Smoke Detectors

[Koolau]

The half-life of the radioactive element in smoke detectors is over 430 years, there is still 98.41% of the radioactive material present after 10 years.
Kinda strange that the self-life of a smoke detector has been "10 years" with no improvements in the last 50 years...

When my latest smoke detector (AC w/ 9V battery backup) needed replacement I replaced it with a combination carbon monoxide (CO)/smoke detector that uses two AA batteries, so I installed lithium Energizer AAs instead of the alkaline batteries that came with it.

IIRC, as alluded to in other posts, all new smoke detectors 'self-destruct' after 10 years, removable battery or not.

Can't confirm the "self destruct" feature, but I'm assuming NO detector manufacturer wants liability beyond 10 years - even if the alpha emitter is good for a human life time. There are other components (electronics, etc.) that are not as reliable as the decay of Am 241.

General aviation aircraft manufacturers virtually quit the business for several years because they were being sued for "defects" on aircraft dating back to near antiquity. This issue was "solved" by the General Aviation Revitalization Act of 1994. Smoke detector manufacturers don't have such protection so I'm assuming they protect themselves by stating that the detector is only good for 10 years. Apparently, the "smart" mfgs. make their detectors self destruct?? YMMV

 

[jazz4cash]

I was lying in bed one morning and I kept hearing a faint "chip, chip" coming from outside. I texted a neighbor two doors down....he heard it too but did not know the source. I walked around the inside and outside but could NOT determine where it was coming from. It's truly amazing how difficult it is to determine the direction of the source. After a while I ignored it. Then the Fire Department showed up. They fanned out in all directions and eventually congregated near a collection of trash bags and cans that had been left out the next-door neighbor. They had just moved out and left a bunch of cans, bags and junk for pickup. The discarded smoke detector was located deep inside one of the trash bags. They removed the battery and then stomped it to bits with a heavy boot (). When you discard your detectors, don't forget to remove the battery!

 

[JoeWras]

As you say, heat detectors are not a substitute for smoke alarms. They are not considered life safety devices and do not comply with current code requirements for residences. You can keep them installed, of course, but these days they are typically considered collector's items.

First of all regarding the 10 year battery models. About 90% of the ones I installed work well for about 10 years. No chirps. Some start chirping way too early. It is a crap shoot.

Second, I have a story about the quoted mechanical school bell types... My dad was a sucker for in-house salesmen pitches. I don't know why. I remember going to western union with mom sending a telegram in the 3 day window to unwind a contract on burial plots. But back to detectors. Dad invited this guy to quote us on fire safety, sometime around 1975. He spent a few hours in our house, and even gave me fire safety tips. In retrospect, they were bad tips (like breaking the window instead of opening it on getting out).

The quote came to something like $2k. This was 1/3 to 1/2 the price of a nice car. It mostly was made of those bell heat detector types. I remember that because I thought they were cool. I was a budding engineer, after all.

Dad looked at him. Stood up from the table and said: "Get the hell out of here!" It was shocking to me. Dad had a bit of a temper, but this one really sealed it in my memory. He felt it was all a scam.

It wasn't but 7 years later or so when I was in college that I came back on break and installed a few of the new cheap smoke detectors for them. Mom and dad were so happy. Dad even recalled the incident. These came in handy as they got older and had kitchen incidents.

I still think those old bell ringers are cool. I've seen some recent videos of people setting them off, but only after applying fire to them after too long a period of time.

 

[old medic]

I still think those old bell ringers are cool. I've seen some recent videos of people setting them off, but only after applying fire to them after too long a period of time.

We had some issues with someone coming into our house, and made a pull tab hooked to the door. wish i had video of when he opened the door...

 

[JoeWras]

Ha ha! The mechanical bell is crazy loud and irritating. Must have been fun.

Most of us grew up with that kind of emergency bell. We've now been conditioned to the high pitched beep and strobes. Nothing wrong with that, just different. I appreciate the strobes too. I wish more home detectors had strobes.

