Proud to Protect Canada – Episode 5: CGSB 155.20 vs. NFPA 2112

In Episode 4 of our Proud to Protect Canada series, Tyndale’s Canada Sales Director, Paul Castelli, and VP of Technical, Scott Margolin, answer the question, what is a flash fire. Scott explained how flash fires differ from other types of fires and how wearing flame resistant (FR) clothing dramatically reduces the chances of suffering fatal or devastating flash fire burn injuries. In case you missed it, check it out now!

In today’s episode, we’ll look at CGSB 155.20, the Canadian standard governing workwear for protection against flash fire. In the video below, Tyndale Canada Sales Director Paul Castelli, talks to Canada Technical Advisor Sara Olsen about CGSB 155.20 and the similarities and differences between it and its US counterpart, NFPA 2112. Sara’s extensive background in the protective clothing industry includes conducting over 1,500 flash fire tests while working at the University of Alberta’s Protective Clothing and Equipment Research Facility. She has also served on several standards committees that govern protective clothing, including CGSB 155.20. So, let’s learn more as she shares her first-hand expertise on this Canadian standard:

What are the objectives of flash fire workwear standards?

CGSB 155.20 is a standard of the Canadian General Standards Board (CGSB) for Workwear for Protection Against Hydrocarbon Flash Fire and Optionally Steam and Hot Fluids. As Sara explains, in Canada, both CGSB 155.20 and NFPA 2112, Standard on Flame-Resistant Clothing for Protection of Industrial Personnel Against Short-Duration Thermal Exposures from Fire, are commonly requested by companies who need to ensure workers are protected from flash fire hazards on their work sites. These two standards are very similar. As you may recall from our last episode, a flash fire is a fire that spreads rapidly through a diffused fuel-air mixture, and as CGSB 155.20 points out, flash fires can vary in duration. Both standards use three seconds as the maximum duration of a typical flash fire.

The need for flash fire standards emerged when the safety industry realized that workers wearing non-FR PPE were essentially wearing fuel; in a flash fire, non-FR clothing would ignite and continue to burn long after the flash fire was over. Therefore, the primary objective of both CGSB 155.20 and NFPA 2112 is to ensure that protective clothing is flame resistant, meaning it will self-extinguish once the source of heat and flame are removed from the garment. The other objectives of the standard are to reduce or prevent burns by ensuring that a fabric insulates the body from substantial heat for at least three seconds and the garments remain intact and operable after a thermal event.

What tests are required by CGSB 155.20 and NFPA 2112?

Both CGSB 155.20 and NFPA 2112 require protective workwear fabric to be tested to determine if it will protect the wearer from flash fire conditions. Fabrics are tested for:

• Flammability
• Heat resistance
• Thermal shrinkage
• Thermal insulation

To test for flammability, the edge of the fabric is exposed to a flame for 12 seconds. The fabric must not ignite or must self-extinguish no more than two seconds after the flame has been removed. The damaged length (also known as the “char length”) of the fabric is measured, and the maximum allowable damaged length is 100 mm, or about four inches for both CGSB 155.20 and NFPA 2112.

Heat resistance and thermal shrinkage tests are conducted to ensure that the fabric will not melt and drip or ignite at high temperatures or shrink to the point of impeding the wearer if exposed to high heat. Hardware and thread are also tested in this way. Thread can't melt, and hardware must remain operable after five minutes in a 260°C oven or 500°F. Both standards test in the same way and have the same requirements for these items.

Additionally, fabric is tested to ensure it protects the wearer’s body in a thermal incident. The test methods for thermal insulation vary between CGSB 155.20, which uses the Thermal Protective Performance (TPP) method, and NFPA 2112, which uses the Heat Transfer Performance (HTP) method. The heat flux for both tests is 84 kW/m², and the results of these tests must demonstrate that the fabric will protect the skin for at least three seconds of heat exposure. The differences between the TPP and HTP methods are described in greater detail in the next section.

Both CGSB 155.20 and NFPA 2112 use the ASTM F1930 manikin test. For this test, a standard coverall is made without pockets, waistbands, or other features and is dressed on a sensored manikin. The manikin stands in a ring of torches and is exposed to a flash fire for three seconds. The heat flux is around 84 kW/m², as in the TPP and HTP tests. The sensor data provides the predicted second- and third-degree burn injury during the three-second exposure. However, the two standards differ in the maximum allowable body burn percentage – more on this topic in the next section.

How do CGSB 155.20 and NFPA 2112 differ?

The chart below summarizes the similarities and differences in flash fire testing requirements for
CGSB 155.20 versus NFPA 2112

While both CGSB 155.20 and NFPA 2112 require flammability testing on new fabric and laundered fabric, the standards differ in the number of industrial laundry cycles required:

• For CGSB 155.20, testing is conducted after 50 or more cycles.
• For NFPA 2112, testing is conducted after 100 cycles.

CGSB 155.20 and NFPA 2112 have identical methods for both heat-resistance and thermal shrinkage testing. Both standards require that fabrics not melt and drip, separate or ignite during testing, and both standards require the measurement of fabrics before and after heat exposure to determine thermal shrinkage. For both CGSB 155.20 and NFPA 2112, fabrics cannot shrink more than 10% in any direction.

As stated earlier, CGSB 155.20 and NFPA 2112 use different test methods to determine thermal insulation:

• CGSB 155.20 uses TPP for thermal protective performance. This test uses a sensor that mimics the heat absorption properties of skin. Below the sensor is a torch and in between the sensor and the torch is the fabric being tested. The test measures the time it takes for the sensor to hit second-degree burn criteria based on the Stoll Curve.
• NFPA 2112 uses HTP for heat transfer performance. This test uses a combination of direct heat from a torch and radiant heat to measure the heat a fabric would block to prevent a second-degree burn.

As described in the previous section, both CGSB 155.20 and NFPA 2112 use the ASTM F1930 manikin test, which exposes garments to a three-second flash fire with a heat flux of 84 kW/m², and the total predicted body burn is measured:

• For CGSB 155.20, a maximum of 40% predicted burn is allowable.
• For NFPA 2112, a maximum of 50% is accepted.

Sara notes that most fabrics perform well below these maximums.

Other key differences

Some final differences between the CGSB 155.20 and NFPA 2112 beyond the test methods described above include:

• For CGSB 155.20, third-party certification is optional, but for NFPA 2112, it’s mandatory.
• CGSB 155.20 also includes optional additional testing requirements for rainwear, as well as steam and hot water protective garments.

Stay tuned for the next episode in this series which covers Canadian standards for high-visibility clothing and reflective striping. Visit our series hub to read episode summaries and catch up on all topics in the series.