UN 1758 — Chromium oxychloride
Placard: Corrosive. ERG Guide 137. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1758 is Chromium oxychloride, a corrosive toxic oxidizing liquid assigned to ERG Guide 137. It fumes in moist air and reacts violently with water, producing hydrochloric acid fumes and chromium-containing contamination.
Hazard overview: UN 1758 presents corrosive fume, oxidizer, water-reaction and toxic chromium contamination hazards. Avoid water contact, keep combustibles away and control runoff and decon waste.
Response guidance: For a UN 1758 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 137. Establish incident command, isolate the area, stay upwind, prevent incompatible contact, control runoff and choose entry or fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1758 should emphasize oxidizing corrosive fuming liquid behavior, violent water reaction, chromium contamination, dry-agent selection, runoff control and decontamination. Use ERG 137, SDS and hazmat SOP.
Regulatory context: Chromium oxychloride is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, pesticide/waste handling where applicable, storage and environmental requirements may vary by formulation, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Chromium oxychloride should be stored in tightly closed compatible containers in a cool, dry, well-ventilated area away from water, moisture, bases, oxidizers/reducing agents where incompatible, heat and unauthorized access. Protect containers from corrosion, leakage and contamination.
UN 1758 Quick Details
Common Hazards of UN 1758
- TOXIC, CORROSIVE and strong oxidizing fuming liquid; inhalation or contact may cause severe injury.
- Reacts violently with water or moist air, releasing heat, hydrochloric acid fumes and chromic acid contamination.
- Chromium(VI)-type contamination may be toxic and persistent on surfaces, runoff and equipment.
- May ignite or intensify combustion of combustibles and organic materials.
- Dense reddish-brown fumes may collect in low or poorly ventilated areas.
- Fire may produce irritating, corrosive and/or toxic gases.
- Containers may rupture or fail when heated or contaminated with water.
Chemical Identity & Physical Properties
Dark red to brownish-red fuming liquid with a pungent, acrid odor. Forms dense reddish-brown vapors in moist air due to hydrolysis.
| Also known as | Chromyl chlorideChromium dichloride dioxideChromic oxychlorideChlorochromic anhydride |
| CAS Number | 14977-61-8 |
| Appearance | Dark red to brownish-red fuming liquid with a pungent, acrid odor. Forms dense reddish-brown vapors in moist air due to hydrolysis. |
| Flash Point | Not applicable (non-flammable oxidizer) |
| Boiling Point | 117C (243F) |
| Vapor Density | 5.3 (heavier than air) |
| Water Reactivity | Reacts violently with water producing heat, hydrochloric acid fumes, and chromic acid; extreme corrosive hazard |
Fireground Response Guidance — UN 1758
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and fully encapsulating chemical protection for close entry or unknown vapor levels. PPE should address corrosive fumes, oxidizer reactivity and chromium(VI)-type contamination; select suit/glove material from SDS and incident command.
Isolation & Evacuation
First Actions for a UN 1758 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.
- Avoid breathing vapors, fumes, dust, mist or spray and avoid skin or eye contact.
- Keep water and moisture away from released product unless incident command confirms a compatible cooling or control use.
- Do not touch or walk through spilled 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 leak area and expand the perimeter if vapor, dust, fire involvement, water reaction or unknown concentration is present.
- Use ERG Guide 137, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1758 — Chromium oxychlorideUse 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.