Without starting the pump, the medium flows through the pump body under its own pressure
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Dear experts, without starting the pump, the medium flows through the pump body under its own pressure. What damage can forward flow cause to the pump? What is the reason? Counterflow is definitely not an option; the biggest problem it causes is that it can easily lead to the detachment of the impeller.
First is the mechanical seal with a flushing scheme
It’s probably the forward flow that makes it easy for the impeller to come off. Am I wrong in thinking this?
Reverse flow, with the medium rebounding, can easily cause the impeller to loosen and fall off
Packing-sealed pumps will leak； Pumps with mechanical seals under pressure allow the medium to enter between the friction pairs, thereby damaging those friction pairs ； If the medium is prone to crystallization, it can lead to crystalline blockages in the components subjected to high flow rates
Normally, such situations occur only with centrifugal pumps, but the use of centrifugal pumps is related to the inlet and outlet valves; when the outlet valve is closed while the pump is started, there is no effect of fluid flow by gravity. If a positive displacement pump is used, there is no impact at all from opening the inlet and outlet check valves.
As long as the cooling water for the mechanical seal is running, the pressure difference between the inlet and outlet isn’t too high, and the pump isn’t running at high speed, there are generally no problems