🔥 Fire reaction of construction materials
Fire classification of construction products according to Euroclass system (A1–F) based on series of fire reaction tests: non-combustibility, bomb calorimeter, SBI and small flame.
Overview
The Euroclass fire classification system, described in standard PN-EN 13501-1, is the basic tool for assessing fire safety of construction materials in the European Union. CPR Regulation (305/2011) requires that every construction product placed on the market has a declaration of performance with fire reaction classification.
The system includes 7 main classes: A1 and A2 (non-combustible or almost non-combustible products), B, C, D (products with decreasing fire resistance), E (flammable but self-extinguishing) and F (no requirements / unclassified). Additionally, smoke production (s1, s2, s3 — from low to high) and flaming droplets formation (d0, d1, d2 — from none to intensive) are classified. Full class looks e.g.: B-s1,d0 (flame retardant, low smoke, no droplets).
Classification is based on results of several test methods: non-combustibility test (EN ISO 1182), bomb calorimeter (EN ISO 1716), SBI test — Single Burning Item (EN 13823) and small flame test (EN ISO 11925-2). Test selection depends on target class — e.g. class A1 requires meeting non-combustibility and calorimeter criteria, class B–D requires SBI and small flame.
These tests are performed only by notified laboratories (in Poland e.g. ITB, CNBOP-PIB, IMBiGS). The manufacturer of construction materials commissions tests, and based on them the notified body issues a classification report.
Method principle
Euroclass classification is based on a hierarchy of fire tests. Non-combustibility test (EN ISO 1182): sample is placed in tubular furnace at 750°C and temperature rise, mass loss and flame time are measured. Bomb calorimeter (EN ISO 1716): sample is burned in oxygen atmosphere under pressure 3.0–3.5 MPa — heat of combustion must not exceed 2.0 MJ/kg (A1) or 3.0 MJ/kg (A2). SBI test (EN 13823): two samples (1.5×0.5 m + 1.0×0.5 m) set at an angle are exposed to 30 kW propane burner — FIGRA (fire growth index), THR600s (total heat release), SMOGRA (smoke production index) and flaming droplets occurrence are measured. Small flame test (EN ISO 11925-2): 20 mm flame is applied to sample edge for 15 or 30 s — flame spread is assessed.
Applications
- Fire classification of thermal insulation materials (EPS, XPS, mineral wool, PIR)
- Testing of floor coverings, wall and ceiling linings
- Certification of facade materials (ETICS systems)
- Classification of pipes and installation insulation (linear pipe insulation)
- Testing of interior design materials (furniture, fabrics)
- Declarations of performance (DoP) according to CPR 305/2011
- Fire expert opinions for fire protection experts
Key parameters
| Parameter | Value |
|---|---|
| Main classes | A1, A2, B, C, D, E, F |
| Smoke subclasses | s1 (low), s2 (medium), s3 (high) |
| Droplet subclasses | d0 (none), d1 (limited), d2 (intensive) |
| FIGRA (class B) | ≤120 W/s |
| THR600s (class B) | ≤7.5 MJ |
| Heat of combustion A1 | ≤2.0 MJ/kg (bomb calorimeter) |
Standard
- Standard number
- PN-EN 13501-1+A1:2018
- Title (PL)
- Klasyfikacja ogniowa wyrobów budowlanych i elementów budynków — Część 1: Klasyfikacja na podstawie badań reakcji na ogień
- Title (EN)
- Fire classification of construction products and building elements — Part 1: Classification using test data from reaction to fire tests
Step-by-step procedure
1. Sample acceptance and conditioning
Condition samples min. 48 h under conditions: 23±2°C, 50±5% RH. Prepare required number of samples for each test.
2. Non-combustibility test EN ISO 1182
Place cylindrical samples ∅45×50 mm in furnace at 750°C. Measure temp. rise (ΔT <30°C for A1), mass loss (<50%) and flame time (<20 s).
3. Bomb calorimeter EN ISO 1716
Burn powdered sample (1–1.5 g) in calorimeter bomb in O₂ atmosphere (3 MPa). Measure heat of combustion. Criterion A1: PCS ≤2.0 MJ/kg.
4. SBI sample preparation
Prepare 2 panels: long (1500×500 mm) and short (1000×500 mm). Mount on support frame with substrate according to standard.
5. SBI test EN 13823
Set panels at angle under exhaust hood. Ignite propane burner (30 kW). Record HRR, FIGRA, THR600s, SPR, SMOGRA, droplets for 20 min.
6. Small flame test EN ISO 11925-2
Place 250×90 mm sample vertically in chamber. Apply 20 mm flame to edge for 15 s (or 30 s). Assessment: spread to 150 mm in 60 s.
7. Data processing and calculations
Calculate FIGRA, THR600s, SMOGRA from SBI data. Compare with classification criteria tables 1–3 of PN-EN 13501-1.
8. Classification and report
Based on results assign Euroclass (e.g. B-s1,d0). Prepare classification report with laboratory notification number.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| SBI stand (Single Burning Item) | FTT SBI, Netzsch SBI 915 | 400 000–800 000 PLN |
| Furnace for non-combustibility testing EN ISO 1182 | FTT Non-Combustibility Furnace, Netzsch | 120 000–250 000 PLN |
| Bomb calorimeter EN ISO 1716 | IKA C 6000, Parr 6400 Calorimeter | 50 000–120 000 PLN |
| Small flame stand EN ISO 11925-2 | FTT Ignitability Apparatus, Atlas HVUL | 30 000–80 000 PLN |
| Gas analyzers (O₂, CO₂, CO) | Servomex 4900, ABB EL3020, Siemens Ultramat | 30 000–80 000 PLN |
| Data acquisition and control system | FTT Data Station, NI DAQ + software | 40 000–100 000 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Technical propane (SBI fuel gas) | 74-98-6 | Purity ≥95%, 33 kg cylinder, burner power 30.7±2 kW |
| Benzoic acid (calorimeter standard) | 65-85-0 | Certified CRM, heat of combustion 26 454 J/g, for bomb calorimeter calibration |
| Compressed oxygen (bomb calorimeter) | 7782-44-7 | Purity ≥99.5%, bomb filling pressure 3.0–3.5 MPa |
| Ignition wire (Fe-Cr-Ni) | — | Resistance wire for sample ignition in calorimeter, known energy value |
Health and safety (OHS)
- Open fire and flammable gases (propane) — risk of fire and explosion! Powder and CO₂ extinguishers within reach
- Toxic combustion products (CO, HCN, HCl, HF) — mechanical exhaust mandatory, CO detectors
- Calorimeter bomb — O₂ pressure up to 3.5 MPa, explosion risk in case of bomb damage
- Hot elements (750°C furnace, post-combustion residues) — heat-resistant gloves, fire-resistant aprons
- Automatic fire suppression system in SBI testing hall
- Training in fire safety and fire equipment operation