I have a question regarding the outlet pressure of centrifugal pumps; I hope experts can help answer it
Thread Content
Hello, experts. I encountered a rather tricky problem today; I don’t know much about it and would like to ask for some advice: Regarding centrifugal pumps, if there is a valve in the outlet pipeline of a pump that is currently in operation, 1. will the pressure at the pump’s outlet increase when I reduce the flow rate? 2. If I gradually close this valve while the pump is still running, will the pressure at the pump’s outlet rise to the pressure corresponding to zero flow rate as indicated on the pump’s performance curve? 3. If, while the pump is in operation, the elevation difference at the end of the pump’s outlet pipeline decreases significantly (becoming higher than the pump’s outlet level), then according to the formula, the outlet pressure should increase. Is this correct? Please help.
1\ Check where the pressure gauge is installed; by closing the outlet valve, the pressure at the pump’s outlet will increase, while if the gauge is located after the valve, the displayed pressure will decrease. 2\ No. 3\ Reducing the pressure difference will result in a lower reading on the pressure gauge
Dear expert, regarding question 1, the pressure gauge is located after the pump and before the valve. Is this increase in pressure due to holding back pressure? 2. If not, then doesn’t the characteristic curve lose its guiding value? 3. Is the decrease due to a reduction in pump efficiency, or what is the reason?
This post was last edited by ylb913 on 2016-6-17 at 22:33. 1. Will the pressure at the pump outlet increase when the flow rate is reduced? ——Yes. 2. If the valve is gradually closed while the pump is running, will the pressure at the pump outlet increase to the pressure corresponding to the head at zero flow rate on the characteristic curve? ——Theoretically, this is fine, but in practice the values may not be that accurate; there are also issues related to the precision of the pressure gauge and its installation location. ——Don’t forget to include the pressure at the pump inlet. ——A short time is fine; if it’s too long, the pump will become empty, and the pressure will fluctuate and drop. 3. If, while the pump is in operation, the elevation difference at the end of the pump’s outlet pipeline decreases significantly (becoming higher than the pump’s outlet level), then according to the formula, the outlet pressure should increase. Is this statement correct? ——I don’t quite understand it, but the significant reduction in the height difference at the end of the pump outlet pipeline should lead to a decrease in the pump outlet pressure and an increase in the pump outlet flow rate.
1. An increase in the pump outlet pressure is due to pressure buildup. 2. I have conducted experiments: with a filter pump having a capacity of 60 M3/H and a head of 60 meters, excessive pressure at the end of the filtration process could damage the filter plates; after closing the outlet valve, the pressure dropped to 0. 7MPa 3. The decrease is due to a reduction in the total resistance of the pipeline