View source for Self-contained breathing apparatus

{{Short description|Breathing gas supply system carried by the user}}
{{Redirect|SCBA}}
{{Broader|Breathing Apparatus}}
{{distinguish|text=[[Scuba set|SCUBA (self-contained '''underwater''' breathing apparatus)]]}}
{{refimprove|date=May 2012}}
{{Infobox regulated PPE|image=TFS SCBA gear.jpg|imagealt=Toronto firefighter wearing an SCBA}}
{{US respirator topics}}
A '''self-contained breathing apparatus''' ('''SCBA''') is a [[respirator]] worn to provide an autonomous supply of breathable gas in an atmosphere that is [[immediately dangerous to life or health]] from a [[gas cylinder]].<ref>{{harvnb|Bollinger|1987|p=184}}</ref> They are typically used in [[firefighting]] and industry. The term ''self-contained'' means that the SCBA is not dependent on a remote supply of [[breathing gas]] (e.g., through a long hose). They are sometimes called '''industrial breathing sets'''. Some types are also referred to as a '''compressed air breathing apparatus''' ('''CABA''') or simply '''breathing apparatus''' ('''BA'''). Unofficial names include ''air pack'', ''air tank'', ''oxygen cylinder'' or simply ''pack'', terms used mostly in [[firefighting]]. If designed for use under water, it is also known as a [[scuba set]] (self-contained underwater breathing apparatus).

An open circuit SCBA typically has three main components: a high-pressure gas storage cylinder, (e.g., {{convert|2216|to|5500|psi|abbr=on|lk=on}}, about 150 to 374 atmospheres), a pressure regulator, and a respiratory interface, which may be a mouthpiece, half mask or full-face mask, assembled and mounted on a framed carrying harness.{{sfn|IFSTA|2008|p=190}}

A self-contained breathing apparatus may fall into one of three categories: open-circuit, closed-circuit,{{sfn|IFSTA|2008|p=191}} or continuous-flow.<ref name=hoodhelmetmouth />

== Types ==
=== Closed-circuit ===
[[File:Aa savox1.jpg|right|thumb|[[Siebe Gorman]] Savox in a coal mining museum]]{{See also|Rebreather|Self-contained self-rescue device}}
The closed-circuit type, also known as a rebreather,<ref name=fivesix /> operates by filtering, supplementing, and recirculating exhaled gas. It is used when a longer-duration supply of breathing gas is needed, such as in [[mine rescue]] and in long [[tunnel]]s, and going through passages too narrow for a big open-circuit air cylinder. Before open-circuit SCBA's were developed, most industrial breathing sets were [[rebreather]]s, such as the [[Siebe Gorman Proto]], [[Siebe Gorman Savox]], or [[Siebe Gorman Salvus]].{{citation needed|date=June 2024}} An example of modern rebreather SCBAs would be the [[SEFA]].

==== As of 1987, under 30 CFR 11 ====
Duration of closed-circuit SCBAs is somewhere between 1-4 hours. A closed-circuit SCBA system is negative-pressure, increasing the risk of leaks.<ref name=fivesix>{{harvnb|Bollinger|1987|pp=55-56}}</ref>

There are two types of closed-circuit SCBA according to [[NIOSH]]:
* Uses '''compressed oxygen'''.
* Uses an '''oxygen-generating solid'''. This involves a chemical reaction between [[potassium superoxide]] with exhaled water and carbon dioxide. A chlorate candle has to be struck to start the device.
To reduce pressure buildup from use, a pressure-relief valve with saliva trap is included. Closed-circuit SCBAs are also noticeably smaller than open-circuit ones.<ref name=fivesix />

[[Self-contained self-rescue device]]s are also closed-circuit SCBAs, working on the same principles, being designed for emergency use in mines, and lasting about one hour.<ref name=fivesix />

=== Open-circuit ===
{{For|underwater open-circuit breathing sets|Scuba set#Types}}
==== As of 1987, under 30 CFR 11 ====
[[File:SCBA TruckMount JDiPierro.jpg|thumb|upright=0.8|left|SCBA packs carried on a rack in a [[firetruck]]]]
[[File:30 CFR 11 SCBA label.svg|thumb|right|upright=0.8|[[NIOSH air filtration rating#History|30 CFR 11]] approval label for an open-circuit, pressure-demand SCBA respirator]]
An open-circuit SCBA does not recirculate air; it instead allows respired air to be exhausted outside. While [[30 CFR 11]] does not restrict the gas that can be used (although compressed air is usually chosen), use of compressed oxygen is not allowed due to the system's exposure to outside air. Duration is usually limited to 30-60 minutes.<ref name=open>{{harvnb|Bollinger|1987|pp=59-64}}</ref>

There are two types of open-circuit SCBA according to NIOSH:
* '''Demand''': 2000 psi to the regulator from the main valve, plus a bypass valve in case of failure, with a two-stage regulator reducing pressure to 50-100 psi.
* '''Pressure-Demand''': Similar to demand, but with a spring in the diaphragm, which holds the admission valve open, for continuous air flow to the facepiece.

