CAFS And Its Impact In Fire Scene Investigations

Investigators were concerned about how the use of the foam would impact the use of accelerant detection canines, conceal scene hazards or create slippery conditions and how much time was required for the foam to dissipate in order to conduct an origin and...

Some of the respondents stated that the foam was less destructive to the scene than water and that the foam protected the areas where an ignitable liquid was present. Those that had accelerant detection canines reported that the canine gave positive alerts and did not have any issues when the foam was present.

Additional Assistance

Montgomery County investigators contacted a subject matter expert in CAFS field, Dominic J. Colletti, Global Foam Systems Product Manager for Hale Products, Inc. Mr. Colletti provided information and demonstrations on the use of CAFS and agreed to assist in potential test burns at a future date. He also educated fire investigators on the differences between standard nozzle aspirated class A foam, and compressed air Class A foam applications. When using CAFS, less foam concentrate will typically be exhibited within the structure or room of origin as compared to what would be seen when using standard nozzle aspirated Class A foam for fire suppression or overhaul. The reason: CAFS application results are in one way different (as compared with the application of standard nozzle aspirated Class A foam) in that typically from two-thirds to about half of the total water supply (total gallons of foam solution) is required to extinguish a given size fire.

It was then determined that the next course of action was to enlist the assistance of the ATF Fire Research Laboratory located in Ammendale, MD. The Montgomery County Fire Department has had a long standing relationship with ATF as their laboratory was previously located within Montgomery County. ATF Special Agent/CFI Gregg Hine and Section Chief Kenneth Steckler were contacted to discuss a potential research project to further examine the impact that CAFS would have on fire investigations. Special Agent Hine, who has worked with Montgomery County, concurred with the concerns expressed by fire investigators and canine handlers. The use of foam was also a concern for the new ATF Fire Research Laboratory because of the potential that foam would be used in the future to suppress fires in the laboratory. At the Fire Research Laboratory, all run-off from fire suppression is treated on-site by a water treatment center. Section Chief Steckler was particularly interested in how the foam would be handled by the water treatment system and to determine any problems that may arrive from inserting foam into the treatment system.

Testing Methodology

To evaluate the impact of CAFS on fire investigations in a real-life scenario, two burn cells were constructed at the ATF Fire Research Laboratory (FRL). Both burn cells were identical in size and geometry. No instrumentation was placed within the burn cells during the tests, however, both tests were photographed using a digital SLR camera and a digital video recorder.

The burn cells were constructed of standard wood framing materials and the interior was finished with gypsum sheetrock panels screwed to the walls. The cells measured eight feet deep by 22 feet wide. A large six-foot opening that was eight feet deep, similar in geometry to a hallway, provided access and ventilation to each cell. This opening allowed clear visibility into the burn cell during the tests and allowed ample ventilation. The ceiling was the standard eight feet and the floors of the burns cells were a combination of both carpet and vinyl sheet goods applied directly to a sheetrock sub-floor. The interior of each burn cell was furnished with various residential items to replicate a typical residence.


Two fire tests were conducted at the ATF FRL. An ignitable liquid was utilized in each burn cell as an accelerant, thus providing a substance to examine canine performance. Ignition of the liquid was conducted using a standard ATF FRL technique involving a propane torch affixed to a 10-foot wand. The fire was allowed to spread throughout the interior of each burn cell and then progress to a flashover. Each burn cell was then allowed to continue to free burn for approximately one minute post-flashover to replicate a normal room and contents fire as seen in Montgomery County, MD. Fire suppression of both burn cells was conducted by a representative of Hale Products utilizing Hale Products equipment. Additional fire suppression support was provided by the ATF FRL Fire Brigade utilizing standard firefighting hose lines connected to standpipes within the facility. In addition, positive pressure ventilation (PPV) was utilized after the fires were knocked-down with the CAFS to removed trapped smoke and identify any hot spots within the burn cells.