NPSH
Thread Content
How does a double-suction impeller achieve cavitation margin prevention?
For a double-suction impeller, the flow rate of each impeller is half of the original value. As the flow rate decreases, the required NPSH must also decrease; as a result, the difference between the effective NPSH and the required NPSH becomes larger, making cavitation less likely to occur.
NPSHr is closely related to the pump’s flow rate; as the flow rate increases, NPSHr also increases. This can be seen from the pump’s performance curve. The reason why double-suction impellers can reduce cavitation is that, with such impellers, the flow rate through each impeller is half of what it would be otherwise. Since the flow rate decreases, NPSHr also decreases, and as a result, the difference between NPSHa and NPSHr increases, making cavitation less likely to occur
Reply to 3# 3968668: First of all, thank you for your answer. But isn’t the required net positive suction head determined by the pump manufacturer?
Reply to 4# Feitian Xiaoyu: The required net positive suction head is determined by the performance of the pump itself; the manufacturer cannot set this value