There is air in the inlet and pump
(1) some users do not fill enough water before the pump starts; sometimes the water that appears to have overflowed from the vent hole, but did not turn the pump shaft to air completely exhausted, leaving a little air still in the inlet pipe or pump The
(2) with the water pump in contact with the horizontal section of the water flow direction of the application of more than 0.5% of the downward slope, connecting the pump inlet is the highest end, not completely horizontal. If you tilt up, the inlet pipe will keep the air, reducing the water pipes and pumps in the vacuum, affecting water.
(3) the packing of the pump has been worn out due to long-term use or the packing is too loose, causing a large amount of water to be ejected from the gap between the packing and the shaft of the shaft. As a result, the outside air enters the inside of the pump from these gaps, Affecting the water.
(4) the inlet pipe due to long-term potential underwater, pipe wall corrosion holes, water pump work after the water is declining, when these holes exposed to the water, the air from the hole into the water pipe.
(5) the inlet pipe elbow cracks, water pipes and water pumps connected to a small gap, are likely to make air into the water pipe.