Method for Classification of Flame Spread of Products
1989 Edition

1. Scope (Clause 2.0)

• Clarifies terminology related to surface flame spread testing of building materials.
• Covers classification parameters based on flame spread behavior.

2. Flame Spread Classifications (Clause 9.1, Table 2)

3. Calibration of Radiant Heat Source (Clause 6.1.1, Table 6.2)

Distances measured horizontally from the vertical edge of the calibration board closest to the heat source.

4. Apparatus Components (Clause 4.1, Figures 2-4)

• 9 gas-fired radiant panels enclosed in refractory surround
• Metal framework with specimen holder guides
• Pilot burner with fuel and air controls
• Backing board and specimen holder with standby and test positions

1. Definitions (Clause 2.0)

• Clarifies terms used in flame spread surface testing.

2. Flame Spread Classes (Clause 9.1, Table 2)

• See classification table under Section 1.

3. Radiant Heat Source Calibration (Clause 6.1.1, Table 6.2)

• Heat flux values at specified distances must be maintained within ±0.5 kW/m².

4. Key Apparatus Elements (Clause 4.1, Figures 2-4)

• External radiant heat source: 9 gas-fired panels in refractory surround
• Specimen holder: Mounted securely with guides
• Pilot burner: For ignition
• Metal support framework
• Fuel and air supply controls

flowchart LR
    A[External Radiant Heat Source] --> B[Specimen Holder]
    B --> C[Specimen]
    A --> D[Pilot Burner]
    A --> E[Fuel & Air Supply]
    E --> A

1. Specimen Dimensions (Clause 3.3)

• Samples must be standardized in size according to test requirements.
• Typical dimensions vary but must comply with IS 12777 guidelines.

2. Specimen Fabrication (Clause 3.4)

• Samples should be free of defects such as cracks or voids.
• Prepared using molds or cutting with smooth surfaces and chamfered edges to minimize stress.

3. Conditioning and Marking (Clause 3.6)

• Specimens should be conditioned and cured as per test instructions.
• Surfaces cleaned and dried prior to testing.
• Measurement points must be marked clearly.

4. Specimen Holder Requirements (Clause 4.3)

• Must securely hold specimens without introducing stress.
• Designed for quick positioning and uniform load application.

Apparatus Components (Clause 4.1, Figures 2-4)

• External radiant heat source: 9 vertical gas-fired panels within refractory surround
• Specimen holder: Mounted on metal framework with guides for rapid placement
• Pilot burner: Provides ignition flame
• Fuel and air supply system including Venturi mixer
• Backing board positioned behind the specimen
• Minimum clearance: 5 m in front, 6 m floor-to-ceiling in a draught-free enclosed space (Clause 4.6)

Calibration (Clause 6.1.1)

• Heat flux at specimen surface controlled within ±0.5 kW/m²
• Uniform temperature checked visually and with optical pyrometer
• Periodic calibration ensures accuracy

flowchart LR
    A[Gas-fired Radiant Panels (9)] --> B[Refractory Surround]
    B --> C[Metal Framework]
    C --> D[Specimen Holder with Guides]
    D --> E[Specimen]
    A --> F[Pilot Burner]
    F --> G[Fuel & Air Supply]
    E --> H[Backing Board]

1. Radiant Heat Source Calibration (Clause 6.1.1 & 6.2)

• Radiant heat flux at the specimen surface must be calibrated according to Table 6.2.
• Heat flux values along a horizontal line must be within ±0.5 kW/m².
• Uniformity of temperature on the radiating surface verified by visual inspection and optical pyrometer.

