# Talk:Smoke detector

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## General Problems with Article

The article hardly cites any sources and reads like smoke-detector propaganda, prescribing use, suggesting positioning, no asserting that batteries need be replaced semi-anually, etc. Additionally, the article is very North-America-centric, discussing NIST, UL, NFPA, "building codes" (which are presumably in the States?). Perhaps it could be rewritten / modified to have a broader, more neutral perspective. —Preceding unsigned comment added by 98.223.202.213 (talk) 03:05, 14 March 2008 (UTC)

Specifically, it says UK Building Regs require alarms but fails to provide a reference! —Preceding unsigned comment added by 91.84.88.136 (talk) 19:22, 17 July 2009 (UTC)

Chip Currier invinted the Smoke Detector, Find him and he can prove it. He still holds the first ever working smoke detector, and the original plans. —Preceding unsigned comment added by 72.193.147.236 (talk) 01:02, 9 October 2009 (UTC)

I need a book,encyclipedia,etc. on George Darby

how is the anecdote 'unconfirmable' if his device was patented?131.111.200.200 (talk) 00:49, 26 August 2008 (UTC)

## Photoelectric detectors

• Note: There has been some recent research that has proven that "Photo-Electric" smoke alarms do a much better job at detecting large fires, whereas the Ionization detectors could only detect a small fire (which could in turn, could burn rapidly out of control) after a minimum of ten minutes! The photo-electric alarms however detected the fires almost a fast as they detected a large fire. This issue is still under investigation and research but the word is spreading and a few government (Australian, I'm not sure about others) organizations have admitted that these new alarms do work a lot better. - Random Australian Guy (Sydney)

## Reliability

The two paragraphs under the reliability section are conflicting:

In the 1990s Texas A&M University did a full scale scientific investigation... The study determined that in a smoldering fire, with its relatively low number of large smoke particles, optical detectors fail 4.06% of the time, while ionization detectors fail 55.8%. For flame ignition fires, which have a large number of small, energetic smoke particles, photoelectric smoke detectors had a 3.99% probability of failure while ionization smoke detector failed 19.8%.

In 2004, NIST issued a comprehensive report... The report concludes, among other things, that "consistent with prior findings, ionization type alarms provided somewhat better response to flaming fires than photoelectric alarms, and photoelectric alarms provided (often) considerably faster response to smoldering fires than ionization type alarms".

The A&M study is likely interpreted or transcribed incorrectly and should be removed until clarified

Reasoning:

As a class, flaming fires produce larger numbers of invisible (.1 to .01 micron) particles of combustion than slow smoldering fires, (owing to the process of agglomeration of smaller smoke particles as they cool).

Photelectric detectors are by definition unable to detect invisible particulates (particulates so small they do not reflect a particular wavelength of light, e.g. less than 20% of the wavelength) Ionization detectors are readily influenced by these invisible particulates. Detectors operating on the ionization principle detect particles of combustion as they collide and combine with ionized air molecules, causing the ionized air to lose thier mobility . Each smoke particle thus becomes a collector of ions, and the number of ionized particles in the chamber once reduced, naturally reduces current flow proportionately. This reduction in current triggers the electronic circuitry and is interpreted as a smoke signature.

Simple observation will verify that the smoke particulates are most visible (larger) further from the fire.

a quick check of the Texas A&M Engineering web site supports this conclusion

Also reference the 18th edition of the Fire Protection Engineering Handbook for supporting documentation, and The NEMA Guide for Proper Use of Smoke Detectors Axcadd 04:09, 24 June 2007 (UTC) Axcadd 04:43, 26 June 2007 (UTC)

## Smoke Detector vs Smoke Alarm

The introduction paragraph makes a statement that may need a rewrite of the article and its structure;

A smoke detector or smoke alarm is an active fire protection device, subject to stringent bounding, that detects airborne smoke and issues an audible alarm, thereby alerting nearby people to the danger of fire.

What I mean by this is that there is a difference between a Smoke Alarm comprising a sensor and audible warning device and a Smoke Detector that forms part of a network of sensors connected to an alarm panel.

Perhaps the article could be written with a summary of the technology of smoke detection (ionisation vs optical) and then the application of these technologies, being in the form of smoke alarms and smoke detectors.

Alternatively (by someone else): A smoke alarm is a device comprising a smoke detector and audible device. etc. The smoke detector might be incorporated into a device which communicates with an alarm panel.

