☣️ UN 3309 • CLASS 2
Liquefied gas, poisonous, flammable, corrosive, n.o.s. (Inhalation Hazard Zone A)
Placard: Toxic Gas. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
Advertisement
Quick details
UN 3309
Class: 2
Placard type: Toxic Gas
ERG: Guide 119 (check current ERG)
Isolation: ERG 119: Initial isolation 800m (½ mile) all directions; protective action distance 3.2km (2 miles) downwind for large spills; 7.0km (4.3 miles) downwind if tank/rail car involved in fire
Chemical & Response Details
| Also known as | Liquefied poisonous gas n.o.s.Toxic liquefied gas n.o.s.Compressed poisonous gas flammable corrosiveLiquefied toxic gas Zone A |
| Appearance | Liquefied gas under pressure, appearance varies by specific composition. Contact with liquid causes severe frostbite; gas may be colorless or have varying colors depending on components. |
| Flash Point | Not applicable (liquefied flammable gas under pressure) |
| Boiling Point | Varies by composition; typically below -40C (-40F) for Zone A materials |
| Vapor Density | Heavier than air (specific gravity > 1.0); vapors accumulate in low areas |
| Water Reactivity | May react with water producing toxic/corrosive gases; reaction severity depends on specific components |
| Extinguishing | Dry chemical, CO2, or inert gas; water spray only for cooling containers from distance |
| PPE | ⚠️ Level A required: fully encapsulating chemical protective suit with SCBA; Zone A indicates extreme inhalation hazard |
| Isolation | ERG 119: Initial isolation 800m (½ mile) all directions; protective action distance 3.2km (2 miles) downwind for large spills; 7.0km (4.3 miles) downwind if tank/rail car involved in fire |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and
- Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- Flammable; may be ignited by heat, sparks or flames.
- May form explosive mixtures with air. Ethylene oxide (UN1040) may react explosively even in the
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Many gases are heavier than air and will spread along the ground and collect in low or confined areas
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
Advertisement
📋 Copy & Share
UN 3309 — Liquefied gas, poisonous, flammable, cor HAZMAT RADIO NOTE — UN 3309
Product: Liquefied gas, poisonous, flammable, corrosive, n.o.s. (Inhalation Hazard Zone A)
Class 2 / Toxic Gas / ERG 119
PPE: Level A required: fully encapsulating chemical protective suit with SCBA; Zone A indicates extreme inhalation hazard
ISOLATION: ERG 119: Initial isolation 800m (½ mile) all directions; protective action distance 3.2km (2 miles) downwind for large spills; 7.0km (4.3 miles) downwind if tank/rail car involved in fire
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 3309 — Liquefied gas, poisonous, flammable, corrosive, n.o.s. (Inhalation Hazard Zone A)
Class: 2 | Placard: Toxic Gas | ERG Guide: 119
Appearance: Liquefied gas under pressure, appearance varies by specific composition. Contact with liquid causes severe frostbite; gas may be colorless or have varying colors depending on components.
Water Reactivity: May react with water producing toxic/corrosive gases; reaction severity depends on specific components
Extinguishing: Dry chemical, CO2, or inert gas; water spray only for cooling containers from distance
PPE: Level A required: fully encapsulating chemical protective suit with SCBA; Zone A indicates extreme inhalation hazard
Isolation: ERG 119: Initial isolation 800m (½ mile) all directions; protective action distance 3.2km (2 miles) downwind for large spills; 7.0km (4.3 miles) downwind if tank/rail car involved in fire
— Key Hazards —
• TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and
• Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
• Fire will produce irritating, corrosive and/or toxic gases.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Many gases are heavier than air and will spread along the ground and collect in low or confined areas
SOURCE: allfirefighter.com/hazmat/un/3309 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3309 Liquefied gas, poisonous, flammable, corrosive, n.o.s. (Inhalation Hazard Zone A) Cls2 ERG119 | allfirefighter.com/hazmat/un/3309SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/3309
Advertisement
FAQ
TOXIC; may be fatal if inhaled or absorbed through skin. Some may cause severe skin burns and Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause environmental contamination. Flammable; may be ignited by heat, sparks or flames. May form explosive mixtures with air. Ethylene oxide (UN1040) may react explosively even in the Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Vapors from liquefied gas are initially heavier than air and spread along ground.
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level A required: fully encapsulating chemical protective suit with SCBA; Zone A indicates extreme inhalation hazard
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 119 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles. This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.