Elasto Proxy supplies UL 94 HB EPDM gasket material in standard and custom extrusions. Whether you need coils, cut lengths, or finished gaskets, you can use this flame-resistant EPDM sponge rubber to solve sealing and insulation challenges for some of today’s fastest-growing applications. This material is UL Listed and has a UL Product iQ number.

UL 94 HB is a  flammability standard from Underwriters’ Laboratories (UL) for slow burning on a horizontal part. The material that Elasto Proxy supplies has a medium durometer and is black in color. Choose our standard extrusion, or request a custom profile. Keep reading to learn more, or contact us for a quote.  

UL 94 HB EPDM Gasket Applications

Applications for UL 94 HB EPDM gasket material include data centers, electric vehicle (EV) charging stations, solar panels, and plastic enclosures. Elasto Proxy can provide you with flame retardant rubber that you fabricate yourself, or we can supply custom gaskets that arrive ready-to-install.   

data centersData Centers

Data center operators need to prevent fires from spreading. Most fire suppression systems are water-based, and EPDM rubber offers excellent resistance to water, heat, and steam. Elasto Proxy’s UL 94 HB EPDM gasket material resists horizontal burning while providing dependable sealing for data centers.

Data Centers and UL 94 HB Flame Resistant Gaskets

ev charging stations

EV Charging Stations

The high-voltage electricity that’s transferred between charging stations and EV poses a risk of fire. For EV charging couplers, UL 94 HB is America’s flammability standard. It’s also a key flammability standard for the aesthetic component of EV charger cabinets. Elasto Proxy supplies solutions for both. 

EV Charging Stations and Rubber Products

solar panels

Solar Panels

Solar panels use gaskets to fill the gaps between solar cells. EPDM rubber resists sunlight, withstands tough weather conditions, and remains flexible in freezing temperatures. If a solar panel fire occurs, gaskets made from Elasto Proxy’s UL 94 HB EPDM sponge rubber can resist horizontal burning.

Solar Panels and Rubber Products

plastic enclosures

Plastic Enclosures

UL 94 HB gaskets are used in the plastic enclosures that house printed circuit boards (PCBs), electrical connectors, and DIN Rail mounted components for test equipment and medical and scientific instruments. Silicone may be required for some applications, but EPDM costs less and isn’t in short supply.

Rubber Gaskets for Plastic Enclosures

UL 94 HB EPDM Material Specifications

As listed on the UL Yellow Card, Elasto Proxy’s UL 94 HB EPDM sponge rubber (EP-60020-FR) has the following flammability, ISO/IEC flammability, and thermal properties. The values below are for a 5.7 mm sample that is black in color.



Test Method

Flammability Properties






ISO/IEC Flammability Properties


IEC 60695-11-10




Thermal Properties


Relative Thermal Index – Electrical Strength

50° C (122° F)

UL 746B

Relative Thermal Index – Mechanical Impact

50° C (122° F)

UL 746B

Relative Thermal Index – Mechanical Strength

50° C (122° F)

UL 746B

EC28-101 is Available: UL 94 HB EPDM Gasket Material (Standard Extrusions)

Elasto Proxy is ready to supply you with EC28-101, the medium-durometer, EPDM sponge rubber product that you see below. It’s reinforced with a spring steel clip, designed for 1/8” thick panels, and black in color.

EC28-101-EM UL 94 HB EPDM Gasket Material

Custom Extrusions for UL 94 HB Gasket Applications

We can also supply you with custom extrusions of this flame-retardant gasket material with or without the metal reinforcement. The minimum economic order quantity is 2500 ft., and it takes about eight weeks to make the die and sample. Once you approve the sample, production takes two weeks.

Ready to request a quote? Contact us to get started.

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