Diaphragm Pump Introduction
A diaphragm pump is a kind of positive displacement pump that employs the reciprocating motion of a flexing diaphragm to push fluid in and out of the pumping chamber. It works when the flexing diaphragm develops a vacuum at the chamber’s inlet. As the diaphragm moves in the opposite direction, it results in a decrease in the pumping chamber’s volume and this action will force the fluid out the pump’s discharge port.
The diaphragm pump uses check valves at the pumping chamber’s inlet and outlet to ensure that the liquid only flows in one direction without any backward motion. Diaphragm pumps work within the following general ranges. Their flow rates range from 1 gallon per minute to 1,800 gallons per minute, while their total pressure (head) will range from 25 to 15,000 psi. Their horsepower ranges from 0.5 to 2,000 horsepower.
How it Works
A diaphragm pump is mainly distinguished according to the mechanism that it uses to drive the reciprocating diaphragm. Diaphragm pumps work using four mechanisms.
The mechanically actuated diaphragm pump has a reciprocating mechanical connection that is attached directly to the diaphragm. The pump usually includes a set of gears or other mechanical mechanisms that convert the motor’s rotation into a reciprocating motion of the connection that is attached to the diaphragm. The pump’s flow rate can be varied by adjusting the pump speed or stroke length.
A hydraulically actuated diaphragm pump employs an intermediate hydraulic liquid that is located on the non-product section of the diaphragm to flex the pump’s diaphragm. A reciprocating plunger pressurizes the hydraulic fluid. Although the plunger works like a mechanically actuated diaphragm, it is not attached to the diaphragm. Instead, the plunger pressurizes the intermediate hydraulic liquid that flexes the diaphragm. The pump’s flow may be varied by adjusting the amount of hydraulic liquid that is bypassed or the pump’s speed.
A solenoid diaphragm pump uses an electric motor that energizes and de-energizes a solenoid in an alternating action, creating an electro-magnetic force that reacts with a metal part on the diaphragm, flexing the diaphragm. The pump’s flow may be varied by adjusting the pump’s speed.
An air operated double diaphragm pump (AODD) is a kind of double acting pump. It has two diaphragms and a double set of check valves. It is driven by compressed air which operates alternately on the non-product section of one diaphragm, followed by the other. Air is supplied to both sides of the diaphragm through a shuttle valve in an alternating motion. The pump’s flow can be varied by adjusting air pressure that is supplied to the pump.
Usage of diaphragm pump
The diaphragm pump has many applications ranging from industrial, commercial, scientific and municipal fields. Diaphragm pumps are commonly employed as metering pumps for pumping precise amounts of liquids used for treating water. They are also employed in process applications that require extremely high pressures. They are ideal for pumping liquids that contain solids and where electrical power is not available.