This is one of the few OSHA construction rules that literally tells you what to buy and where to put it. The whole requirement fits in two sentences — and the ratings printed on the cylinder map to it directly.
In a hurry — the picks (affiliate links — as an Amazon Associate I earn from qualifying purchases; the rules below)
| Default single unit | Kidde Pro 340 (3-A:40-B:C) — clears both OSHA rules in one rating |
| Covering the 100-ft rule | Amerex B500 5 lb ABC, 2-pack |
| Fuel storage / hot work | Buckeye 10 lb (4-A:80-B:C) |
The label rating is the compliance currency. A covers ordinary combustibles (wood, paper), B flammable liquids, C means safe on energized electrical equipment. The numbers are relative extinguishing capacity — so a 3-A:40-B:C unit simultaneously satisfies the 2A area rule and the 10B liquids rule, which is why the standard 5 lb ABC extinguisher is the default jobsite answer. Bigger sites don't need bigger units so much as more units placed within the 100-foot travel rule.
Fits: the default single unit — one rating that clears both the 2A area rule and the 10B liquids rule (5,000+ ratings).
Fits: covering the 100-foot travel rule with multiple placements — pro-grade, rechargeable, metal-valve units (3,000+ ratings). Check the listed UL rating against the rule you're covering.
Fits: fuel storage areas, hot-work zones, and anywhere you'd rather have double the capacity hanging on the wall.
A full gauge doesn't mean a unit is still in service. Extinguishers age out by date, and the date rule depends on whether the unit is disposable or rechargeable. Check these in order:
How this applies to the picks above: the Kidde Pro 340 is a rechargeable unit (Kidde says rechargeable models "can stay in service longer"), and the Amerex B500 is a rechargeable all-metal unit, so both follow the 6- and 12-year service schedule rather than a hard 12-year retirement. Write the manufacture date on the inspection record the day a new unit is mounted, so the 6-year exam doesn't come as a surprise.
One rated at least 2A per 3,000 square feet of protected building area, with no point more than 100 feet of travel from an extinguisher — plus at least one per floor (adjacent to the stairway) on multistory work, and a 10B unit within 50 feet wherever more than 5 gallons of flammable liquids are in use.
The letters are fire classes (A ordinary combustibles, B flammable liquids, C safe on energized electrical); the numbers are relative capacity. A 3-A:40-B:C unit exceeds both the 2A area requirement and the 10B flammable-liquids requirement, which is why it's the standard jobsite answer.
1926.150 requires periodic inspection and maintenance; the accepted practice that satisfies it is a monthly visual check (gauge in the green, pin seated, no damage) plus annual maintenance per NFPA 10 — recorded on the tag, because the tag is what an inspector reads.
Start with the manufacture date on the bottom or the cylinder. Kidde's guidance is that a unit with its gauge in the green and a manufacture date under 12 years old is still good. Under NFPA 10, disposable dry-chemical units come out of service 12 years after manufacture; rechargeable dry-chemical units get an internal exam every 6 years and a hydrostatic test every 12 (per Amerex), and stay in service as long as they pass.