Bromotrifluoromethane

Bromotrifluoromethane, commonly known as Halon 1301, R13B1,^[3] Halon 13B1 or BTM, is an organic halide with the chemical formula C Br F₃. It is used for fire suppression and refrigeration. Human exposure to Halon 1301 can be toxic, affecting the central nervous system and other bodily functions. Additionally, it is known to contribute to the depletion of Earth's atmospheric ozone layer when released. As such Halon's use as a refrigerant has been virtually eliminated and alternatives are being used increasingly for fire suppression.

Table of physical properties

Property	Value
Critical temperature (T_c)	66.9 °C (340.08 K)
Critical pressure (p_c)	3.956 MPa (39.56 bar)
Critical density (ρ_c)	5.13 mol.l⁻¹
Ozone depletion potential (ODP)	10 (CCl₃F = 1)
Global warming potential (GWP)	6900 (CO₂ = 1)

Uses

Warning sign for fire suppression system

Civilian Halon 1301 Fire Extinguisher, USA, 1980s.

Halon 1301 was developed in a joint venture between the U.S. Army and DuPont in 1954, and introduced as an effective gaseous fire suppression fixed systems agent in the 1960s, and was used around valuable materials, such as aircraft, mainframe computers, and telecommunication switching centers, usually in total flooding systems. It was also widely used in the maritime industry to add a third level of protection should the main and emergency fire pumps become inoperable or ineffective. Halon 1301 was never widely used in portables outside military and spacecraft applications, due to its limited range, and invisible discharge. It does not produce the characteristic white cloud like CO2 and is difficult to direct when fighting large fires. Halon 1301 is ideal for armored vehicles and spacecraft, however, because it produces less toxic by-products than does halon 1211, which is critical for combat or space conditions where a compartment may not be able to be ventilated immediately. Halon 1301 is widely used by the U.S. Military and NASA in a 2-3/4 lb portable extinguisher with a sealed, disposable cylinder for quick recharging. Other agents such as CO2 and E-36 Cryotech wet chemical are largely replacing halon 1301, however, due to environmental concerns. Civilian models in 2-3/4, 3, and 4 lb sizes were also made.

It is considered good practice to avoid all unnecessary exposure to Halon 1301, and to limit exposures to concentrations of 7 percent and below to 15 minutes. Exposure to Halon 1301 in the 5 to 7 percent range produces little, if any, noticeable effect. At levels between 7 and 10 percent, mild central nervous system effects such as dizziness and tingling in the extremities have been reported.^[4] In practice, the operators of many Halon 1301 total flooding systems evacuate the space on impending agent discharge.

There is also a risk of the production of toxic and irritant pyrolysis products, mainly hydrogen bromide and hydrogen fluoride.

Due to lessons learned in the Vietnam War, the use of Halon 1301 began in the F-16 fighter aircraft to prevent vapors in the fuel tanks from becoming explosive. Upon entering areas with possible unfriendly fire, Halon 1301 is injected into the fuel tanks for one-time use. Due to environmental concerns, trifluoroiodomethane (CF₃I) is being considered as an alternative.^[5]

Bromotrifluoromethane was also used as a filling of the bubble chamber in the neutrino detector Gargamelle.

Before the dangers of Halon 1301 as an ozone depleter were known, many industrial chillers used it as an efficient refrigerant gas.

Alternatives

Halon 1301 hazard sign, with instructions upon gas discharge.

Alternatives to Halon 1301 in fire extinguishing systems are being deployed. Many installations from which halon is removed can be protected with fire sprinklers, depending on the level of damage the equipment in the space will incur by exposure to water. In other cases, different total flooding agents can be used. The alternatives for normally occupied areas include (PFC-410 or CEA-410), C₃F₈ (PFC-218 or CEA-308), HCFC Blend A (NAF S-III), HFC-23 (FE 13), HFC-227ea (FM 200), IG-01 (argon), IG-55 (argonite), HFC-125, or HFC-134a. For normally unoccupied areas, the alternatives include carbon dioxide, powdered Aerosol C, CF₃I, HCFC-22, HCFC-124, HFC-125, HFC-134a, gelled halocarbon/dry chemical suspension (PGA), blend of inert gas, high expansion foam systems and powdered aerosol (FS 0140), and IG-541 (Inergen).^[6] Perfluorocarbons, i.e., PFCs such as C₃F₈, have very long atmospheric lifetimes and very high global warming potentials. Hydrochlorofluorocarbons, i.e., HCFCs including HCFC containing NAF S-III, contain chlorine and are stratospheric ozone layer depleters, although less so than Halon 1301. Their selection for usage as Halon replacements should consider those factors, and is restricted in some countries.

