Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Understanding CAN CGSB 4.2 No. 27.7-2013: Vertical Flame Test for Textile Flame Resistance
A Comprehensive Guide to the Canadian Standard for Evaluating Textile Flammability
Introduction and Scope
CAN CGSB 4.2 No. 27.7-2013, titled Textile Test Methods — Flame Resistance — Vertical Flame Test, is a Canadian standard developed by the Canadian General Standards Board (CGSB). This standard specifies a laboratory test method for measuring the flame resistance of textile materials when exposed to a controlled vertical flame. The test evaluates key parameters including afterflame time, afterglow time, and char length, providing a quantitative basis for assessing the flammability of fabrics and textile products.
The standard applies to a wide range of textiles, including woven, knitted, and nonwoven fabrics, as well as coated, laminated, or otherwise treated materials. It is commonly referenced in regulations for protective clothing, workwear, curtains, upholstery, and other interior furnishings that must meet flame resistance requirements in Canada. Compliance with this standard is often mandated by federal or provincial regulations, such as those under the Canada Consumer Product Safety Act for children’s sleepwear and other high-risk textile products.
This article provides a detailed examination of the technical requirements, implementation considerations, and compliance aspects of CAN CGSB 4.2 No. 27.7-2013, intended for textile manufacturers, quality assurance professionals, and regulatory compliance specialists.
Technical Requirements and Test Methodology
Test Apparatus
The test apparatus specified in the standard includes a vertical flame test chamber constructed of non-combustible material with a transparent observation window. Inside the chamber, a specific burner with a defined gas (typically butane or propane) is positioned to apply the flame perpendicular to the bottom edge of the vertically mounted specimen. The specimen holder clamps the fabric securely, ensuring consistent exposure geometry.
Specimen Preparation
Specimens are cut to the size required by the standard; typical dimensions are 70 mm × 300 mm with the long axis oriented vertically. For textile products with directional characteristics, specimens are taken from both warp and weft directions. The number of specimens and the sampling plan follow the standard’s provisions.
Conditioning is critical: all specimens must be conditioned at a temperature of 21 °C ± 1 °C and a relative humidity of 65 % ± 2 % for a minimum of 24 hours prior to testing. Testing must be conducted within the same environmental conditions to ensure reproducibility.
Test Procedure
The flame is applied to the bottom edge of the specimen for a specified duration, commonly 12 seconds. After removing the flame, the following measurements are recorded:
- Afterflame time (s): The duration for which the specimen continues to flame after the ignition source is removed.
- Afterglow time (s): The duration of glowing combustion after flaming ceases.
- Char length (mm): The length of material destroyed by the flame, measured from the specimen edge to the farthest point of visible damage, including holes, tears, or melting.
The test may be repeated for multiple specimens; the average results are reported. The standard defines acceptance criteria for each parameter depending on the end-use application, which are often specified in referencing regulations.
The table below summarizes key test parameters as defined in CAN CGSB 4.2 No. 27.7-2013:
| Parameter | Specification |
|---|---|
| Specimen size (mm) | 70 × 300 |
| Flame application time (s) | 12 ± 0.5 |
| Burner hole diameter (mm) | 0.41 ± 0.03 |
| Gas mixture | Butane or propane (technical grade) |
| Conditioning temperature (°C) | 21 ± 1 |
| Conditioning RH (%) | 65 ± 2 |
| Number of specimens per sample | 5 (warp + 5 weft) |
Implementation Highlights
Successfully implementing CAN CGSB 4.2 No. 27.7-2013 in a testing laboratory requires attention to several practical aspects:
- Calibration and verification: The burner flame height and heat output must be calibrated regularly. A standard reference fabric with known flame resistance should be tested periodically to verify system performance.
- Environmental control: Maintaining the exact conditioning environment is vital. Variations in temperature and humidity can significantly affect test results, particularly for hygroscopic fibers like cotton and rayon.
- Operator training: Operators must be trained to consistently apply the flame and record measurements. Subjectivity in char length measurement can introduce variability; using a defined technique (e.g., following the char to the point of unbroken yarns) improves precision.
- Safety precautions: The test involves open flames and combustion products. Adequate ventilation, fume extraction, and fire safety measures are essential in the testing area.
Tip: When testing multi-layer textile assemblies, ensure all layers are treated as a composite specimen. The standard may require special preparation for such cases. Always consult the latest edition of the standard for clarification.
Warning: The vertical flame test is a controlled laboratory method. Results should not be used to predict the behavior of textiles in every real fire scenario. Always interpret results in conjunction with risk assessments and applicable regulations.
Compliance Tip: Many Canadian regulations specify performance thresholds based on this standard. For example, CSA Z96-15 for high-visibility safety apparel or CAN/ULC-S109 for flame-resistant fabrics often reference CGSB 4.2 No. 27.7. Ensure your test lab is accredited by a recognized body to perform the standard correctly.
Compliance and Documentation
Compliance with CAN CGSB 4.2 No. 27.7-2013 is often a prerequisite for placing textiles on the Canadian market, particularly for products intended for use in protective clothing, public buildings, and transportation. Manufacturers should:
- Maintain detailed test reports from accredited laboratories.
- Ensure regular testing of production lots, especially if the textile formulation or finish changes.
- Understand the relationship between this standard and similar international methods (e.g., ASTM D6413, ISO 6940/6941). While similar in principle, variations in specimen size, burner geometry, and conditioning can lead to different results; direct comparison is not always valid.
- For product certification, testing must be performed by a laboratory accredited to ISO/IEC 17025 and recognized by the Standards Council of Canada (SCC) or equivalent.
The standard is current as of the 2026 revision cycle. Users are encouraged to verify they are referencing the latest version, as amendments may refine parameters or expand applicability to new textile technologies.
Frequently Asked Questions
Q: What is the purpose of char length measurement?
A: Char length indicates the extent of material damage caused by the flame. It is a measure of the textile’s ability to resist flame travel. A shorter char length generally indicates better flame resistance.
A: Char length indicates the extent of material damage caused by the flame. It is a measure of the textile’s ability to resist flame travel. A shorter char length generally indicates better flame resistance.
Q: How does conditioning affect the results?
A: Moisture content significantly influences flammability. Standardized conditioning ensures that results are comparable across different tests and laboratories. Testing unconditioned specimens can lead to highly variable outcomes.
A: Moisture content significantly influences flammability. Standardized conditioning ensures that results are comparable across different tests and laboratories. Testing unconditioned specimens can lead to highly variable outcomes.
Q: Is this standard mandatory for all textiles in Canada?
A: No. This standard is a test method, not a regulation. Mandatory application depends on specific product regulations (e.g., children’s sleepwear, protective clothing). However, demonstrating compliance with this method is a common industry requirement.
A: No. This standard is a test method, not a regulation. Mandatory application depends on specific product regulations (e.g., children’s sleepwear, protective clothing). However, demonstrating compliance with this method is a common industry requirement.
Q: Can the test be used for coated or laminated fabrics?
A: Yes, the standard applies to coated and laminated textiles, provided the specimen is representative of the final product. However, heavy coatings may cause dripping or melting that can affect measurement. The test report should note any anomalous behavior.
A: Yes, the standard applies to coated and laminated textiles, provided the specimen is representative of the final product. However, heavy coatings may cause dripping or melting that can affect measurement. The test report should note any anomalous behavior.