Tradeindia Catalogs: How to Select AODD (Air-operated double diaphragm) Pump ?

Air-operated double diaphragm pumps are utilized in various facilities. With a variety of applications, the pumps are practical in different industries. They are versatile, and popular in petrochemical, food & beverage, paints & oils, etc. AODD pumps have unique design, which is effective for transferring viscous or highly abrasive products.

While selecting diaphragm pump, there are some important parameters to consider:

1. Fluid – One of the essential factors for consideration is the Type, Nature & Composition of the Fluid. It helps to avoid corrosion of wetted parts, as well as to prevent wear of the pump. There is a need to determine the chemical composition of the fluid and its consistency. And to determine that, is it a slurry or a clean fluid?

Nature Of Fluid – It is one of the indispensable factors. a.) Corrosive fluids: Corrosive fluids such as Nitric acid, Sulfuric acid and Sodium hydroxide generally damages/destroys the material. Hence, there should be a careful selection of the wetted part and diaphragm. For instance, PTFE diaphragm for sulfuric acid, and PP/PVDF as wetted material.

b.) Abrasive Fluids: Paints, inks and ceramic slurry are a few abrasive fluids, which contain solid particles. They can damage the contact material by wearing or scraping. For example, we can use PTFE Diaphragm and SS 316 material for paints.

c.) Toxic Fluids: Fluids like lead and mercury etc. can be toxic or poisonous. Diaphragm pumps are seals-less with leak-free design, and are appropriate for such liquids.

d.) Flammable Fluids: Flammable chemicals such as acetone, benzene and petroleum easily catch fire. Air driven, the AODD pumps are intrinsically safe. However, some fluids may create a static charge. Hence the pump should be entirely grounded. Antlia Pumps are perfect for such applications.

e.) Shear Sensitive Liquids: Tomato ketchup, curd, paste, emulsions, and allied liquids can change product characteristics, when subjected to shear (churned-up). The liquids may be shear thinning or shear thickening. Diaphragm pumps are perfect for such liquids, as they run at lower speed. For such applications, pump should run at slower speed than normal.

f.) Vapor Pressure: There are liquids with low vapor pressure, such as diesel and hydrocarbons. For that, pumps should run at low speed and the suction lift is controlled. Otherwise, the AODD pump may not be able to present the needful flow.

2.Viscosity – Resistance to the flow, viscosity is the stickiness of fluid. It is essential to ascertain that how viscous the fluid is. Pump size is determined, depending on the frictional losses and viscosity in the pipeline. For liquids above 5000 cps, using 1.5” or 2” size diaphragm pumps is good, depending on the head.

3. Pressure – Pressure conditions should be determined at the suction (Inlet) and discharge (outlet). It will help to choose the best suited diaphragm pump size. a. Suction Pressure: It is the pressure at the pump Inlet. Self-priming in nature, AODD pumps work on flooded suction as well as suction lift condition. It is essential to determine, if suction pressure is high, it may affect the pump performance.

b. Discharge Pressure: It is the necessity of head, for the pump discharge. It is also called delivery pressure. In other words, at what height the fluid has to be delivered. It also involves frictional losses in the pipeline.

4. Flow Rate – It is very essential to consider the flow rate. It helps select the right size of the diaphragm pump. One should choose the larger pump with larger port sizes, effective for higher flow rate. In other words, suction & discharge connection, and vice versa. It is measured in LPM / GPM, or m3/hr.

5.Temperature – There are temperature limitations for the pump materials. We must understand the operating temperature, and ambient conditions too. It helps ensure that diaphragm pump material is appropriate for a specific application. For instance, Santoprene diaphragms are restricted to, or less than 104.4°C.

6. Service – AODD Pumps are crucial for both, continuous and intermittent use. Perfect for Unloading and Transfer Purposes, the air-pumps are easy to operate. Also, they can be mounted on a mobile trolley, so as to be used at requisite place. There is exact availability of compressed air too.