Editing Smoke detector (section)

=== Performance differences ===
Photoelectric detectors and ionization detectors differ in their performance depending on the type of smoke generated by a fire.

A presentation by [[Siemens]] and the [[Canadian Fire Alarm Association]] reports that the ionization detector is the best at detecting incipient-stage fires with invisibly small particles, fast-flaming fires with smaller 0.01–0.4 [[micron]] particles, and dark or black smoke, while more modern photoelectric detectors are best at detecting slow-smouldering fires with larger 0.4–10.0 micron particles, and light-coloured white/grey smoke.<ref name=siemens/>

Photoelectric smoke detectors respond faster to fire that is in its early, smoldering stage.<ref name="criticalapps">{{cite web |title=Fire and Life Safety in Mission-Critical Applications |url=http://www.systemsensor.com/lifesafety/2011/05/sophisticated-strategic-fire-and-life-safety-in-mission-critical-applications/ |archive-url=https://web.archive.org/web/20120416013553/http://www.systemsensor.com/lifesafety/2011/05/sophisticated-strategic-fire-and-life-safety-in-mission-critical-applications/ |archive-date=April 16, 2012 |access-date=2011-07-01 |publisher=Life Safety Magazine}}</ref> The smoke from the smoldering stage of a fire is typically made up of large combustion particles between 0.3 and 10.0&nbsp;[[μm]]. Ionization smoke detectors respond faster (typically 30–60 seconds) to the flaming stage of a fire. The smoke from the flaming stage of a fire is typically made up of microscopic combustion particles between 0.01 and 0.3&nbsp;μm. Also, ionization detectors are weaker in high airflow environments.<ref name="criticalapps" />

Some European countries, including France,<ref>{{Cite web |title=Lycée Blaise Pascal Rouen – Smoke alarms |url=http://pascal-lyc.spip.ac-rouen.fr/spip.php?article1399&debut_article_actuel=5 |access-date=2015-12-28 |website=pascal-lyc.spip.ac-rouen.fr}}</ref> and some US states and [[Municipality|municipalities]] have banned the use of domestic ionization smoke alarms because of concerns that they are not reliable enough as compared to other technologies.<ref>{{cite web | url = http://cfpa-e.eu/wp-content/uploads/files/guidelines/CFPA_E_Guideline_No_10_2008.pdf | title = Smoke Alarms in the Home | website = CFPA-E.eu | publisher = Confederation of Fire Protection Associations in Europe | page = 5 | date = 2008 | access-date = 2015-05-11 | url-status = live | archive-url = http://archive.wikiwix.com/cache/20150511004024/http://cfpa-e.eu/wp-content/uploads/files/guidelines/CFPA_E_Guideline_No_10_2008.pdf | archive-date = 2015-05-11 }}</ref> Where an ionizing smoke detector has been the only detector, fires in the early stages have not always been effectively detected.

In June 2006, the Australian Fire & Emergency Service Authorities Council, the peak representative body for all Australian and New Zealand fire departments, published an official report, 'Position on Smoke Alarms in Residential Accommodation'. Clause 3.0 states, "Ionization smoke alarms may not operate in time to alert occupants to escape from a smoldering fire."<ref>{{cite web | url = http://knowledgeweb.afac.com.au/positions/documents/AFACSmokeAlarmposition1June2006.pdf | title = Position on Smoke Alarms in Residential Accommodation | publisher = Australasian Fire & Emergency Service Authorities Council | access-date = 2006-06-01 | archive-url = https://web.archive.org/web/20121224033049/http://knowledgeweb.afac.com.au/positions/documents/AFACSmokeAlarmposition1June2006.pdf | archive-date = 2012-12-24 }}</ref>

In August 2008, the [[International Association of Fire Fighters]] (IAFF) passed a resolution recommending the use of photoelectric smoke alarms, saying that changing to photoelectric alarms "Will drastically reduce the loss of life among citizens and firefighters."<ref>{{cite web | url = https://www.scribd.com/doc/76855071/IAFF-Resolution-Photoelectric-Smoke-Alarms-August-2008 | title = International Association of Fire Fighters Resolution 15 | publisher = The International Association of Fire Fighters, California, USA | access-date = 2013-06-27 | url-status = live | archive-url = https://web.archive.org/web/20130828021903/http://www.scribd.com/doc/76855071/IAFF-Resolution-Photoelectric-Smoke-Alarms-August-2008 | archive-date = 2013-08-28 }}</ref>

In May 2011, the Fire Protection Association of Australia's (FPAA) official position on smoke alarms stated, "The Fire Prevention Association of Australia considers that all residential buildings should be fitted with photoelectric smoke alarms..."<ref>{{cite web |date=May 2011 |title=Position Statement – Selection of Residential Smoke Alarms – clause 5.0 |url=http://www.fpaa.com.au/media/38231/ps_01_v1_selection_of_residential_smoke_alarms.pdf |url-status=live |archive-url=https://web.archive.org/web/20130510011502/http://www.fpaa.com.au/media/38231/ps_01_v1_selection_of_residential_smoke_alarms.pdf |archive-date=2013-05-10 |access-date=2013-06-27 |publisher=Fire Protection Association Australia |page=7}}</ref>

