A.Vapor pockets formed in the suction flow stream
B.Rough easing volute surfaces
C.Worn wearing rings
D.Heavy fluid in the flow stream

A.primarily to lubricate the shaft seals
B.due to the inability of this type of pump to lift water to cover the suction (eye) of the impeller
C.to initially unload the pump by having its head pressure equal to discharge pressure
D.in order to overcome the potential energy of water in the discharge line