2. Rotating speed The rotating speed of the sanitary pump refers to the number of revolutions per minute of the impeller of the water pump, which is represented by the symbol n, and its unit is revolutions per minute. The centrifugal pump is designed, manufactured and operated according to a certain speed. When the speed of the negative pressure pump changes, other working parameters will change accordingly. Therefore, the speed is an important technical index that determines the performance of the water pump. The speed marked on the nameplate of the pump refers to the speed of the pump at the highest efficiency, which is called the rated speed. The corresponding marked flow, head, power and other parameters refer to the performance of the pump running at the rated speed.