References

1 2 3 4 "NIOSH Pocket Guide to Chemical Hazards #0634". National Institute for Occupational Safety and Health (NIOSH).
↑ "Trifluorobromomethane". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH).
↑ "National Refrigerants MSDS" (PDF). Retrieved 2009-07-17.
↑ NFPA 12A Standard on Halon 1301 Fire Extinguishing Systems, 2004 Edition / Annex D, Hazards to Personnel , section D.2.2
↑ Halon Substitute Protects Aircrews and the Ozone Layer
↑ Halon 1301 Replacements

External links

Halomethanes

Monosubstituted	CH₃F CH₃Cl CH₃Br CH₃I

Disubstituted	CH₂F₂ CH₂ClF CH₂BrF CH₂FI CH₂Cl₂ CH₂BrCl CH₂ClI CH₂Br₂ CH₂BrI CH₂I₂

Trisubstituted	CHF₃ CHClF₂ CHBrF₂ CHF₂I CHCl₂F CHBrClF CHClFI CHBr₂F CHBrFI CHFI₂ CHCl₃ CHBrCl₂ CHCl₂I CHBr₂Cl CHBrClI CHClI₂ CHBr₃ CHBr₂I CHBrI₂ CHI₃

Tetrasubstituted	CF₄ CClF₃ CBrF₃ CF₃I CCl₂F₂ CBrClF₂ CClF₂I CBr₂F₂ CBrF₂I CF₂I₂ CCl₃F CBrCl₂F CCl₂FI CBr₂ClF C*BrClFI CClFI₂ CBr₃F CBr₂FI CBrFI₂ CFI₃ CCl₄ CBrCl₃ CCl₃I CBr₂Cl₂ CBrCl₂I CCl₂I₂ CBr₃Cl CBr₂ClI CBrClI₂ CClI₃ CBr₄ CBr₃I CBr₂I₂ CBrI₃ CI₄

* Chiral compound.

Fluorine compounds

AgF AgF₂ Ag₂F AlF₃ AmF₃ AmF₄ AsF₃ AsF₅ AuF₃ BF₃ B₂F₄ BaF₂ BeF₂ BiF₃ BiF₅ BrF₃ BrF₅ CF₄ C₂F₆ CaF₂ CdF₂ CeF₃ ClF₃ ClF₅ CoF₂ CoF₃ CrF₂ CrF₃ CrF₄ CrF₅ CrF₆ CsF CuF DyF₃ ErF₃ EuF₂ EuF₃ DF HF FI KF LiF NaF RbF TlF FeF₂ HgF₂ Hg₂F₂ KrF₂ MgF₂ MnF₂ NiF₂ F₂O F₂O₄ PbF₂ PdF₂ SnF₂ SrF₂ XeF₂ ZnF₂ ZrF₂ FeF₃ GaF₃ GdF₃ HoF₃ InF₃ LaF₃ LuF₃ MnF₃ F₃N NdF₃ F₃P PrF₃ PuF₃ SbF₃ ScF₃ SmF₃ TbF₃ TiF₃ TlF₃ TmF₃ UF₃ VF₃ YF₃ YbF₃ GeF₄ HfF₄ MoF₄ F₄N₂ PbF₄ PuF₄ SF₄ SeF₄ SiF₄ SnF₄ TeF₄ ThF₄ UF₄ VF₄ WF₄ XeF₄ ZrF₄ IF₅ NbF₅ PF₅ SbF₅ TaF₅ UF₅ VF₅ WF₅ MoF₆ OsF₆ PtF₆ ReF₆ SF₆ SeF₆ TeF₆ UF₆ WF₆ XeF₆ IF₇ ReF₇ IrF₃ IrF₆ OsF₄ OsF₅ PmF₃ PrF₄ PuF₆ ReF₄ ReF₅ RhF₆ RuF₃ RuF₄ RuF₅ RuF₆ TcF₅ TcF₆ VF₂ YbF₂ AgBF₄ AgPF₆ Cs₂AlF₅ K₃AlF₆ Na₃AlF₆ KAsF₆ LiAsF₆ NaAsF₆ HBF₄ KBF₄ LiBF₄ NaBF₄ RbBF₄ Ba(BF₄)₂ Ni(BF₄)₂ Pb(BF₄)₂ Sn(BF₄)₂ BaClF BaSiF₆ BaGeF₆ BrOF₃ BrO₂F CBrF₃ CBr₂F₂ CBr₃F CClF₃ CCl₂F₂ CCl₃F CFN CF₂O CF₃I CHF₃ CH₂F₂ CH₃F C₂Cl₃F₃ C₂H₃F C₆H₅F C₇H₅F₃ C₁₅F₃₃N ClFO₂ CrFO₄ CrF₂O₂ CsBF₄ NH₄F FNO FNO₂ FNO₃ KHF₂ NaHF₂ ThOF₂ NH₅F₂ F₂OS F₃OP F₃PS HPF₆ HSbF₆ KPF₆ KSbF₆ LiPF₆ NaPF₆ NaSbF₆ Na₂SiF₆ Na₂TiF₆ Na₂ZrF₆ TlPF₆ IOF₃ K₂NbF₇ K₂TaF₇ IO₃F

Chemical formulas

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