fire alarm

A fire alarm is a device that when activated sounds an alert indicating that a fire has been detected within a building. The trouble with fire alarms is that they are so tempting to activate. They are always there with their red and white faces, standing out against the pale paint of the walls. The red lettering which reads "PULL HERE" just makes me want to pull it!

As a general rule, fire alarms not linked to a fire drill will always be when it is least inconvienient for everyone around, and at least twice as inconvienient when you live in residence halls or dormitories on the campus of your University of choice.

Continuing with the sweeping generalizations, when fire alarms go off, you will either be studying for a test, sleeping, going to sleep, watching a movie with your significant other, or just getting up. In the rare circumstances when the alarms don't inconvienience you immediately, you will invariably be forced to stay outside for half an hour in weather that is at least ten degrees below freezing with gusts of wind at and above thirty miles per hour. Sometimes, you get both- depends on how much karma you've been saving up.

Most fire alarms are triggered by the same people- those individuals who smoke in a non-smoking section, and people who are making microwave popcorn under the influence of booze, weed, pr0n, or anime. Surprisingly enough, when the trigger can be traced, he/she in the future refrains from doing something stupid that would force everyone from their comfortable rooms. Maybe it's the duct tape that their door gets plastered with. I dunno.

Means of warning occupants of a building that a fire (smoke) is present, so that they might escape before it reaches them.

In earlier times watchmen who sat in high perches were the only warning. Many of these watch towers were part of the fire hall, and are still standing in many places.

Modern fire alarms are automatic, and there are a few types.

Thermostat alarms detect a rise in the temperature and go off when there is a quick rise in temperature or when the temperature reaches a set point.

Photo-electric cell activated alarms detect the darkening of the room by smoke. (It seems to me this alarm would be the least effective and the most annoying, going off everytime you try to set the mood.)

Radioactive alarms are the most sensitive and reliable. They contain a small amount of radioactive material with ionizes the air in a small compartment. The battery or power source supplies the compartment with a small current which flows through the ionized air. When products produced by combustion enter the compartment they reduce the electrical flow and the alarm is set off.

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Reference: Encyclopædia Britannica