How to Conduct a Single Burning Item (SBI) Test in Accordance with EN 13823:2020+A1:2022

1. General Requirements & Preparation

Before initiating the SBI test sequence, test operators must observe critical timing and environmental conditions:

• Conditioning Limit: The complete testing procedure must be executed within 2 hours after removing the specimen from the conditioning environment.
• Thermal & Equipment Equilibrium: All electronic instruments, pumps, and sensors must be switched on with sufficient warm-up time to reach thermal equilibrium before calibration or testing.
  • General Electronics: A minimum of 30 minutes pre-heating is recommended.
  • Gas Analyzers (O2 & CO2): Gas analyzers require significantly longer stabilization time; it is recommended to keep them continuously powered on.

2. Step-by-Step Testing Timeline & Operations

The operational process follows a precise chronological timeline under specified exhaust flow rates:

A. Flow Rate Adjustment & Pre-Test Baseline

1. Exhaust Volume Flow: Set the exhaust volume flow V 298 (t) to (0.60 ± 0.05) m³/s. The flow rate must be continuously maintained within 0.50 m³/s to 0.65 m³/s throughout the entire test. (Note: Manual or automatic adjustments may be required during testing due to heat output fluctuations).
2. Temperature Stabilization (at least 300 s): Continuously record thermocouples T1, T2, and T3 in the exhaust duct along with ambient temperature.
   • Ambient Temperature: Must remain within (20 ± 10) °C.
   • Duct Temperature: Must not deviate by more than 6 °C from the ambient temperature.
3. Pilot Flames & Pre-Test Conditions: Ignite pilot flames (gas supply changes must not exceed 5 mg/s). Record ambient pressure (Pa), ambient relative humidity (%H2O), and baseline temperature.

B. Execution Timeline (t = 0 s to End of Test)

• t = 0 s (Test Start): Initiate the chronometer and automated data acquisition system.
• t = (120 ± 5) s (Auxiliary Burner Ignition): Ignite the auxiliary (secondary) burner and adjust the propane mass flow rate (mgas) to (647 ± 10) mg/s before t = 150 s.
  • Baseline Measurement: The period between 210 s < t < 270 s measures the baseline for the Heat Release Rate (HRR).
• t = (300 ± 5) s (Main Burner Switch): Switch the propane gas supply from the auxiliary burner to the main (primary) trolley burner to expose the test specimen to direct thermal attack.
• t = 300 s to 1560 s (Specimen Exposure Period): Observe and manually record combustion behavior over a nominal exposure period of 1,260 seconds (performance evaluation is based on a 1,200 s window).
• t ≥ 1560 s (Test Termination): Shut off the propane gas supply to the burner and stop automatic data logging.
• Post-Test Record (≥ 1 min after extinction): Record final baseline conditions (light transmission, O2 and CO2 mole fractions) once any remaining specimen flaming is completely extinguished.

3. Visual Observations and Manual Data Logging

During testing, an observer equipped with an event-logging chronometer must visually monitor and record critical fire behaviors:

A. Lateral Flame Spread (LFS)

Record the occurrence of sustained flames reaching the far edge of the specimen’s long wing at any height between 500 mm and 1000 mm. The criterion requires sustained flaming at the boundary for a minimum of 5 seconds.

B. Flaming Droplets and Particles

Continuous high-resolution video recording is required if flaming droplets or particles are anticipated.

• Time & Location Window: Recorded only within the first 600 seconds of exposure when droplets/particles fall onto the trolley floor outside the burner zone (< 0.3 m radius from the corner line).
• Categorization:
  1. Short-duration: Flaming particles that burn for ≤ 10 seconds.
  2. Persistent: Flaming particles that burn for > 10 seconds.

Key:
1. obstruction plate I U-profile
2. burner zone border
3. burner

C. Other Critical Events

Operators must record occurrences such as surface flash, smoke escaping into the test room, specimen collapse, or joint failure at backing board corners.

5. Early Termination Criteria & Equipment Protection

To protect testing equipment and maintain validity, operators should understand early termination protocols:

1. Choking / Flame Disturbance: Stop the main burner immediately if fallen specimen material enters the burner’s sand-bed and severely distorts or chokes the flame. Tests terminated early are invalid for Euroclass classification.
2. Thermal Protection Thresholds: Operators may consider early termination if parameters exceed maximum limits:
   • Heat Release Rate (HRR): Exceeds 350 kW instantly, or 280 kW for more than 30 seconds.
   • Exhaust Duct Temperature: Exceeds 400 °C instantly, or averages above 300 °C for over 30 seconds.

SBI Test Key Calculated Parameters and Euroclass Ratings

Once the test concludes, the system’s advanced software automatically processes the raw data to determine final performance indexes. These calculations are vital for assigning material ratings under EN 13501-1:

• HRR & THR (Heat Release Rate & Total Heat Release): Measures how rapidly and how much energy the burning product contributes to a fire.
• FIGRA (Fire Growth Rate Index): Derived from HRR data, indicating how fast the fire grows.
• SPR & TSP (Smoke Production Rate & Total Smoke Production): Quantifies visibility loss and smoke hazards generated during combustion.
• SMOGRA (Smoke Growth Rate Index): Evaluates how rapidly smoke accumulates during the critical early stages of the fire.

Conclusion

Mastering the BS EN 13823 Single Burning Item (SBI) test procedure ensures that building products meet stringent European safety standards. By maintaining strict control over calibration, specimen conditioning, and real-time data analysis, manufacturers can reliably classify their materials and bring safe, compliant products to the global market.