UL 154: Carbon Dioxide Fire Extinguishers

Overview

UL 154 is the construction and performance standard for portable carbon dioxide fire extinguishers. The current edition (Edition 10) was published and approved as ANSI/UL 154 on October 21, 2025, replacing the long-running Edition 9 from 2005. It is the type-specific standard for hand-held and wheeled units that discharge stored carbon dioxide as the extinguishing agent.

UL 154 sits parallel to UL 299 (dry chemical type) and UL 2129 (halocarbon type). All three pair with UL 711 for fire testing. Type standard plus rating method produces the "UL Listed" mark on the cylinder. The chemistry differs; the listing structure is the same.

Scope & Coverage

UL 154 governs the parts of a CO2 portable that determine whether the unit holds pressure, discharges reliably, and survives normal handling. It does not cover fire-test performance, which is handled by ANSI/UL 711 / CAN/ULC-S508.

• High-pressure cylinder construction (DOT-spec for service pressure)
• Stored-pressure valve assemblies and operating mechanisms
• Discharge horn or hose-and-horn assembly
• Mechanical durability tests (impact, vibration, salt spray, temperature cycling)
• Material compatibility with high-pressure CO2 service
• Hand-held models and wheeled industrial models
• Labeling, warnings, and operating instructions

Buckeye's public spec sheets state the listing language plainly: "Manufactured in accordance with ANSI/UL 154 and ANSI/UL 711 Standards. USDOT compliant cylinders are tested to 3000 psi." That 3000 psi figure is the hydrostatic test pressure for the cylinder; the steady-state service pressure of the agent inside is much lower (CO2 is stored as a liquid under its own vapor pressure, around 850 psi at 70°F).

How CO2 Extinguishes

CO2 puts out fire by displacing oxygen and providing modest cooling at the point of discharge. It is electrically non-conductive, leaves no residue, and does not promote corrosion the way dry-chemical powder does. That is why it is favored for energized electrical equipment and for rooms full of expensive electronics.

The agent is stored as a liquid under its own vapor pressure. When the valve opens, the liquid flashes to gas as it leaves the horn, and the rapid expansion cools sharply. The visible white "snow" at the horn is solid CO2, and horn surface temperatures can reach roughly minus 110°F. Operators are trained to grasp the horn handle, never the horn itself, to avoid contact frostbite.

Because CO2 cools only at the point of discharge and leaves no residual coating, it does not soak into Class A combustibles the way water or ABC powder does. Re-ignition risk on deep-seated wood, paper, or fabric fires is high after the visible flame is knocked down. For that reason, commercial CO2 portables under UL 154 are typically rated B:C only, not A:B:C.

Hand-portable cylinders use polyester-epoxy powder-coated aluminum with plated brass valves. Wheeled units use carbon steel cylinders for the higher agent weights. Operating temperature is rated minus 22°F to 120°F across the Buckeye line. Discharge range is 4 to 8 ft on hand-portables and around 15 ft on the wheeled units.

UL 154 vs NFPA 12

UL 154 and NFPA 12 both deal with carbon dioxide fire suppression. They are not the same scope. The two standards govern different products and different installations.

NFPA 12 ("Standard on Carbon Dioxide Extinguishing Systems") is the older fixed-system standard. It predates the clean-agent split and is its own document, separate from NFPA 2001 (which covers halocarbon and inert-gas clean agents). Many industrial sites run both: a fixed NFPA 12 system protects a hazard area like a paint booth or transformer vault, and one or more UL 154 portables sit nearby for spot use during work.

UL 154 vs UL 711

UL 154 says how a CO2 portable is built. UL 711 says how it has to perform against fire. Both are required to earn the UL Listing.

This is the same arrangement found across the type-standard family. Dry-chemical units pair UL 299 with UL 711. Halocarbon units pair UL 2129 with UL 711. CO2 units pair UL 154 with UL 711. UL 711 is the universal fire-test method. The type-specific standard is what changes by chemistry.

On a Buckeye CO2 spec sheet, both listings appear together: ANSI/UL 154 for construction and ANSI/UL 711 for the fire-test rating that produces the B:C numbers on the cylinder label. Canadian markets add CAN/ULC-S503 (CO2 construction) and CAN/ULC-S508 (rating method) for ULC-listed units; Buckeye hand-portable CO2 sheets do not carry the Canadian listings, so confirm with the manufacturer if Canadian deployment matters for your project.

Confined-Space Safety

CO2 puts out fire by displacing oxygen. The same mechanism that suppresses the fire is hazardous to anyone left in the space. This is the dominant operator-safety story for CO2 portables and the single largest difference from any other extinguisher type.

EPA published a public study in 2000 ("Carbon Dioxide as a Fire Suppressant: Examining the Risks") documenting 119 deaths and 152 injuries globally from CO2 fire-suppression systems in incidents up to that point. The vast majority were from fixed systems during maintenance and inadvertent actuation, not from portable units. That body of evidence is the empirical backbone for OSHA's pre-discharge alarm requirements on fixed systems.

Federal rules on fixed CO2 systems are at 29 CFR 1910.160 and 1910.162. Section 1910.160(c)(3) requires a pre-discharge employee alarm on total-flooding systems, perceptible above ambient noise and light, with enough time for employees to safely exit. Section 1910.162(b)(5) calls out the alarm specifically when the design concentration is hazardous, including CO2 systems at 4% or more. Those rules do not apply to portables, but the underlying physics does.

The second hazard is cold. Discharge horn surfaces can reach roughly minus 110°F. Skin contact for even a few seconds will produce frostbite. Operators are trained to grasp the horn handle and never the horn itself or the swivel discharge tube, and to keep the horn pointed at the fire, not at hands or face.

NFPA 10 incorporates these realities into its placement and selection guidance for portables. CO2 portables are not recommended as primary protection in unventilated machinery spaces, walk-in coolers, small closed rooms, or other confined locations where the operator could be exposed to the discharge in a way that prevents safe egress.

Applications and Restrictions

CO2 portables are favored anywhere dry-chemical residue or water would damage the contents being protected. The agent leaves no residue, does not conduct electricity, and does not promote corrosion. On the right hazard, that justifies the heavier cylinder and the safety training that comes with the agent.

Appropriate uses

• Energized electrical equipment (Class C): switchgear, motor control centers, panelboards
• Server rooms, data halls, and colocation cabinet rows for spot use
• Telecom MDF and IDF rooms
• Laboratory equipment, instrumentation, and analytical bays
• Print shops and printing presses
• Engine rooms and shipboard equipment spaces (with proper ventilation)
• Commercial-kitchen Class B liquid fires when the appliance is OFF (CO2 is not a Class K agent)

Restricted or inappropriate uses

• Outdoors or in large open spaces, where the agent dissipates before it can smother the fire
• Confined or unventilated spaces where the operator cannot exit clear of the discharge
• Class A deep-seated fires (wood, paper, textiles) where re-ignition risk is high
• Reactive metal fires (Class D): magnesium, titanium, sodium, lithium, where CO2 can react exothermically
• Cooking-oil and fat fires under load (Class K) where wet chemical is required

In every appropriate setting, NFPA 10 still governs sizing, mounting height, travel distance, and inspection cadence. UL 154 only tells you the unit is built and rated for the job. NFPA 10 tells you how many to install and where to put them.

For buyers planning around mission-critical infrastructure, our Mission-Critical Extinguisher Guide covers the buying decision in more depth, including when to spec a CO2 portable versus a halocarbon portable versus an ABC dry chemical and how to size by room volume.

Related Standards

Frequently Asked Questions