The diaphragm pump is a pump that forces the liquid out of the outlet through forced pressure. Diaphragm pumps are available in various sizes and types, the choice depends on the thickness of the medium to be pumped, the pressure and capacity.
The suction side is generally at the bottom with the pressure side (outlet) at the top, but there are versions with single-sided membranes that can be supplied with other suction and pressure connections. This actually applies to almost all diaphragm pumps. Diaphragm pumps are generally driven by (compressed) air; the average required air pressure is 6 bar.
A piston rod is steered alternately to the left and right by means of the air, as shown schematically above. This pulls the membrane in on one side and pushes the other side out at the same time. Because two check valves are mounted on both membrane sides, the pressure side is closed during the retreating movement and the suction side is opened, causing liquid to be sucked into the membrane chamber. With the outwardly moving diaphragm, the opposite happens: the suction is closed and the pressure is opened, forcing the liquid out of the diaphragm chamber. Since this happens alternately with a double diaphragm pump, there is a suction and pressure movement with every movement of the piston rod. This does result in a pulsating fluid flow.
In general, diaphragm pumps are adjustable by limiting or increasing both air pressure and piston rod movement. This results in more or less capacity.
The pump can be divided into three parts; the drive with valve block seat, the liquid part and the pressure and suction connection(s).
