Centrifugal pump

Single-surface sealing will wear out, the inner sides of the double surfaces will also wear out, residual fluid will cause cavitation, with no flow of fluid in or out, mechanical energy is completely converted into internal energy, which leads to an increase in temperature; thermal radiation causes the bearing housing to overheat, damaging the bearings. The back cover of the impeller is subjected to greater stress, resulting in issues such as wire entanglement. In short, it doesn’t work.

Single-surface sealing will wear out, the inner sides of the double surfaces will also wear out, residual fluid will cause cavitation, with no flow of fluid in or out, mechanical energy is completely converted into internal energy, which leads to an increase in temperature; thermal radiation causes the bearing housing to overheat, damaging the bearings. The back cover of the impeller is subjected to greater stress, resulting in issues such as wire entanglement. In short, it doesn’t work.

When a centrifugal pump runs idle, the impeller does not come into contact with, or only minimally comes into contact with, the fluid, and thus it is unable to perform effective work; as a result, the liquid cannot be transported properly, and all of this constitutes wasted effort. Since no useful work is done, the load on the motor is very low, and the current generated is also small; therefore, this has little impact on the motor. However, idle operation of a water pump can be fatal for the pump itself. A pump running idle is prone to cavitation, which can cause damage to the pump body and the flow-through components ； When a pump runs idle, whether it uses a mechanical seal or a packing seal, it lacks the lubrication provided by liquid, which leads to dry friction and rapid damage ； The rotating parts of the pump and the pump body will heat up when the pump is running idle; without liquid for cooling, those narrow gaps (such as seal rings) are prone to becoming stuck due to thermal expansion and contraction ； The balance disk of an idling multi-stage centrifugal pump receives no lubrication, and it will soon be burned out and damaged. 【Why can fans do it? 】

Idling has little effect on the motor; the greatest risk of idling is damage to the mechanical seal. However, since the poster has the seal flushing oil turned on, I don’t think significant harm will occur, but it’s not recommended to do this for long periods of time.

Pumps must never operate without liquid; although some companies have developed pumps that can run without liquid, they cannot do so for an extended period, as this will damage the pump

But why did you reply to me? Aren’t we saying different things?

1. Assuming it is a single-stage centrifugal pump with double seals and a flushing water pump, and there is no liquid medium present, can it operate without any fluid? There are 2 pairs of seals with flushing water; you say that the inner seal will get damaged, but don’t all single-face seals have flushing water on one side as well? 3 No-load operation: How can there be heat generation without a liquid medium?

Idling is not allowed for any reason

If such operating conditions exist, it is necessary to communicate with the manufacturer in advance; I believe that it is possible to handle this through proper design!

1. When there is flushing water, the operation of the mechanical seal is fine at first. 2. If there is no fluid inside the pump, then after it is started, the pump works on air only. Since the density of air is very low, it cannot meet the conditions required for centrifugal operation; as a result, the power consumption is very low. No matter how large the motor is, the actual output power remains low. In this situation, with both the inlet and outlet of the pump open, almost no significant heat generation occurs. 3. If the design of the pump requires self-lubrication or cooling, idling will lead to the failure of the friction pairs.