UN 2503 — Zirconium tetrachloride
Placard: Corrosive. ERG Guide 137. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2503 is Zirconium tetrachloride, a corrosive moisture-reactive chloride solid assigned to ERG Guide 137. Humid air can cause strong HCl fuming.
Hazard overview: CORROSIVE moisture-reactive solid; dust or fumes can burn eyes, skin and respiratory tissue. Reacts with water or moist air, releasing hydrogen chloride fumes and heat. Fumes strongly in humid air and can create acidic runoff.
Response guidance: For UN 2503, isolate the spill, stay upwind and use SCBA with chemical protection. Control moisture contact, contain acidic/toxic runoff and use dry compatible agents under SDS and ERG 137 guidance.
Firefighter training notes: Training for UN 2503 should emphasize water-reactive corrosive fuming, dry-agent selection, SCBA/Level A decisions, decontamination and acidic/toxic runoff control. Use ERG 137, SDS and local SOP.
Regulatory context: Zirconium tetrachloride is regulated as a hazardous material for transport and emergency response. Storage, exposure, spill reporting, waste and fire-code duties depend on quantity, concentration and jurisdiction; verify shipping papers, SDS and local authority requirements.
Storage & handling: Zirconium tetrachloride should be stored dry in tightly closed compatible containers away from water, moisture, bases, oxidizers/reducing agents where incompatible, heat and unauthorized access. Provide secondary containment.
UN 2503 Quick Details
Common Hazards of UN 2503
- CORROSIVE moisture-reactive solid; dust or fumes can burn eyes, skin and respiratory tissue.
- Reacts with water or moist air, releasing hydrogen chloride fumes and heat.
- Fumes strongly in humid air and can create acidic runoff.
- Non-combustible, but heating can produce toxic/corrosive chloride fumes.
- Runoff may be acidic, corrosive and environmentally harmful.
- Containers may rupture or fail when heated or contaminated with water.
- Avoid dust generation and direct water contact with released material.
Chemical Identity & Physical Properties
White crystalline solid or granular powder. Odorless when pure, but may have a pungent odor due to hydrolysis in moist air. Hygroscopic and fumes in moist air.
| Also known as | Zirconium chlorideZirconium(IV) chlorideTetrachlorozirconiumZrCl4 |
| CAS Number | 10026-11-6 |
| Appearance | White crystalline solid or granular powder. Odorless when pure, but may have a pungent odor due to hydrolysis in moist air. Hygroscopic and fumes in moist air. |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | 331C (628F) sublimes |
| Vapor Density | Not applicable (solid, but vapors heavier than air upon sublimation) |
| Water Reactivity | Reacts violently with water producing heat, corrosive hydrochloric acid fumes, and zirconium oxychloride |
Fireground Response Guidance — UN 2503
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical-resistant protective clothing. Level A may be needed for heavy fuming, splash risk or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 2503 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Keep water contact controlled because moisture can increase heat release, corrosive fuming or toxic gas formation.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 137, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2503 — Zirconium tetrachlorideUse 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.