As long as the topic of cavitation came up, it's worth noting that you can have cavitation only within the pump or in the tubing leading up to the pump. If it's the former, then porting, raising overall pressure, or reducing flow rate will all help. If it's the latter, you'll be able to see a fine stream of bubbles in the tubing leading to the pump suction. In this instance, porting the pump will have no effect. Lowering flow rate or raising overall system pressure are the only options. I've never seen a case where a closed system had cavitation occuring ahead of the pump but see it frequently in open systems that have odd suction resistances.
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