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Construction Safety and Health
Outreach Program
U.S. Department of Labor
OSHA Office of Training and Education
May 1996

WATER

  • Removes heat
  • Effective on Class A fires
  • Inexpensive
  • Plentiful
  • Non-toxic

Disadvantages:

  • Conducts electricity
  • May spread Class B fires
  • Freezes in cold climates
  • May carry pollutants as run-off water

CARBON DIOXIDE (CO2)

  • Reduces oxygen to less than 15%
  • Effective on Class B and C fires
  • No residue
  • Relatively inert

Disadvantages:

  • Generally >35% concentration by volume required for total flooding system
  • Toxic to humans at >4% by volume
  • Not the best agent for smoldering deep-seated fires (maintain concentration for >20 minutes)
  • Dissipates rapidly - allows reflash
  • Has a cooling/chilling effect on some electronic components
  • Vapor density = 1.5 (collects in pits and low areas)

DRY CHEMICAL

  • Interrupts chemical reactions
  • Sodium bicarbonate (baking soda)
  • Very effective on Class B and C fires
  • Not considered toxic

Disadvantages:

  • Leaves a residue
  • Obscures vision
  • Not good on deep-seated Class A fires
  • Absorbs moisture and may "cake" within container
  • May be irritating
  • Nozzle pressure may cause burning liquids to splash

MULTIPURPOSE DRY CHEMICAL

  • Interrupts chemical reactions
  • Ammonium phosphate
  • Effective on Class A, B, and C fires
  • Non-conductive

Disadvantages:

  • Obscures vision
  • More irritating than ordinary dry chemical
  • Nozzle pressure may cause burning liquids to splash

HALON TERMINOLOGY

Halon 104: Carbon tetrachloride (CCl4) Halon 1211: Bromochlorodifluoromethane (CBrClF2) Halon 1301: Bromotrifluoromethane (CBrF3)

C F Cl Br
1 0 4 -
1 2 1 1
1 3 0 1

HALON 1301

  • Interrupts chemical reactions
  • Bromotrifluoromethane
  • Effective on Class A, B, and C fires
  • Not acutely toxic at <10% by volume
  • Generally used at <7% by volume
  • No residue
  • No chilling effect on electronic parts and components

Disadvantages:

  • Acutely toxic at >10% by volume (anesthetic and cardiac effects)
  • Delayed effects and effects of chronic exposure not well known
  • Toxic decomposition products are generated by fire
  • Vapor density = 5 (collects in pits and low areas)
  • Production restricted per Montreal Protocol due to depletion of ozone layer

HALON 1301

DECOMPOSITION PRODUCTS

  • Hydrogen fluoride (HF)
  • Hydrogen bromide (HBr)
  • Bromine (Br2)
  • Carbonyl Fluoride (COF2)
  • Carbonyl Bromide (COBr2)

HALON 1211

  • Interrupts chemical reactions
  • Bromochlorodifluoromethane
  • Effective on Class A, B, and C fires
  • No residue
  • May be sprayed (Boiling Point = 25oF)
  • Used in portable fire extinguishers

Disadvantages:

  • Acutely toxic at >4% by volume (dizziness, impaired coordination and cardiac effects)
  • Must be used at >5% by volume
  • Toxic decomposition products are generated by fire
  • Vapor density = 5.7 (collects in pits and low areas)
  • Production restricted per Montreal Protocol due to depletion of ozone layer

HALON 1211

DECOMPOSITION PRODUCTS

  • Hydrogen bromide (HBr)
  • Hydrogen chloride (HCl)
  • Hydrogen fluoride (HF)
  • Bromine (Br2)
  • Chlorine (Cl2)
  • Fluorine (F2)
  • Carbonyl bromide (COBr2)
  • Carbonyl chloride (COCl2)
  • Carbonyl fluoride (COF2)