UN 2498 — Tetrahydrobenzaldehyde
Placard: Flammable. ERG Guide 129. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2498 is Tetrahydrobenzaldehyde, a flammable aldehyde liquid assigned to ERG Guide 129. Heavy vapors can travel to ignition sources and flash back.
Hazard overview: FLAMMABLE aldehyde liquid; vapors may ignite and form explosive mixtures with air. Vapors are heavier than air and may travel to ignition sources and flash back. Vapor explosion hazard exists in drains, sewers, basements and confined spaces.
Response guidance: For UN 2498, isolate the area, eliminate ignition sources, keep vapors out of drains and use SCBA. Select foam, dry chemical or CO2 based on SDS and contain contaminated runoff.
Firefighter training notes: Training for UN 2498 should emphasize vapor travel, sewer flashback, toxic/corrosive exposure, SCBA use, decontamination, runoff control and foam selection. Use ERG 129, SDS and local SOP.
Regulatory context: Tetrahydrobenzaldehyde 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: Tetrahydrobenzaldehyde should be stored in approved flammable/toxic or corrosive-liquid containers with ventilation, secondary containment and separation from heat, ignition sources, oxidizers and incompatible materials.
UN 2498 Quick Details
Common Hazards of UN 2498
- FLAMMABLE aldehyde liquid; vapors may ignite and form explosive mixtures with air.
- Vapors are heavier than air and may travel to ignition sources and flash back.
- Vapor explosion hazard exists in drains, sewers, basements and confined spaces.
- Aldehyde vapor can irritate eyes, skin and respiratory tract.
- Runoff to sewers may create fire or explosion hazards.
- Fire may produce carbon monoxide and irritating/toxic smoke.
- Containers may rupture or explode when heated.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid with a characteristic aldehyde odor. Liquid at room temperature.
| Also known as | Tetrahydrobenzaldehyde3-Cyclohexene-1-carboxaldehydeDelta-3-tetrahydrobenzaldehydeTHB aldehyde |
| CAS Number | 100-50-5 |
| Appearance | Colorless to pale yellow liquid with a characteristic aldehyde odor. Liquid at room temperature. |
| Flash Point | 57°C (135°F) |
| Boiling Point | 164-166°C (327-331°F) |
| Vapor Density | 3.8 (heavier than air) |
| Water Reactivity | No significant reaction with water; slightly soluble |
Fireground Response Guidance — UN 2498
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fire or confined-space exposure. Wear chemical-resistant gloves, eye/face protection and flame-resistant protection as appropriate.
Isolation & Evacuation
First Actions for a UN 2498 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.
- Eliminate ignition sources if this can be done safely.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- 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 129, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2498 — TetrahydrobenzaldehydeUse 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.