What is UL94?
UL 94 is a flame resistance rating standard developed by Underwriters Laboratories (UL) in the United States, used to classify the flammability of plastic and polymer materials. Although this standard was originally established for rigid plastics, it is now widely applied to elastomers, porous foams, and sponges, including many materials used in gaskets and sealing applications.
UL 94 testing helps engineers evaluate material ignition characteristics, burning rate, and self-extinguishing properties—key factors in applications where fire safety and reliability are critical. Common applications requiring materials to meet UL 94 ratings include:
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Electronic enclosures and electrical equipment
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Automotive interiors and components
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Aerospace applications
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Medical devices and equipment
UL certification enhances confidence in material selection and helps comply with industry safety requirements. Now, let’s take a deeper look at the actual testing methods within the UL 94 standard.
Flame Test Methods in UL 94
UL 94 includes six test configurations, each designed to measure flame resistance under different conditions. Each test has its own set of pass/fail criteria. The three most commonly conducted tests in gasket manufacturing and elastomer design are:
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Vertical Burning Test (V-0)
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Horizontal Burning Test (HB)
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Horizontal Burning Foam Test (HBF)
In most industrial sectors, the required flame resistance certification for materials is UL 94 V-0. Achieving this certification indicates that the material can self-extinguish in the event of a fire without propagating flames.