Regarding the problem of water balance between two storage tanks
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There are three pure water storage tanks in the factory. The storage tanks from left to right are V1, V2, and V3, with heights of 7.5 meters, 3 meters, and 6 meters respectively. The normal water level of H1 is between 3 and 5 meters. The height of the pipeline bridge H2 is 5.5 meters. The pipeline level is DN40 stainless steel pipe, and the pipe length is 250 meters. Left and right, the number of elbows is 20. Pure water is supplied by a centrifugal pump. There is a manual ball valve in front of the pump, and a check valve and a ball valve behind the pump. There is a manual ball valve in front of the storage tank V2. The water outlet and inlet are at the bottom. The storage tank V3 is a backup storage tank. There is a bottom connecting pipe between V2 and V3. All valves are normally open. Now we encounter such a problem. After the pump stops running for a period of time, the water in the storage tank V2 becomes full and overflows. When the pump stops, the water level in the storage tank has not reached the top of the tank. A test has been done and the water inflow flow rate is about 4 cubic meters in 3 hours. Please tell me what is causing this, I would like to thank you.
Are the bottoms of the tanks at the same elevation? If it is the same, it is like a U-shaped pipe. The valve should not be closed when you stop the pump. The liquid level on V1 is higher than V2, so even if you stop the pump, water will still flow due to the liquid level difference. I don’t know if this is the case, just for reference.
Siphon effect. When stopping the pump, try closing both the front and rear valves of the pump.
The elevation of the tank bottom is the same, so it seems necessary to add a pneumatic valve in front of the V2 tank. Thanks for the answer
The elevation of the tank bottom is the same, so it seems necessary to add a pneumatic valve in front of the V2 tank. Thanks for the answer
Okay, thanks for the answer, I'll try it later
Okay, thanks for the answer, I'll try it later
Okay, thanks for the answer, I'll try it later
Personally, I think you can connect a 20mm pipe to V1 at the high point of the pipeline bridge as a balance pipe to break the siphon, so that you won't have the flooding situation when the pump is stopped as you mentioned.
For siphon function, keep No. 2 tank as a backup and No. 3 tank as main use. Just connect the pump outlet between No. 2 and No. 3.
It is indeed caused by the siphon phenomenon between V1 and V2. It should be a very common operation requirement to close the outlet valve of the pump after stopping the pump. Just close it (if it is not closed tightly, close it again).