what it be possible to create an pressure ventilation system in a airtight room?

Question

suppose you had a completley air-tight room with ventilation system that was closed until a certain amount of air pressure was created it could open and suck out all the air as fast as possible and then push fresh air back in.

i wish to create air-tight room in which if a fire is lit and the air will heat and start to expand the pressure valve, as on a ship uses to open when a certain amount of water pressure builds up, will open and then a fan of some sort can suck all the air out extuingishing any fire and then push air back in to preserve any life left in it if possible

i imagine it work a little something like this
when the fire starts the air will expand the lightly pressure sensitive vent opens air is sucked out the fire is extuingished air pressure builds up even greater in the room another vent opens air flows back in
i would like to know if this is possible and how it would be accomplished

**thank you in advance**

Answer 1

Your people are already dead. And forget air tight, unless you need it for something else.
Better to use specialized heat and ionization detectors to sense a fire while it is small. Have a sprinkler system to control the fire as people are leaving and before it becomes major. (Too bad Halon is no longer permissible. Thank the idiots in Washington,)
Yes, you do want to put the fire room on exhaust with the exhaust stack directed well away from any building air intakes. Shut off the ventilating air supply to the room with smoke-rated fire dampers and automatically close and securely latch (not lock) the doors. Pressurize the adjoining rooms and the floor above and perhaps below the fire. By this procedure you are controlling the smoke and heat which is the real killer and depriving the flames of air.

Answer 2

This idea seems to have several flaws. First, nobody can be in the air tight room for more then the time it takes to use up the oxygen in the room. Second, the change in air pressure would be pretty small, so you'd either get lots of false trips or it wouldn't trip when you wanted it to. It would be better to use a sensor that used heat rise. Third, what would a person do if they were in the room when a fire broke out? They would die from the lack of oxygen (faster then in the first case). And finally, since this room is of limited space, it will burn off the oxygen in the room during the fire and snuff itself out even if you don't evacuate the remaining air in the room. And if you haven't done anything but take the oxygen out of the room, the fire would likely restart when you vent air back into the room.

Answer 3

You may be confusing pressure and oxygen. In an air-tight room you would suffocate as the oxygen is used up. So would a fire.
try this experiment if you like, with adult supervision,if your to young to play with matches.
Place a small lit candle in a large jar or can. Cover the top with a piece of tin foil and seal it with a rubber band. The foil should be tight across the top.
Notice the foil does not raise (no pressure increase) Wait about a minute and notice the foil curve down into the jar or can. This is because the fire has removed the oxygen from the air.
It may help to visit the 'How stuffworks.com' website