NIOSH emphasizes that facepieces between both SCBA types cannot be interchanged, but certain SCBAs can be switched to both 'demand' and 'pressure-demand' operation. However, both modes require different training.<ref name=open />

==== Common traits ====
[[File:PASS device.png|thumb|left|upright=0.8|SCBA pack with [[PASS device]] (ADSU)]]

{{citation needed span|date=June 2024|text=Open-circuit industrial breathing sets are filled with filtered, compressed air. Typical open-circuit systems have two stage regulators. The first stage reduces the pressure from storage pressure of up to more than 300 bar to about 10 bar for supply to the second stage on the mask, which further reduces it to just above atmospheric pressure via a demand valve when the pressure drops on inhalation. A positive pressure mask has the demand valve set to close when the pressure inside the mask is slightly above the external ambient pressure, so when the mask is removed from the face or leaks around the skirt, the demand valve will free-flow.}}

{{citation needed span|date=June 2024|text=An open-circuit rescue or firefighting SCBA has a [[full-face mask]], also called the face-piece, a demand [[diving regulator|regulator]], air cylinder,  pressure gauge, (sometimes with an integrated [[PASS device]]), and a harness with adjustable shoulder straps and waist belt which lets it be worn on the back. The air cylinder is commonly 4 liter, 6 liter, or 6.8 liter, but other sizes are also available. The endurance of the cylinder can be calculated from the volume, pressure and breathing rate of the user. The formula: volume (in liters) × pressure (in bars) / 40 (litres per minute) - 10 minutes (the 10 minutes is a safety margin, or reserve), so a 6-liter cylinder, of 300 bar, is 6 × 300 / 40 - 10 = 35 minutes working duration. The fitness and level of exertion of the wearer affect breathing rate, and result in variations of the actual usable time of the SCBA.}}

{{citation needed span|date=June 2024|text=Air cylinders are made of [[aluminium]], [[steel]], or of a composite construction (usually glass or [[carbon-fiber]] wrapped.) The composite cylinders are the lightest in weight and are therefore preferred by [[fire department]]s (UK: fire and rescue services previously called [[fire brigade]]s), but they also have the shortest lifespan and must be taken out of service after 15 years. Air cylinders must be [[hydrostatic test|hydrostatically tested]] every 5 years.{{clarify|where? Hydrostatic test intervals vary by country|date=March 2021}} During extended operations, empty air cylinders can be quickly replaced with fresh ones and then refilled from larger tanks in a [[cascade storage system]] or from an [[air compressor]] brought to the scene.}}

=== Continuous-flow ===
Escape SCBAs, also known as ESCBAs, come with hoods, are meant for escapes only, and are operated in continuous flow mode.<ref name=twoseven /><ref name=hoodhelmetmouth /><ref name=scbaescape />

Escape only SCBAs, designed for escape from [[Immediately dangerous to life or health|IDLH]] situations, regardless of type, are usually limited to 3-10 minutes.<ref name=open />{{clarification needed|date=June 2024}}
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== Differences under 42 CFR 84 ==
42 CFR 84 replaces the 30 CFR 11 respirator regulation used by [[NIOSH]]. As of 2001, quality assurance of SCBA harnesses is required. Labels have been updated to remove [[Mine Safety and Health Administration|MSHA]] emblems from respirator labels, as MSHA is no longer involved in respirator approval except for respirators approved for mining. As a result, new SCBAs now have to specify whether the SCBA is "intended for mine use".<ref>{{cite web|url=http://www.cdc.gov/niosh/pdfs/sap_0101.pdf|archive-url=https://web.archive.org/web/20030319064642/http://www.cdc.gov/niosh/pdfs/sap_0101.pdf|date=January 2001|archive-date=2003-03-19|title=STANDARD APPLICATION PROCEDURES FOR THE CERTIFICATION OF RESPIRATORS|publisher=NIOSH}}</ref>
{{Gallery
|title=Updated SCBA labels under 42 CFR 84
|width=160 | height=170 |align = center
|File:SCBA respirator 42 CFR.jpg
 |[[42 CFR 84|Part 84]] SCBA respirator label
|File:SCBA harness 42 CFR.jpg
 |Harness label
|File:SCBA chemical scrubber 42 CFR.jpg
 |Scrubber label
}}

