Here is a clarification to the previous post.

Sorry, if I would have asked others I would have learned that the committee’s justification as to not including the information as to the same test being conducted with the same fuel to air ratio could produce a different value was that, “Table 23.8.1 and Figure 23.8.1 contains sufficient guidance on MIE and the general definition of ignition energy is sufficient.”

I wonder if they read what is submitted or what they write as a justification. They are saying that the table and the figure gives a general definition of ignition energy. First of all, is a general definition good enough?

Her it the wording from Table 23.8.1, “Minimum Ignition Energy of Selected Fuels.” Can someone show me where there is a general definition of ignition energy in that statement? Here is what is said in the figure the committee references. “An Experimental Comparison of the Minimum Ignition of Methane as a Function of Percentage of Methane in Air.” Is there a general definition of ignition energy in that statement?

Here is what section 23.8.1 states, “Gaseous fuel-air mixtures are the most easily ignitable fuels capable of causing an explosion. Minimum ignition temperature is in the 370ºC to 590ºC (700ºF to 1100ºF) range are common, and they can be even lower for heavier hydrocarbons such as n-neptane at 215ºC (419ºF). Minimum ignition energies of some selected fuels are shown in Table 23.8.1. While Table 23.8.1 shows single values, minimum ignition varies with the fuel air ratio shown in Figure 23.8.1 for methane. According to this statement the only time there will be a change in the value is when there is a change in the fuel/air ratio. The test used to obtain these values is ASTM E 582. The section of this standard titles “Precision and Bias” states the following, “Available indications are that reproducibility (and presumably accuracy) of +/- 10% in minimum ignition energy and +/- 2% in ignition quenching distance are readily achieved in those instances where the results are readily independent of fuel-oxidizer concentrations.”

Can someone show me what would be considered a general definition of ignition emergency. Is the state that indicates the only factor for a variance in the value the fuel/air mixture a correct statement?

Jim Mazerat
Forensic Investigations Group