Factors To Be Considered While Selecting Diaphragm Pump

Selection of the right diaphragm for an air operated double diaphragm pump is a critical consideration for safety, efficiency operations. A number of factors must be taken into account when choosing the proper diaphragm that will be suitable/capable for a specific application.

Previous experience is always a very helpful guide, but new applications will often require research & outside advice to determine the appropriate diaphragm pump that will meet specific application requirements and parameters.

Fluid – One of the most important factors that needs to be taken into consideration is the Type, Composition & Nature of the fluid in order to avoid corrosion of wetted parts & also to prevent the wear of the pump. It is also necessary to determine - What’s the chemical composition of the fluid? What’s the consistency? Is it a slurry (thick suspension of solids in liquids), or is it a clean fluid?

A peristaltic pump or hose pump is a type of positive displacement pump used in various industrial applications for pumping variety of fluids. The fluid is contained within a flexible tube (i.e. Hose) fitted inside the pump casing having no contact with any other part of the industrial hose pump.

1. Nature of fluid:

Corrosive fluids: Destructive liquids like sulfuric corrosive, Nitric corrosive, Sodium hydroxide and so on for the most part wrecks and harms the material when comes in contact. So a cautious determination for the wetted part and stomach is required.

Abrasive Fluids: Abrasive fluids like paints, inks, ceramic slurry and so on. which occupy solid particles that can damage the contact material by scraping or wearing. For example, for paints we used PTFE Diaphragm & SS316 as the wetted material.

Toxic Fluids: Toxic fluids like lead, mercury and so on. has the quality of being toxic and poisonous. Diaphragm pumps are seals-less & have leak free design hence they are suitable for such liquids.

Flammable Fluids: Flammable chemicals like acetone, benzene, petroleum etc. that simply catches fire. Therefore AODD pump are used as they are air driven & intrinsically safe. However, some liquids may generate a static charge, so pump should be completely grounded. We recommend using Antlia Pumps for such applications.

Shear Sensitive Liquids: Liquids like tomato ketchup, emulsions, curd, paste so on when subjected to shear (or churning) can change the product characteristics. few liquids are shear thinning, some are shear thickening. Since Diaphragm pump run at slower speed, they are ideal for such liquids. We recommend running the pump at a slower speed than normal for such applications.

Vapour Pressure: Liquids such as diesel, hydrocarbons have low vapour pressure. We need to ensure that such pumps run at low speed & also the suction lift is limited, otherwise the AODD pump may not be able to deliver required flow.

2. Viscosity – Viscosity is resistance to the flow. We can say in other way it the stickiness of the fluid. It is important to determine how viscous the liquid is. Depending on the viscosity & frictional losses in the pipeline pump size needs to be determined.

For example, it is better to use 1.5” or 2” size diaphragm pumps for liquids above 5000 cps depending on the head.

3. Pressure: determining the pressure conditions at the suction (Inlet) & discharge (outlet) will help to select the appropriate double diaphragm pump size.

Suction Pressure: Simply it is the pressure at the Inlet of the pump. AODD pump can work on both flooded suction as well as suction lift conditions as they are self-priming. It is also important to determine if high suction pressure is there, as it may hamper the lifting of the suction valves affecting pump performance.

Discharge Pressure: It is the head requirement at the discharge of the pump. It is also known as delivery pressure i.e. at what height the fluid/liquid has to be delivered along with frictional losses in the pipeline.

4. Flow Rate – To select the size of the diaphragm pump, the flow rate is considered at first. For higher flow rate one can select the larger pump with larger port sizes i.e. Suction & Discharge connection & vice versa. It can be measured in LPM or GPM or m3/hr.

5. Temperature – Pump materials have temperature limitations. We must know the operating temperature as well as ambient conditions to ensure that diaphragm pump material is best suited for a particular application. For example, Santoprene diaphragms are limited to or less than 104.4°C.

6. Cost Effective Aodd Pump: Antlia Engineering Works is one of the leading manufactures peristaltic pump and AODD pumps in Middle East, Africa, Australia & India. One can choose pumps that best suits their needs.