What should I do when my centrifugal pump doesn't run?

　　Centrifugal pump with its simple structure, easy to use and maintain, high efficiency and become the most widely used in agriculture, a pump, but also because sometimes lift the water and double the trouble.

　　Centrifugal pump intake pipe and pump body air

　　(1) Some users do not fill enough water before starting the pump; sometimes it seems to fill the water has overflowed from the bleeder hole, but did not turn the pump shaft to turn the air completely discharged, resulting in a small amount of air is still left in the intake pipe or the pump body.

　　(2) contact with the water pump into the horizontal section of the water pipe against the direction of the water flow should be more than 0.5% downward slope, connected to the inlet end of the pump for the highest, do not be completely horizontal, if the upward cocking, the inlet pipe will be retained within the air, reducing the vacuum in the water pipe and pump, affecting the suction.

　　(3) pump packing due to long-term use has been worn or packing pressure is too loose, resulting in a large amount of water from the packing and pump shaft sleeve gap in the spray, the result is that the external air from these gaps into the interior of the pump, affecting the lifting of water.

　　(4) inlet pipe due to long-term potential underwater, pipe wall corrosion holes, pump work after the water surface continues to fall, when these holes exposed to the water surface, the air from the holes into the inlet pipe.

　　(5) Cracks appear at the bend of the inlet pipe, and tiny gaps appear at the connection between the inlet pipe and the pump, all of which may allow air to enter the inlet pipe.

　　Centrifugal pump speed is too low

　　(1) man-made factors. There are a considerable number of users due to the original motor damage, it is arbitrarily matched with another motor driven, resulting in low flow, low head and even pumping the consequences of the water.

　　(2) drive belt wear. There are many large water pumps from the use of belt transmission, due to long-term use, transmission belt wear and loose also, the phenomenon of slippage, thereby reducing the speed of the pump.

　　(3) improper installation. Two pulley center distance is too small or two shafts are not too flat line, drive belt tight side installed to the top, resulting in the wrapping angle is too small, the two pulley diameter calculation error as well as coupling transmission of the pump two shafts eccentric distance is larger, will cause changes in the speed of the water pump.

　　(4) mechanical failure of the pump itself. Loose impeller and pump shaft fastening nut or pump shaft deformation and bending, resulting in more impeller shift, direct friction with the pump body, or bearing damage, are likely to reduce the speed of the water pump.

　　(5) Power machine maintenance is not recorded. Motor due to winding burned, and demagnetization, maintenance of the winding turns, wire diameter, wiring method of change, or maintenance of the fault is not completely excluded factors will also make the water pump speed change.

　　Suction range is too large

　　Some water sources are deeper, some water sources of the periphery of the terrain is more flat, while ignoring the allowable suction range of the pump, which produces less suction or simply suck the results of the water. It is important to know that the pump suction port can be established at the vacuum is limited, absolute vacuum when the suction range of about 10 meters high water column, and the pump can not establish an absolute vacuum, and vacuum is too large, easy to make the pump gasification of water, the pump is not conducive to the work of the centrifugal pumps have their maximum permissible suction range, generally in the range of 3 to 8.5 meters, the installation of pumps must not just want to facilitate simple.

　　Water flow inlet and outlet pipes in the resistance loss is too large some users have been measured, although the cistern or water tower to the water surface of the vertical distance slightly less than the head of the pump, but still lifting the amount of water is small or lifting the water. The reason is often too long, water pipe bends, water flow in the pipeline resistance loss is too large. The reason is often too long, water pipe bends, water flow in the pipeline resistance loss is too large. In general, 90-degree bends than 120-degree elbow resistance, each 90-degree bend head loss of about 0.5 to 1 meter, every 20 meters of pipe resistance can make the head loss of about 1 meter. In addition, some users also arbitrary pump inlet and outlet pipe diameter, which also has a certain impact on the head.

　　The impact of other factors

　　(1) bottom valve can not be opened. Usually due to the pump is set aside for too long, the bottom valve gasket is sticking dead, no gasket bottom valve may be rusted.

　　(2) Bottom valve strainer mesh is clogged; or bottom valve potential sludge layer in the water caused by clogging the strainer.

　　(3) The impeller is badly worn. Impeller blades worn by long-term use, affecting the pump performance.

　　(4) gate valve or check valve failure or clogging will cause flow reduction or even pumping water.

　　(5) The sink leakage of the outlet pipe will also affect the amount of water lifting.