​Working Principle and Applications of Air-Operated Diaphragm Pumps

The air-operated diaphragm pump is a new type of conveying machinery and represents one of the most innovative pump categories in the Chinese market. It uses compressed air as the power source and is capable of handling a wide variety of liquids, including corrosive fluids, liquids containing solid particles, as well as those with high viscosity, volatility, flammability, or high toxicity.

These pumps are available in four material types: plastic, aluminum alloy, cast iron, and stainless steel. The diaphragms are made of materials such as nitrile rubber, neoprene, fluororubber, polytetrafluoroethylene (PTFE), or polyhexafluoropropylene to suit different liquid media. This flexibility allows the pump to be adapted to special applications where conventional pumps fail, delivering satisfactory performance in challenging conditions.

I. Applications of Air-Operated Diaphragm Pumps

Given these characteristics, diaphragm pumps have been gradually capturing market share from other pump types since their introduction. They dominate in areas such as paint spraying and the ceramics industry, and are increasingly used in environmental protection, wastewater treatment, construction, sewage handling, and fine chemicals—fields where they offer irreplaceable advantages.

Key benefits of air-operated diaphragm pumps include:

1.Their airflow-driven operation allows output to adjust automatically with changes in back pressure (outlet resistance), making them suitable for medium- to high-viscosity fluids. In contrast, centrifugal pumps are designed for water-like fluids; handling thicker liquids would require a reducer or variable-frequency drive, significantly increasing cost. The same applies to gear pumps.

2.These pumps offer a reliable and cost-effective solution in flammable or explosive environments, such as when transporting fuels, gunpowder, or explosives. Advantages include: no spark risk after grounding; no heat generation during operation, preventing overheating; and minimal fluid heating due to low agitation.

3.In harsh environments like construction and mining sites with contaminated wastewater containing complex impurities, pipelines are prone to clogging. Electric pumps often overload under these conditions, causing motor burnout. Diaphragm pumps, however, can pass solids, allow flow adjustment, and stop automatically when blockages occur, resuming once the line is clear.

4.Their compact size, portability, and minimal installation requirements (no foundation needed) make these pumps ideal as portable transfer units.

5.They provide complete isolation when handling hazardous or corrosive materials.

6.In laboratory settings, these pumps prevent contamination of sensitive fluids.

7.They are suitable for pumping chemically unstable fluids (e.g., photographic materials, flocculants) thanks to their low shear force, which minimizes physical impact.

II. Working Principle of Air-Operated Diaphragm Pumps

1.Powered by compressed air.

2.As a positive displacement pump relying on diaphragm reciprocation, its operating principle is similar to that of a plunger pump. This design offers the following features:

(1) No overheating: The expansion of compressed air during exhaust absorbs heat, lowering operating temperature without emitting harmful gases.

(2) No electric sparks: Since no electricity is used, and grounding prevents static sparks.

(3 Handles particle-laden liquids: The ball valve design and positive displacement operation reduce clogging risk.

(4) Very low shear: Gentle fluid handling makes it suitable for sensitive or unstable materials.

(5) Adjustable flow: A throttle valve can be installed at the outlet to regulate output.

(6) Self-priming capability.

(7) Can run dry safely.

(8) Suitable for submerged operation.

(9) Handles an extremely wide range of fluids, from low to high viscosity and corrosive to sticky.

(10) No complex control systems, cables, or fuses required.

(11) Compact, lightweight, and easy to move.

(12) Maintenance is simple with no lubrication needed, avoiding leaks and contamination.

(13) Maintains high efficiency without degradation from wear.

(14) 100% energy utilization: The pump stops automatically when the outlet is closed, preventing overload and heat damage.

(15) No dynamic seals, eliminating leaks; maintenance is easy with no dead spots in operation.