When is EPDM rubber the right choice for sealing and insulation? EPDM gaskets and seals are used extensively with vehicles and equipment. However, this synthetic elastomer has unsatisfactory resistance to diesel fuel, gasoline, and motor oil. On the other hand, the benefits of EPDM are numerous. Hence, this cost-effective compound is often a better choice than silicones, especially in outdoor environments.
If engineers are wondering whether EPDM is the right choice for their sealing and insulation applications, Elasto Proxy invites them to take a closer look at this M-class elastomer. The M in M-class denotes that EPDM is part of ASTM D1418, a common specification for characterizing rubber compounds. Usually, product or design engineers use ASTM specifications to designate the rubber material on a part drawing.
This article examines the applications and advantages of EPDM. The drawbacks of EPDM are also considered. In addition to these, the article considers how EPDM rubber compares to some other materials. To conclude, the article sheds light on how EPDM is fabricated and supplied.
Ethylene propylene diene monomer (EPDM) is a compound that resists sunlight, oxygen, ozone, water, aging, alkalis, acids, and severe weather conditions. This odor-free elastomer also provides high heat resistance and excellent color stability. Service temperatures can range from 70 °C to 250 °C depending on the compound’s chemistry. All EPDM rubber is not the same. Therefore, differences in ethylene content and the dienes that are used can affect physical properties.
EPDM rubber also provides elasticity and good-to-high tensile strength. Tensile strength is the resistance of a material to breaking under tension. It is typically measured in pounds per square inch (PSI). Typical EPDM values are in the 1000 PSI range. Elasticity is a measure of a material’s ability to regain its normal shape after being compressed or stretched. It is expressed as a percentage. Typical EPDM values are in the 300% range. Almost all EPDM rubber has a durometer (hardness) of 40 to 90 (Shore A).
With its strong combination of mechanical and thermal properties, EPDM is a great choice for the door and window seals that are used with mobile equipment. These rubber gaskets secure the mobile equipment against water, wind, mud, dust, and a range of outdoor temperatures. EPDM gaskets also provide a measure of acoustic insulation against equipment sounds and road noise. Additional vehicle applications include hood seals. EPDM’s elasticity and strength also make it an ideal choice for the vibration isolation mounts that are used with machinery.
Certified-transit grade (CTG) seals can be made from a special EPDM rubber. These seals can meet specific flame, smoke, and toxicity (FST) requirements. This is especially useful for bus, rail, and subway manufacturers. EPDM rubber is used for indoor applications where there is contact with saturated steam or hot and cold water. A few of the examples include freezer and refrigerator gaskets, rubber pipe sleeves, and dust boots. EPDM is also a good choice for HVAC gaskets because of its support for thermal expansion and contraction and its resistance to vibration.
The main drawback of EPDM is its unsatisfactory resistance to specific categories of chemicals. In addition to diesel fuel, motor oil, and gasoline, EPDM is not recommended for use with synthetic diester oils, which are lubricants found in certain types of industrial machinery. EPDM also provides unsatisfactory resistance to Freon. Freon is a category of fluorocarbons that are used as refrigerants. It is essential to check for chemical compatibility before selecting an EPDM compound.
EPDM is usually used instead of silicones, thermoplastic elastomers (TPEs), or nitrile elastomers. Silicones can weather higher and lower temperatures. However, they lack EPDM’s resistance to cutting, abrasion, and tearing. EPDM also provides better tensile strength than silicone rubber. Nitrile is a better choice than EPDM for applications that require resistance to greases, fuels, and oils. Engineers can choose TPEs for applications that need recyclable materials.
EPDM Rubber and Custom Fabrication
EPDM sheets and profiles aid custom fabrication through manufacturing methods such as lamination, gasket taping, water jet cutting, and parts marking. They are available in standard and special grades and can be supplied as sponge, solid, and foam materials. Examples of specialty materials include EPDM that meets UL 94, NSF, or FDA standards.
This information has been sourced, reviewed and adapted from materials provided by Elasto Proxy.
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