Chief Charles Scripps of Painted Rocks Fire and Rescue in Darby, Montana conducted what they call a “foam experiment”. Here is their description of the video:
We flowed foam using a Chemguard foam generator to see if it would have value in the wildland environment. We used 1000 gallons of water with a 2% foam solution (Hale digital foam system). The test took about ten minutes. The foam line was about 1000-1200 feet, 20-40 feet wide and 2-4 feet deep. Further testing for ‘foam and roll’ as well as different percents of foam will take place.
(THE VIDEO IS NO LONGER AVAILABLE)
I have seen photos of this procedure before, and it has been used on prescribed fires, but has anyone ever seen it used on a wildfire?
In order to do this, you need a high-expansion foam generator, as opposed to a much smaller medium-expansion foam nozzle which is about 8-12 inches in diameter. Some high-expansion foam generators are so large they are mounted in the back of a pickup truck and most use either a water motor or a gasoline engine to drive a fan, which introduces a large quantity of air into the water/foam solution.
Thanks Chief Scripps and The Latest.
UPDATE September 15, 2009
From The Latest, we have more information from Chief Scripps:
The unit is a Chemguard model 300WP. This is a water driven unit so the engine does not need extra equipment. There are units that are electric or gas driven but neither develops the rpms of the Pok water motor.
I chose this one as it weighs 115 lbs and the next size up weighs 225 lbs. There is a limit to what I can get old volunteers to load, unload and carry safely. The foam was Silvex at 2% as measured by a Hale digital unit. The engine holds 1000 gallons so that was the limit of the trial. The factory recommendation is to run it at 80 psi. So for our first test that’s what we did.
I had seen the YouTube videos of high expansion foam filling aircraft hangers. What intrigued me was when they opened the hanger doors and the foam flowed out on the apron. I wanted to see how it would flow down a mountain. It seems to do this very well. High expansion foam lacks the durability of the denser stuff but it makes a very fast wetline. I think it would be excellent for ‘foam and roll’ in low fuels. I am trying to engineer a method to mount it to my engine so it would function off either side. One of the difficulties for testing is we are running out of summer weather so testing in hot weather conditions is getting difficult.
This is the engine we used.