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An Explosive Garbage Truck

When a flash fire erupted near a CNG-powered garbage truck, Beacon Scientific was called in to perform a fire/explosion origin and cause analysis and to determine the factors that caused and/or contributed to the incident.

The Physical Inspections

Beacon performed a site inspection immediately upon being brought in to the case. That inspection led to identification and retrieval of evidence and full documentation including over 500 high resolution color digital photographs. Evaluation of the site led to an initial conclusion that a hole in a flexible high-pressure supply line likely allowed CNG to escape into the atmosphere and eventually ignite.

Shortly after the site inspection, Beacon participated in a laboratory examination of he subject and exemplar hose assemblies that included both non-destructive and destructive testing using a variety of techniques and tools including visual and microscopic inspection and metallurgical and chemical analysis. This laboratory examination supported the conclusion that a hole in the supply line was the source of fuel for the explosion and provided insight into the likely cause of the failure: exposure to road salt.

Beacon later participated in a CT scan of portions of the evidence and exemplar hose. The CT scans showed that hollow wires were prevalent in the stainless steel braided line that failed.

The Document Inspections

Beacon reviewed 19 depositions, 8 expert reports and almost 50 additional documents related to interrogatories and salient subject matter (manuals, spec sheets, etc) in this matter.

The Analysis

The analysis began with determining the origin of the fire. All parties agreed that the origin was a leaking CNG hose that resulted in CNG being exposed to a flame from a nearby device. Beacon's report addressed this element by reviewing training records and depositions to determine which individuals should have known or should have been trained to know about the danger. This provided assignation of a share of responsibility.

The next part of the analysis was to determine the cause of the hose failure. Information from the laboratory examination and CT scan was integral to this along with review of documentary evidence including manufacturer guidance, recall alerts, spec sheets, standards and operator's manuals. This information was used to determine if

1) the hose assembly was proper for use in CNG systems,

2) the failure was related to past recalls

3) the manufactured hose complied with the requested configuration

4) the assembly had been tested for use in the specific application

5) previous recalls were sufficient

6) parties were appropriately notified of previous recalls

7) process control systems were sufficient in the design and manufacturing process

8) other common safeguards would have prevented the catastrophic failure

9) end users were aware of the issue and should have mitigated the risk

10) end users considered operations when upgrading their fleet from diesel fuel to CNG

11) end user maintenance personnel performed appropriate and competent inspections

12) misrepresentations occurred in the stream of commerce

13) representations by other experts were accurate

14) components were appropriately applied

The Conclusion

Beacon concluded through the above that there were multiple failures from the point of manufacture to the moment that the explosion occurred. These were detailed in a 63 page report. This report was integral in the parties settling this case.


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