What material selections for a Diffuser Membrane are best for a specific application? Diffuser membranes, including the ones used in DDI SuperFlex Aeration Diffusers, can come in a variety of polymer types. It is one of the most important decisions to make for proper operating efficiency in your application and increasing the life-span of your aeration Diffuser. Below, we list and describe typical polymer types, with their physical characteristics and in what applications they are most used.
EPDM
Ethylene Propylene Diene Monomer (EPDM) is typically employed successfully in most municipal and many industrial applications. EPDM has a history in the wastewater treatment industry of providing excellent physical characteristics, including weathering and aging, ozone resistance.
EPDM is non-polar which provides very good resistance to polar materials such as water, ketones and alcohols. EPDM has excellent heat age properties and is effective in temperatures as low as of -76°F (-60°C) and up to 240°F (170°C) (depending on the cure system). EPDM is not flame resistant and has poor performance in the presence of aliphatic or aromatic hydrocarbon oils.
Polyurethane (PU)
Polyurethanes are made up of either a polyether or a polyester backbone. The polyether types, alone, are used in wastewater applications. Polyurethanes are typically used in applications where EPDM would be an inappropriate choice, such as the presence of hydrocarbon oils and aromatic solvents. Industrial wastes such as some pulp and paper applications, food processing applications, etc. are often good applications for the use of PU.
Industrial wastes (some Pulp & Paper applications, food processing applications, etc.) are often good applications for the use of PU. The temperature range is typically -50°F to 160°F (-45°C to 70°C). Concentrated acids, ketones, esters, etc. can attack and damage PU. High Temperature PU is available for applications up to 180°F (80°C).
Silicone
Silicone is significantly different from other polymers in which the normal carbon-carbon bonds are replaced with carbon-silicone-oxygen bonds. This chemistry makes it very resistant to heat, ozone, electrical current and some chemicals (strong bases). Its surface chemistry offers excellent release characteristics.
Silicone would be used in high temperature applications or with specific chemical compatibilities. It is susceptible to degradation by solvents, oils and concentrated acids. The major advantage of silicone is the very high heat resistance; its temperature range is -85°F to 390°F (-65°C to 315°C). If high temp may be of limited value as piping systems have the critical design temp of approx 150°F to 180°F (60°C to 82°C) temperature limited.
Neoprene
Neoprene is a chlorinated butadiene polymer. It is very resistant to ozone, acids, fats, greases and aliphatic oils. Neoprene is susceptible to degradation by strong acids and ketones as well as aromatic and nitrogen containing hydrocarbons. It would generally be used in petrochemical, meat processing or oily/greasy wastes. The temperature range for Neoprene is -40°F to 250°F (-40°C to 120°C).
Diffuser Membrane Materials Selection Table
| POLYMER | LOW TEMP | HIGH TEMP | RESISTANT TO | ATTACKED BY |
| EPDM | -60°C | 115°C | Heat, Oxygen, Ozone,Animal and Vegetable Fats | Solvents, Aromatic Hydrocarbons |
| Polyurethanes | -45°C | 70°C | Oils, Solvents. High abrasion Resistance | Acids, Ketones, Esters |
| Silicone | -65°C | 200°C | Heat, Ozone, Oxygen, Concentrated Bases | Solvents, Oils, Acids |
| Neoprene | -40°C | 120°C | Ozone, Acids, Fats, Greases | Acids, Ketones, Aromatic Hydrocarbons |
Take your time making a decision on diffuser membrane materials selection. Carefully selecting the correct material will assure successful operational efficiency of your diffuser in your application.
Consider speaking with a representative from Dorian Drake International on all the available diffuser membrane materials.
Dorian Drake International presents it’s DDI SuperFlex line of aeration diffusers, membrane diffusers, and specialty diffusers for new and existing municipal and industrial aeration applications. Our goal is to supply quality products and service at competitive pricing. Our diffusers service all major brands.