Regarding recirculating water vacuum pumps
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I was doing an experiment today; when using a recirculating water vacuum pump for filtration, after turning off the pump, some of the water inside the vacuum pump flowed back into the bottle that was being evacuated! I’d like to ask everyone what the reason is? It’s never happened before!
Before stopping the pump, please break the vacuum first; this will prevent water in the pump from being drawn into the bottle due to the pressure difference between atmospheric pressure and the lower pressure inside the bottle.
Check the seal of the vacuum pump; air may have leaked in
Isn’t there a check valve in the exhaust line? How is there still water flowing back?
When shutting down the pump, the return valve should be opened first and then the inlet valve, which will prevent backflow when stopping the pump
Improper operation: the inlet valve was closed first, and the check valve did not function
It might be due to operational errors; when stopping the pump, the return valve should be opened first before closing the inlet valve； If the operation is fine, check if there is any air leakage