Does the size of the storage tank affect the flow rate of the transfer pump?
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Our facility is equipped with two atmospheric pressure storage tanks: one with a capacity of 200 cubic meters (with an inner diameter of 5200 and a height of 5772), and the other with a capacity of 1000 cubic meters (with an inner diameter of 11500 and a height of 11963). The outlet pipelines for both tanks are of the same size, and they share one discharge pump; the outlet pipelines from both tanks meet at the pump’s inlet. One issue that arises is that when the larger tank transfers liquid to the smaller tank, the pump’s outlet can handle a flow rate of 22 m3/h. However, when the smaller tank transfers liquid to the larger tank, even a slight increase in the opening of the pump’s outlet valve results in vacuum formation. We can preliminarily conclude that there is no problem with the pump, and the inlet filter has been cleaned; nothing is blocking it. We suspected a blockage in the outlet pipeline of the small tank, so we back-washed it, but it didn’t work; opening the outlet valve of the pump still resulted in vacuum conditions, and only about 8 m3/h could be transported. If the inlet pipeline is not blocked, could it be that the tank’s volume is too small and the inlet pressure of the pump is too low, resulting in insufficient suction at the pump’s inlet? I seek your guidance!
When transferring from a small tank to a large tank, a high head is required – does this mean the pump’s head is not sufficient?
Is the outlet pipeline of the small tank very thin?
This post was last edited by iwjtueabk on 2019-4-25 09:24. It’s about back pressure issues... When the storage is full, the back pressure in one tank is 0.5 KG/CM2, while in another it’s 1.1 KG/CM2... One more thing: if you want to pump liquid from tank A to tank B, you can simply connect the tanks with pipes, but be careful about the height difference between them. The pump should be used for discharging liquid only, not for transporting it
The problem has been resolved. Upon inspecting the pipelines, we found that the lining of the metal hose on the tank discharge line had come off, blocking the discharge pipeline.
Not really; the outlet diameters of the two storage tanks are the same.
It's great that there is timely feedback on the issues raised and resolved. To save everyone from guessing. Give it a like!
That’s good; many people don’t provide feedback after their issues are resolved!
It is preliminarily determined that there was an error in the design of the effective net positive suction head during pump design; when transferring liquid from the large tank, the liquid level in the tank is high, resulting in a high static pressure difference at the pump inlet, so cavitation does not occur. In the small tank, the static pressure difference is low, which leads to cavitation and vacuum formation. To further determine whether this is the issue, the liquid level in the large tank can be lowered to the level it was at when the small tank was emptied, to see if the pump runs dry under these conditions.