Method for Classification of Flame Spread of Products

IS 12777: Scope & Key Specifications

1. Scope (Clause 2.0)

• Defines terminology related to surface spread of flame tests for building materials.
• Covers classification of materials based on flame spread extent.

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

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

Measured horizontally from the vertical edge of the calibration board nearest the radiant source.

4. Apparatus Details (Clause 4.1 & Figures 2-4)

• Components:
  • 9 gas-fired radiant panels
  • Castable refractory surround
  • Metal framework and specimen holder guides
  • Pilot burner with fuel & air supply controls
  • Backing board and specimen holder with standby/test positions

flowchart LR
    A[External Radiant Heat Source]
    B[Specimen Holder]
    C[Pilot Burner]
    D[Backing Board]
    A --> B
    C -->

IS 12777 - Key Definitions & Specifications

1. Definitions (Clause 2.0)

• Terminology as per the standard applies to flame spread testing of materials.

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

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

• Distance measured horizontally from the vertical edge near the heat source.

4. Apparatus Key Components (Clause 4.1, Figs. 2-4)

• External radiant heat source: Gas-fired radiant panels (9 nos.) in refractory surround.
• Specimen holder: Guides and backing board to position specimen.
• Pilot burner: For ignition.
• Metal framework: Supports apparatus.
• Fuel and air supply controls: Ensure proper combustion.

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

IS 12777: Specimen Preparation Key Points

1. Size of Specimens (Clause 3.3)

• Specimens should be standardized in size for uniform testing.
• Typical dimensions depend on the test type but must conform to IS 12777 recommendations.
• Example: For tensile tests, specimens might be 150 mm length, 20 mm width, and thickness as per material.

2. Construction of Specimens (Clause 3.4)

• Specimens must be free from defects like cracks or voids.
• Prepared using standard molds or cutting techniques ensuring smooth surfaces.
• Edges should be rounded or chamfered to avoid stress concentrations.

3. Preparation of Specimens (Clause 3.6)

• Specimens should be cured or conditioned as per test requirements.
• Surface should be cleaned and dried before testing.
• Marking for measurement points must be clear and precise.

4. Specimen Holder (Clause 4.3)

• Must securely hold specimens without inducing additional stresses.
• Designed to accommodate specimen dimensions and allow uniform load application.

Summary Table: Specimen Preparation Checklist

If you need specific dimensions or formulas, please specify the test type (e.g., tensile, compression).

IS 12777 — Test Apparatus Key Details

Apparatus Components (Clause 4.1 & Figures 2-4)

• External radiant heat source: 9 gas-fired radiant panels arranged vertically in a castable refractory surround.
• Specimen holder: Mounted on metal framework with guides for quick positioning.
• Pilot burner: Ensures ignition.
• Fuel & air supply: Includes Venturi mixer, air & fuel lines for proper combustion.
• Backing board: Positioned behind specimen.
• Clearances: Minimum 5 m in front, 6 m floor-to-ceiling in an enclosed, draught-free environment (Clause 4.6).

Calibration (Clause 6.1.1)

• Heat flux: External radiant heat flux at specimen surface must be controlled within ±0.5 kW/m².
• Uniformity check: Visual inspection and optical pyrometer for temperature uniformity on radiating surface.
• Calibration: Periodic checks against Table 1 (not provided here) to maintain accuracy.

Summary Table: Apparatus Dimensions & Requirements

flowchart LR
    A[Gas-fired Radiant Panels (9)] --> B[Castable Refractory Surround]
    B --> C[Metal Framework]
    C --> D[Specimen Holder with Guides]
    D --> E[Specimen]
    A --> F[Pilot Burner]
    F --> G[Fuel & Air Supply (Venturi Mixer)]
    E --> H[Backing Board]
    style A fill:#f9f,stroke:#333,stroke-width:2px
    style D fill:#bbf,stroke:#333,stroke-width:2px

This setup ensures controlled, uniform radiant heat exposure for surface spread of flame tests per IS 12777.

IS 12777 - Instruments and Calibration Key Points

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

• The external radiant heat flux at the specimen surface must be calibrated as per Table 6.2.
• The heat flux values along the horizontal reference line must be within ±0.5 kW/m² tolerance.
• Uniformity of the radiating surface temperature must be checked visually and with an optical pyrometer.

2. Calibration Table (Clause 6.1.1 - Table 6.2)

• Distance is measured horizontally from the vertical edge of the calibration board nearest the radiant heat source.

3. Calibration Board (Clause 5.5)

• Used as a reference surface for calibration.
• Ensures consistent measurement of radiant heat flux.

Summary:

• Maintain heat flux uniformity within ±0.5 kW/m².
• Use Table 6.2 for reference flux values at specified distances.
• Verify temperature uniformity by optical pyrometer and visual inspection.

