Portable fire extinguishers are mandatory in every building. ABC dry chemical (monoammonium phosphate, NH4H2PO4) fits 90 percent of facilities as a universal choice. NFPA 10 (Standard for Portable Fire Extinguishers) defines travel distance, rating, hydrostatic testing and monthly inspection.
Fire Classes
- A: solids (wood, paper, textile)
- B: flammable liquid (gasoline, thinner)
- C: electrical (panels, switchgear)
- D: metal (magnesium, sodium) - special dry salts
- K: kitchen oil (saturated oil) - wet chemical
ABC covers three classes universally.
ABC Mechanism
Monoammonium phosphate (MAP):
- Class A: heat decomposes it into metaphosphoric acid coating paper
- Class B: chain reaction interruption (radical scavenging)
- Class C: non-conductive (dielectric)
- Corrosion risk: may damage electronics - clean after
NFPA 10 Rating and Distribution
NFPA 10 Table 6.2.1:
- Light Class A: 2A - 23 m max travel
- Ordinary Class A: 3A - 23 m
- Light Class B (1 L fuel): 5B - 9 m
- Ordinary Class B: 10B - 15 m
- Typical 6 kg ABC: 4A:55B:C rating - office-appropriate
Inspection and Testing
- Monthly visual: pressure gauge, tag, unobstructed
- Annual: certified technician, full service
- Every 6 years: internal inspection, powder-clumping check
- Every 12 years: hydrostatic test (visual + pressure)
- Records: maintain tag and logbook
Extinguisher distribution with SprinkCalc
SprinkCalc lays out portable extinguishers on a building plan using NFPA 10 Table 6.2.1 travel distances.
Download SprinkCalc on the App Store
Sources & Further Reading
NFPA 10, UL 154, ANSI/UL 626 certification, TS EN 3-7 (Turkey). NFPA 10 Portable Fire Extinguishers.