Vertical Centrifugal PumpDue to its simple structure, easy use and maintenance, and high efficiency, it has become one of the most widely used water pumps, but it also causes inconvenience due to the lack of water supply. Now analyze based on the malfunction of not being able to supply water.
There is air in the inlet pipe and pump body:
(1) Some users fail to fill the water pump with enough water before starting it; It seems that the water has overflowed from the vent hole, but the pump shaft has not been rotated to discharge the air *, resulting in a small amount of air remaining in the inlet pipe or pump body.
(2) The horizontal section of the inlet pipe in contact with the water pump should have a descending slope of at least 0.5% against the direction of water flow, and the end connected to the inlet of the water pump should be the highest, not horizontal. Lifting upwards will retain air in the inlet pipe, reducing the vacuum level in the water pipe and pump, and affecting water absorption.
(3) Due to long-term use, the packing of the water pump has worn out or the packing pressure is too loose, causing a large amount of water to spray out from the gap between the packing and the pump shaft sleeve. As a result, external air enters the interior of the water pump through these gaps, affecting water lifting.
(4) Due to long-term diving, holes have appeared on the wall of the inlet pipe due to corrosion. After the water pump starts working, the water surface continues to drop. When these holes are exposed to the water surface, air enters the inlet pipe through the holes.
(5) Cracks at the bend of the inlet pipe and small gaps at the connection between the inlet pipe and the water pump may allow air to enter the inlet pipe.
Low speed of water pump:
(1) Human factors. A considerable number of users, due to the damage of the original motor, randomly installed another motor to drive it, resulting in low flow rate and low head, making it impossible to pump water.Vertical Centrifugal Pump
(2) The drive belt is worn. Many large centrifugal pumps use belt transmission, but due to long-term use, the transmission belt may become loose and slip, reducing the pump speed.
(3) Improper installation. The center distance between the two pulleys is too small or the two shafts are not very parallel, the tight edge of the transmission belt is installed on top, resulting in a small wrap angle, calculation errors in the diameter of the two pulleys, and a large eccentricity between the two shafts of the coupled transmission water pump, all of which can cause changes in the speed of the water pump.
(4) The water pump itself has mechanical failure. Loosening of the fastening nut between the impeller and the pump shaft or deformation and bending of the pump shaft can cause excessive movement of the impeller, direct friction with the pump body, or damage to the bearings, all of which may reduce the speed of the water pump.
(5) Power machine maintenance not recorded. The motor loses magnetism due to burnt windings, and changes in winding turns, wire diameter, and wiring methods during maintenance, or failure to eliminate faults during maintenance, can also cause changes in the speed of the water pump.
Excessive suction:
Some water sources are deeper, while others have flatter outer surfaces, neglecting the allowable suction range of the water pump, resulting in less or no water absorption. It should be noted that the vacuum degree that can be established at the suction port of the water pump is limited, with a suction height of about 10 meters of water column during vacuum, and the water pump cannot establish a vacuum. Excessive vacuum can cause water inside the pump to vaporize, which is detrimental to the operation of the water pump. Each centrifugal pump has its maximum allowable suction range, generally between 3-8.5 meters. When installing the pump, it is important not to only consider convenience and simplicity.
Excessive resistance loss in the water inlet and outlet pipes
Some users measure that the vertical distance from the reservoir or water tower to the water source surface is slightly less than the pump head, but the water lifting capacity is small or unable to lift water. The reason is often that the pipeline is too long, there are many bends in the water pipe, and the resistance loss in the water flow pipeline is too large. The reason is often that the pipeline is too long, there are many bends in the water pipe, and the resistance loss in the water flow pipeline is too large. In general, the resistance of a 90 degree bend is greater than that of a 120 degree bend. The head loss of each 90 degree bend is about 0.5-1 meter, and the head loss can be about 1 meter for every 20 meters of pipe resistance. In addition, some users also arbitrarily choose the diameter of the inlet and outlet pipes of the water pump, which also has a certain impact on the head.
Other factors affecting:
(1) The bottom valve cannot be opened. Usually, if the water pump is left idle for too long, the gasket of the bottom valve may stick to it, and if there is no gasket, the bottom valve may rust.
(2) The bottom valve filter mesh is blocked; Or the bottom valve may cause blockage of the filter screen in the sludge layer during submergence.
(3) The impeller is severely worn. The wear and tear of impeller blades over long-term use has affected the performance of the water pump.
(4) Malfunctions or blockages in gate valves or check valves can cause a decrease in flow and prevent water from being pumped out.
（5）Vertical Centrifugal PumpLeakage in the export pipeline can also affect the amount of water extracted.