Testing

According to the New Oxford American Dictionary, “test” is defined as “a procedure intended to establish the quality, performance, or reliability of something.” In the context of vehicle fire investigation, testing is often conceptual as opposed to physical (such as burn-testing vehicles or components). Hypotheses can be tested conceptually by evaluating the consistency of all conditions and information with known principles – that is, by using deductive reasoning.

Vehicle burn tests are expensive and logistically difficult within city limits of most municipalities. There are also limitations regarding the ability of the investigator to define or control all the variables of importance in an actual fire event. When possible, however, burn tests can be very useful in evaluating specific conditions or hypotheses. Tests of individual components can also be performed to assist in understanding the potential for fire in various hypotheses. For example, if one hypothesizes that a fluid was ignited on a hot exhaust manifold, temperature measurements can be made of the manifold in a similar vehicle under similar operating conditions. If the manifold is not hot enough for autoignition of the fluid in question, the hypothesis can be eliminated. If the manifold is hot enough, the hypothesis is possible. Unless all other hypotheses are eliminated, the exhaust manifold is one, but not necessarily the only, possible ignition source.

Analyzing results of conceptual or physical tests may lead to collection of additional data and formulation of new hypotheses to test. In such cases, the methodical process is iterated until either all questions are answered or all possible sources of information are exhausted.