## Volume

I "heard" that in Canada tests have caused the volume of the smoke detector alarms to be increased beyond the pain threshold level. This was apparently driven by the discovered that many people, particularly children, had no trouble sleeping through a normal smoke detector even when it was positioned directly above their bed. A quick look around, and I couldn't find a cite.

Personal experience tells me this is true, though. My parents moved from their temporary apartment that was less than a year old into a newly constructed house. The detectors in both these locations are so loud as to be very painful, even for a few seconds while you push the "silent for 20 minutes" button (i.e. after burning the toast). FractureTalk   06:11, 2 September 2006 (UTC)

There's a ton of research on the volume of alarms. Recent studies gaining attention have tested the effectiveness of waking children with alarms of different volumes and in combination with voice recordings (parent's voices) Here's one such study from Australia's Victoria University: THE EFFECTIVENESS OF DIFFERENT ALARMS IN WAKING SLEEPING CHILDREN It supports your claim children are generally more difficult to awaken.MikeDayoub 22:07, 8 November 2006 (UTC)
I can believe it, too. I put some chips in the oven last year while drunk, fell asleep, and only woke up when every alarm in the house was going. The pain in my ears from the things was incredible. Very ow. And this little drunken baby would almost certainly have slept through an alarm only as loud as, say, my alarm clock.Unreadablecharacters 15:50, 29 November 2006 (UTC)

## Disposal

What about discarding an old smoke alarm? Should a smoke detector be treated as special waste because of the radioactive source? Do people putting smoke detectors in the trash cause an environmental problem? I only found little about it here: [[1]] --Sasper 23:20, 15 December 2006 (UTC)

British-Columbia is currently the only current province in Canada that does any recyclign of alarms: http://www.productcare.org/BC-Smoke-and-CO-Alarms-FAQ Otherwise, the only method of disposal available is general household waste.

## Replacement: Every 10 Years

http://money.aol.com/smoney/general/replacing-common-household-items —The preceding unsigned comment was added by 70.126.236.103 (talk) 07:20, 19 February 2007 (UTC).

## Testing Section

I am not happy with the phrase "virtually all" because it is also uncited, but I feel that it is better than the previous wording. The problem here is that each state in the US has it's own codes for smoke detectors, and the NFPA doesn't require a test button that I can find anywhere. I have never seen a detector without one, and I talked to several friends (a couple internationals) and they concurred. I do not think it is universally required, but I think it is fairly universal. Thoughts? Zab 15:35, 7 April 2007 (UTC)

Also, this sentence: "Many people simply wave a lit match underneath the detector to test it; this is dangerous, however, as it can set the smoke alarm and the rest of the house on fire. A better way is to blow cigarette smoke into the detector." is one of the stupidest things I've ever seen. First of all, a lit cigarette waved under the detector is as dangerous, if not moreso than a lit match, partially because over several tests, the unfiltered tar can collect on the sensors and impair their function. Second, a lit match waved under a detector is not going to burn long enough to melt and ignite the plastic in a detector - even if held in one place. A better test than cigarette smoke would be: Light a match, blow it out, THEN wave it under the smoke detector. The match test is reliable, convenient, costs nothing, and I'd imagine is the preferred test for the majority of people who are nonsmokers and don't really want to buy or burn tobacco products in their homes for the sole purpose of testing their smoke detectors. 97.82.247.200 17:44, 5 July 2007 (UTC)
Funnily enough, the place I used to work, which manufactures detection systems, we did test it with cigarette smoke... It was much cheaper, and easier than canned smoke Nabifly (talk) 11:21, 11 May 2009 (UTC)
Under no circumstances should alarms be tested using actual flames and smoke. There are no pathways for the smoke/heat to reach the test chamber from the front of any commercial alarms. That pathway is along the edge at the back of the alarm.
Even "smoke-in-a-can" product are dubious at best as the manufacturers of alarms do not test for that product. There is no way to know if there is any residue left in the detection chamber without opening it up afterwards. --— Preceding unsigned comment added by 192.249.47.203 (talkcontribs) 2014-01-03T16:47:03‎ (UTC)
Most smoke detectors are not home residential. And these non-residential detectors, DO NOT have test buttons. The majority of detectors are in apartment blocks, hotels, office buildings, and so forth, and these are commercial detectors, which DO NOT have test buttons. So it is just incorrect. I'm adding {{fact}} Nabifly (talk) 11:21, 11 May 2009 (UTC)
Meh, I rewrote it to say that retail detectors had test buttons. Still, it seems to be in the wrong section (Design section). This article is horrible to tell the truth. It talks about smoke detectors as if retail were the only kind, when in fact, there is a much larger market in commercial/industrial detectors, and a lot of the information doesn't apply to the standard detector one would see in schools, high rises, etc. WRONG WRONG WRONG :-( Nabifly (talk) 11:30, 11 May 2009 (UTC)

