What is a Diaphragm Pump?

What is a Double Diaphragm Pump

What is a diaphragm pump? Also known as a Membrane pump that uses a combination of the reciprocating action of a rubber, thermoplastic or PTFE and suitable valves on either side of the body (check valve, butterfly valves, flap valves, or any other form of shut-off valves) to pump a fluid.

There are three main types of diaphragm pumps:

Those in which the pump is sealed with one side in the fluid to be pumped, and the other in air or hydraulic fluid. The diaphragm is flexed, causing the volume of the pump chamber to increase and decrease. A pair of non-return check valves prevent reverse flow of the fluid.
Those employing volumetric positive displacement where the prime mover of the diaphragm is electro-mechanical, working through a crank or geared motor drive, or purely mechanical, such as with a lever or handle. This method flexes the diaphragm through simple mechanical action, and one side of the diaphragm is open to air.
Those employing one or more unsealed sections with the fluid to be pumped on both sides. The diaphragm(s) again are flexed, causing the volume to change.

When the volume of a chamber of either type of pump is increased, the pressure decreases, and fluid is drawn into the chamber. When the chamber pressure later increases from decreased volume, the fluid previously drawn in is forced out. Finally, the diaphragm moving up once again draws fluid into the chamber, completing the cycle. This action is similar to that of the cylinder in an internal combustion engine. Pumps deliver a hermetic seal between the drive mechanism and the compression chamber, allowing the pump to transfer, compress, and evacuate the medium without a lubricant.

An elastomeric membrain can be used as a versatile dynamic seal that removes many of the limitations found with other sealing methods. They do not leak, offer little friction, and can be constructed for low pressure sensitivity. With the right material consideration, Yamada pumps can seal over a wide range of pressures and temperatures without needing lubrication or maintenance.

Common Fluids