Diaphragm Pumps: Types and Industry Applications

Abrasive, viscous or particle-laden liquids are a challenge for many conventional pumps. Diaphragm pumps are positive displacement pumps that work through the reciprocating movement of a flexible diaphragm (membrane) and transfer such liquids safely, without leaks and in a controlled way.

This article explains how diaphragm pumps work, the differences between air-operated and electric types, the material options and their applications by industry.

How Does a Diaphragm Pump Work?

When the diaphragm is drawn back, low pressure forms in the pump chamber and liquid fills it through the inlet check valve. When the diaphragm is pushed forward, the liquid is sent through the outlet check valve into the discharge line. Because the diaphragm forms a barrier between the pumped liquid and the drive mechanism, the liquid never contacts moving mechanical parts. For a detailed look at the working principle of air-operated double diaphragm pumps, see our article on the double diaphragm pump.

Types of Diaphragm Pumps

Advantages

• Broad liquid compatibility: Handles abrasive, viscous, particle-laden and shear-sensitive liquids.
• Leak-free operation: The diaphragm design eliminates rotating shaft seals.
• Dry-running capability: Air-operated models are not damaged by running dry.
• Self-priming: Depending on the model, can lift liquid from about 4–5 metres when dry and up to about 9 metres when primed with liquid.
• Gentle product handling: Low shear keeps sensitive products intact.
• Solids handling: Can pass solid particles up to a certain size depending on pump size.
• Easy maintenance: The simple design allows quick diaphragm and ball replacement.
• Bolted casing option: A bolted casing provides more secure sealing than clamped designs.

Material Options

• Casing: Materials such as aluminium, stainless steel, PP and PVDF.
• Diaphragm: Plastics and elastomers such as PTFE, EPDM and NBR, selected according to the chemical nature and temperature of the liquid.

Applications by Industry

• Chemical industry: Transfer of acids, alkalis, solvents, adhesives, paints and inks.
• Water and wastewater treatment: Chemical dosing, sludge and chemical waste transfer.
• Food and beverage: Viscous products such as milk, cream, ayran, mustard, mayonnaise, ketchup, chocolate and jam (with models made of food-grade materials and holding the relevant certificates).
• Pharmaceuticals: Liquid transfer requiring hygiene.
• Mining and construction: Sludge, particle-laden water and site wastewater.
• Petrochemicals: Transfer of petroleum products and solvents.
• Ceramics: Slip transfer and glazing applications.
• Shipyards: Bilge water removal and waste transfer.
• Textiles: Dye and chemical transfer.
• Machining: Coolant (cutting fluid) transfer and waste management.
• Vehicle service stations: Waste oil transfer.
• Meat and fish processing: Animal by-product transfer, fish oil storage and filling.

Frequently Asked Questions

Conclusion

With their leak-free design, broad liquid compatibility and choice of drives, diaphragm pumps are a reliable transfer solution across industries from chemicals to food. For models suited to chemical transfer, explore our acid and chemical pumps product group.