• rumba@lemmy.zip
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        2 hours ago

        They run off batteries, using either isotope decay or light sensor (or both)

        I actually have one hanging off my ceiling right now, it’s battery was fine, but it tripped likely due to dust or a spider on the optical sensor. It went off at 2am, network sent them all off, took me 10m to find the right one I wasn’t about to just blow it out and out put it back on the ceiling :)

      • Natanael@infosec.pub
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        7 hours ago

        Depends on model. Almost all older ones does (using radiation from the isotope to electrically charge smoke particles that pass through, which then can be detected by a sensor).

        Many newer ones are optical.

        • SaveTheTuaHawk@lemmy.ca
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          4 hours ago

          The A-241 does not charge the particles, it ionizes the air in a small chamber that allows a steady current. Any smoke particles disrupt these currents to set off the alarm.

    • SGforce@lemmy.ca
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      18 hours ago

      Don’t know what it’s like where you live but around here if they are old enough to fall apart they aren’t to code anyway. They need replacing like every two years, I think.

      • SaveTheTuaHawk@lemmy.ca
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        4 hours ago

        Seven to ten years, depending on manufacturer. The newer ones use a lithium battery and last ten years.

    • shalafi@lemmy.worldOP
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      19 hours ago

      Our floor plan + regulations made for a stupid setup. All three bedrooms and hallway require an alarm. All 4 are within 8’ of each other.

      And there isn’t one in the kitchen!

      • FrederikNJS@lemmy.zip
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        10 hours ago

        The ones in the kitchen will be set off by burnt food… Leading to people disabling the alarm anyway.

        In your kitchen you can get heat sensitive fire alarms instead.

      • lovely_reader@lemmy.world
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        17 hours ago

        Afaik, it’s not recommended to have them in kitchens, because harmless culinary mistakes can set them off so people end up disabling them in annoyance. You have to have one in a common area on every floor, but ideally not the kitchen.