==Facepiece==
SCBAs usually come with full-facepieces,<ref name=twoseven>{{harvnb|Bollinger|1987|p=207}}</ref> but can also come with half-mask or mouthpiece in demand or pressure-demand mode, though use of mouthpieces are limited to escapes only, as of 1987.<ref name=hoodhelmetmouth />

Hoods and helmets are limited to continuous flow mode only, and are also used in [[Supplied-air respirator|air-line respirators]] in addition to escape-only SCBAs.<ref name=hoodhelmetmouth>{{harvnb|Bollinger|1987|pp=7-8}}</ref><ref name=scbaescape>{{harvnb|Bollinger|1987|p=65}}</ref>

==Usage==
<!-- Because someone labelled this as citation needed earlier... sorry -->
[[File:Interschutz_2010_Brandbekämpfung_(1).jpg|thumb|Elastomeric masks linked to backpack air tanks: self-contained breathing apparatus, worn by firefighters advancing with a [[firehose]].]]
There are two major application areas for SCBA: [[firefighting]], and industrial use in confined spaces.<ref>{{harvnb|Bollinger|1987|p=120}}</ref>

{{citation needed span|date=June 2024|text=For firefighting, the design emphasis is on heat and flame resistance above cost. SCBAs designed for firefighting tend to be expensive because of the exotic materials used to provide the flame resistance, and to a lesser extent, to reduce the weight penalty on the firefighter. In addition, modern firefighting SCBAs incorporate a [[PASS device]] (personal alert safety system) or an ADSU (automatic distress signal unit) into their design. These units emit distinctive, high-pitched alarm tones to help locate firefighters in distress by automatically activating if movement is not sensed for a certain length of time (typically between 15 and 30 seconds), also allowing for manual activation should the need arise. In firefighting use, the layout of this breathing set should not interfere with [[Fireman's carry|ability to carry a rescued person over the firefighter's shoulders]].}}

{{citation needed span|date=June 2024|text=The other major application is for industrial users of various types. Historically, mining was an important area, and in Europe this is still reflected by limitations on use in the construction of SCBAs of metals that can cause sparks. Other important users are [[petrochemical]], chemical, and nuclear industries. The design emphasis for industrial users depends on the precise application and extends from the bottom end which is cost critical, to the most severe environments where the SCBA is one part of an integrated protective environment which includes gas-tight suits for whole-body protection and ease of decontamination. Industrial users will often be supplied with air via an air line, and only carry compressed air for escape or decontamination purposes.}}

==Other regulations and standards==
[[File:Volunteer Fire Fighter.jpg|thumb|left|Volunteer fire fighter exiting live burn structure wearing NIOSH-certified SCBA, NFPA compliant turn-out gear, and holding a pike pole]]
In the United States and Canada, SCBAs used in firefighting must meet guidelines established by the [[National Fire Protection Association]], NFPA Standard 1981. If an SCBA is labeled as "1981 NFPA compliant", it is designed for firefighting. The current version of the standard was published in 2018.<ref>{{cite web|url=https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=1981|title=NFPA|website=NFPA|access-date=5 May 2018|url-status=live|archive-url=https://web.archive.org/web/20180406040753/https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=1981|archive-date=6 April 2018}}</ref> These standards are revised every five years. Similarly, the [[National Institute for Occupational Safety and Health]] (NIOSH) has a certification program for SCBA that are intended to be used in chemical, biological, radiological, and nuclear (CBRN) environments.

Any SCBA supplied for use in Europe must comply with the requirements of the Personal Protective Equipment Directive (89/686/EEC). In practice this usually means that the SCBA must comply with the requirements of the European Standard EN 137:2006. This includes detailed requirements for the performance of the SCBA, the marking required, and the information to be provided to the user. Two classes of SCBA are recognised, Type 1 for industrial use and Type 2 for firefighting. Any SCBA conforming to this standard will have been verified to reliably operate and protect the user from -30&nbsp;°C to +60&nbsp;°C under a wide range of severe simulated operational conditions.