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]

This ensures accurate and repeatable heat flux calibration per IS 12777.

IS 12777 - Calibration of External Radiant Heat Source

Key Specifications (Clause 6.1.1 & 6.2)

• Calibration must achieve specified radiant heat flux values within ±0.5 kW/m² tolerance.
• Uniform temperature of the radiating surface must be verified visually and with an optical pyrometer.
• Calibration is performed along a horizontal reference line at the specimen surface.

Calibration Table (Clause 6.1.1, Table 6.2)

• Distances measured from the vertical edge of the calibration board nearest the radiant source.

Calibration Procedure Summary

• Measure heat flux at specified distances.
• Adjust radiant source output to meet target flux values.
• Confirm uniform temperature distribution on the radiating surface.
• Repeat periodically to ensure consistent calibration.

flowchart LR
    A[Start Calibration] --> B[Set radiant source]
    B --> C[Measure heat flux at 75mm]
    C --> D{Within ±0.5 kW/m²?}
    D -- No --> B
    D -- Yes --> E[Measure at 225mm, 375mm, ... 825mm]
    E --> F{All within tolerance?}
    F -- No --> B
    F -- Yes --> G[Check uniform temperature]
    G --> H{Uniform?}
    H -- No --> B
    H -- Yes --> I[Calibration complete]

This ensures the external radiant heat source provides consistent and accurate heat flux for testing as per IS 12777.

IS 12777: Test Procedure Key Points

Clause 7.1: Test Procedure

• Follow the prescribed method for conducting the flame spread test on specimens.
• Maintain conditions as per the standard (e.g., temperature, specimen orientation).

Clause 7.2: Observations During Test

• Record flame spread length at specified time intervals.
• Monitor temperature at various points using an optical pyrometer (Clause 6.2.5).

Clause 9.1: Flame Spread Classification (Table 2)

Additional Notes:

• Temperature measurement by optical pyrometer is critical for accuracy.
• Test duration and specimen count affect acceptance criteria.

flowchart LR
    A[Test Setup] --> B[Ignition of Specimen]
    B --> C[Measure Flame Spread at 1:5 min]
    C --> D{Flame Spread Limits?}
    D -->|Within Limits| E[Classify Specimen]
    D -->|Exceeds Limits| F[Reject Specimen]
    E --> G[Record Temperature via Optical Pyrometer]
    G --> H[Complete Test & Report]

This summarizes the test procedure and classification criteria per IS 12777.

IS 12777: Reporting of Results - Key Points

Rounding Off (Clause None)

• Follow IS 2:1960 for rounding numerical values in test results.

Invalid Tests (Clause 8.2)

• Report reasons for invalid tests clearly.
• Mark such results distinctly.

Flame Spread Classification (Clause 9.1)

Test Report Contents (Clause 10.1)

• Laboratory name & address
• Sponsor name & address
• Manufacturer/supplier details
• Date of test
• Product description: trade name, construction, thickness, color, density
• Individual test results per Clause 8

Summary Diagram of Reporting Flow

flowchart TD
    A[Test Conducted] --> B{Valid?}
    B -- Yes --> C[Record Results]
    B -- No --> D[Report Reason for Invalidity]
    C --> E[Round Off Values (IS 2:1960)]
    D --> E
    E --> F[Classify Flame Spread (Clause 9.1)]
    F --> G[Prepare Test Report (Clause 10.1)]

This ensures clarity, traceability, and compliance with IS 12777.

IS 12777: Classification of Flame Spread Results (Clause 9)

Key Specifications (Table 2: Flame Spread Classification)

Classification Rules

• At least 5 of 6 valid specimens must meet the 1.5 min and total test duration limits for the class.
• One specimen may exceed limits within tolerance (shown above).
• If more than 6 specimens are tested (up to 9) due to invalid tests, suffix 'R' is added.
• If softening or behavior affecting flame spread occurs post-extinction, suffix 'Y' is added.

Invalid Tests (Clause 8.2)

• Reasons for invalid tests must be reported clearly.
• Invalid results must be marked distinctly.

flowchart TD
    A[Start Testing] --> B{Valid Test?}
    B -- Yes --> C[Record Flame Spread]
    B -- No --> D[Report Reason for Invalidity]
    C --> E{6 Valid Results Obtained?}
    E -- No --> F[Test up to 9 Specimens]
    E -- Yes --> G[Classify per Table 2]
    F --> B
    G --> H{Softening/Behavior Post Extinction?}
    H -- Yes --> I[Add 'Y' Suffix]
    H -- No --> J[Final Classification]

This summarizes the classification criteria and reporting requirements per IS 12777 Clause 9.