A diaphragm pump transfers liquids at a variety of speeds using either compressed air or a motor. Diaphragm pumps transfer liquids of all velocities, including ones with large solids content. The pumps are capable of handling liquids with aggressive chemicals, such as acid depending on the materials used to complete their construction.

There are a variety of different diaphragm pump styles made from a vast array of manufacturers. Each pump style offers a unique set of features that offer both advantages and disadvantages depending on what the intended use is for the pump.

Air-operated diaphragm pumps

These pumps use compressed air to operate. The units include two chambers with a diaphragm that shifts air from one chamber to the other, forcing liquid from one chamber into a discharge piping system while the other chamber fills with liquid. These pumps offer a slight pulsating in the discharge flow.

Small motor driven diaphragm pumps

These diaphragm pumps are equipped with inlet and outlet ports with flow rates that range from 1 to 7 gallons per minute. Most pumps this size create a pressure of 60 to 100 pounds per square inch. The design with these two pumps generally come in two styles, a "demand" style and a "by-pass style." The demand style offers a built-in pressure switch and the by-pass style offers a discharge valve that can be shut off, but there is a risk of overheating the liquid if the valve is shut off for several minutes.