump can not only facilitate simple drawings.
4, the flow of water in and out of the resistance loss is too large
Some users have been measured, although the water tank or water tower to the vertical distance the water is slightly less than the pump head, but a little water or no water. The reason is that the pipe is too long, the water pipe bends more, the water flow in the pipeline resistance loss is too large. The reason is that the pipe is too long, the water pipe bends more, the water flow in the pipeline resistance loss is too large. Under normal circumstances 90 degrees bend than 120 degrees, the resistance is large, every 90 degrees bend head loss of about 0.5-1 meters, meters per 20 meters of resistance can make the head loss of about 1 meters. In addition, some users are free to pump inlet, outlet pipe diameter, which has a certain impact on the head.
5, the impact of other factors
(1) at the end of valve to open. Is usually set aside a long time due to water pump, valve gasket is stuck, no washer valve may be rust.
(2) filter mesh bottom valve is blocked; or potential water valve at the end of the sludge layer caused by the blockage of the strainer.
(3) impeller wear is serious. Impeller blades have been worn for a long time, which affects the performance of the pump.
(4) gate valve can check valve failure or blockage will cause flow to reduce or even draw no water.
(5) the leakage of the export pipeline will also affect the water extraction.
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