Idizayini ye-impeller ene-impeller evaliwe(okujwayelekile) kanye ne-impeller evulekile ngokuya ngokubanjwa(ZGPO).Ukuhambisana kahle nezimo ezihlukahlukene zokusebenza, i-impeller evaliwe esebenza kahle kakhulu, amanani aphansi we-NPSHr avula impeller yoketshezi oluyigesi kakhulu, ukugxila okuqinile okuphakeme (kufika ku-10%), amaphampu ane-NPSHr ephansi kakhulu.