The efficiency of the brushless DC pump is the product of the three efficiencies of mechanical, volume and hydraulic power. The efficiency of the brushless DC pump is the product of the pump efficiency and the motor efficiency. The main factors that cause the low efficiency of the brushless DC pump are as follows:

1. The efficiency of the pump itself is fundamental. Pumps under the same working conditions may differ in efficiency by more than 15%.

2. The operating conditions of the brushless DC pump are lower than the rated operating conditions of the pump, with low pump efficiency and high energy consumption.

3. The efficiency of the motor remains basically unchanged during use. Therefore, choosing a high-efficiency motor is very important.

四、机械效率的影响主要与设计及制造质量有关。泵选定后，后期管理影响较小。

五、水力损失包括水力摩擦和局部阻力损失。无刷直流水泵运行一定时间后，不可避免地造成叶轮及导叶等部件表面磨损，水力损失增大，水力效率降 低。

六、无刷直流水泵的容积损失又称泄漏损失，包括叶轮密封环、级间、轴向力平衡机构三种泄漏损失。容积效率的高低不仅与设计制造有关，更与后期 管理有关。泵连续运行一定时间后，由于各部件之间摩擦，间隙增大，容积效率降低。

七、由于过滤缸堵塞、管线进气等原因造成离心泵抽空及空转。