NFPA 385: Tank Vehicle Fire Extinguisher Requirements

What NFPA 385 covers

NFPA 385, Standard for Tank Vehicles for Flammable and Combustible Liquids, is the consensus standard that governs the construction and operation of chassis-mounted cargo tank vehicles — the trucks petroleum jobbers, heating-oil dealers, fuel terminal operators, ethanol blenders, and jet-fuel haulers actually run. The current edition is NFPA 385-2022; a 2026 revision cycle is in development. NFPA 30A §14.6.1 brings any chassis-mounted cargo tank over 110 gal (415 L) into the standard’s scope.

Fleet types subject to NFPA 385 include:

• Gasoline and diesel jobbers running 2,500–5,500 gal bobtails
• Heating-oil delivery trucks (#2 fuel oil, kerosene)
• Ethanol and biodiesel transports (E85, B100 included)
• Jet-fuel refueler tankers operating airside (see also NFPA 407 for the airside layer)
• Terminal trucks and tank-truck haulers (highway transports >10,000 gal)
• Solvent and chemical haulers carrying Class I/II/III liquids

The standard also covers loading and unloading attendance (§9.2), tank-truck marking and identification, bonding/grounding during transfer, and the rules around making a tank gas-free before repair. This page focuses on the portable fire extinguisher clause in §9.3 because that is the one buyers ask about.

The fire extinguisher requirement (§9.3)

Two practical reads of that rule:

• One-unit option: a single ABC dry chemical handheld in the 10 lb class typically lists at 4-A:80-B:C, which clears the 4-A:40-B:C floor with margin. A 20 lb ABC unit typically lists at 10-A:120-B:C and clears it with significant margin.
• Two-unit option: two 5 lb ABC at 3-A:40-B:C each comfortably clear the 2-A:20-B:C per-unit floor (3-A > 2-A; 40-B > 20-B). Two smaller 2.5 lb ABC at 1-A:10-B:C each do NOT qualify — both the 1-A and 10-B portions fall short of the per-unit minimum. Two 10 lb ABC at 4-A:80-B:C is the typical pair-up when a fleet wants redundant coverage front and rear.

Agent type is not restricted by NFPA 385 itself — ABC dry chemical, BC dry chemical (sodium or potassium bicarbonate, including Purple K), or other UL-listed agents are all acceptable so long as the UL rating clears the floor. The catch is that every counted unit must carry a Class A rating: the single-unit option requires 4-A, and each unit in the two-unit option must be rated at least 2-A. Pure B:C agents like Purple K have no Class A rating at all, so a PK unit cannot satisfy §9.3.1 on its own and cannot count toward the two-unit pair either. PK can ride along as a supplemental knockdown tool, but the compliant baseline has to be one or two A:B:C-rated extinguishers.

How §9.3 interacts with DOT 49 CFR §393.95

Two federal layers, two different floors:

NFPA 385 contains an interstate-deference clause: a tank vehicle in interstate service transporting an ignitible liquid is considered in compliance with NFPA 385 if it meets the DOT requirements in 49 CFR 171–179. In practice that carves out a narrow path where a pure interstate placarded hauler can satisfy NFPA 385 by clearing §393.95. Most jobbers do not rely on that carve-out because (a) state-adopted NFPA 385 covers intrastate runs, (b) OSHA 29 CFR 1926.152(g) demands 20-B:C on tank trucks at construction jobsites, and (c) insurance underwriters reference NFPA 385. The simplest path is to outfit the truck to NFPA 385 and let it ride on both rules.

See our full breakdown of DOT 49 CFR §393.95 fire extinguisher requirements for the federal placarded-hazmat layer, including mounting rules, visual indicator requirements, and the §393.95(f) warning device cross-reference.

Who is subject to NFPA 385

Real operational examples of fleets covered by the standard:

