Few pumps are as adaptable as the diaphragm pump. The same basic design moves clean water, thick slurry, aggressive acid and delicate pharmaceutical product, all by flexing a membrane back and forth to draw fluid in and push it out. Because that membrane keeps the liquid away from the pump’s moving parts, a diaphragm pump can run dry, self-prime and stay leak-free where other pumps would struggle.
We stock air-operated diaphragm pumps, the AODD type, from Aro, Dellmeco, Enviroflex, Graco, Nomad, Samoa and Yamada, in materials from aluminium and cast iron through to stainless steel, polypropylene and PTFE. Other brands can be sourced if a job needs them. We also run a dedicated electric diaphragm pumps page. Browse the ranges below or call +44 1332 913500.
A diaphragm pump moves fluid with a flexible membrane that flexes in and out, drawing liquid through an inlet valve on one stroke and pushing it out through a discharge valve on the next. The membrane seals the pumped liquid completely away from the mechanical drive, which is what lets these pumps handle corrosive, abrasive, viscous and shear-sensitive liquids without contaminating the product or wrecking the mechanism.
That sealed layout also means they run dry without harm, prime themselves from dry and stay inherently leak-free, all of which matter in chemical, pharmaceutical and food-grade settings. The full pumping cycle is set out in our guide: How Do Diaphragm Pumps Work?
AODD pumps run on compressed air. An air distribution valve switches pressure between two diaphragm chambers, so as one diaphragm pushes out on its discharge stroke the other pulls in on its suction stroke, with four check valves steering the fluid through.
They dominate industrial diaphragm pumping for good reason: no electrics in the fluid path makes them intrinsically safe, they will run dry indefinitely, they self-prime to several metres of lift, and they cope with viscosities up to around 30,000 cPs. Port sizes run from a quarter inch to four inches, with body and diaphragm materials to match almost any fluid. For where air drive wins and where electric makes more sense, see our blog: Air Operated vs Electric Operated Diaphragm Pumps.
The diaphragm is the key wear part and has to suit the fluid. Common materials are Neoprene, Nitrile, EPDM, Santoprene, Hytrel, Viton and PTFE, each matched to particular chemical families, temperatures and abrasion levels. Get this right and the pump lasts; get it wrong and it does not. Our Diaphragm Selector tool will point you to the right material, or call and we will advise.
Many of the pumps we supply carry ATEX rating for explosive atmospheres, FDA and 3A for food and pharmaceutical contact, and EHEDG for hygienic design. Tell us the application and we will confirm what it needs.
Four questions get you to the right pump: what fluid you are pumping (composition, viscosity, solids, temperature), what flow rate you need, what discharge pressure the system demands, and what air supply you have to drive it. Pump size, body material and diaphragm material follow from there.
We carry AODD pumps from Aro, Dellmeco, Enviroflex, Graco, Nomad, Samoa and Yamada, with the breadth to match the pump to the job rather than forcing a fit, and we source other makes on request. Call +44 1332 913500 with the details.
Got a question about AODD Find the answers to our most common questions here.
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A diaphragm pump is a positive displacement pump that uses a flexible membrane (the diaphragm) to move fluid. The diaphragm seals the pumped liquid completely away from the pump’s mechanical components, which means diaphragm pumps can handle corrosive, abrasive, viscous and shear-sensitive fluids without contamination or mechanical damage.
Pharmaceutical diaphragm pumps are usually constructed in 316 stainless steel or PTFE, with FDA, 3A and EHEDG certifications that meet the strict hygiene and validation standards of pharmaceutical manufacturing. Their gentle, low-shear pumping action protects sensitive formulations, and their clean-in-place compatibility minimises downtime between batches.
AODD pumps are dry-run capable; these pumps can operate without fluid for short periods without immediate damage.
The diaphragm material must be chemically compatible with the fluid being pumped and rated for its temperature. Common materials include PTFE for aggressive chemicals, Santoprene for general-purpose duty, Neoprene for petroleum-based fluids, and EPDM for water-based applications. Use our Diaphragm Selector tool, or call us and we’ll recommend the right material for your fluid.
The pump body itself typically lasts 15–20 years or more with proper maintenance. Diaphragms are the main wear item and last anywhere from six months to several years, depending on the fluid, operating pressure and cycle rate. Valve balls and seats are also periodic replacement items. We stock spare kits for all AODD pump models we supply.
