Jim

What you say about the two experts sounds like you are on the same case with me in that the other expert stated in his deposition there were five competent sources of ignition in his area of origin and he picked the one my client was responsible for as the one that the level of certainty was probable. When asked how he tested the hypothesis for all the potential sources of ignition and what finding left him with just the one as probable he said he just looked at them and picked one. He said he never attempted to develop an ignition scenario for any of the potential sources of ignition. All he was concerned with is that he believed he met the requirement of the opinion section of NFPA 921.

You know how to hit the nail on the head by your comment that there is too much art to boil the answer to this topic down to a single word or phrase. I think this area of 921 has been worked over as much or more than any other section because of what you said and it may never be just right for everyone because of the same reason. I know the person involved in the development of the opinion section are the most professional and want everything in the document to be just right. Because the information in the document is a consensus document the final text may not be one person’s idea on the subject and at times this adds to the clarity of the subject there are other times it detracts. This idea adds to the possibility that was made in an earlier posting where it was said the problem may not be what 921 says but how it is said.

Take care

Jim