## Cigarette detector

I have removed this section. This section does not belong in this article, as it refers to optical flame detectors. However, there presently is not a flame detector article. Additionally, the specific application cited in this section - detection of smoking in schools - is not used as a portion of a fire alarm system, but rather is a method of aiding rule enforcement in schools. As this system and components have not been listed by a third party testing laboratory for use in fire alarm systems as required by model building codes, it cannot be used for that purpose. Therefore, it does not really belong in any article pertaining to fire alarm systems. Fireproeng 03:24, 23 July 2007 (UTC)

## why is there a commercial website selling smoke detector products on this page???

Range of detectors from smoke to ultra violet - http://www.discountfiresupplies.co.uk/category/72/Fire-Alarm-Detectors

This link is actually a sales link with very limited useful information - please remove —Preceding unsigned comment added by 130.219.8.253 (talk) 20:25, 25 October 2007 (UTC)

## Typical Quantity of Americium-241 in a Household Detector

The article says this is 0.2 microgram, meaning one gram of Am-241 could make about 5 million detectors. According to my physics text book and http://www.uic.com.au/nip35.htm, one gram would make only 5000 detectors, meaning each contains about 0.2 milligrams. It matters little whether the material is oxide or pure metal, as each Am atom weighs many times more than an oxygen atom. I'll change the page now, but would welcome more info. StuFifeScotland (talk) 15:06, 27 January 2008 (UTC)

The wiki article on americium states "(about 0.2 microgram)" which seems more reasonable.Skipweasel (talk) 22:04, 4 February 2008 (UTC)

You don't need to rely on dubious sources, if you easily can calculate the amount. A commercial smoke detector contains about 1 µCi or 40 kBq 241-Am. The half-life of 241-Am is about $T_{1/2}=$430 years and the decay follows the exponential law $\frac{dN}{dt} = -\lambda N_0 e^{-\lambda t}$ where $\lambda$ is the decay constant $\lambda=\frac{\ln 2}{T_{1/2}}=5\times 10^{-11}s^{-1}$. If now at time $t=0$ the smoke detector contains 40 kBq then this means that 40000 atoms of 241-Am decay per second and $\frac{dN}{dt} = 40000\mathrm{s}^{-1}$.
This given we can calculate the total number of 241-Am atoms $N_0 = \frac{A}{\lambda}e^{\lambda t} = 7.8\times 10^{14}$ atoms. Each of these atoms weighs 241 AMU=$4\times 10^{-25}$ kg this gives a total weight for the 40 kBq of 241-Am of 0.3 µg or 300 ng. I will now again recorrect the article...
This also means that you can make more than 3 million smoke detectors from a single gram of 241-Am. Uwezi (talk) 18:31, 29 August 2009 (UTC)
in re: accuracy: that government guys c a need for 3 digits, so we can c it, 2... in re "dubious sources": the government guys r not dubious (but a src in compliance with WP:Q) and say 5000(sic! they 2) devices from 1gram 241AmO2... btw: i find ur computation WP:OR-ish... --Homer Landskirty (talk) 18:48, 29 August 2009 (UTC)
This has nothing to do with OR. 1 gram of radium has an activity of 1 curie (the definition of 1 curie). Americium has about 3 times the activity of radium because of the shorter half-life and the difference in atomic weight. 1 µCi of radium is 1 µgram - this should give you the ballpark figure without "own research". Their canadian neighbors get it right though: [2] Uwezi (talk) 22:46, 30 August 2009 (UTC)
ok - i m convinced now... i was just puzzled by the numbers given by the US gov... now ur 2 mathematical approaches (i didnt realize that u r a physicist...) and the new (canadian) reference feel fine... --Homer Landskirty (talk) 05:11, 31 August 2009 (UTC)

