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As safety standards become more stringent and engineers and product designers look for more durable and versatile components, flame retardant materials have become more popular. A common standard for polymers is the UL94 burn rating. The purpose of that is to qualify how a material handles open flame and in what manner it does or does not burn. provides a brief overview of those ratings.

While the UL94 rating speaks specifically about “plastics,” the same concepts are often applied to rubber parts. The key concepts to remember are that some materials will burn easily and melt, which will spread flames all over the product surrounding the affected part. Other materials may burn, but will not drip or melt, so they are less likely to spread the flames. The best materials will self-extinguish, and that can help tremendously when a worst-case scenario occurs. Functionally, this means a flexible plastic or rubber material can only hold a flame when a flame is actively applied to it. The minute a heat source is removed, the product will stop burning. Often times the only thing flammable inside a product is the rubber and plastic material, so if some or all can be converted to flame retardant rubber then the risk of catastrophic burning inside a product can be drastically reduced.

There are specific EPDM rubber blends that are available with flame retardant properties. Some Nitrile and Neoprene options also exist, but are far more expensive in most cases. The EPDM products offer excellent weathering and aging properties, very good operating temperature ranges, and can also self-extinguish. These advantages can often outweigh the small additional cost of the material in durable goods like appliances, heavy equipment, production machinery, vehicles, medical device, or breathing safety applications.

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