==Human factors==
SCBA is intended to be personal protective equipment, but its use is not without cost. The weight of the unit and work of breathing affect the work capacity and agility of the wearer, and the full-face mask, while protecting the face and eyes from heat, smoke, and toxic gases, also reduces peripheral vision and awareness of the surroundings. The weight and harness straps may limit tidal volume, ventilation rate, and oxygen consumption, and heart rate may increase in comparison with the same exercise levels without the equipment. Shoulder harness straps of heavy SCBA can reduce free motion of the thorax which affects breathing.<ref name="Louhevaara et al 1985" >{{cite journal |last1=Louhevaara |first1=V. |last2=Smolander |first2=J. |last3=Tuomi |first3=T. |last4=Korhonen |first4=O. |last5=Jaakkola |first5=J. |title=Effects of an SCBA on breathing pattern, gas exchange, and heart rate during exercise |journal=J Occup Med |date=1985 |volume=27 |issue=3 |pages=213–216|pmid=3981278 }}</ref>
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==See also==
* {{annotated link|NIOSH|wedge=regulator of SCBAs in the United States}}
** {{annotated link|Fire Fighter Fatality Investigation and Prevention Program|wedge=NIOSH investigations on causes of firefighter fatalities}}
* {{annotated link|Glossary of firefighting|Glossary of firefighting terms}}
* {{annotated link|Respirator}}
* {{annotated link|PASS device|PASS device (personal alert safety system)|aka=ADSU (automatic distress signal unit)}}
* {{annotated link|Scuba set|SCUBA}}
* {{annotated link|Smoke hood|aka=Short Term Air Supply (STAS)}}
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==Notes==
{{reflist}}

==References==
{{refbegin|2}}
* {{cite book |last=IFSTA |date=2008 |title=Essentials of Fire Fighting and Fire Department Operations |edition=5th }}
* {{cite book |url=https://books.google.com/books?id=1Y64oZHP9zYC | title=NIOSH Guide to Industrial Respiratory Protection | last1=Bollinger | first1=Nancy J. | date=1987 }}
{{refend}}

==Further reading==
{{columns-start|num=2}}
{{Commons-inline|list=
* [[commons:File:Two Career Lieutenants Killed and Two Career Fire Fighters Injured Following a Flashover at an Assembly Hall Fire—Texas.pdf|Two Career Lieutenants Killed and Two Career Fire Fighters Injured Following a Flashover at an Assembly Hall Fire—Texas.pdf]] - Contains information on SCBA damage
}}
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{{wikisource-inline|list=
* [[s:Safety Advisory on The Potential for Sudden Failures of Fiberglass-wrapped Composite Aluminum Cylinders Following Exposure to Acidic Chemical Cleaning Agents|Safety Advisory on The Potential for Sudden Failures of Fiberglass-wrapped Composite Aluminum Cylinders Following Exposure to Acidic Chemical Cleaning Agents]]
* [[s:Announcement of Public Meeting to Discuss Potential Standards or Guidelines for Respiratory Protective Devices Used to Protect Emergency Response Workers Against Chemical, Biological, and Radiological Agents|Announcement of Public Meeting to Discuss Potential Standards or Guidelines for Respiratory Protective Devices Used to Protect Emergency Response Workers Against Chemical, Biological, and Radiological Agents]]
}}
{{columns-end}}

==External links==
{{Commons category multi|Self-contained breathing apparatus|30 CFR Part 11|42 CFR Part 84}}
<!-- *[http://www.avon-fire.com/comparison.phtml Comparison of 5 makes of SCBA, by Avon, Scott, MSA, Drager, and Survivair] -->
* [https://web.archive.org/web/20090415235244/https://www.cdc.gov/niosh/npptl/topics/respirators/cbrnapproved/scba/ CBRN SCBA interim user guide and list of approved CBRN SCBA (Archived)]
* [https://web.archive.org/web/20061122170359/https://www.cdc.gov/niosh/npptl/standardsdev/cbrn/scba/ CBRN SCBA standard development and publication leading to the first NIOSH-Certified SCBA with CBRN protection offered by the US DHHS/CDC/NIOSH/NPPTL on June 3, 2002 (Archived)]
* [https://web.archive.org/web/20110710204856/http://www.euinfrastructure.com/media/article-images/article-image/INFRAEU/issue-8/web-images/MSA-3_AirGo_Pro.jpg Image of 2-cylinder open-circuit SCBA]
* [http://usminedisasters.com/rescuer_deaths.htm Rescuer Deaths in Underground Mines]
* [http://www.iom-world.org/pubs/IOM_TM9405.pdf Study of the physiological effects of wearing breathing apparatus] {{Webarchive|url=https://web.archive.org/web/20140513175818/http://www.iom-world.org/pubs/IOM_TM9405.pdf |date=2014-05-13 }} by RG Love and others. [[Institute of Occupational Medicine]] Research Report TM/94/05

{{Breathing apparatus|industrial}}
{{Fire fighting}}

{{DEFAULTSORT:Self-Contained Breathing Apparatus}}
[[Category:Personal protective equipment]]
[[Category:Breathing apparatus]]
[[Category:Functional masks]]
[[Category:Respirators]]
[[Category:National Institute for Occupational Safety and Health]]