At the June 2013 ASTM F23 committee meeting, there was a task group that met to discuss improvements to the ASTM F1930 Instrumented Manikin Burn Test method. During the meeting we considered possible ways to achieve more consistent results among the different testing laboratories around the world. An insight from this discussion made me rethink what the results of the test actually mean.
Why are there Inconsistent Results?
A standardized test is designed to provide testing labs with a reproducible method so each lab is performing the test in the same manner, which is true for this test method. However, there is some degree of variability within the test method primarily around the equipment. Those variables include:
- Sensors – The standard states the manikin must have at least 100 sensors that can measure the incident heat flux between 0 and 4 cal/cm². Some of the manikins have more than 100 which can provide more accurate information. Also, the type of sensor technology used by the labs is different, which likewise allows for variability.
- Manikin – The manikin size and shape is spelled out in the test method but over time the manikins need to be repaired. They are typically repaired rather than replaced because they are very costly. However, the repairs required the refurbished area to be reshaped by hand, which allows for variations that can affect the results.
- Burners – The method requires a minimum of 8 burners, but some labs use 12 in order to get more uniform coverage. The angle of the burners and the distance from the manikin can vary, which also may have an effect.
Because the cost of these units is very high, and there is no documentation that definitively shows one set up is better than another, a natural reluctance exists for any of the labs to change to a different sensor technology, manikin replacement plan, or burner standardization.
So What is the Insight?
The key piece to remember is the ASTM F1930 Instrumented Manikin Burn Test was developed to provide a more consistent method to test fabrics at a 6 cal/cm² exposure to set a minimum pass/fail point of 50% predicted body burn. It was not developed to use as a marketing tool to pit one fabric against another or to say one is better than another because of the body burn results. This test is just one of several found in NFPA 2112. All the fabrics that pass this test must also pass the other tests in order to be considered acceptable to provide a degree of protection and reduce the severity of burn injuries resulting from short-duration thermal exposures or accidental exposure to flash fires.
Also, this is a simulated flash fire exposure test. It does not actually replicate a flash fire, and is in fact, a jet fire.
Until the F1930 group finds a more consistent way for the various labs to run the test, the results should be taken for what they are – a minimum requirement to determine if a fabric meets the NFPA 2112 requirements. It is simply a pass/fail method and is the best we have today.