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sprinkler systems & class A foam
A question came up in training (and i didnt know the answer). Does anyone think or know if class A foam could be used in a building's sprinkler system? If yes how long have you been doing it and how does it work for you, if not do you think it would work at all or make a difference
Replies to This Discussion
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Permalink Reply by John Crabbe on
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Could it be used? Sure...however, never seen it for a building sprinkler system.
Realistically, such a system is not much different than having a Class A foam system on a pump. It is basically an injection type of system where foam concentrate would be injected into the sprinkler system while water goes to the open head.
Basically, this is the same basic system one would see on a Navy ship. All U.S. Navy ships have AFFF foam systems on them with two basic breakdowns for sprinklers. There is a balanced pressure proportioning system that basically measures water flow and foam and mixes at a set rate. Then there is an injection system with a seperate foam injection pump to run when the rest of the system runs and injects concentrate at a predetermined rate. Difference between the two, one injects right into the stream while one measures out the right concentration.
Aircraft Carriers utilize an injection system for the hangar and flight deck sprinkler systems. To mirror a similar setup for a building sprinkler system would not be too difficult to do.
Limitations are most likely like that of a fire engine.....you would want to adequately flush the system, outlets, and handlines after a use......doing similar for a building system could be an issue.....especially considering most building sprinklers are a wet type system as opposed to dry.
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Permalink Reply by Moose on
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I have seen foam systems before, but in large, high hazard buildings mainly, not in residential settings. I have taken the Fire Inspector I training at the academy and they showed us a video of a foam system in an aircraft repair hanger. It was a total flooding system and it had 6 large discharges, 3 on each side of the hanger along the roof line, when the system was activated the foam started to flood into the area and it took only 2 minutes before it was over head level. Very effective for the jet fuels used today.
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I would agree and that for the most part one would see foam sprinklers associated with fuels and aircraft as opposed to a simple building sprinkler system. I think overall, while possible to have Class "A" foam in such a system, the practicality and cost effectiveness are not there. There haven't been too many examples of an operating sprinkler system being ineffective to necessitating Class "A" foam, so how do you truly justify going that route. Besides, cleanup could be more difficult as opposed to just water....tought to say for sure....just don't see the cost effectiveness, nor practiclity of Class "A" foam for building sprinklers.....but definately possible.
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Permalink Reply by ashfire on
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I had a volunteer chief who was a federal FF at a Naval ammunition site in the suburbs of Washington DC. Much of what was kept there was in underground bunkers which I was told had a flooding system in the event of a fire in the bunkers.
There was a day way back when I guess something didn't work because the site and the surrounding neighborhoods felt the big boom in one of the bunkers.
The site closed down and the area was sold for public use.
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Permalink Reply by mike clark on
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Foam has been used for years in pre-action systems for high hazard locations - airplane hangers, and other potential high heat producing areas. The foam is stored in a bladder type tank and the sprinkler heads are open (no fusing required) and the system is activated by a heat detecting device, or manual activator In the event of a fire, the system is either activated automatically, or by manual mode..
Most standard sprinkler systems are made up with black iron piping. If the foam was stored in the piping system the heavy detergent effect of the foam would cause a corrosive action to be created within the piping. This would lead to obstruction and either reduced flow characteristics, or no flow at all.
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Permalink Reply by Ben Waller on
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There is another way to approach this.
Any sprinkler system designed to operate with water can use Class A foam that is supplied by a fire department pumper. Example: my department carries Class A foam in an onboard tank with an onboard injection/proportioning system. We can use that foam from 6% (let it snow) all the way down to 0.1% (essentially Light Water).
We have a large number of sprinklered buildings in our jurisdiction. All of them have both a domestic water supply and a FDC so that we can supplement pressure and volume. It is pretty easy for us to simply add foam to our supplemental FDC supply lines - it will pump out of the open sprinkler heads - usually no more than one or two, and usually with less GMP than our standard 150 GPM 1-3/4 hoselines.
You can do this with a CAFS pumper, too. Simply add the foam concentrate to the attack lines at whatever % is desired and don't turn on the CAFS air compressor.
As with a lot of things in our business, there's more than one way to do it. This way doesn't require on-site foam storage, it doesn't corrode cast-iron pipes prior to the fire, and it leaves a very small amount of foam solution in the line that can be flushed out during the system re-set.
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Permalink Reply by Russ on
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Thanks to everyone for your responses. i think i will give it a shot in a couple of setup rooms at a traiing burn (might have something here) ya never know
Ben: i was thinking 1% would do it but i'd be curious to see what 6% would do
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Depends on what you are looking to use it on.....6% seems like quite a bit. The navy uses AFFF class B at 6% in sprinkler systems and well, it can leave quite a mess when activated. The 6% is to create that barrier on flammable liquids. If looking at Class A, I would say 1% could be enough, but may be too much......perhaps try a lower concentration first.
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Permalink Reply by Cody McClung on
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Supposing you did pump foam through an FDC into a sprinkler system, I would imagine that flushing the system would be a nightmare, or just disregarded. I would have to say that it would be easier to send a hose line into the structure and flow foam through the hose line rather than the sprinkler system.
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Let's say the structure is a 100,000 square foot home improvement store and you have three firefighters on the first-due engine.
In that situation, pumping into the sprinkler system is much easier and quicker unless the system is not built to code. If the system is built to code, the FDC will be within 100 feet of a hydrant.
There's no way a two-person hose team will get a hoseline deep into the home improvement store more quickly than the same crew can pony up to a hydrant and stretch 100 feet of 2-1/2 to one of the FDC intakes, then repeat one time.
Flushing the system is easy - just disconnect from the FDC, shut down the OS&Y valve, drain the system at the main drain, then re-charge the system by opening the OS&Y valve. If the building has a zoned sprinkler system, it's even easier, as you only have to drain the zone where the fire occurred, not the protection for the entire building.
Even strip malls are typically large enough that supplementing the sprinklers is quicker than a hoseline unless the fire is close to the front door.
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Foam tends to leave less of a mess than either fire damage or water damage, especially in civilian commercial structures.
Our foam systems default to 0.5% for Class A. We can adjust up or down as needed/directed by Command.
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Russ,
We typically use our Class A foam at either 0.5% or 0.1% in handlines. It works the same way in either sprinkler or standpipe systems.
Our onboard system gives us the option to use either Class A or Class B foam at any range the system allows - up to 6%.
We generally don't use Class A at concentrations above 0.5% for interior attacks with hoselines.
We use Class A foam all the way up to 6% at wildland and wildland interface fires to create ground fire and ladder fuel barricades. Applying Class A foam through forestry hose is way easier than ranking handlines or chainsawing ladder fuels, it's faster, and it leaves the environment more intact afterwards.
We use the new National "green" foam that is completely non-toxic and completely biodegradable.
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