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Ask the Technician

Douglas Krantz -- Fire Alarm Engineering Technician, Electronic Designer, Electronic Technician, Writer





Harry Flanagan Wrote:

I moved into a 1-bedroom apartment recently that has 3 smoke detectors (the flat, round kind mounted on the ceiling), but also mounted on one wall is a red strobe alarm that I believe, through web research, to be a Gentex Commander 2 alarm, probably installed in 2004 when the complex was built.

Could you tell me how this operates, and especially what activates it? There is no "pull handle" near my apartment, or on the device itself. I was wondering if perhaps the smoke detectors trigger it, or if a pull handle elsewhere at the apartment complex (a common hallway, etc.) activates it. It seems like a rather commercial-looking object for a small apartment and I'm considering covering it with a picture, as I wouldn't need a strobe to find my exit, and it's a real eyesore. There are also several sprinkler heads in the ceiling covered with pod-like covers. Would it be safe to cover the alarm?

Douglas Krantz Wrote:

You mention 3 different fire safety features of the apartment building you're in.

Smoke detectors on the ceiling are there to give you an alert quickly that there's even just a little smoke starting to build up in the room. Breathing smoke from the materials in your apartment can and will kill you, so this safety feature gets you out of danger quickly before the smoke becomes a real danger.

Sprinkler heads are there to protect the property and prevent the rapid spread of fire that's already in the room. For the sprinkler head to spray water, the temperature of the room is already quite high, and by that time you should have left the apartment.

The red Gentex (Brand Name) strobe alarm is called a "mini horn/strobe". It is actually connected to the common fire alarm system of the whole building. The common fire alarm system is activated by any pull stations next to stairs or exits, by smoke detectors in the hallways of the building, and by water flowing out of a sprinkler head anywhere in the building. When this sounds off, you need to get out of the building right away. On the way out, just don't breathe any smoke if you don't want to be carried the rest of the way out by the firefighters.

The reason that this mini horn/strobe is inside your apartment is that the sound of the alarm out in the halls is quieted quite a bit by the apartment walls. If the sound is just in the halls outside the apartment, some people can sleep through the building alarm sounds. To wake up everyone if there's a fire detected in the building, these sound off near the people living inside the apartment.

I know it's an eyesore, but the mini horn/strobe is there for your protection. Covering up the strobe means it doesn't get your attention and covering up the horn means it becomes muffled. Don't cover it, just pretend it's part of the apartment and ignore it. If you leave it alone, someday it just may save your life.

Harry Flanagan Wrote:

Thank you so much, Mr. Krantz, for your quick response and thorough and detailed answers to my questions. I had spent quite a bit of time on this on the internet and just found myself going around in circles, never getting close to the explanation you've given me. I'm so glad I came across your site and am grateful for your time, expertise, and obvious desire to help people. A rarity!






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Douglas Krantz

Describing How It Works
facpdoug@douglaskrantz.com

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Electrical Flow


On this website, most references to electrical flow are to the movement of electrons.

Here, electron movement is generally used because it is the electrons that are actually moving. To explain the effects of magnetic forces, the movement of electrons is best.

Conventional current flow, positive charges that appear to be moving in the circuit, will be specified when it is used. The positive electrical forces are not actually moving -- as the electrons are coming and going on an atom, the electrical forces are just loosing or gaining strength. The forces appear to be moving from one atom to the next, but the percieved movement is actually just a result of electron movement. This perceived movement is traveling at a consistent speed, usually around two-thirds the speed of light. To explain the effects of electrostatic forces, the movement of positive charges (conventional current) is best.

See the explanation on which way electricity flows at www.douglaskrantz.com/
ElecElectricalFlow.html
.