The Chicago Fire Department and Underwriters Laboratories Inc. recently designed and conducted a laboratory-based test comparing the use of water alone versus a Class A foam-water mixture when suppressing residential fires.

Chicago Deputy Fire Commissioner Gene Ryan and UL Vice President Chris Hasbrook planned the test with input and support from their staff. The goal of the test was to determine if a foam-water mixture was more efficacious in suppressing a fire in a one-room residential fire than water used by itself in a comparable fire. Testers used a temporary, four-room, 1-story concrete house that was built within UL's large-scale fire testing facility in Northbrook, Ill. This temporary building, designed and built with two identical bedrooms, lent itself perfectly to a side-by-side comparison test.

CFD and UL together outfitted each bedroom with the exact same building contents, including a bed and bedding, a couch, one desk and chair, carpeting, wall-coverings, end tables, and light fixtures. UL and CFD also closed the two window openings in each of the two bedrooms by installing double-pane windows and frames, and left open the bedroom door for each fire scenario. UL installed thermocouples and sensors in each bedroom to capture temperatures and oxygen levels, and used thermal-imaging and digital-video cameras to capture the events.

The first bedroom fire was suppressed with water only. The second was suppressed using a mixture of water and a Class A foam produced by Chemguard at a concentration of 0.5% in water. In each case the bedroom fire was ignited when a lit match was dropped into a small garbage can situated next to the bed. Each bedroom fire was allowed to reach flashover, which occurred within minutes.

In each scenario the fire was attacked from outside of the temporary building. Firefighters vented the bedroom window closest to the bed, and sprayed water (in the first fire) and the water-foam mixture (in the second fire) in a circular pattern against the ceiling of each bedroom for 15 seconds.

Flashover occurred in both bedrooms and the temperatures reached roughly 1,700°F. Water suppressed the fire in the first bedroom, but the fire re-ignited within seconds after the hose line was shut off. The water-foam mixture suppressed the fire in the second bedroom within 15 seconds, and the fire in the second bedroom did not re-ignite. Additionally, data from the thermocouples in both bedrooms revealed that the heat from the fire was reduced more quickly in the second bedroom.

“This test validated our approach to using a water-foam mixture when possible to suppress residential and commercial building fires,” said Ryan.

Chicago Fire Commissioner Ray Orozco was pleased with the test and with the results. “This test is an example of the benefit of this partnership, or as we say about this partnership, ‘When science meets the street.’”