A Quick Guide To Air-Operated Double Diaphragm (AODD) Pumps

Air-operated double diaphragm (AODD) pumps are positive displacement pumps that run on compressed air. Appropriate for use in many applications, including the transfer or abrasive or viscous fluids, the AODD pump is employed in most facilities and industries.

When you connect the pump to compressed air, it directs the air through an air motor. This motor pushes the air from one chamber to another through a connected passage, producing a simultaneous back and forth movement. This motion forces liquid out of the one chamber and to the discharge piping while the other chamber fills up. Simply put, both chambers are filled and emptied as liquid is drawn through a shared inlet and released through another (single) outlet.

Benefits of AODD pumps:

1. Abrasive or viscous fluid transfer AODD pumps are appropriate for highly viscous or abrasive fluids transfer.

2. Ability to handle solids
AODD pumps are able to pass solid particles and shear-sensitive materials. This makes them useful for pumping sludges and slurries or food products containing seeds or particles.

3. Can be operated continuously
AODD pumps are self-priming, with rugged anti-freeze and lube-free air valves that prevent them from stalling. This ensures that the pump can run continuously.

4. Simple to maintain
AODD pumps operate without seals, making them leak-free, and easy to repair, maintain and replace. For example, All-Flo Pump Company's AODD pumps have 28 internal parts. Less parts mean less preventable wear of the pump and quick repair of wearable parts throughout the pump's lifespan.

5. Ability to run dry
AODD pumps can run dry without causing any damage to the pump. This is a useful feature when suction conditions are variable and can change.
5. Flow rate and discharge
With variable flow-rate and discharge pressure, the AODD pump is useful when flow and/or pressure changes.

6. Energy efficient
While AODD pumps may be less energy-efficient than other types of pumps, when compared to other diaphragm pumps, some AODD pumps are superior. A standard 2-inch diaphragm pump costs anywhere between CAD 5,000-$6,500 to operate over a year. However, the same-sized AODD pump from a manufacturer such as All-Flo Pump Company could save, on average, 35-67% on operating costs per year.

7. Safe to operate
AODD pumps have no power or auxiliary requirements, which means they are appropriate for use in hazardous applications, such as those required by operations such as underground coal mines.

8. Submersible
Most AODD models may be submerged but it must be compatible with the material it will be submersed in. It must also have a hose attached to the exhaust, which in turn must be piped over the submersible liquid.

9. Can be used in any industry
AODD pumps come in sizes from ¼ inch to 3 inches, and a range of materials that ensure the pump can transfer almost every fluid across any industry. Due to its flexible use, it is considered robust and dependable for most applications.

Some disadvantages of AODD pumps

1. Pulsation
AODD pumps pulsate when they shift direction. This may cause "water hammer" (a pressure surge that might damage the pump when fluid in motion is forced to stop or change direction) unless a dampener is fitted to mitigate pulsation.

2. Can be noisy
Some AODD pumps generate noise, so a muffler on the air vent line could be required.

3. Limit on flow and pressure
Most AODD pumps handle flow rates up to 300 GPM. Anything above this may indicate a need for a different type of pump such as a piston, gear or centrifugal pump.

4. Can raise expenses
An AODD pump is fairly cheaply priced upfront, but it can cost approximately 4-5 times more to operate than an electric-powered pump. Based on the number of pumps, and flow rates required, this might raise your overall costs.

AODD Pumps are appropriate for almost any application but choosing the right pump for the job isn't simple. If you need advice on the right type of pump for your application, call our toll-free number 1-800-367-4180. We have experts on hand to help you choose, install, and maintain a variety of equipment. And to answer questions about things you've previously tried gone wrong.