2. Calibration Table (Clause 6.1.1, Table 6.2)

3. Calibration Board (Clause 5.5)

• Used as a reference surface to ensure consistent flux measurements.

flowchart LR
    A[External Radiant Heat Source] --> B[Calibration Board]
    B --> C{Measure Heat Flux at Distances}
    C -->|75 mm| D[30 kW/m²]
    C -->|225 mm| E[20 kW/m²]
    C -->|375 mm| F[15 kW/m²]
    C -->|525 mm| G[11 kW/m²]
    C -->|675 mm| H[8 kW/m²]
    C -->|825 mm| I[6 kW/m²]
    B --> J[Check Uniformity]
    J --> K[Visual Inspection]
    J --> L[Optical Pyrometer]

Calibration Requirements (Clause 6.1.1 & 6.2)

• Radiant heat flux must be maintained within ±0.5 kW/m² tolerance at the specimen plane.
• Uniform temperature distribution across the radiating surface must be verified visually and with optical pyrometer.
• Calibration is performed along a horizontal reference line at the specimen surface.

Calibration Table (Clause 6.1.1, Table 6.2)

Procedure Summary

• Measure heat flux at each specified distance.
• Adjust the radiant source output to achieve target flux values.
• Verify uniform temperature distribution.
• Repeat calibration periodically for consistency.

flowchart LR
    A[Start Calibration] --> B[Set Radiant Source Output]
    B --> C[Measure Heat Flux at 75 mm]
    C --> D{Within ±0.5 kW/m²?}
    D -- No --> B
    D -- Yes --> E[Measure at 225 mm, 375 mm, … 825 mm]
    E --> F{All Within Tolerance?}
    F -- No --> B
    F -- Yes --> G[Check Temperature Uniformity]
    G --> H{Uniform?}
    H -- No --> B
    H -- Yes --> I[Calibration Complete]

Test Method (Clause 7.1)

• Conduct flame spread tests following the prescribed procedure.
• Maintain test conditions such as temperature and specimen orientation.

Observations (Clause 7.2)

• Record flame spread length at specified time intervals.
• Monitor temperatures using optical pyrometer.

Classification of Flame Spread (Clause 9.1, Table 2)

flowchart LR
    A[Setup Test] --> B[Ignite Specimen]
    B --> C[Measure Flame Spread at 1.5 min]
    C --> D{Within Limits?}
    D -- Yes --> E[Classify Sample]
    D -- No --> F[Reject Sample]
    E --> G[Record Temperature]
    G --> H[Complete and Document Test]

Rounding of Results

• Numerical values should be rounded as per IS 2:1960.

Handling Invalid Tests (Clause 8.2)

• Clearly state reasons for invalid results.
• Mark invalid test data distinctly.

Flame Spread Classification Summary (Clause 9.1)

Test Report Contents (Clause 10.1)

• Laboratory and sponsor details
• Manufacturer/supplier information
• Date of test
• Product description including trade name, construction, thickness, color, density
• Individual test results

flowchart TD
    A[Test Completed] --> B{Valid Test?}
    B -- Yes --> C[Record and Round Results]
    B -- No --> D[Document Reason for Invalidity]
    C --> E[Classify Flame Spread]
    E --> F[Compile Test Report]
    D --> F

Flame Spread Classification (Clause 9, Table 2)

Classification Guidelines

• Minimum 5 out of 6 valid specimens must comply with limits.
• One specimen may exceed limits within tolerance.
• For tests involving more than 6 specimens (up to 9) due to invalidity, suffix 'R' is appended.
• If post-extinction softening or behavior influences flame spread, suffix 'Y' is added.

Invalid Test Reporting (Clause 8.2)

• Clearly document reasons for invalid results.
• Mark invalid data distinctly.

flowchart TD
    A[Begin Testing] --> B{Is Test Valid?}
    B -- Yes --> C[Record Flame Spread]
    B -- No --> D[Note Reason for Invalidity]
    C --> E{Have 6 Valid Results?}
    E -- No --> F[Conduct Additional Tests (up to 9 Specimens)]
    E -- Yes --> G[Classify Results]
    F --> B
    G --> H{Softening or Post-Extinction Effect?}
    H -- Yes --> I[Add 'Y' Suffix]
    H -- No --> J[Finalize Classification]