Diaphragm pumps transfer liquid by the up-and-down movement of a cupped, elastic surface. They are usually made from polytetrafluoroethylene (PTFE), Teflon or synthetic rubber.

They are used in various industries, including petrochemical, metal fabrication, mining, water, construction and cleaning. These pumps are often powered by compressed air.

Types of Pumps

Diaphragm Pumps are of various types based on the power used to push or pull the diaphragm. These include hydraulic, air-operated, and motor-driven pumps.

Hydraulic: These pumps work with a reciprocating piston. The pump moves the fluid to one side and through a discharge valve.

Air Operated Double Diaphragm (AODD): This is the most common type of diaphragm pump. It has two pumping chambers with two diaphragms and an air valve that directs compressed air to the back of the first diaphragm.

This action forces the liquid out of the pump by causing the outlet ball valve to move away from its seat. Then, the air valve pushes the air behind the second diaphragm.

These diaphragm pumps are widely applied in various industries, and they can handle high, medium or low-viscosity liquids and fluids with an effective solids content. They can also be designed with a wide range of body materials and membranes to handle harsh chemicals like acids.

Hydraulic

Hydraulic pumps work through a pressurized fluid and can be used for various applications. These pumps are found in vehicles, construction equipment, and airplanes.

Using a fluid instead of a mechanical drive source is an essential advantage because it means fewer moving parts and less potential failure. It also eliminates the need for a relief valve to handle high-pressure fluctuations.

A hydraulic diaphragm pump is a positive displacement pump that uses the up-and-down movement of a cupped, elastic surface (PTFE, Teflon, synthetic rubber) to generate liquid flow. It is similar to a rotary vane or axial flow pump but without a lubricant.

The pump’s shape, material, and durometer affect its lifespan, stiffness, and chemical or environmental corrosion resistance. Typically, the body of the diaphragm is molded or rolled to account for the required stroke length.

Solenoid

Different types of diaphragm pumps can be used for various applications. Those with positive volumetric displacement can be electro-mechanical, working through a crank or geared motor drive or purely mechanical, such as with a lever or handle.

They can also be made using one or more unsealed sections with fluid pumped on both sides. This method requires more pumping power because the diaphragm needs to be flexed again.

Another type of diaphragm pump is the solenoid pump. It consists of an electromagnet and spring assembly that displaces the fluid into the discharge line.

It is a popular pump for chemical dosing applications, mainly when working with dangerous and corrosive chemicals. It is also suitable for wastewater treatment systems and water purification applications. Its wetted parts are designed with rugged materials which can withstand the chemical compounds and acids used in these applications.

Mechanical

Mechanical diaphragm pumps are simple pumps that include a diaphragm, displacement chamber, two valves and a driving mechanism. The diaphragm is a round disc made from a flexible material that displaces fluid in and out of the room. The material of the diaphragm determines its lifespan, stiffness (durometer), and resistance to chemical and environmental corrosion.

Diaphragms are available in various materials, such as EPDM rubber, PTFE, and others. They come in multiple shapes, including flat and rolled/molded.

These pumps are generally less expensive than hydraulically-actuated pumps. They also offer greater efficiency, durability and low maintenance.

Pumps with double diaphragms can be used for various applications, particularly for pumping sludge or slurries with a high amount of grit and solid content. They can also handle highly viscous liquids.

Air-operated double diaphragm (AODD) pumps are a simple technology that can be applied to many applications. They are available in different sizes and have a flow rate ranging from 2 GPM to 10 GPM.