Most users do not understand the principle of self-priming pump knowledge, when the pump can not pump water are at a loss, some customers will call the manufacturer to consult the on-site working conditions to the manufacturer, so that it can understand the industry and mining, and require the manufacturer technician to teach the solution measures of self-priming pump can not suck up water. Some customers do not understand the specific reason is the pump performance problem requires the manufacturer to send people to the scene to solve the problem, the results are caused by the scene conditions, such as the import pipe seal is not good, the size of the eye can lead to self-priming pump suction water, A good way to check whether the inlet pipe of the self-priming pump is leaking is to stop the self-priming pump after running for 3 to 4 minutes and then listen carefully to where there is a wheezy inspiratory sound around the pipe to find the leak point and repair the idea.
Pump can not pump water is divided into the following reasons
First, there is air in the inlet pipe and pump body
(1) Before the pump is started, enough water is not filled, sometimes it seems that the water has been spilled from the vent, but the air is completely discharged without rotating the pump shaft, resulting in a little air remaining in the inlet pipe or pump body.
(2) The horizontal section of the inlet pipe in contact with the water pump shall apply a drop slope of more than 0.5% in the direction of reverse water flow, and the end connected to the inlet of the water pump shall be high and not completely horizontal. If it is upturned, air will remain in the inlet pipe, reducing the vacuum degree in the water pipe and pump, and affecting water absorption.
(3) The pump packing due to long-term use has worn out or the packing pressure is too loose, resulting in a large amount of water from the filler and pump shaft sleeve gap in the jet, the result is that the external air from these gaps into the pump interior, affecting the water lift. The mechanical seal of the pump is damaged and leaked.
(4) The water inlet pipe has holes due to long-term potential underwater pipe wall corrosion. After the water pump works, the water surface continues to drop. When these holes are exposed to the water surface, the air enters the water inlet pipe from the holes.
(5) Cracks appear at the bend of the inlet pipe, and small gaps appear at the connection between the inlet pipe and the water pump, which may make air enter the inlet pipe.
Two, the pump speed is too low
(1) Human factors. Some users because of the original motor damage, at will with another motor drive, resulting in small flow, low head and even no water consequences.
(2) Mechanical failure of the pump itself. The fastening nut of the impeller and the pump shaft is loose or the pump shaft is deformed and bent, resulting in more impeller movement, direct friction with the pump body, or bearing damage, which may reduce the speed of the pump.
(3) The power engine is not properly maintained. Motor because of winding burn, and loss of magnetic, maintenance winding turns, wire diameter, wiring method change, or maintenance failure is not completely eliminated factors will also make the pump speed change.
Three, the suction is too large
Some water sources are deeper, some water sources of the periphery of the terrain is flatter, and ignored the allowable suction of the pump, resulting in less or no water absorption results. It is necessary to know that the vacuum degree that can be established at the suction port of the pump is limited. The suction range of the absolute vacuum is about 10 meters of water column height, and the pump cannot establish an absolute vacuum. And the vacuum is too large, easy to make the water in the pump gasification, unfavorable to the pump work. Therefore, the self-suction centrifugal pump has its large allowable suction range, generally between 3-8.5 meters. When installing the pump, it is not only convenient and simple.
Four, the resistance loss in the water flow in and out of the pipe is too large
Some users have been measured, although the vertical distance from the reservoir or water tower to the water source is slightly less than the pump lift, but the water is still small or not. The reason is that the pipeline is too long, the bend of the water pipe is many, and the resistance loss of water flow in the pipeline is too large. The reason is that the pipeline is too long, the bend of the water pipe is many, and the resistance loss of water flow in the pipeline is too large. Under normal circumstances, the resistance of 90 degree bend pipe is higher than that of 120 degree bend pipe. The lift loss of each 90 degree bend pipe is about 0.5-1 meters, and the resistance of each 20 meters pipe can make the lift loss of about 11 meters. In addition, some users also arbitrarily pump in and out of the pipe diameter, these also have a certain impact on the head.
5. Influence of other factors
(1) The bottom valve cannot be opened. Usually because the pump has been used for too long, the bottom valve gasket is stuck, and the bottom valve without gasket may rust to death.
(2) the bottom valve filter net is blocked; Or the bottom valve can cause filter blockage in the sludge layer in the water.
(3) Serious wear of impeller. The wear of the impeller blade after long-term use affects the performance of the water pump.
(4) Gate valve check valve failure or blockage will cause flow reduction or even pumping water.
(5) Leakage of the outlet pipeline will also affect the water withdrawal.
