Fire safety is a fundamental requirement in the rail and mass transit industry. Materials used within rolling stock must deliver reliable mechanical performance whilst also meeting strict fire protection standards designed to safeguard passengers, crew and infrastructure.
One of the most important of these standards is EN45545. Understanding how this standard works, and how different hazard levels apply, is essential for making correct & compliant material selections.
What is EN45545?
EN45545 is the European standard for the fire protection of railway vehicles. It was developed to harmonise fire safety requirements across Europe and evaluates how materials behave under fire conditions.
The standard considers key performance factors including:
- Flame spread and ignition behaviour
- Heat release
- Smoke density
- Smoke toxicity
EN45545 applies to materials used in interior and exterior applications and considers not only the material itself, but also where and how it is used within the vehicle.
Rather than using a single pass/fail criterion, EN45545 defines Requirement Sets (R) and Hazard Levels (HL) to determine suitability.
Understanding Hazard Levels: HL1, HL2 and HL3
Hazard Levels reflect the severity of fire performance required for a given application. The level specified depends on factors such as passenger density, vehicle type, operating environment and system level fire protection measures.
- HL1 – Lowest hazard level
Typically used in low risk applications or areas with limited fire load, minimal passenger exposure or significant separation from occupied spaces. - HL2 – Medium hazard level
Widely specified across rolling stock and often the most used hazard level for sealing and gasket materials. - HL3 – Highest hazard level
Reserved for high risk, high occupancy or escape-critical areas where the most stringent fire performance is required.
Importantly, HL3 is not required everywhere. Modern rolling stock is designed using a mix of hazard levels, ensuring materials are matched to their specific application rather than over specified.
HL1 vs HL2 vs HL3: Applying the Right Level
Correct specification is about understanding risk and location, not simply choosing the highest classification.
- HL1 may be suitable where fire risk is very low, such as isolated, enclosed or non-passenger facing areas.
- HL2 is intentionally specified for many sealing and gasket applications where fire risk is controlled through enclosure, material volume or system design.
- HL3 is essential in escape routes, areas with high passenger density or locations where ignition risk and exposure are greatest.
Using the appropriate hazard level helps OEMs and operators achieve compliance while managing weight, cost and material performance over the vehicle lifecycle.
| Hazard Level | Risk Level | Typical Location Characteristics | Common Use Cases |
| HL1 | Low | Areas with very low fire load, minimal passenger exposure, or significant separation from occupied spaces | Isolated or enclosed technical areas, low risk external or auxiliary components |
| HL2 | Medium | Enclosed or semi-enclosed areas where fire risk is mitigated by design, housing, or limited material volume | Door seals, equipment enclosures, HVAC seals, lighting gaskets, panel seals, non escape-critical glazing |
| HL3 | High | Areas with high passenger density, direct passenger exposure, or escape-critical function | Passenger saloons, escape routes, high risk interior zones |
Suitable Rail Applications for Silicone Sponge Materials
Silicone sponge rubber is widely used in rail applications due to its combination of fire performance, environmental resistance and durability.
Depending on hazard level and location, silicone sponge materials are commonly specified for:
- Interior and vestibule door seals
- Electrical and control cabinet gaskets
- HVAC ducting and enclosure seals
- Lighting and control panel gaskets
- Panel-to-panel seals and gap fillers
- Window and glazing seals (non escape-critical zones)
- Exterior and underframe seals where resistance to moisture, dust and weathering is critical
In these applications, silicone sponge offers:
- Excellent compression recovery
- Resistance to UV, ozone and weathering
- Stable performance across wide temperature ranges
- Long service life with minimal maintenance
PREMSIL RG250: A Robust HL2 Silicone Sponge Solution
PREMSIL RG250 is our medium density, closed cell silicone sponge developed specifically for the rail and mass transit industry.
Manufactured in accordance with EN45545-2 R22/R23, RG250 achieves HL2 performance, making it suitable for a wide range of interior and exterior sealing applications where balanced fire performance and durability are required.
Key performance characteristics include:
- Flame retardant, halogen free formulation
- Low smoke density and low smoke toxicity
- Reliable temperature performance from -50°C to +200°C
- Low compression set for long term sealing integrity
- Excellent resistance to UV, ozone, weathering and moisture ingress
- Lightweight, closed-cell structure with a smooth outer skin
What PREMSIL Offers Rail OEMs and Maintenance Providers
At PREMSIL we understand that compliance alone is not enough. OEMs and maintenance providers also need consistency, availability and technical support throughout the life of a rail platform.
We supply RG250 in a wide range of formats, including:
- Sections & bespoke profiles
- Sheets
- Cords
- Tubes
- Gaskets
- O-rings
Self adhesive backing options are also available to support efficient installation and maintenance operations.
With full in-house manufacturing control, PREMSIL delivers repeatable quality, reliable lead times and responsive technical support, whether for new build OEM programs, refurbishment projects or ongoing maintenance.
Honest Specification for Long Term Performance
Effective fire protection in rail vehicles is achieved through correct specification, not blanket use of the highest hazard level.
By offering a proven HL2 silicone sponge solution, alongside clear guidance on hazard level selection, PREMSIL supports engineers and specifiers in making informed, compliant and practical material choices that perform throughout the asset lifecycle.
For technical advice or application support, our team is always available to help.