UL Classifications

UL Classifications

UL Classifications for Fire Standards

UL Classifications are referenced across a multitude of industries. But what are they?

Underwriters Laboratories (UL) is an organisation which tests and certifies the safety of products; items with a UL mark provide reassurance to manufacturers and consumers that products have been thoroughly tested and are safe for use.

With silicone we talk about fire safety performance using the UL94 classification scale. It is important to note that there are two different UL categories which indicate separate levels of testing, UL-Listed and UL-Classified. Items that are UL-Listed pass all of the UL’s requirements and can be widely used under these standards. Materials that are UL-Classified have only been approved for specific conditions and properties.

Furthermore, some products will state they have been tested but are not listed. For example, our MF775 sheeting has been independently tested to the UL94 criteria, it passed the tests for the UL94V0 at 3mm thick but is not Listed or Classified by UL.

UL94 tests look at the flammability standard of materials and how flames spread amongst them. Tests are carried out by burning a specimen at a horizontal or vertical angle – a flame is applied to one end of the specimen for a set amount of time, and how fast and far the flame spreads is recorded. The results of this test determine the UL94 Classification of the material.


Due to its quick extinguish time and limited debris, UL94 V0 is considered the greatest flame-retardant grade and is the best a material can be awarded.

It is important to understand if you require a listed material, or indeed if you can accept something formulated to meet the criteria. Other considerations when starting your project will be any adhesives that may be in use and if they are required to meet any UL standards too.

Products tested by UL are listed in the UL Prospector database which can be accessed to check the certification of your material – known as the UL Yellow Card Scheme. At Silex, we keep stock of a huge number of UL-Listed products as well as offering bespoke items to meet these criteria. Products such as our R401 extrusions and SIL 16 sheeting are HB Listed, whereas Rogers materials BF1000, BF2000 and HT800 are V0 Listed. We can offer conversion of these materials into your gasket requirements, as well as offering extruded items and joining of materials.

Other accreditations related to fire safety include EN45545-2 for the rail industry which is met with the MF775, FR8775 and Wacker R770/50 grades. If you have any questions regarding these specifications, please feel free to contact us by email or by phone. Our experienced team are happy to assist with all your technical requirements.

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