Idea for Room Fire Sprinkler Comments?

vanity | 10/4/03 | Ken Roberts

[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.

[Chummy]

Would this involve having 75 gallon water heater tanks, etc. for each individual room? How does one safeguard the common areas, eg, dining halls, hallways, restrooms, support facilities for the building?

[Old Professer]

It opened the valve and held it open against water pressure.

I think I misstated the volume of the room; it is, of course 800 cubic feet.

[supercat]

Sorry; the dip tube would be removed prior to using the tank for this purpose. The hot water pipe picks up from the bottom in my proposal and no heating elements need be incorporated.

What he's referring to as the "dip tube" I think is the cold water pipe. You need to take water from the bottom of the tank, since gas will accumulate at the top. If you remove the pipe that goes to the bottom, you'll get nothing but gas out.

This is basically an oversized version of the old-fashioned water-filled hand-held fire extinguishers Class A.

Have you considered other substances besides water? 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.

How effectively can you make sure that water will get to or stay at places other than the floor? Would detergent or some other such substance help?

[supercat]

It opened the valve and held it open against water pressure.

That requires a 120CUFT N2 bottle? Why not use a pilot-valve arrangement like that used in electropneumatic pipe organs (in a pipe organ, a small valve allows pressurized air into a bellows which then operates the main valve; for water, I'd sugget having a small valve let water into a piston to do likewise).

[Old Professer]

Indeed, it is one such unit for each room; the hallways and the rest are generally low-risk ignition areas and not necessarily protected in many buildings.

Actually, I started with the idea of using a bladder-fitted tank with the bladder enclosed inside the tank and chargeable from an outside source with air at normal ASME air tank pressures of 120-200PSI but this would require a special construction and would cost more but would be far simpler.

In any case, I figure the device would need to dump (rain) at least one inch of water in less than 5 minutes to be effective, which is why I said it would take at least 63 gallons for a 10 foot by 10 foot floor area.

[Old Professer]

This is a nursing home; people are immobile. Any gas that will smother the fire will smother the people.

This whole thing relies on a single fire sprinkler head of an industry standard design that is capable of delivering 25 GPM and will cover the entire enclosed area, floor-to-ceiling thereby smothering the fire.

If the fire has a secondary source of fuel and air, all is lost.

[Chummy]

Kitchens? Mechanical areas? Storage areas?

[Old Professer]

I didn't design it, I just made the rounds with the fire inspector testing the units. I arranged to have all the bottles hydrostated and they all passed - even the one stamped 1937 as its first hydrostat date. This was in 1991.

[Old Professer]

Kitchens have their own fire-suppression already by code; mechanical areas are generally manned or policed apart from the quarters areas; storage areas are supposed to be isolated from ignition sources by code.

[Chummy]

I recognized immediately and share in your concern with this problem: it's a choice between protecting the vulnerable and the massive expense of retrofitting existing buildings to a new code.

I'm just wondering if there is not a more efficient means of solving the problem.

Where would all of these water heaters and support apparatus be placed?

[supercat]

Any gas that will smother the fire will smother the people.

I wasn't intending the CO2 as a primary fire suppression agent; I was suggesting its use as a propellent (though having large quantities of it dissolved in water may not be too good, limitting the time that water is exposed to CO2 under pressure would keep that down). The quantity of gas needed as a propellent is small enough that asphyxiation should not be a problem.