The head of the asphalt heat preservation pump is lower than that of the design working point. It is often encountered in practice. In one case, when the pump is selected, the lift of the pump is too high, and in actual use, the pump is The use of the lift is reduced; in another case, the operating point of the pump is not well determined in use, in other words the flow of the pump needs to be adjusted frequently; there is also a case where the asphalt insulated pump needs to be changed frequently. These three situations may overload the pump and affect the reliability of the pump. It can be said that for pumps without full lift characteristics (including submersible sewage pumps), the scope of use is greatly limited.