Pump problem

Check whether the valve at the water pump inlet is open; if not, open it. Is there water at the inlet, and is it blocked by any foreign objects? If there is no water, it means the water tank is low on water; adding water will resolve the issue. 2. During the first start-up, the water pump needs to be emptied. 3. Check whether the pump is running in reverse; if it is, water cannot be pumped. Adjusting the pump to run in the correct direction will resolve this issue (clockwise rotation means forward rotation). If a frequency converter is used for control, test both manual and automatic operation modes separately. 4. Check whether the outlet pipeline is blocked. 5. If everything is normal, then check what the head pressure is indicated on the pump’s nameplate. If water comes out but the pressure is not sufficient, first close the main outlet valve, start the water pump, and check whether the pressure can reach or exceed the set level; try this step by step. If the set pressure can be reached or exceeded, then start N-1 pumps (where N is the total number of main pumps), and slowly open the main valve until the pressure matches the value indicated on the nameplate, at which point stop turning it. If the flow rate is not sufficient for the users at this time, it means the flow rate of the water pump is too low; in such a case, it is necessary to add more pumps or replace them with pumps that have a higher flow rate. 6. If the pressure still doesn’t rise even after turning off the main valve, it is necessary to disassemble the water pump to check whether the impeller inside has fallen off or been damaged; if so, it needs to be replaced. 7. If it is not due to the reasons mentioned above, please confirm that your water pump is capable of achieving the designed flow rate and head pressure.

What was said upstairs is very comprehensive; here are a few additional points: ① There is gas inside the pump, which causes gas entrapment； ②There is a problem with the pump’s net positive suction head. Whether the installation height is appropriate – this is generally not a problem with low-flow cold water pumps; it tends to occur with high-flow pumps or hot water pumps. It’s also possible that there is an issue with the net positive suction head provided by the pump itself. ③Whether the impeller is damaged.

Thank you all for your help! It wasn’t explained clearly enough: we are using a long-shaft submersible pump; there is no valve at the inlet, no reverse rotation, and the outlet is not blocked either! It can draw in water at first, but after running a few times, it stops taking in water! ! Is it because of an obstruction in the import process or is there a problem with the shaft? ? ?