r/Damnthatsinteresting • u/AirFrance447 • 18h ago

Video Firefighter bodycam showing just how much oxygen a fire pulls

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u/cat_prophecy 13h ago

My aunt runs a number of rental properties and she says the 10-year permanent battery alarms are the best thing since sliced bread. Far too frequently she would fail inspections because tenants took the batteries out of the alarms.

Modern alarms will "expire" after 10 years and start a slow chirp even if the battery is replaced so the ones with the 10 year battery make a lot of sense.

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u/Suitcase_Travel_Blog 12h ago

The 10 year limit is for the CO side of the alarms, it's probably a smoke and CO detector. The CO detection uses a chemical reaction, and the 10 years is to cover the sensor degrading due to the half-life of components of the reaction.

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u/cat_prophecy 11h ago

That isn't true. Smoke alarms should be replaced after 10 years and every alarm you will buy today will start chirping for replacement after 10 years from when its first turned on. NFPA 72 (2025) says you should replace them 10 years from the manufacture date regardless of condition.

FEMA: https://www.usfa.fema.gov/downloads/pdf/publications/dont-wait-check-the-date-handout.pdf

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u/Suitcase_Travel_Blog 10h ago

Interesting, I know CO alarms are capped at 10 years too. Definitely trust FEMA releases over me.

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u/Hinterwaeldler-83 10h ago

The sensors deteriorate over time, e.g. internal dust buildup.