Smoke Detector Born On Date

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kwired said:
I did not claim to know how much impact on performance the half life has in 10 years, but it kind of makes sense that it will be a limiting factor in some way, even for a device that has not been placed in service yet but the radioactive material is decaying even though it is not being used.
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Yes, it does make sense that the time factor starts from time of manufacture, since you cannot "turn off" the radioactivity.
But for americium, the intensity of the radiation after ten years is still greater than 99% of the original level. If the isotope used had a half-life of ten years, then at ten years the output would be 50% of original, at 20 years 25% of original, etc.
The other electronic components are much more likely to fail in ten years than the radiation source!
 
PetrosA said:
Both, AFAIK. I still don't know whether I'd trust them in my house, but since our smokes need upgrading, I need to make a decision. Unfortunately, it's not wired for interconnected smokes, so the battery units would make my life a lot easier...
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I suggest the First Alert Onelink units. They are wireless and easy to set up. We just put 15 of them in a small apartment.

We paid 33 bucks each at the supply house. Here is a 2-pack for 43 something:

http://www.amazon.com/First-Alert-SA501CN2-Wireless-Operated/dp/B000FBQC1K
 
Keep in mind that the "fire alarm code' is completely irrelevant to household smoke detectors. That said ...

There are three basic types of alarm elements. Central,commercial systems might use temperature sensors - which are not used in homes.

Photoelectric- type detectors will operate virtually forever, and the test button is a realistic test.

The most common type of detector, though, is the "ionization' type. These detectors use a radioactive element to ionize the air in the test chamber. Since everything radioactive decays - loses its' radioactivity over time - eventually the thing won't put out enough radiation to be effective in detecting smoke. For the household detector, this period is 10 years. After 10 years, the device may work fine with the 'test' button, but never see smoke.

CO detectors have a similar issue; earlier models had a life of five years.
 
Based on what I've read here, I would venture to say at least 50% of smoke detectors installed in this country are useless because the average homeowner doesn't have a clue they have expiration dates.
 
A/A Fuel GTX said:
Based on what I've read here, I would venture to say at least 50% of smoke detectors installed in this country are useless because the average homeowner doesn't have a clue they have expiration dates.
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Do they have a true "expiration date", or is it just the fact that after 10 years the risk of something failing is increased enough that it is a good idea to replace them just in case?
 
kwired said:
I did not claim to know how much impact on performance the half life has in 10 years, but it kind of makes sense that it will be a limiting factor in some way, even for a device that has not been placed in service yet but the radioactive material is decaying even though it is not being used.
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If it makes sense why is their no similar time limit for system smoke detectors?
 
kwired said:
Do they have a true "expiration date", or is it just the fact that after 10 years the risk of something failing is increased enough that it is a good idea to replace them just in case?
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I agree with your statement but in reality, EVERYTHING has a finite lifespan so why are smoke detectors singled out? Perhaps the fact that they are in the life safety realm and the manufacturers see this as a chance to sell more units? Bottom line, I have a case of brand new BRK 9120B's that have a date of 2005 on them. Should I toss them in the trash?
 
iwire said:
If it makes sense why is their no similar time limit for system smoke detectors?
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Not knowing what differences in construction standards may be or what testing results may be I can't really answer that question.

Devices that are a part of a system may still have a recommended time to replace, but may not be same time as typical residential grade detectors.
 
K8MHZ said:
With RoHS lead free solder, it's probably accurate to say there is a 10 year life span. Or less.
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Do you have any evidence on lifespan of lead-free assemblies other than tin whisker theory?
 
Too many people come out of their home in a body bag.
Dying over a $20 appliance is senseless.


Does anyone on here unplug their coffee maker when it's not being used? Those things are notorious for spontaneous combustion.

Just lost my house on June 19 because of an overheated stereo I had setting on my patio. 4 o'clock in morning I heard noise and found patio on fire breacj=hing into house. Smoke detectors had not activated yet but had we waited until they had to wake up, I feel we would have crawled under flame to exit. Just replaced detector 1 1/2 year ago and will replace every 5 years after we rebuild. FYI, I have also been a volunteer firefighter for 30 years and building inspector for 24 years. It was sad and neat to watch my house burn.
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kwired said:
Not knowing what differences in construction standards may be or what testing results may be I can't really answer that question.

Devices that are a part of a system may still have a recommended time to replace, but may not be same time as typical residential grade detectors.
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If you look at the link I put up you will find that they do not have a time limit.
 
102 Inspector said:
Just lost my house on June 19 because of an overheated stereo I had setting on my patio. 4 o'clock in morning I heard noise and found patio on fire breacj=hing into house. Smoke detectors had not activated yet but had we waited until they had to wake up, I feel we would have crawled under flame to exit. Just replaced detector 1 1/2 year ago and will replace every 5 years after we rebuild. FYI, I have also been a volunteer firefighter for 30 years and building inspector for 24 years. It was sad and neat to watch my house burn.
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That sucks, glad all are OK, that is scary.
 
iwire said:
If you look at the link I put up you will find that they do not have a time limit.
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Sorry, I did not look at the link before. It does suggest that the detectors that are a part of a system typically are tested on a regular basis, where a stand alone smoke alarm may not be tested all that often, which is very possibly the reason for the difference. Now the instructions with the average stand alone smoke alarm do say to test monthly, and we know that always happens:happyyes:
 
mgookin said:
Do you have any evidence on lifespan of lead-free assemblies other than tin whisker theory?
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The lifespan difference is due to the solder not flowing and sticking as well as lead solder. People in the circuit board business have been having trouble with RoHS solder. Especially on the parts that are still hand soldered. I first heard about it from people I know in radio. Search 'RoHS solder failures'. There is lot's of info on it there.

We were supposed to be 'lead free' by now, even for hand soldering. But lead solder is still available. The lead free stuff is garbage to a hobbyist. At the mfg. level it's just tough to work with and makes for a higher failure rate and shorter lifespan. I heard the military will not allow RoHS solder in their components. I don't know if it's true or not, but it makes sense.
 
K8MHZ said:
The lifespan difference is due to the solder not flowing and sticking as well as lead solder. People in the circuit board business have been having trouble with RoHS solder. Especially on the parts that are still hand soldered. I first heard about it from people I know in radio. Search 'RoHS solder failures'. There is lot's of info on it there.

We were supposed to be 'lead free' by now, even for hand soldering. But lead solder is still available. The lead free stuff is garbage to a hobbyist. At the mfg. level it's just tough to work with and makes for a higher failure rate and shorter lifespan. I heard the military will not allow RoHS solder in their components. I don't know if it's true or not, but it makes sense.
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Thanks. Using your search suggestion I found info I had not previously seen.

We manufacture using lead-free and I can tell you most of what's being said is simply not true. All of our equipment, machinery, processes & product are designed for lead-free and it all works very well. It's amazing how small components have got in the few decades I've been messing with the stuff. A capacitor today is smaller than a flake of pepper. We have robotics for all of it. We have robots that make robots. Failure rate <3% and we haven't even looked into why - we just accept that as a favorable result. Of course we'll always be looking for tin whiskers and we're not building the space shuttle here - just space-aged outdoor light controls.

Thanks again.
 
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