UN 1023 — Coal gas, compressed
Placard: Toxic Gas. ERG Guide 119. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1023 is Coal gas, compressed, a Class 2 toxic gas assigned to ERG Guide 119. It combines a serious inhalation hazard with flammable gas behavior, so responders must manage both exposure and ignition risks.
Hazard overview: UN 1023 is dangerous because it can poison responders without strong warning properties and may also form flammable mixtures with air. Container heating, leaks in confined areas and ignition sources can quickly escalate the incident.
Response guidance: For a UN 1023 incident, responders should confirm product identity using shipping papers, SDS, cylinder markings and ERG Guide 119. Establish incident command, isolate the area, use atmospheric monitoring, control ignition sources when safe and require SCBA for suspected exposure areas.
Firefighter training notes: Training for UN 1023 should emphasize combined toxic and flammable gas risk, atmospheric monitoring, ignition control and SCBA use. Common errors include treating the release only as a fire problem, relying on smell, entering without CO/toxic gas monitoring and failing to control ignition sources.
Regulatory context: Coal gas, compressed is regulated as a Class 2 hazardous material for transportation and emergency response purposes. Cylinder, workplace exposure, storage, reporting and environmental requirements may vary by product, quantity and jurisdiction. Responders should verify current requirements through shipping papers, SDS, cylinder markings, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Coal gas, compressed cylinders should be stored secured, upright where required, well ventilated and away from heat, ignition sources, oxidizers, incompatible gases and physical damage. Storage areas should control leaks, cylinder impact, unauthorized access and accumulation of gas in low or confined spaces.
UN 1023 Quick Details
Common Hazards of UN 1023
- TOXIC; may be fatal if inhaled.
- Colorless and often odorless gas may provide little or no warning of exposure.
- Flammable gas; may ignite by heat, sparks or flames.
- May form explosive mixtures with air.
- Cylinders or pressure containers may rupture or rocket when heated.
- Fire may produce irritating or toxic combustion products.
- Gas monitoring is essential because toxic and flammable hazards may both be present.
Chemical Identity & Physical Properties
Colorless to pale yellow gas with a characteristic coal tar or aromatic odor. Lighter than air. Typically a mixture of hydrogen, methane, carbon monoxide, and other hydrocarbons produced by coal distillation.
| Also known as | Town gasIlluminating gasManufactured gasCoal distillation gasRetort gas |
| Appearance | Colorless to pale yellow gas with a characteristic coal tar or aromatic odor. Lighter than air. Typically a mixture of hydrogen, methane, carbon monoxide, and other hydrocarbons produced by coal distillation. |
| Flash Point | Not applicable (flammable gas) |
| Boiling Point | Not applicable (gas mixture, components vary) |
| Vapor Density | 0.4-0.6 (lighter than air) |
| Water Reactivity | No significant reaction with water |
Fireground Response Guidance — UN 1023
Extinguishing Media
PPE Requirements
Positive-pressure SCBA is essential for suspected carbon monoxide or toxic gas exposure. Chemical suit selection depends on the product and cylinder condition, but respiratory protection, monitoring and exclusion zones are the key controls.
Isolation & Evacuation
First Actions for a UN 1023 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Do not touch damaged cylinders, tanks, valves or released material unless properly trained and equipped.
- Avoid breathing gas and eliminate ignition sources if it is safe to do so.
- Use gas monitoring when available because toxic and flammable hazards may both be present.
- Ventilate closed spaces before entering, but only if properly trained, equipped and authorized by incident command.
- Isolate the spill or leak area for at least 100 meters (330 feet) in all directions.
- For highlighted materials, consult ERG Table 1 for Initial Isolation and Protective Action Distances.
- Use ERG Guide 119, shipping papers, SDS and incident command for evacuation and entry decisions.
📋 Copy & Share Field Card
UN 1023 — Coal gas, compressedUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.