... construction, factory and mine.PrincipleYou should fill the pump with water before start, then the impeller ... to high.Use and maintenanceyou should make the pump working in the standard rotate speed in use ... using it in case frost crack.After the pump every 1000 hours operating time, you should take down ... increased1,the rotate speed is too high1,adjust2,pump shaft bended2,adjust or replace3,bearing wear ...