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Re: Comparison Sample
Posted by:
PMK140
()
Date: March 12, 2014 01:19PM
Just what is it about the Section on Comparison samples in NFPA 921-2014 that is so hard to understand? (Rhetorical Question)
Comparison samples have been in 921 for 22 years, and yours is the first complaint ever put forward.
NFPA 921-2014
17.5.4.6* Comparison Samples. When physical evidence is collected
for examination and testing, it is often necessary to also
collect comparison samples.
17.5.4.6.1 The collection of comparison samples is especially
important in the collection of materials that are believed to
contain liquid or solid accelerant. For example, the comparison
sample for physical evidence consisting of a piece of carpeting
believed to contain a liquid accelerant would be a piece
of the same carpeting that does not contain any of the liquid
accelerant. Comparison samples allow the laboratory to evaluate
the possible contributions of volatile pyrolysis products to
the analysis and also to estimate the flammability properties of
the normal fuel present.
17.5.4.6.2 When collected for the purpose of identifying the
presence of accelerant residue, the comparison sample should
be collected from an area that the investigator believes is free
of such accelerants, such as under furniture or in areas that
have not been involved in the fire. Assuming that the comparison
sample tests negative for ignitible liquids, any ignitible
liquids that are found in the suspect sample can be shown to
be foreign to the area when the suspect sample was taken.
17.5.4.6.3 It is recognized that comparison samples may be
unavailable due to the condition of the fire scene. It is also
recognized that comparison samples are frequently unnecessary
for the valid identification of ignitible liquid residue. The
determination of whether comparison samples are necessary
is made by the laboratory analyst, but because it is usually impossible
for an investigator to return to a scene to collect comparison
samples, they should be collected at the time of the
initial investigation.
17.5.4.6.4 If mechanical or electrical equipment is suspected
in the fire ignition, exemplar equipment may be identified
and collected or purchased as a comparison sample.
The only Public Comment suggested to these two decades old sections was put forward in 2001 by John and I when the improper analysis of comparison samples was used to put an innocent couple, Karen and Paul Stanley, in jail for arson and murder. Ultimately all charges against the Stanleys were dropped.
[truthinjustice.org]
Pat Kennedy, CFEI, CFPS, MIFireE
Fire and Explosion Analyst
Sarasota, Florida
[www.kennedy-fire.com]
Comparison samples have been in 921 for 22 years, and yours is the first complaint ever put forward.
NFPA 921-2014
17.5.4.6* Comparison Samples. When physical evidence is collected
for examination and testing, it is often necessary to also
collect comparison samples.
17.5.4.6.1 The collection of comparison samples is especially
important in the collection of materials that are believed to
contain liquid or solid accelerant. For example, the comparison
sample for physical evidence consisting of a piece of carpeting
believed to contain a liquid accelerant would be a piece
of the same carpeting that does not contain any of the liquid
accelerant. Comparison samples allow the laboratory to evaluate
the possible contributions of volatile pyrolysis products to
the analysis and also to estimate the flammability properties of
the normal fuel present.
17.5.4.6.2 When collected for the purpose of identifying the
presence of accelerant residue, the comparison sample should
be collected from an area that the investigator believes is free
of such accelerants, such as under furniture or in areas that
have not been involved in the fire. Assuming that the comparison
sample tests negative for ignitible liquids, any ignitible
liquids that are found in the suspect sample can be shown to
be foreign to the area when the suspect sample was taken.
17.5.4.6.3 It is recognized that comparison samples may be
unavailable due to the condition of the fire scene. It is also
recognized that comparison samples are frequently unnecessary
for the valid identification of ignitible liquid residue. The
determination of whether comparison samples are necessary
is made by the laboratory analyst, but because it is usually impossible
for an investigator to return to a scene to collect comparison
samples, they should be collected at the time of the
initial investigation.
17.5.4.6.4 If mechanical or electrical equipment is suspected
in the fire ignition, exemplar equipment may be identified
and collected or purchased as a comparison sample.
The only Public Comment suggested to these two decades old sections was put forward in 2001 by John and I when the improper analysis of comparison samples was used to put an innocent couple, Karen and Paul Stanley, in jail for arson and murder. Ultimately all charges against the Stanleys were dropped.
[truthinjustice.org]
Pat Kennedy, CFEI, CFPS, MIFireE
Fire and Explosion Analyst
Sarasota, Florida
[www.kennedy-fire.com]
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