Know your standards


CarolinaFireJournal - Richard Meier
Richard Meier CFEI, CFII, CVFI
05/06/2014 -

Fire and Explosion Investigation involves understanding the many materials, systems and applicable standards, codes, regulations and laws that specify how they may be constructed and used. This column is intended to give the investigator a basic knowledge of these. In future issues, we will attempt to address a particular standard, code or regulation.

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Figure 1. ASTM – D 1929 Auto-ignition test being conducted. Picture taken precisely at time of ignition. Note temperature at left.

ASTM D 1929 — Standard Test Method for Determining Ignition Temperature of Plastics
The purpose of this test is to determine the ignition temperature of a plastic material. There are two versions of the test. The first test determines the auto-ignition temperature and the second test determines the piloted ignition temperature.

A simple explanation of the test is as follows:

  1. A standard weight sample of the material is placed into a metal cup attached to a rod.
  2. A thermocouple is placed immediately above the cup.
  3. The sample is placed into vertical tubular furnace (known as a Setchkin furnace).
  4. The temperature is slowly raised until the material begins to pyrolize.
  5. The ignition temperature is determined as follows:

a. Auto-Ignition Temperature.
i. The temperature is raised until the material ignites
ii. The highest temperature reached before ignition is recorded.
b. Piloted Ignition Temperature
i. A pilot flame is placed at the top of the furnace at the beginning of the test.
ii. The highest temperature reached before ignition is recorded.

Typical Observations

  • First appearance of smoke (material has begun to pyrolize).
  • First appearance of flame (material has ignited).

What does this test tell us? The Ignition Temperature Test is used to help determine the suitability of a material in any application where high heat may occur. It is a way of comparing different materials considered.

Limitations of the Test
As with most standardized tests, the Ignition Temperature Test is intended to compare various materials (i.e. ‘A’ is better than ‘B’. ‘C’ is better than ‘A’ or ‘B’.) It should not be considered the “end all, be all” test. A standardized test WILL NOT tell you if a material is appropriate for a particular application. Once a material is chosen, prototypes should be made and thoroughly tested under real world conditions by a qualified laboratory.

Testing a Theory
If your intent is to test a fire cause hypothesis, this standardized test give both qualitative and quantitative answers to typical questions.

  • My ignition source is a hot wire or surface of X oF. Is that hot enough to ignite my first fuel?
  • Or, How hot does my ignition source have to be to ignite my first fuel?

WARNINGS
The ASTM – D 1929 Ignition Temperature Test involves high heat, flammable vapors and specialized test equipment. A qualified technician in a properly equipped laboratory should only perform this test. Personal protective equipment should be used, and a fire extinguisher should be kept close at hand.

Where to Find More Information on this Standard
This standard is available for sale from ASTM, International (formerly American Society of Testing and Materials). Go to ASTM.org for more information.

Richard Meier, CFEI, CFII, CVFI is currently a Staff Expert, Fire and Explosion Analyst for John A. Kennedy and Associates in Sarasota, FL. Prior to entering the fire field, he spent 24 years in product and manufacturing engineer making a wide variety of automotive, marine, consumer and industrial products.
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Issue 34.1 | Summer 2019

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