EN 45545-3: European Rail Fire Barrier Specs Revealed

Understanding EN 45545-3: Fire Resistance Requirements for Fire Barriers in Railway Vehicles

EN 45545-3 is a critical part of the European standard for fire protection on railway vehicles. Its primary purpose is to define the fire resistance requirements for fire barriers and partitions. Unlike EN 45545-2, which deals with the reaction to fire of individual materials, this part focuses on the ability of a complete assembly (like a wall, floor, or door) to contain a fire and prevent it from spreading to adjacent areas for a specified period.

The fundamental goal of EN 45545-3 is to ensure structural integrity and thermal insulation during a fire event, thereby maintaining safe evacuation routes for passengers and crew and protecting critical equipment. The requirements are essential for compartmentalizing a fire, limiting its growth, and providing valuable time for emergency procedures.

Key Fire Resistance Criteria

EN 45545-3 evaluates fire barriers based on three primary performance criteria. These criteria are measured during a standardized fire test where one side of the barrier is exposed to a controlled fire that follows a specific time-temperature curve.

• Integrity (E): This criterion measures the ability of the barrier to prevent the passage of flames and hot gases. A barrier fails the integrity test if cracks or openings appear through which fire can spread, or if sustained flaming occurs on the unexposed side.
• Insulation (I): This criterion measures the ability of the barrier to prevent an excessive temperature rise on the unexposed (non-fire) side. The goal is to prevent the ignition of materials adjacent to the barrier and to ensure the surface remains safe enough not to harm evacuating passengers. A failure occurs if the average temperature on the unexposed face rises by more than 140 °C above the initial temperature, or if the temperature at any single point rises by more than 180 °C.
• Radiation (W): This is an alternative, less stringent criterion than Insulation. It measures the amount of heat radiated from the unexposed surface of the barrier. It is used in situations where limiting heat transfer is important, but full insulation is not required. A failure occurs if the measured heat radiation exceeds a limit of 15 kW/m² at a specified distance.

Fire Resistance Classifications and Applications

The standard uses a classification system that combines the criteria (E, I, W) with a time duration in minutes. For example, a classification of ‘EI 30’ means the barrier must maintain both Integrity and Insulation for a minimum of 30 minutes when exposed to the standard fire test. The required classification depends on the location of the barrier and the operational and design category of the railway vehicle as defined in EN 45545-1.

Below is a table illustrating common classifications and their typical applications within rolling stock.

Technical Testing Procedures

To achieve a specific fire resistance classification, a full-scale sample of the fire barrier assembly must be subjected to a rigorous test in accordance with test methods like EN 1363-1. The test involves several key steps:

• Sample Construction: The test specimen must be constructed exactly as it would be in the final railway vehicle, including all joints, fixtures, and penetrations.
• Furnace Exposure: The sample is mounted to a test furnace, and one side is exposed to a fire that follows the standard ISO 834-1 time-temperature curve.
• Data Measurement: During the test, thermocouples continuously monitor the temperature on the unexposed face to assess the Insulation (I) criterion. The Integrity (E) criterion is assessed visually by looking for cracks and by using a cotton pad to check for the passage of hot gases that could cause ignition. Radiation (W) is measured using radiometers.
• Classification: The barrier is classified based on the time it successfully meets the required E, I, and/or W criteria without failure.

Relationship with Other Parts of EN 45545

EN 45545-3 is not a standalone document; it functions as part of an integrated set of standards to create a comprehensive fire safety strategy.

• EN 45545-1 (General): This part defines the vehicle Operation Categories (OC1 to OC4) and Design Categories (A, B, D, S). These categories determine the overall level of fire risk and, consequently, the fire resistance time required for barriers under EN 45545-3.
• EN 45545-2 (Materials): While Part 2 specifies the fire performance (flammability, smoke, toxicity) of individual materials used to build a barrier, Part 3 specifies the fire resistance performance of the entire assembled barrier system. A barrier built from materials compliant with Part 2 must still be tested as a complete assembly to prove its performance under Part 3.

Conclusion: A Pillar of Railway Fire Safety

EN 45545-3 provides a robust, performance-based framework for ensuring fire containment on railway vehicles. By defining clear requirements for Integrity, Insulation, and Radiation, the standard ensures that fire barriers can effectively prevent fire spread, protecting evacuation routes and critical systems. Its integration with other parts of the EN 45545 series creates a multi-layered defence system that is fundamental to modern railway passenger safety.