Bromotrifluoromethane

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Bromotrifluoromethane
IUPAC name Bromotrifluoromethane
Other names Trifluorobromomethane, Monobromotrifluoromethane, Trifluoromethyl bromide, Bromofluoroform, Carbon monobromide trifluoride, Halon 1301, BTM, Freon 13BI, Freon FE 1301, R 13B1, Halon 1301 BTM, UN 1009
Identifiers
CAS number [75-63-8]
PubChem 6384
EINECS number 200-887-6
UN number 1009
RTECS number PA5425000
SMILES C(F)(F)(F)Br
InChI 1/CBrF3/c2-1(3,4)5
Properties
Molecular formula CBrF3
Molar mass 148.91 g/mol
Appearance Colorless gas
Density 1.538 g.cm−3 at -58 °C
Melting point

−167.78 °C
Boiling point

-57.75 °C
Solubility in water 0.03 g/l at 20 °C
log P 1.86
Vapor pressure 1434 kPa at 20 °C
Hazards
Main hazards Dangerous for the environment (N)
R-phrases R59
S-phrases S59
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Bromotrifluoromethane, also known by the trade name Halon 1301, is an organic halide with the chemical formula CBrF3.

Contents

[edit] Table of physical properties

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

[edit] Uses

Warning sign for fire supression system
Warning sign for fire supression system

It was introduced as an effective gaseous fire suppression 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.

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[1]. In practice, the operators of many Halon 1301 total flooding systems evacuate the space on impending agent discharge.

There is also a risk of toxic and irritant pyrolysis products, 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.[2]

[edit] Alternatives

Halon 1301 hazard sign, with instructions upon gas discharge.
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 and powdered aerosol (FS 0140), and IG-541 (Inergen).[3] 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.

[edit] References

  1. ^ NFPA 12A Standard on Halon 1301 Fire Extinguishing Systems, 2004 Edition / Annex D, Hazards to Personnel , section D.2.2
  2. ^ Halon Substitute Protects Aircrews and the Ozone Layer
  3. ^ Halon 1301 Replacements

[edit] See also

[edit] External links

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