Air Operated Double Diaphragm Pumps

Air Operated Double Diaphragm Pumps, or AODD pumps, as a Positive Displacement pump are ideal for fluids with highly abrasive solid content or high viscosity fluids.

Problems AODD Pumps Solve

When most people think of the issue with solids in a fluid that is being pumped, their concern usually is about clogging. While a very valid concern, clogs can be removed. A more challenging effect of solids comes from the more abrasive silt, mud, or small suspended particles like sand.

As these particles are drawn through the pump, they can scratch into the parts much like sanding. For high velocity and high-pressure pumps, the force with which these particles contact the elements inside the pump cause extensive wear and damage. The AODD pumps are designed to minimize this friction with key elements of the pump.

In a centrifugal pump design, the impeller forces the fluid to the side of the pump housing and out the discharge line. This action forces the high-friction fluid to be pumped over the impeller and causes greater wear.

As a positive displacement pump, the AODD also handle variability in pressure and viscosity very well. These pumps maintain their operational efficiency as temperature changes, at different altitudes and in pumping different fluids.

How Air Operated Double Diaphragm Pumps Operate

AODD pumps move liquid by sucking the fluid into a large chamber created by expanding a flexible material and then discharging it through the discharge line by re-compressing the chamber. With this action happening in two separate chambers it creates a steady flow of fluid.
AODD pump flow diagrahm
  • The two chambers are situated such that their diaphragms are facing back-to-back air chambers.
  • The pump starts by opening an air valve for one air chamber while taking air from the other.
  • As air enters the air chamber it forces the diaphragm into the water chamber, thus pushing the water out the discharge pipe.
  • In the second water chamber, the reverse action takes place.
  • Air is removed from the air chamber, causing the diaphragm to be “pulled back” from the water chamber, drawing water in from the inlet pipe.
  • As these two diaphragms expand and contract, the ball valves seat and unseat to ensure the fluid flows in the proper direction.


While no pump is impervious to the wear of abrasive materials suspended in fluids, the diaphragm pumps are less susceptible to the hazards these material create than the centrifugal pumps. And, as mentioned, when steady pumping rates are needed even under variable conditions and changing fluid viscosity, AODD pumps are an ideal option.