## VESDA Merger Proposal

Rather than outright deleting the VESDA article, I believe it would be worthwhile to merge the content into the Smoke detector article, as it is another form of smoke detection that is not already covered in this article. While it may not meet notability on its own grounds, it may do so as a member of the smoke detector article/family. --206.53.253.150 (talk) 19:11, 2 April 2008 (UTC)

Asperating smoke detection systems should have thier own page as they are such different technology to standard point detection systems. As an installer of both I believe that while it should have a link from the smoke detection page, it should not be merged altogether. Standard point detection sytems are based on photo electric and ionisation technologies. The majority of asperating systems are based on laser detection chambers, and there should be more detail on that. —Preceding unsigned comment added by 210.9.193.66 (talk) 01:15, 14 April 2009 (UTC)

Agreed. It seems silly to merge, as they are very different from point detectors. However, there also exist point detectors with laser chambers, so that's not so much what sets it apart, but yes, there should probably be more detail on that. The article has already been renamed as Aspirated smoke detector, so it includes more than just VESDA. Should it have its merge tag removed? --Nabifly (talk) 10:19, 11 May 2009 (UTC)

I would agree that the aspirating article should be merged with the smoke alarm article, as it is a subset of the smoke alarm group. User6344 (talk) 18:15, 7 December 2009 (UTC)

Either the aspiration article needs to be merged with the smoke detector article, or the other unique detectors (like beam for example) should be given their own pages EEthug (talk) 19:47, 27 June 2011 (UTC)

## CO2 - a better indicator?

hi! should we mention that CO2 level can help to distinguish between dangerous smoke and "harmless" cig smoke or smoke from a pan or steam from a pot...? [3] i have heard that in kitchens IR detectors r the fire detectors of choice... bye --Homer Landskirty (talk) 13:57, 8 September 2008 (UTC)

i just did it... :-) --Homer Landskirty (talk) 09:03, 11 September 2008 (UTC)

## Americanium nuclear bomb

because the americanium in smoke detectors is fissile it could be use to make an A-bomb. I just did the math and according to this it would that over 62 million smoke detectors to make said atom bomb.--GMWhilhuffTarkin (talk) 02:30, 8 April 2009 (UTC)

#Typical_Quantity_of_Americium-241_in_a_Household_Detector...? --Homer Landskirty (talk) 08:49, 16 November 2010 (UTC)

## Overhaul

Over the next week, I have decided to overhaul this article. A lot of the information talks as if it were talking about smoke detectors, when really it is talking about household smoke alarms. Most smoke detectors are not household smoke alarms. Therefore I am going to split all information related to household smoke alarms into its own section.

Thirdly, it completely lacks references. So I will be doing some research, and adding references into appropriate places.

--Nabifly (talk) 03:24, 12 May 2009 (UTC)

I have removed the section that gave times for fire -> alarm differences between ION and OPT detectors. According to a 2004 study by two British fire brigade departments: [4], there is usually very little difference between the performance of ION and OPT detectors, and also, the ION often outclassed the OPT detectors, even for smouldering fires. So unless, someone comes with solid proof, that there is a difference worth mentioning, there should not be this silly paragraph. 나비Fly Talk/Contributions 05:29, 13 May 2009 (UTC)

## Am-241 also emits gamma rays

According to Americium#Physical, 241Am also emits low energy gamma rays, which would presumably be able to escape the smoke detector. This should be mentioned in the article, which currently only says that it emits alpha particles which are stopped by the plastic. --169.232.246.70 (talk) 20:47, 16 April 2010 (UTC)

i added this: http://en.wikipedia.org/w/index.php?title=Smoke_detector&diff=356561460&oldid=356521437 --Homer Landskirty (talk) 08:03, 17 April 2010 (UTC)

should we additionally mention that 0.2µCi of 241Am create about 74Bq gamma decays? the 40K in a normal human body makes 4kBq according to WP... --Homer Landskirty (talk) 23:15, 2 May 2010 (UTC)

The article presents the term "Analog Addressable". An analog detector is a subset of addressable detectors, not all addressable detectors are analog type. In the industry, "analog" means that the detector (sensor) is relaying information (amount of smoke) back to the panel for the panel to make decisions on. The panel decides how much smoke constitutes an alarm condition.

