Heat transfer oil explosion-proof electric heater pump has become the most widely used water pump in agriculture due to its simple structure, convenient operation and maintenance, and high efficiency of heat transfer oil pump. However, sometimes air cooling will make it annoyed that centrifugal hot oil pump can not supply water. This paper analyzes the reason why the centrifugal pump can not lift water.

There is air in the water inlet pipe and pump body

(1) Some users of high temperature heat transfer oil pump do not have enough water before starting the pump; sometimes the filled water seems to have overflowed from the exhaust hole, but the heat transfer oil pump does not rotate the pump shaft to completely discharge the air, resulting in a small amount of air remaining in the water inlet pipe or pump body.

(2) The reverse flow direction of the horizontal section of the water inlet pipe contacting with the pump should be greater than 0.5%, and the inlet end connecting the pump should be the highest and not completely horizontal. If increased, air will stay in the inlet pipe, thereby reducing the vacuum degree of water pipe and pump, affecting water absorption.

(3) The packing wear of thermal conductive oil pump or the packing looseness for a long time leads to a large amount of water gushing from the gap between the pump packing and the shaft sleeve. As a result, external air enters the pump from these gaps, thus affecting the water lift.

(4) Due to the long-term potential in the water, the inlet pipe has holes due to the corrosion of the pipe wall. After the pump works, the water surface continues to drop. When these holes come out of the water, air enters the inlet pipe through these holes.

(5) There is a small gap between the water inlet pipe and the water pump, which makes the air enter the water inlet pipe.

The influence of other factors that the centrifugal oil pump can not lift water is as follows

1) The bottom valve cannot be opened. Generally, due to the pump service time is too long, the bottom valve gasket of heat transfer pump and hot oil pump is stuck, and the bottom valve without gasket may rust to death.

2) The filter screen of bottom valve is blocked; the filter screen of potential cement layer of bottom valve is blocked.

3) The impeller is seriously worn. The wear of impeller blades after a long time of use affects the performance of the pump.

4) Failure or blockage of gate or check valves can reduce flow and even prevent pumping. 5) The leakage of heat transfer oil pump and heat pump outlet pipe will also affect the increase of water volume.