Full definition
Fire-resistant belts are specially designed conveyor belts that are engineered to minimize the risk of fire in environments where flammable materials are present. These belts are self-extinguishing, meaning that once the external flame source is removed, the belt will not continue to burn or propagate flames. This characteristic is crucial in applications like underground mining, where the risk of a fire can have catastrophic consequences. The design of these belts incorporates various flame-retardant compounds, such as chloroprene (CR) and PVC, which help to reduce the likelihood of ignition. Chloroprene is particularly favored due to its inherent flame-retardant properties linked to its chlorine content. PVC is commonly used in lighter-duty applications due to its cost-effectiveness and adequate fire resistance for less hazardous environments.
To ensure that fire-resistant belts meet stringent safety standards, several international norms govern their production and testing. For example, ISO 340 specifies that belts must self-extinguish within a defined distance after being exposed to flame, while ISO 284 mandates that the surface resistance of these belts must be ≤300 MΩ to prevent static electricity buildup, which can ignite flammable dust or gases. EN 12882 outlines categories for fire-resistant materials, ensuring that belts can be classified based on their specific applications and environments. Additionally, DIN 22109 is the standard for approval within the German mining industry, and compliance with MSHA regulations is required in the United States, ensuring that these belts are safe for use in sensitive environments.
Fire-resistant belts also incorporate specific flame retardant additives during manufacturing. Common additives include alumina trihydrate (ATH), which acts as a fire retardant by releasing water vapor when heated, and antimony trioxide, which enhances the effectiveness of halogen-based flame retardants. The design often features a carcass made of EP (ethylene-propylene) with a flame-retardant skim. In high-tension applications, such as long underground conveyor systems, steel cord versions are available to provide additional strength and durability. Testing of these belts involves rigorous procedures, including drum friction tests that simulate the conditions of belt slip on a locked drum and propane burner tests to assess their fire resistance under direct flame exposure. Overall, fire-resistant belts are integral to maintaining safety in environments where flammable materials are present, making them essential in industries like coal mining, potash extraction, and wood processing.