• A three-truck heating-oil dealer in upstate New York running 2,500 gal bobtails on residential routes. NY adopts the International Fire Code, which pulls NFPA 385 by reference through §5706.6. Each truck needs 4-A:40-B:C single or 2-A:20-B:C × 2.
• A regional gasoline jobber operating 8,000 gal transport trailers from a terminal to retail stations across two states. Subject to §393.95 (FMCSA roadside) and to NFPA 385 wherever it’s adopted at the state level. Most operators standardize on a single 10 lb or 20 lb ABC unit per power unit.
• An into-plane jet-fuel refueler operating a 5,000 gal airport tanker. Subject to both NFPA 385 (chassis-mounted cargo tank over 110 gal) and NFPA 407 (the airside aviation layer, which requires two 40-B:C / 20 lb dry chem units on each side). NFPA 407 is the binding rule airside.
• A construction general contractor with a 1,000 gal on-site diesel tank truck refueling earthmoving equipment. OSHA 29 CFR 1926.152(g) demands a 20-B:C unit on the truck via its (outdated) incorporation of NFPA 385-1966 — modern compliance means meeting the current edition (4-A:40-B:C single or two 2-A:20-B:C).
• A small farm-fuel trailer (≤110 gal nurse tank) is generally outside NFPA 30A §14.6.1’s trigger, so NFPA 385 does not pull it in by default. State farm-plate exemptions can still vary — confirm with the state fire marshal or AHJ.

Mounting and inspection

NFPA 385 §9.3.3 sets a behavior-level rule (“accessible place”) rather than a specific location. Industry practice on a typical bobtail:

• One unit mounted in a driver-side cab-step locker or behind the seat
• A second unit (if running the two-unit option) in a curbside body compartment near the manifold for delivery operations
• Heavy-duty bracket UL-listed for vehicle vibration — the standard defers bracket selection to NFPA 10 and the extinguisher’s own listing
• 49 CFR §393.95(b) overlays a federal mounting rule for placarded hazmat: securely mounted to prevent sliding, rolling, or vertical movement

Inspection follows NFPA 10 per §9.3.4: monthly visual by the driver, annual maintenance by a licensed service company, 6-year internal exam, 12-year hydrostatic test on stored-pressure dry chemical cylinders. Pre-trip and post-trip walk-arounds typically cover the monthly visual.

State adoption and enforcement

Confirmed direct adoptions: Indiana (675 IAC 28-1-34, NFPA 385-2000 edition), Maine (Office of State Fire Marshal, 2007 edition), Kansas (State Fire Marshal, 2007 edition), Wisconsin (ATCP 93.615 references NFPA 385 for mobile fueling). Most other states pick up NFPA 385 indirectly via International Fire Code §5706.6 (Tank Vehicles and Vehicle Operation), which references NFPA 385 by name.

Three enforcement lanes a fleet should expect:

• State fire marshal — bulk-plant inspections, intrastate delivery routes. Cites against the adopted edition.
• OSHA — construction sites, via 29 CFR 1926.152(g) and its incorporation of NFPA 385.
• FMCSA roadside — interstate placarded hazmat enforcement is via §393.95, not NFPA 385 directly. The interstate-deference clause means §393.95 compliance technically satisfies NFPA 385 for interstate runs.

Confirm the specific edition adopted in your operating state(s) with the state fire marshal’s office or the local Authority Having Jurisdiction (AHJ).

NFPA 385-compliant extinguisher options

The qualifying handhelds we stock for the single-unit 4-A:40-B:C option, plus the wheeled option fleets put on the bulk plant or the loading rack:

Purple K (potassium bicarbonate) is a B:C-only agent with no Class A rating, so it cannot satisfy §9.3.1 by itself in either the single-unit or two-unit option — every counted extinguisher needs the 2-A or 4-A rating. PK is useful as a supplemental knockdown tool alongside an A:B:C-rated baseline (some fleets run a 20 lb ABC plus a 20 lb PK for extra hydrocarbon-pool capacity), but the compliant minimum is one or two A:B:C-rated units.

Related standards

• DOT 49 CFR §393.95 — the federal placarded-hazmat extinguisher floor. NFPA 385 stacks on top of this for tank vehicles in scope.
• NFPA 10 — placement, inspection, maintenance, and travel-distance rules. NFPA 385 §9.3.4 cross-refers to this for maintenance cadence.
• UL 299 — the listing standard behind every stored-pressure ABC dry chemical extinguisher referenced by NFPA 385’s 20-B:C minimum rating.
• NFPA 30 — Flammable and Combustible Liquids Code. Governs storage and dispensing at the bulk plant that loads the tank truck.
• NFPA 30A — Motor Fuel Dispensing Facilities. §14.6.1 is the 110 gal threshold that pulls a chassis-mounted tank truck into NFPA 385’s scope.
• NFPA 407 — the airside aviation layer that overrides for jet-fuel refuelers and hydrant carts at airports.
• NFPA 58 — the LP-gas analogue for propane bobtails and cylinder delivery vehicles. Different agent-weight floor (18 lb dry chemical).
• DOT fire extinguisher sizing guide — vehicle-by-vehicle product picks with prices.

Frequently Asked Questions