When it is time to choose or replace the diaphragm on an air-operated double diaphragm pump, there are a number of factors to take into consideration. You will want a diaphragm that performs the best in your specific application, whether you are pumping wastewater or highly aggressive chemicals, while also seeking a cost-effective solution. Here, we offer some guidelines on choosing the right diaphragm for your AODD pump to ensure safe, efficient operations.
You will need to consider the diaphragm’s compatibility with the fluid being pumped and the temperature of the application. This will depend on whether you are pumping water, aggressive acids, chemicals or caustics, or highly abrasive materials. Extreme temperatures, hot or cold, will also have a bearing on the material of the diaphragm. Consult chemical compatibility guides and seek expert advice to ensure you make the right choice.
The materials used in diaphragms can be broadly placed into three main groups: rubber, TPE, and PTFE.
Rubber diaphragms are widely used in applications requiring flexibility and moderate chemical resistance. They are particularly suited for pumping fuels, oils, and water-based fluids. Here are the available rubber diaphragm and their chemical resistance/applications.
TPE diaphragms are a versatile choice for many industrial applications. These materials combine the flexibility of rubber with enhanced resistance to chemicals and abrasion. TPE diaphragms are ideal for applications involving abrasive slurries, caustic solutions, or general-purpose pumping. Here is a summary of their chemical resistance/applications.
Also known as Teflon®, polytetrafluoroethylene (PTFE) is one of the most chemically inert compounds available. PTFE has excellent flex life and good abrasion resistance. As well as water and wastewater, it is suitable for applications involving ketones and aldehydes, acetates, aromatic hydrocarbons, chlorinated hydrocarbons, oil and gas, with temperature operating limits of 4ºC to 104ºC. A back up diaphragm is needed with a PTFE diaphragm because it is inflexible.
Diaphragms are the heart of AODD pumps, and their material composition must align with the specific thermal demands of your application. This is key to avoid premature failure and costly downtime during your pump’s lifetime. Below is a summary of the temperature ranges for each type of diaphragm.
The above is a basic summary of diaphragm materials. Keep in mind that different materials will provide different levels of resistance to abrasion. Consider how much wear and friction will occur from being in contact with solids and particles in the fluid being pumped when choosing the right diaphragm. An Allied Pumps technician can help you with the selection, but here is also a summary of the abrasion resistance for each type of diaphragm.
In addition, different materials will have a varying flex life. This will determine how long the diaphragm can stay in place before a replacement is needed or repairs are required, which will have implications on ongoing maintenance costs. Below is a general guide on the flex life of each type of diaphragm.
When choosing the right diaphragm for an AODD pump, talk to a technician at Allied Pumps about 1) the capacity of the equipment to pump the required distance 2) the hardware configuration of the pump and 3) whether it is intermittent or continuous pump operation.
We take into account diaphragm material, temperature limits, abrasion resistance, chemical compatibility and flex life and can advise you on the best diaphragm material for your application according to your budget and specific requirements.
Allied Pumps is the sole authorised Wilden pump distributor for Western Australia. We stock a wide range of AODD pumps, including spare parts like diaphragms. Moreover, our expert technicians can provide expert advice in selecting the best pump for your needs. Explore our Wilden range today, and don’t hesitate to contact us for any questions you may have.
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