How does an AODD Pump work? | What are Applications of AODD Pump?

The pumps are used for a wide range of industrial applications. The pumps have multiple types designed for different applications. An Air-Operated Double Diaphragm (AODD) Pump is the most commonly used industrial pump. AODD pumps are used in industries for smooth operation. These pumps have extremely high reliability and efficiency. They are handy and ideal for multiple industries from beverage to mining and food production. This article mainly explains different aspects of the Air-Operated Double Diaphragm (AODD) pump.

What is an Air-Operated Double-Diaphragm Pump?

The AODD Pump is a famous type of reciprocating pump that uses compressed air as its power source to transfer fluids through the pump. It uses two flexible membranes or diaphragms to pump the fluid. These diaphragms are connected by a common crankshaft.

It contains pumping cylinders. The flexible diaphragm or membrane firstly fills the cylinder, pressurizes the fluid, and discharges it to the desired area.

The compressed air drives the repetitive reciprocating motion of the flexible membranes attached to the connecting rod. This reciprocating motion of the diaphragm discharges fluid from one cylinder and transfers it to the second cylinder.

These types of pumps are best suitable to safely pump the viscous liquid. AODD pumps have the capability to control the toughest liquids in the harshest conditions. With only a few parts, this pump remains reliable with low maintenance.

Air Operated Double Diaphragm pumps are most commonly used to transfer shear-sensitive liquids, wastewater treatment, abrasive slurries, and sludges. They have high reliability and easy maintenance.

One of the main disadvantages of the AODD pump is that it generates high noise and is prone to icing. 

Working of AODD Pump

An AODD pump works on the positive displacement principle. It uses compressed air to drive the diaphragms. The reciprocating motion of the diaphragms compresses the fluid and transfers it to the desired area. However, you can drive the diaphragm pump directly by connecting it to an electric motor via a shaft.

An Air Operated Diaphragm pump works in the following way: 

• First of all, the control system transfers compressed air into cylinder A.
• For the suction stroke, the crankshaft shifts the diaphragms from the right to the left side.
• As the diaphragms move to lift, the volume of cylinder A decreases, and the volume of cylinder B increases. In such conditions, the fluid starts going from cylinder A to cylinder B.
• When the diaphragms complete their first stroke, the air valve transfers compressed air from cylinder A to cylinder B.
• For the second stroke (discharge stroke), the shaft shifts the diaphragms to the right. During this stroke, the volume of chamber A increases while the volume of cylinder B decreases.
• As the volume of cylinder A becomes more than the volume of cylinder B, the fluid starts going from cylinder B to cylinder A.
• When the second stroke completes, the air valve discharges compressed air from cylinder B and transfers it to cylinder A, and the whole cycle repeats.

Components of AODD Pump

The air-operated double diaphragm pump has the following components:

• Air Inlet
• Air Valve
• Pneumatic Exhaust
• Liquid Inlet and Outlet
• Diaphragms
• Center Block
• Check Valve
• Pump Housing
• Fasteners
• Muffler

1) Air Inlet

The air inlet of the pump is used to supply compressed air to the pump to run the membranes.

2) Air Valve

This valve is utilized to regulate the compressed air entry into the pump. It switches the pump between the suction and discharge modes.

3) Pneumatic Exhaust

This is the port where the compressed air leaves the pump after running the diaphragm.

4) Liquid Inlet and Outlet

The inlet and outlet ports are used to introduce and discharge fluid from the pump.  

5) Diaphragms

This pump contains two diaphragms. The flexible material is used for the construction of the diaphragm. It acts as a barrier between the liquid chamber and the air chamber. The diaphragms flex back and forth to move the fluid through the pump.

6) Center Block

The center block connects the two diaphragms and houses the air and fluid chambers.

7) Check Valve

The check valve ensures that the fluid flows in only one direction through the pump.

8) Pump Housing

The pump housing contains the diaphragms and check valves and provides support for the pump.

9) Fasteners

The pump contains different fasteners such as clamps, bolts, and screws to the various components together.

10) Muffler

It is installed to reduce the noise generated by the compressed air leaving the pump.

Advantages of an AODD Pump

• The Air-operated double diaphragm pump has no leakage issues. It has a tight seal between the external environment and the wetted components of the pump. Therefore, leakage issues will only appear if one or both membranes fail.
• The rotating parts and internal parts of this pump don’t need lubrication.
• Compared to mechanically operated diaphragm pumps, AODD pumps have less membrane wear due to the advantage of pressure equalization of the compressed air supply.
• They can run dry forever without suffering damage.
• These types of pumps have the capability to pump slurries, sludges, high-viscosity fluids, and abrasives. You may also use them to transfer shear-sensitive liquids.
• These have the self-priming capability.
• They don’t have priming problems.
• They have up to 8m suction lift capability.
• This pump consumes low energy and reduces electricity bills because it uses compressed air as power instead of electrical power.
• They are the best ideal to use in hazardous applications.

Disadvantages of an AODD Pump

• The Air-operated double diaphragm pumps are more costly than the centrifugal pumps.
• The AODD pump can’t deliver constant flow.
• They need frequent maintenance.
• The stability and efficiency of these pumps vary according to the supply of compressed air. The pressure of the compressed air supply must be equal to or more than that of the medium to be pumped. This condition limits the use of these pumps to low-pressure (i.e., 120 psi) applications.
• When the pressure of the compressed air supply increases or the pressure of the pumping fluid decreases, the pumping speed increases. In the case of constant flow, additional flow and pressure controls are required.
• A poorly designed air distribution system can produce icing problems. Continuous air discharge can lead to cooling, and in extreme cases, ice can form in the distribution system or around the ventilation slots.
• These pumps generate very high noise.

Application of AODD Pump

• Pumping Wastewater
• Circulating ceramic slurry
• Filling molds
• Day tank transfer
• Ceramic slips
• Pumping fuels for cars and other machinery
• Pumping solvents for separating minerals
• Dosing reagents
• Pumping sludge and abrasive slurry mixtures

FAQ Section

What is AODD Pump?

The AODD Pump is a famous type of reciprocating pump that uses compressed air as its power source to transfer fluids through the pump.

What are the components of Air-Operated Double Diaphragm Pump?

• Air Inlet
• Air Valve
• Pneumatic Exhaust
• Liquid Inlet and Outlet
• Diaphragms
• Center Block
• Check Valve
• Pump Housing
• Fasteners
• Muffler

What is the difference between AODD and diaphragm pumps?

AODD pumps or Double diaphragm pumps are most commonly employed in a range of fluid transfer systems, indicating their flexibility in accommodating various types of fluids, including those that are shear sensitive, abrasive, and viscous fluids. These pumps are known because of their robustness, dependability, and simple maintenance.