The most debated property of composite material is its combustibility. A standard polyester laminate is an organic polymer and will burn if given enough heat. Yet composite panels are used extensively today in metros, trams, passenger ships and aircraft.
There is no contradiction here — because the question is not whether the material burns, but how it behaves while burning. Only an accredited laboratory test can answer that.
What Actually Kills in a Fire
Every fire safety standard is built on one fact: in enclosed-space fires, most deaths are caused not by flame but by smoke inhalation and toxic gas.
In a metro tunnel, a train carriage or the corridor of a passenger ship, evacuation time is measured in minutes. Three things govern those minutes:
- Heat release: how quickly does the material give up energy? This sets the rate at which the fire spreads.
- Smoke density: can people still see the exit signs? Visibility directly determines evacuation time.
- Toxicity: what proportion of CO, HCN, HCl, HF, SO₂ and NOx appears in the combustion products?
Without measuring these three, a claim that a material is "non-combustible" means nothing.
What a Certificate Actually Measures
| Test method | What it measures | Key parameter |
|---|---|---|
| TS ISO 5660-1 (cone calorimeter) | Heat release rate, mass loss | MARHE (kW/m²) |
| TS EN ISO 5659-2 (single chamber) | Smoke optical density | Ds(4), VOF₄ |
| TS ISO 5658-2 (lateral spread) | Flame spread behaviour | CFE (kW/m²) |
| EN 45545-2 Annex C (FTIR) | Gas toxicity | CITG (conventional toxicity index) |
MARHE (Maximum Average Rate of Heat Emission) indicates the material's capacity to feed a fire — lower is better. Ds(4) is the smoke optical density at four minutes. CITG is the weighted sum of toxic gases released and must stay below 1.
The Certificate Belongs to the Layer Package, Not the Material
This is the most common mistake in the field. Fire performance is a property of the laminate as a whole, not of its individual constituents. A certificate covers all of:
- Resin type and brand
- Gelcoat type and consumption per m²
- Fibre type, weight and number of plies
- Total thickness and mass per unit area
- Paint and primer system, if any
- Core material, if any
Change any one of these — switch to another brand of "equivalent" gelcoat, for example — and the certificate no longer applies to that part. This is why certified production cannot be sustained without ISO 9001 recipe control.
The Real Cost of Uncertified Material
- Disqualification: in rail and marine tenders, certification is not a preference but a precondition. A supplier without it cannot even bid.
- Rejection on site: if the part is rejected after manufacture, the cost falls entirely on the producer.
- Legal and criminal liability: in a fire incident, the use of uncertified material creates direct liability.
- Insurance: insurers look for material conformity in the claim file.
- Reputation: a single incident in public transport affects every firm in the supply chain.
How Fire Performance Is Achieved
Composite fire behaviour is a design output, managed by formulation:
- Flame retardant resin: phosphorus- or halogen-modified unsaturated polyester, or phenolic resin.
- ATH filler: aluminium trihydrate releases its chemically bound water when heated, cooling the environment and diluting flammable gases. It is the most widespread and effective tool in composite fire performance.
- Fire gelcoat: the surface is decisive in the flame spread test.
- Flame retardant paint and primer: an additional layer on visible surfaces.
- Laminate architecture: thickness and mass per unit area affect the test result.
Which Standard Applies Where
| Sector | Standard | Note |
|---|---|---|
| Rail (Europe) | EN 45545-2 | R requirement sets and HL1/HL2/HL3 hazard levels |
| Marine | IMO 2010 FTP Code | Mandatory under SOLAS Chapter II-2 |
| Construction products | EN 13501-1 | Euroclass A1–F classification |
| Rail (USA) | NFPA 130, 49 CFR 238 | Different test protocol |
Zenginler İmalat's Fire Certification
The painted fibreglass laminate used by Zenginler İmalat in rail applications was tested at the TSE Construction Materials Fire and Acoustics Laboratory. TSE laboratories are accredited by TÜRKAK under registration number AB-0001-T to TS EN ISO/IEC 17025:2017.
According to classification report 304218 dated 23.09.2024, the laminate meets all three hazard levels — HL1, HL2 and HL3 — in requirement set R1 of TS EN 45545-2:2023. The measured values:
| Parameter | Measured | HL3 limit | Result |
|---|---|---|---|
| MARHE (kW/m²) | 59.73 | ≤ 60 | Pass |
| Ds(4) | 101.13 | ≤ 150 | Pass |
| CITG | 0.68 | ≤ 0.75 | Pass |
The classification rests on three separate TSE test reports: 304143 (TS ISO 5658-2 — flame spread), 304158 (TS EN ISO 5659-2 — smoke density) and 304180 (TS ISO 5660-1 — heat release). All reports are available as signed PDFs on our Management Systems page.