Construction > Construction Outreach TOC > Common Fire Extinguishing Agents
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Construction Safety and Health
Outreach Program |
U.S. Department of Labor
OSHA Office of Training and Education
May 1996 |
Common Fire Extinguishing Agents |
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| 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
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| 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)
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| 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
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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
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| 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
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HALON 1301
DECOMPOSITION PRODUCTS |
- Hydrogen fluoride (HF)
- Hydrogen bromide (HBr)
- Bromine (Br2)
- Carbonyl Fluoride (COF2)
- Carbonyl Bromide (COBr2)
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| 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
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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)
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