How AODD pumps or diaphragm pumps are used in very many industries?
AODD pumps or diaphragm pumps use the reciprocating action of elastomeric diaphragms and ball valves to pump a fluid. There are many combinations of elastomers and wetted parts – and the fluid to be pumped would define the specific pump to be used. Depending on the flow rate required and the height to which the fluid is to be pumped, the size of the pump should be selected.
How does it work?
A simple air-valve system is used to move the diaphragm rod. Flexible diaphragms are attached at each end of the diaphragm rod. The pilot spool is pushed back and forth whenever the diaphragm rod reaches the end of its throw. This action allows air to move the air distribution valve back and forth. The air distribution rod controls air flow to the left or right air chamber, reversing on each stroke. The four ball valves are operated by pressure differences in the pumped liquid.
Types of fluids that can be pumped and why?
Diaphragm pumps are very versatile pumps and are used in the transfer of highly viscous, abrasive, semi-solid, and shear sensitive materials. These pumps are self-priming hence operation is easy. They are easy to service with fewer moving parts.
Corrosive/abrasive fluids: can be pumped by selecting the wetted parts and elastomers to withstand the types of fluid to be transferred – the pumps are available in various materials such as Aluminium, Stainless steel (withstand abrasive) and Plastics (withstand corrosive) with elastomers like Viton, Buna N, Santoprene to name a few.
Flammable fluids: Fluids like Acetone, Benzene, Petroleum etc. that easily catch fire, are possible to be pumped because AODD pumps are air driven and hence they are inherently safe for use in explosive atmospheres. However, some liquids may generate a static charge, so the pumps should be completely grounded. However, it is recommended that one should use ATEX/IECEx certified pumps for such applications.
Highly Viscous Fluids – Viscosity is the resistance to flow. In other words, we can say it the stickiness of the fluid. Depending on the viscosity of the fluid, the pump size needs to be determined – The higher the viscosity, the larger should the suction and discharge pipe size be. Due to higher frictional losses in the pipeline for high viscosity fluids, the discharge pressure will be high.
Shear Sensitive Liquids like shampoos, milk and paint when subject to shear (or churning) – whilst being transferred – can result in a change of the product characteristics. Since AODD pumps run at lower speed and hence gently move the liquid, they are ideal for use in the transfer of such liquids.
Vapour Pressure: to pump Liquids such as diesel, hydrocarbons which have low vapour pressure, we need to use a pump that runs at low speed with a limited suction lift to ensure the pump delivers the required flow.
Thus we see that AODD pumps or diaphragm pumps are extremely important in industry and one should make sure one gets the right pump for the job. For a free consultation – book an appointment with our experienced engineers at www.teryair.com by sending written email to Vinay Sawant at email@example.com