UN 2186 — Hydrogen chloride, refrigerated liquid
Placard: Toxic Gas. ERG Guide 125. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2186 is Hydrogen chloride, refrigerated liquid, a toxic corrosive refrigerated liquefied gas assigned to ERG Guide 125. It fumes in moist air and forms hydrochloric acid mist.
Hazard overview: TOXIC and CORROSIVE refrigerated liquefied hydrogen chloride; inhalation may be fatal. Fumes strongly in moist air and forms hydrochloric acid mist. Contact with liquefied gas can cause frostbite and severe chemical burns.
Response guidance: For a UN 2186 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 125. Establish incident command, isolate the area, stay upwind, control ignition or incompatibility hazards, prevent runoff or vapor spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2186 should emphasize toxic gas isolation, air monitoring, downwind protection, Level A entry decisions, cylinder control, decontamination and medical coordination. Use ERG 125, SDS and local SOP.
Regulatory context: Hydrogen chloride, refrigerated liquid is regulated as a hazardous material for transportation and emergency response purposes. Storage, workplace exposure, emergency planning, spill reporting, waste handling and environmental requirements vary by exact product, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, container markings and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Hydrogen chloride, refrigerated liquid containers should be secured in a cool, ventilated gas storage area away from heat, physical damage and incompatible materials. Toxic, corrosive, oxidizing or refrigerated gases require leak detection/ventilation and emergency planning as specified by SDS and local code.
UN 2186 Quick Details
Common Hazards of UN 2186
- TOXIC and CORROSIVE refrigerated liquefied hydrogen chloride; inhalation may be fatal.
- Fumes strongly in moist air and forms hydrochloric acid mist.
- Contact with liquefied gas can cause frostbite and severe chemical burns.
- Gas is heavier than air and may collect in low or confined areas.
- Water contact creates corrosive hydrochloric acid solution and heat; runoff becomes strongly acidic.
- Containers may rupture or rocket when heated.
- Fire may produce or spread irritating, corrosive and/or toxic gases.
Chemical Identity & Physical Properties
Colorless to slightly yellow liquefied compressed gas with a pungent, irritating odor. Fumes strongly in moist air.
| Also known as | Hydrochloric acid gasMuriatic acid gasAnhydrous hydrogen chlorideHCl |
| CAS Number | 7647-01-0 |
| Appearance | Colorless to slightly yellow liquefied compressed gas with a pungent, irritating odor. Fumes strongly in moist air. |
| Flash Point | Not applicable (non-flammable gas) |
| Boiling Point | -85C (-121F) |
| Vapor Density | 1.3 (heavier than air) |
| Water Reactivity | Reacts violently with water generating heat and corrosive hydrochloric acid solution; causes violent fuming |
Fireground Response Guidance — UN 2186
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and fully encapsulating chemical protective clothing for close entry or unknown concentrations. Level A may be needed; protect against frostbite where liquefied or refrigerated gas contact is possible.
Isolation & Evacuation
First Actions for a UN 2186 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.
- Treat the release as a serious inhalation hazard and consider downwind protective actions using ERG and incident command.
- Avoid breathing vapors, gas, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled/released material unless properly trained and wearing appropriate protective equipment.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or release area and expand the perimeter for fire involvement, vapor spread, gas accumulation, cylinder heating or unknown product identity.
- Use ERG Guide 125, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2186 — Hydrogen chloride, refrigerated liquidUse 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.