EN 45545-3: Fire Resistance of Barriers & Partitions (E, I, and W Ratings)
EN 45545-3 defines the fire resistance requirements for barriers and partitions in railway vehicles. This guide explains the “Containment” classifications: Integrity (E) to stop flames and Insulation (I) to block heat transfer. It also covers the specific testing protocols for Arc Barriers used to contain high-voltage electrical faults.
EN 45545-3 specifies the fire resistance requirements for barriers and partitions in railway vehicles. Unlike Part 2, which tests small material samples, Part 3 tests the Complete Assembly (e.g., a full door system with hinges and seals, or a floor structure).
The goal is “Containment”: ensuring that fire and smoke generated in one area (e.g., an underframe diesel engine or an electrical cabinet) do not penetrate into the passenger or staff areas for a specific duration, typically 15 to 60 minutes.
1. Classification Codes: E, I, and W
A fire barrier is graded based on three performance criteria under standard furnace testing (ISO 834 curve):
- E (Integrity): The barrier prevents the passage of flames or hot gases. The fire stays on one side; no holes appear.
- I (Insulation): The barrier stops heat transfer. The “cold side” (unexposed face) must not get hot enough to ignite materials (Temperature rise restricted to ΔT 140°C average).
- W (Radiation): Used mainly for large glass areas, ensuring that the thermal radiation passing through does not exceed specific kW/m² limits preventing auto-ignition of nearby objects.
2. Typical Barrier Requirements
The required resistance time depends on the vehicle’s Operation Category (Tunnel length) and the location of the barrier. A sleeper train requires stronger barriers than a tram.Barrier Location Typical Requirement Operational Goal Cross-Partition (Coach to Coach) E 15 / I 15 Stops fire spreading between cars for 15 minutes to allow evacuation. Floor Structure E 30 / I 30 (often higher) Prevents an underframe fire (track/bogie) from burning through the floor into the cabin. Driver’s Cab Rear Wall E 30 / I 30 Protects the driver (or passengers) if a fire starts in the cab/saloon. Electrical Cabinet (Arc Barrier) E 15 (Special Arc Test) Contains the explosive energy of an electrical arc fault.
3. Arc Barriers vs. Fire Barriers
EN 45545-3 has a unique section for Arc Barriers. An electrical short circuit creates a plasma explosion (Arc Blast) distinct from a standard wood/paper fire. Electrical cabinet doors are tested to withstand:
- Mechanical Shock: The pressure wave of the arc.
- Molten Metal: Copper/Aluminum splatter from melting busbars.
- Duration: Usually a very short but intense period followed by a standard fire resistance requirement.
4. Testing Methodology
To achieve an “E30” rating, the full-size component is mounted in a test furnace. The furnace temperature follows a standard time-temperature curve (reaching approx 842°C at 30 mins). If a cotton pad held against the unexposed side ignites, or if a gap gauge can pass through the door seal, the test is a failure.
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