AODD Pumps in the Chemical Industry


An Air Operated Double Diaphragm pump (AODD) may be one of the simplest pump designs found in an industrial plant. The simple design and ease of use makes an AODD one of the most versatile pumps, especially in a chemical plant.


The simple operation of an AODD utilizes compressed air to drive the diaphragms that pump the desired fluid. The AODD includes a series of ball or flap check valves that open and close to allow liquid in and out of the diaphragm chamber. The pump can produce liquid discharge pressures equal to that of the air pressure being used to power the pump. As the diaphragms are balanced with air pressure on one side and liquid process pressure on the other, they see very low stresses during operation and can operate for millions of cycles before fatigue failure. During the suction stroke of a diaphragm, the air behind the diaphragm is discharged to atmosphere.


Because AODD pumps are simple by design, they are also easy to document in an engineering specification. Since there is no electric motor needed to operate the pump, there is no need to provide a motor specification or motor data sheet.


In chemical plants, there are a variety of corrosive and non-corrosive applications. Having a pump that is available in multiple materials of construction and can be easily selected and sourced is very important. AODD pumps are manufactured in a variety of metal and plastic materials to better suit the needs of the application. Metal materials include aluminum, cast iron, stainless steel and higher alloys like Hastelloy-C for corrosive applications. Providing a pump in metal or plastic material with similar dimensions and interchangeable parts is important for a plant’s asset and inventory management. AODD pumps in plastic materials such as Polypropylene, PVDF, PFA, and conductive versions of these materials, allows the pump user to leverage one pump style to support numerous applications.


AODD pumps provide a unique combination of safety features for chemical process pumps. Most importantly, AODDs are air operated and require no electricity. By using air alone, if properly grounded, AODDs are intrinsically safe and can be used in environments with flammable liquids.


When adding a new process to a chemical plant, multiple application aspects need to be considered. Often you may be pumping clean liquids at ambient temperatures. However, conditions can vary greatly throughout a chemical manufacturing process, requiring different pump styles for different applications. If you are looking for one versatile pump that can handle a wide variety of applications and conditions, first consider an AODD. Chemical reactions can increase solids content, viscosity, specific gravity and other fluid characteristics. While an AODD can handle all of these changes, they do have limitations. All application aspects should be checked against the AODD manufacturers’ published limits.


Metrans Makina has been the leading company in providing pumps, equipment and service to fluid handling applications for over 30 years. Metrans is the authorized Wilden distributor in Turkey. Please do not hesitate to contact us, we will be happy to assist.







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