Mechanical diaphragm pumps are majorly used in water treatment industry. In this pump the diaphragm becomes the displacement measuring element, as it moves back and forth in the fluid chamber.

The working principle of a Mechanical diaphragm pump is much simplified as compared to the Hydraulically operated diaphragm pump. The power side of the pump and the capacity control are like that of other types of reciprocating pumps. However, in place of a plunger, the mechanical diaphragm pump uses a connecting rod fastened to the centre of a diaphragm. This mechanism in turn makes the diaphragm to reciprocate which helps in the suction and discharge of the chemical.

Mechanical diaphragm pumps are normally used in water and wastewater treatment plants. These pumps are designed for low pressure but high discharge applications.