What are the reasons for insufficient pumping volume?

The medium components are light and easily vaporize; applying it in gaseous form can cause the pump to become evacuated or fail to deliver the required volume； The pump is not depressurized ；

Inadequate priming of the pump before it is started results in air remaining inside the pump. The filter ahead of the pump is clogged, and the temperature of the fluid is too high, exceeding its boiling point. The inlet pressure is too low, causing the fluid to vaporize. Generally speaking, there are two main reasons why a pump fails to deliver fluid: the fluid vaporizes, or gas is formed inside the pump

Blockage in the inhalation line or filter； Insufficient filling of the pump, with gas remaining inside the pump chamber ； Leak in the inhalation circuit ； The impeller is severely corroded ； The fluid contains components that are easily vaporized ； The installation position is too high, failing to meet the required NPSH

There is a leak in the pipeline, or the seal on the pump’s drive shaft is damaged.

The most common reason is that there is gas remaining inside that hasn’t been expelled. Also, check whether the medium suitable for pumping has been chosen; using an inappropriate medium will also lead to problems

1. Cavitation occurs; there is gas present, and some liquid can still be delivered, but the flow rate is insufficient； 2. When valves are installed for import, it is necessary to consider whether the valve’s actuation mechanism might come loose ； 3. There are leakage points at the inlet, allowing air to enter ； 4. If it is a magnetic pump, it might be that the magnetic drum section has lost its magnetism; I encountered this issue during one project commissioning session, and it was quite confusing ； 5. Impeller corrosion or impeller cavity blockage ； 6. There are other reasons as well, which need to be analyzed based on the specific circumstances.

This question isn’t actually well-posed! Types of pumps include centrifugal pumps, gear pumps, screw pumps, etc. So which type of pump is the landlord actually asking about? Judging from the responses of several respondents, they were all answers related to centrifugal pumps!

Does the inability to pump fluid mean that the pump has been emptied?

Blockage, vaporization, no way forward, reversal

1. No exhaust or insufficient exhaust； 2. Insufficient inlet flow or too low inlet pressure; 3. Clogged inlet pipeline ； 4. Incorrect motor wiring ； 5. Pump impeller installed in reverse ；

The above covers it comprehensively, but I think there is another situation: an overly thick conveying medium can also result in insufficient flow rate.

1. The filter is clogged. 2. The inlet pressure is too low. 3. The pump body is leaking air or air is entering at the inlet. 3. Motor reverses direction.

Here are a few examples I’ve encountered: 1. The centrifugal pump used for discharging oily wastewater from the equipment often fails to deliver sufficient flow. Solution → After starting the pump, open the outlet valve fully first, and then close it fully again. By doing this twice to release the air from the pump’s internal volume, the pump will reach its proper operating level. 2. The centrifugal pump used for discharging oil from the underground oil sump in the facility can also easily fail to deliver sufficient flow. Due to a change in the equipment’s operating conditions, it was urgent to pump out the oil stored in the underground oil tank. I tried many methods (cylinder pump, exhaust…), but nothing worked. Finally, the senior team leader pulled a circulating water hose and poured circulating water on the pump body, resolving the problem. The reason is that the pump inlet filter is a bit clogged, so the pump cannot draw in liquid and ends up running dry. Pumping for extended periods causes the pump body to heat up, which in turn leads to the vaporization of the contaminated oil medium. Circulating water is poured over the pump body to cool it, and the gaseous substances inside the pump condense; gradually, the pump begins to deliver more flow. 3. When refilling (adding lubricant) the circulating hydrogen compressor online, it is easier to do so in summer, but the process is much slower in winter. Temperature changes the viscosity of lubricating oil, resulting in different operating conditions for gear pumps.