1, Air in inlet pipe and the pump body:
(1) Not filled enough water before starting of the slurry pumps, sometimes water overflow from the air vent mostly, but without rotation of shaft to have air completely discharged, there will be a little air remains in the inlet pipe or slurry pump.
(2) With 0.5% or more down slope of the inlet pipe, mine pump side is a bit higher. If upturned inlet pipe, it will be retained air in, reducing the suction distance.
(3) Packing has been worn or too loose, causing a large amount of water discharged from the gap of the packing and the shaft sleeve, let the outside air into the interior of the mine pump, impacting water suction.
(4) Because of the potential long-term underwater, the pipeline maybe with wall corrosion holes, slurry surface declining with slurry pumps working, making these holes out to air, the air entering the pipeline from them.
(5) Air also can into the pipe from cracks at the inlet pipe elbow, the gap between inlet pipe and the mine pump connected.
2, The mine pump speed is too low:
(1) Human factor. Part of the user’s after first motor damaged, they will random accompanied by another motor, resulting in a small flow, low head or even no slurry consequences.
(2) Mechanical factor of the mine pump itself. Mine pump impeller and shaft fastening nut loose or shaft bending deformation, resulting in the impeller shift, direct friction with the slurry pump body, or bearing damage, both will be reduce the speed of the mine pump.
The motor is not working. Motor winding burn case the lose magnetic. The changes of winding turns, wire diameter or wiring methods when maintenance, or repair the fault does not completely also cause the pump speed changes.
3. Suction out of working range:
In some working conditions, the slurry surface is too much deeper, or the peripheral terrain is relatively flat, make it easier to ignore slurry pump suction range, resulting in suction less or simply suck nothing.
4, Too large flow resistance loss in the inlet and outlet pipe
Some times, even the pump working under the suction range, but still suck less water or even no. It cased maybe by the pipeline, too long pipe, too many valves and too many elbows make it too much loss of friction
5, Other factors
(1) The foot valve is not open. Without working for too long time, the valve gasket washer was stuck or rust.
(2) Toot valve filter is clogging.
(3) Impeller wear badly. Impeller blades wear out after long-term use impact the pump performance.
(4) The check valve failure or blockage will cause the flow reduced or even no flow.
(5) The leakage of outlet pipe will also affect flow.