In December 2011, the Volunteer Firefighter's Association of Australia published a World Fire Safety Foundation report, "Ionization Smoke Alarms are DEADLY", citing research outlining substantial performance differences between ionization and photoelectric technology.<ref>{{cite web | url = https://www.scribd.com/doc/76543158/The-Volunteer-Fire-Fighter-Magazine-December-2011 | title = Ionization Smoke Alarms Are DEADLY | publisher = The World Fire Safety Foundation | access-date = 2001-06-27 | url-status = live | archive-url = https://web.archive.org/web/20140416175526/http://www.scribd.com/doc/76543158/The-Volunteer-Fire-Fighter-Magazine-December-2011 | archive-date = 2014-04-16 }}</ref>

In November 2013, the Ohio Fire Chiefs' Association (OFCA) published a position paper supporting the use of photoelectric technology in Ohioan residences. The OFCA's position states, "In the interest of public safety and to protect the public from the deadly effects of smoke and fire, the Ohio Fire Chiefs' Association endorses the use of photoelectric smoke alarms in both new construction and when replacing old smoke alarms or purchasing new alarms."<ref>{{cite web | url = http://www.photoelectricsaves.com/wp-content/uploads/2013/12/Ohio-Fire-Chiefs-Association-Position-Paper.pdf | title = OFCA Position Statement on Smoke Alarms | publisher = Ohio Fire Chief's Association | access-date = 2014-10-03 | url-status = live | archive-url = https://web.archive.org/web/20141006094232/http://www.photoelectricsaves.com/wp-content/uploads/2013/12/Ohio-Fire-Chiefs-Association-Position-Paper.pdf | archive-date = 2014-10-06 }}</ref>

In June 2014, tests by the Northeastern Ohio Fire Prevention Association (NEOFPA) on residential smoke alarms were broadcast on [[American Broadcasting Company|ABC's]] ''[[Good Morning America]]'' program. The NEOFPA tests showed ionization smoke alarms were failing to activate in the early, smoldering stage of a fire.<ref>{{cite web | url = http://neofpa.org/announcements/neofpa-abcs-good-morning-america-conduct-smoke-alarm-tests/ | title = 'GMA' Investigates: Will Your Smoke Detector Respond Fast Enough? | work = NEOFPA | publisher = Good Morning America | access-date = 2014-05-29 | url-status = live | archive-url = https://web.archive.org/web/20140903105443/http://neofpa.org/announcements/neofpa-abcs-good-morning-america-conduct-smoke-alarm-tests/ | archive-date = 2014-09-03 }}</ref> The combination ionization/photoelectric alarms failed to activate for an average of over 20 minutes after the stand-alone photoelectric smoke alarms. This vindicated the June 2006 official position of the [[Australasian Fire and Emergency Service Authorities Council|Australasian Fire & Emergency Service Authorities Council]] (AFAC) and the October 2008 official position of the [[International Association of Fire Fighters]] (IAFF). Both the AFAC and the IAFF recommend photoelectric smoke alarms, but not combination ionization/photoelectric smoke alarms.<ref>{{cite web | url = https://www.scribd.com/doc/35526418/Smoke-Alarm-Myths-Explained | title = Smoke Alarm Myths Explained | publisher = The World Fire Safety Foundation | access-date = 2014-09-03 | url-status = live | archive-url = https://web.archive.org/web/20141006092145/https://www.scribd.com/doc/35526418/Smoke-Alarm-Myths-Explained | archive-date = 2014-10-06 }}</ref>

According to fire tests conformant to [[EN 54]], the {{chem|CO|2}} cloud from open fire can usually be detected before particulates.<ref name=senseair />

Due to the varying levels of detection capabilities between detector types, manufacturers have designed multi-criteria devices which cross-reference the separate signals to both rule out false alarms and improve response times to real fires.<ref name=criticalapps />

[[Wikt:obscuration|Obscuration]] is a unit of measurement that has become the standard way of specifying smoke detectors' [[Sensitivity (electronics)|sensitivity]]. Obscuration is the effect smoke has in reducing light intensity, expressed in percent absorption per unit length;<ref name="siemens">[http://www.cfaa.ca/Files/flash/EDUC/FIRE%20ALARM%20ARTICLES%20AND%20RESEARCH/SMOKE_DETECTOR_SENSITIVITY.pdf Smoke Detector Sensitivity testing: Siemens and Canadian Fire Alarm Association], {{webarchive|url=https://web.archive.org/web/20160222054527/http://www.cfaa.ca/Files/flash/EDUC/FIRE%20ALARM%20ARTICLES%20AND%20RESEARCH/SMOKE_DETECTOR_SENSITIVITY.pdf|date=2016-02-22}}.</ref> higher concentrations of smoke result in higher obscuration levels.

{| class="wikitable"
|+ Typical smoke detector obscuration ratings
|-
! Detector type
! Obscuration
|-
| Photoelectric
| 0.70–13.0% obs/m (0.2–4.0% obs/ft)<ref name="AirflowPatterns" />
|-
| Ionization
| 2.6–5.0% obs/m (0.8–1.5% obs/ft)<ref name="AirflowPatterns" />
|-
| [[Aspirating smoke detector|Aspirating]]
| 0.005–20.5% obs/m (0.0015–6.25% obs/ft)<ref name="AirflowPatterns" />
|-
| Laser
| 0.06–6.41% obs/m (0.02–2.0% obs/ft)<ref>{{cite web | url = http://www.systemsensor.com/en-us/Documents/7251_DataSheet_A05-0314.pdf | title = Low-Profile Plug-in Intelligent Laser Smoke Detector | website = SystemSensor.com | access-date = 2014-05-01 | url-status = live | archive-url = https://web.archive.org/web/20140502002646/http://www.systemsensor.com/en-us/Documents/7251_DataSheet_A05-0314.pdf | archive-date = 2014-05-02 }}</ref>
|}