 

[ERD50]

I was lying in bed one morning and I kept hearing a faint "chip, chip" coming from outside. I texted a neighbor two doors down....he heard it too but did not know the source. I walked around the inside and outside but could NOT determine where it was coming from. It's truly amazing how difficult it is to determine the direction of the source. ...

Yes, that single tone, high frequency is difficult to locate. A sweep tone that went from low frequency to high would not only be heard better (that sweep tone would stand out more than a single tone), but it would make it easier to locate (different frequencies would give different directional cues to our ear/brain).

The newer ones 'talk' to us, which is a big improvement. Yet, AFAIK, the low battery is just a chirp, which is so difficult to track down - especially when it is a few chirps every 10 minutes! By the time you get near it, it stops - stupid.

Now, some rationalization is that those loud 'beepers' are energy efficient (for longer battery operation), because they are resonant at that one frequency, they aren't really like a regular loud-speaker. To make a good sweep tone requires something more like a speaker. A compromise would be two resonant devices at different frequencies, and switch between them (like the European police sirens we hear in movies).

Ahhh, a comment noted that with fixed tones (instead of the ramp up/down of US siren), the Doppler shift is more distinct, so a human can detect movement and direction better. The ramp tone buries that information.

-ERD50

 

[ERD50]

I was not aware of the mechanical bell heat alarms. But I was surprised that our 'new-to-us' house (built 2007), has a heat activated water sprinkler in the furnace/water heater room.

I never saw one of those in a residential area. I'm afraid I'll bump it (this room is my workshop now), or it would false trip, and flood the place. I guess I should build a cage around it to at least prevent me from bumping it.

At least it doesn't take batteries. I assume it is a one-and-done system (melting wax pellet?)? No way to test it, and then reset it?

-ERD50

 

[JoeWras]

Here's a guy applying fire to his as a test. Advance to 2:10 if not directed there.

 

[Koolau]

FIL had a Carbon Tetrachloride fire suppressor in his basement. It worked by melting a plug which then "deluged" the fire with carbon tet. I warned him that the toxicity of the carbon tet meant that this device should be a museum piece and not a real method to save lives now that we had actual smoke detectors and ABC fire extinguishers. He was "old school" and would not replace it. DW and I convinced MIL to allow us to at least install real smoke detectors for them. BUT the carbon tet suppressor was still there when FIL passed and MIL finally went to the nursing home.

 

[RetiredAndLovingIt]

The local gas company had a free weatherization program that I signed up for 3 years ago and they installed 10 year battery operated combo smoke/carbon monoxide alarms in every room except the bathrooms on both levels.
They located them all at a height just above the door frame, one at the same level in the open area at the top of the stairs and another downstairs by the door to the garage at eye level. I think I have a total of 9 or 10 and the location makes them easy to test/remove or replace with a chair or 6' ladder.
I still have my original 2 hard wired ones which take the 9V batteries and usually last a couple of years but now that I think about it, they are probably due for replacement due to their age.
I will say I feel very protected with these in every room. When they were installed, I checked the price, they were selling on Amazon at $30 each at the time which I felt was very reasonable for the protection offered.
Installing new ones at a lower height and longer battery might be an option to consider.

 

[Walt34]

Since I retired from being a fire protection engineer it appears there have been changes to household smoke alarms making them much less susceptible to nuisance alarms from cooking activities. I'm out of the loop and I'm really not up on that, but if true that's very good news.

When I read about house fires that have lines along "...and the smoke detectors were disabled" I can certainly understand why people do that. The ones we have can be temporarily disabled by pushing a button and I won't have any other kind.

Many decades ago I got so tired of the false alarms I finally did give up and disabled the stupid thing.

Getting back to reinstalling new ones, yes it is almost like a light fixture, one white wire (neutral) one black (hot) one red (signal to the others) and a green (ground). The ones we have are on a base that is hardwired and then plug into that but I don't know if the base plug is industry standard to make it easy to change them out in the future or not.