UN 2502 — Valeryl chloride
Placard: Corrosive. ERG Guide 132. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2502 is Valeryl chloride, a flammable corrosive acid chloride assigned to ERG Guide 132. Moisture can release hydrogen chloride fumes and heat.
Hazard overview: FLAMMABLE and CORROSIVE acid chloride liquid; vapors may ignite and cause severe irritation or burns. Reacts with water or moist air to release hydrogen chloride fumes and heat. Vapors are heavier than air and may travel to ignition sources and flash back.
Response guidance: For UN 2502, 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 132 guidance.
Firefighter training notes: Training for UN 2502 should emphasize water-reactive corrosive fuming, dry-agent selection, SCBA/Level A decisions, decontamination and acidic/toxic runoff control. Use ERG 132, SDS and local SOP.
Regulatory context: Valeryl chloride 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: Valeryl chloride 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 2502 Quick Details
Common Hazards of UN 2502
- FLAMMABLE and CORROSIVE acid chloride liquid; vapors may ignite and cause severe irritation or burns.
- Reacts with water or moist air to release hydrogen chloride fumes and heat.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Liquid contact can burn eyes, skin and respiratory tissue.
- Fire may produce hydrogen chloride, carbon monoxide and other toxic/corrosive gases.
- Runoff may be acidic, corrosive and flammable-contaminated.
- Containers may rupture or explode when heated or contaminated with water.
Chemical Identity & Physical Properties
Clear to pale yellow liquid with a pungent, irritating odor. Corrosive liquid that fumes in moist air.
| Also known as | Pentanoyl chlorideValeric acid chloriden-Valeryl chloridePentanoic acid chloride |
| CAS Number | 638-29-9 |
| Appearance | Clear to pale yellow liquid with a pungent, irritating odor. Corrosive liquid that fumes in moist air. |
| Flash Point | 26C (79F) |
| Boiling Point | 124-127C (255-261F) |
| Vapor Density | 4.1 (heavier than air) |
| Water Reactivity | Reacts violently with water, releasing heat and corrosive HCl fumes. Do not use water directly on material. |
Fireground Response Guidance — UN 2502
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 2502 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 132, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2502 — Valeryl chlorideUse 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.