With a plain addressable panel, the detector makes the decision of what constitutes an alarm, similar to a conventional detector. The detector has a hard coded alarm threshold.

The analog type allows advanced features such as variable sensitivity, pre-alarm warning, etc. Analog systems are generally more expensive. —Preceding unsigned comment added by 65.175.229.152 (talk) 21:21, 8 June 2010 (UTC)

i changed it... please cross check... --Homer Landskirty (talk) 08:13, 9 June 2010 (UTC)

## smoldering fire response time

hi! this+this edits r dubious to me... according to the source for that paragraph, it is about thousands of seconds, when a ionization detector tries to detect a smoldering fire... what is right? thx. Bye. --Homer Landskirty (talk) 06:22, 21 October 2011 (UTC)

cäse cloased (Pink Panther (2006 film) is funny...): http://en.wikipedia.org/w/index.php?title=Smoke_detector&diff=456668002&oldid=456348833 :-) --Homer Landskirty (talk) 13:10, 21 October 2011 (UTC)

## misnomer?

The title of the article is incorrect and misleading. A smoke detector is but a component of a stand alone household smoke alarm or smoke alarm system. Calling an alarm a "detector" is like an automobile (or car) an "engine" or "motor". — Preceding unsigned comment added by 192.249.47.202 (talk) 15:06, 1 February 2012 (UTC)

ok, but: http://www.merriam-webster.com/dictionary/smoke%20detector --Homer Landskirty (talk) 07:53, 2 February 2012 (UTC)

## Lives saved?

Any info on how many lives per year are likely saved by these devices? --71.174.164.7 (talk) 05:48, 7 March 2012 (UTC)

in german wikipedia they say that 1987 9% of the UK househbolds had smoke detectors and 1998 about 75% in that time the number of death caused by fire shrunk by 40%... but maybe people stopped smoking in bed in the same time... or electrical devices became safer... :-) --Homer Landskirty (talk) 07:22, 7 March 2012 (UTC)

## Suggest merge

Americium smoke detector contains no information not available from reading the package it came in and is redundant with this article; any unique content should be merged to give it context. --Wtshymanski (talk) 16:25, 18 March 2012 (UTC)

Done in April. --Wtshymanski (talk) 14:00, 13 August 2012 (UTC)

## Alternative explanation of operation

Moved from in-line with article:

Note: The response mechanism given above -- "the ions will attach to the particles and so will be less able to carry the current" -- is repeated verbatim in many web-references regarding "how smoke detectors work", but is at best imprecise and at worst incorrect. A reduction in charge mobility results in a reduced signal current only if there also is a mechanism for removing charge that competes significantly with the collection of charge by the ionization chamber plates. That removal mechanism is recombination of positive and negative charged atoms, molecules, or smoke particles, as the case may be in any specific circumstances. Increased recombination rate can be the result of charge attachment to particles, but if that were the dominant mechanism then the ionization-based detector would have no supplementary advantage to the optical-scattering-based detector. The actual differential utility of the ionization detector is that it is sensitive not only to particles, but also to vapors or fumes generated by the fire, many of which -- particularly in home and hotel fires -- contain numerous halogen compounds which typically have large electron affinities, hence which capture electrons to form negative ions. The recombination rate between negative ions and positive ions is typically much greater than the recombination rate between electrons and positive ions. Negative ion formation and the concomitant increase in positive-negative charge recombination rate is the mechanism that makes the ionization-based detector an essential supplement to the optical-attenuation-based detector: it detects vapors or fumes, which often reach the "smoke" detector substantially sooner than any actual smoke particles reach it. See also the entry on the electron capture detector (ECD), commonly used as a gas chromatography detector for halogenated compounds, a detector that is exquisitely sensitive to species of molecules that have large electron affinities. A good experimental test of whether any particular "smoke" detector model is responsive to vapors or fumes versus particles is to probe it with a little chloro-fluoro-carbon (Freon) refrigerant or propellant -- which the ECD was invented to detect at low atmospheric concentration -- or sulfur hexafluoride (SF6) -- which is used to suppress arcs in high-voltage electrical equipment.

If this was referenced and cleaned up for style, it could be a useful addition to the article. Encyclopedia articles shouldn't have internal debate, but this is a byproduct of the Wikipedia process. --Wtshymanski (talk) 13:58, 13 August 2012 (UTC)