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FreeRepublic , LLC PO BOX 9771 FRESNO, CA 93794
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Posted on 10/04/2003 8:03:18 PM PDT by Old Professer
We had a nursing home fire here in Nashville a week ago and 11 old people died; no fire sprinklers in the building and now there is a hue and cry to require retrofitting of all the "grandfathered" buildings.
I've tried to do some on-line research to see if there was a room-sized, pre-charged unit that could be installed to protect the occupants while permanent fixtures were installed.
So far, I've come up empty, but I have a great idea using a system that could be made from off-the-shelf components.
What I envision is a 75 gallon water heater tank connected to an 80Cubic Foot gas bottle charged to ~2300PSI and fitted with a double-regulated valve set at 75PSI connected to the cold water inlet line; the hot water outlet would in turn be piped across the ceiling to a conventional fire-sprinkler head that would "burn-out" at 155 degrees F.
This design would flood a 10X10X8 foot ceiling room with a bit over 1 inch of water in just over 2 minutes.
The two tanks would be clamped together with a bracket made in a figure-eight shape about the mid point from the floor.
The clamp would be equipped with flanges to bolt to the wall for earthquake protection and accidental jarring or bumping.
The whole thing could be hand-trucked into the room and filled from a garden hose and a temporary outflow pipe; the ideal location would be in a corner adjacent to the door.
I am placing it here mainly for comment and to register the idea (date and time stamp).
If I am out of order, I apologize.
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FreeRepublic , LLC PO BOX 9771 FRESNO, CA 93794
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It is in the breaking news sidebar! |
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It should work, so long as the fire gets to the sprinkler head before it gets to this bomb.
Fire sprinkler heads normally cover 100 square-foot areas and any fire in an enclosed area will cause a curtain of heat to rise up the walls along the ceiling and trigger the head before the temperature in the room rises 15 degrees overall.
Even if one took a cutting-torch directly to the tank while in the room the sprinkler would go off and drown the silly-ass trying such a stunt long before he could heat the tank to raise the pressure to a critical point.
An 80 degreeF temperature change on a car tire will only result in a 5PSI change.
If what you suggest would be a concern, a simple 16gauge metal cabinet around the assembly would shield quite effectively.
What would be the effect of using CO2 rather than air to pressurize the water? This would seem to have a number of advantages: (1) CO2 will liquify at IIRC about 1,000PSI allowing better density than air at 2,000PSI; (2) if the CO2 dissolves in the water, it would effervesce upon hitting the fire, acting as a useful additional extinguishing agent; (3) CO2 storage tanks are quite common in soda-fountain applications and may be cheaper than air storage tanks.
Otherwise, even if you don't like CO2, I'd suggest that pure water probably isn't the best extinguishing agent; some sort of foam (water-based or not) could probably do better. What would happen if you threw some dish detergent or other such stuff into the water tank?
At 75PSI? Note that he did specify a regulator between the pressure tank and the water tank.
The initial investigation points to wiring, either in the bed itself or an extension cord or a power strip.
The courts have enjoined the investigation at this point.
If you want to read all the articles (or as much as it left available) go to
The fire department is convinced that a working sprinkler would have extinguished the intitial fire and probably have limited the casualties to that room.
A 2,000PSI tank can do an awful lot of damage if it explodes. On the other hand, I wouldn't see any problem with putting a safety valve on the thing; such a valve would certainly be required on a CO2 tank, but should probably be used on an air tank as well.
A bed with a polyurethane foam mattress?
I like the basic concept. I thought though that standard sprinkling systems operated at pressures above 200psig though I may be mistaken.
Using CO2 or N2 would risk asphyxiation of occupants after the fire was out.
If the fire was allowed to burn with no abatement, everyone in the room would die or open the door and spread the fire to the rest of the building floor first and other floors next.
The sprinkler pipes were connected to a 10 inch water main piped under the floor from a perimeter square circle arrangement at ordinary city pressure.
The sprinklers were triggered by a sensor array on the ceiling and an emergency trip-handle in the fire closet where a 120 cubic foot Nitrogen bottle was piped to the unloading valve against a spring closure.
If triggered, the gas would open the valve and hold it open until the valve was manually reset.
The beauty of this system is that it required no electrical power to operate.
Back to the bottle as an explosive, over-pressured device: the amount of heat necessary to over-pressure air in a bottle would also be sufficient to burn through the piping long before the over-pressure condition ever occurred thereby releasing pressure and then this is a concern only if the sprinkler head fails to open and put out the fire (the source of heat).
Not unless you have a whole lot of extra gas. If there were 100 gallons of extra gas (which would mean there was more than twice as much gas as is needed to displace the 80 gallons of liquid) that would be about 13 cuft. The room you described is 800cuft. A 1.6% extra N2 concentration would be a total non-factor; a 1.6% CO2 concentration could be toxic with extended exposure in the absense of other ventilation, but again that shouldn't be a factor.
If it weren't for the DuPont-led environmentalists, freon would probably be a really good propellant, but unfortunately its replacements wouldn't be nearly as good here.
So getting the water to the pipes required about an atmosphere of pressure.
The sprinklers were triggered by a sensor array on the ceiling and an emergency trip-handle in the fire closet where a 120 cubic foot Nitrogen bottle was piped to the unloading valve against a spring closure.
What was the function of the N2 bottle?
This is basically an oversized version of the old-fashioned water-filled hand-held fire extinguishers Class A.
The difference here is the secondary pressure tank to fully flood the fire in less than five minutes.
An 80 cubic foot room measures 10 feet on a side and 8 feet high; an inch of water on the floor is about 63.5 gallons.
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