When buying elastomeric material to seal a joint many people go straight for neoprene gaskets. Neoprene works well in many applications, but there are cases where other materials will perform better. One such material that should be considered for outdoor use, or situations where abrasive wear is possible, is EPDM.
EPDM is rubber-like in appearance and properties, so good compressibility and recovery is a hallmark of EPDM gasket material. Like all gasket materials though, it has strengths and weaknesses. This overview should help prospective buyers decide whether to consider EPDM gaskets.
Chemistry and properties
EPDM is an acronym for ethylene-propylene diene monomer. Ethylene and propylene are hydrocarbons and gases at room temperature, yet combine to make solid polymers like polyethylene and polypropylene. By adjusting the proportions and controlling the polymerization process it’s possible to create long molecular chains with more rubbery properties. That’s EPDM.
Sometimes referred to just as EPM, EPDM is a very stable material that resists heat, oxidation, and the aging effects of ultraviolet light. Unlike many other elastomers it’s flexible at low temperatures, and depending on how it’s formulated, works over a range of -60°F to 300°F.
EPDM has good mechanical properties too. Tensile strength is in the range of 7 to 21 Mpa, which is higher than other elastomers like silicone (5 – 10 MPa), nitrile (12 – 15 MPa) and neoprene (5 – 8 MPa). It’s also resistant to abrasive wear, which can’t be said for silicone.
In terms of chemical resistance, EPDM holds up well to acids and alkalies and is a good choice when dealing with both brake fluids and ketones. It also has good resistance to steam. Where it fares less well is against hydrocarbon oils and petroleum products as these produce swelling.
EPDM gasket applications
Relatively immune to sunlight, water and low temperatures, EPDM is often a smart choice for gaskets that will be outside. Good compression set resistance means it recovers well in applications where a joint may open up from time to time, and high electrical resistance means EPDM gaskets may be appropriate for some electrical installations.
A silicone competitor
In the gasket world silicone is known as a high performance material with a wide temperature range and good flexibility. In many applications though, an EPDM gasket could be a more cost-effective choice. Its temperature range is almost as wide and it’s a stronger, more durable material.
Consult the materials specialists
EPDM is available in a wide range of formulations with properties that vary considerably. To get a better understanding of EPDM gasket material options for your application a discussion with the specialists at Hennig Gasket & Seals Inc. is recommended. Contact us today.