UL’s certification program for gaskets and seals covers test procedures and performance criteria for the evaluation of nonmetallic gasket and seal materials such as elastomers, composite gasket material, flexible cellular material, thermoplastics and thermoplastic elastomers for use as components and parts of end products. The general use of these materials is to exclude or hold within an enclosure liquids, gases, or vapors.
The final acceptance of a gasket or seal in a particular UL certified end-product is determined by UL, with reference to the specific end -use requirements and the design of the device in which the gasket or seal is used. Most UL certified gasket and seal materials are intended only for factory installation in complete equipment, where traceability of the material can be verified by UL inspection.
Gasket and seal materials that meet UL’s requirements are certified as UL Recognized Components and are published in UL’s Online Certifications Directory. This enables users of UL Certified Components to achieve UL Certification for an end-product or device with less testing.
The basic standard that covers the test methods used to investigate elastomeric gaskets and seals is ANSI/UL 157, the Standard for Safety of Gaskets and Seals.
Many UL Standards require gaskets used to seal enclosure openings to comply with UL 50E, the Standard for Safety of Enclosures for Electrical Equipment, Environmental Considerations. The certification of gaskets for compliance with UL 50E enables gasket suppliers to provide end-product manufacturers with gaskets certified for periodic recompression as well as continuous compression applications.