When safety and performance matter, flame-retardant silicone rubber gaskets play a vital role in protecting equipment and people from fire hazards.
In industries such as electrical, automotive, aerospace, and railways, fire performance testing ensures that silicone rubber products meet the highest safety standards.
Below are the five key fire performance parameters that determine how silicone rubber performs in demanding applications:
1. Burning Behaviour – EN ISO 4589-2 (Oxygen Index)
The Burning Behaviour test measures the minimum oxygen concentration needed to sustain combustion. Using EN ISO 4589-2, the Oxygen Index (%) is determined by exposing the sample to a controlled oxygen–nitrogen atmosphere. A higher oxygen index means the material is more flame-resistant. Silicone rubber typically shows excellent results, making it ideal for applications where fire safety is critical.
2. Smoke Generation – EN ISO 5659-2 (Ds Max)
During a fire, smoke can be more dangerous than flames. The Smoke Generation test (25 kW/m² radiant heat) measures Ds Max – the maximum smoke density produced. This parameter is dimensionless but critical for visibility and evacuation safety. Flame-retardant silicone rubber produces significantly lower smoke compared to many organic polymers, improving safety in enclosed environments such as trains, aircraft, and control rooms.
3. Toxicity – NFX 70-100-1 & -2 (CITNLP)
Toxic gases from burning materials can be lethal. The Toxicity Test evaluates CITNLP (Conventional Index of Toxicity for Non-Lethal Products) by burning the sample at 600°C and analyzing gases such as CO, HCN, NOx, and others. Silicone rubber has inherently low toxicity levels, making it suitable for public transportation, defence, and medical equipment where human exposure risk must be minimized.
4. Maximum Average Rate of Heat Emission – ISO 5660-1 (MARHE)
The MARHE test conducted in a cone calorimeter measures the maximum average rate of heat release (kW/m²) during combustion. Lower MARHE values indicate slower fire growth and reduced energy output, giving more time for evacuation and fire control. Silicone’s thermal stability helps achieve low MARHE results, reducing the risk of rapid flame spread.
5. Gross Heat of Combustion – ISO 1716 (MJ/kg)
Also known as the Calorific Value, this test determines the total energy released when the material is completely burned. Conducted in an oxygen bomb calorimeter, it provides a value in MJ/kg. Lower values are preferable for flame-retardant applications, as they indicate less total heat available for fire propagation.
Why Choose Flame-Retardant Silicone Rubber Gaskets?
By excelling in burning behavior, smoke generation, toxicity, MARHE, and gross heat of combustion, silicone rubber ensures maximum fire safety performance. At Centroid Polymer Technologies, we design custom silicone rubber gaskets that meet global safety standards for industries ranging from railways to renewable energy.