- Author
- Brown, E. R.
- Title
- Ion Chemistry of CF3Br Fire Suppressant.
- Coporate
- Worcester Polytechnic Institute, MA
- Keywords
- halon 1301 | halons | flame extinguishment | chemistry | fire extinguishing agents
- Identifiers
- selected ion flow drift tube (SIFDT) apparatus; pressure dependence; kinetic energy dpenedence; collison rate constants
- Abstract
- Halogenated hydrocarbons, or halons, are commonly used fire extinguishing agents. Because of environmental concerns, replacements for halons are being sought. However, the detailed chemical mechanism for extinguishment by halons is not fully understood. In particular, there is continuing debate in the chemical literature regarding the possible role of ions in the mechanism. It is hoped that by better understanding the chemistry of halon fire suppression, alternative compounds may be developed. In this thesis, a large body of ion chemistgry for reactions involving Halon 1301 (CF3Br) is reported. The measurements were conducted using a variable temperature-selected ion flow drift tubve (SIFDT) apparatus. Rate constants for a large number of reactions were measured at 300 and 525 K. In addition, ionic products of the reactions were identified and quantified at both temperatures. The reactions studied include those of CF3Br with ions abundant in hydrocarbon flames: HCO+, CH3+, CH5+, CH2OH+, CH3OH2+ and H3O+. The ions HCO+, CH3+ and CH5+ were found to react rapidly with CF3Br and the major ionic products were CF3+ and CF3Br+. These product ions were investigated for their reactivity toward a variety of hydrocarbon fuels and toward hydrogen and oxygen. In most cases, CF3+ and CF2Br+ reacted rapidly with the hydrocarbons studied. Reactions of C2H4 and C3H6 withCF3+ produced HF, a corrosive and highly poisonous compound. This thesis represents the first investigation of most of these reactions. The implications of the results for fire extinguishment are discussed. It is concluded that ion chemistry is probably unimportant in fire suppression by Halon 1301, but may have side effects that deserve further research.