☣️ UN 3056 • CLASS 3
UN 3056 — n-Heptaldehyde
Placard: Flammable. ERG Guide 129. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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UN 3056 Quick Details
UN 3056
Product name: n-Heptaldehyde
DOT Class: 3
Placard type: Flammable
ERG Guide: 129 (check current ERG)
Initial isolation: ERG 129: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions
Common Hazards of UN 3056
- HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
- Vapors may form explosive mixtures with air.
- Vapors may travel to source of ignition and flash back.
- Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
- Vapor explosion hazard indoors, outdoors or in sewers.
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
- Runoff to sewer may create fire or explosion hazard.
- Containers may explode when heated.
Chemical Identity & Physical Properties
| Also known as | heptanalheptaldehydeenanthaldehydeenanthalenanthic aldehydeoenanthaldehydeoenanthic aldehyde |
| CAS Number | 111-71-7 |
| Appearance | Colorless to pale yellow liquid with a pungent, fatty, fruity odor. Oily consistency at room temperature. |
| Flash Point | 46C (115F) |
| Boiling Point | 153C (307F) |
| Vapor Density | 4.0 (heavier than air) |
| Water Reactivity | No significant reaction with water; slightly soluble |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3056
Extinguishing Media
AFFF foam, alcohol-resistant foam, CO2, dry chemical
PPE Requirements
⚠️ Level B minimum with SCBA; flash fire hazard requires full protective clothing
Isolation & Evacuation
ERG 129: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 129).
First Actions for a UN 3056 Incident
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area for at least 50 meters (150 feet) in all directions.
- Consider initial downwind evacuation for at least 300 meters (1000 feet).
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📋 Copy & Share Field Card
UN 3056 — n-HeptaldehydeHAZMAT RADIO NOTE — UN 3056
Product: n-Heptaldehyde
Class 3 / Flammable / ERG 129
PPE: Level B minimum with SCBA; flash fire hazard requires full protective clothing
ISOLATION: ERG 129: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 3056 — n-Heptaldehyde
Class: 3 | Placard: Flammable | ERG Guide: 129
Appearance: Colorless to pale yellow liquid with a pungent, fatty, fruity odor. Oily consistency at room temperature.
Water Reactivity: No significant reaction with water; slightly soluble
Extinguishing: AFFF foam, alcohol-resistant foam, CO2, dry chemical
PPE: Level B minimum with SCBA; flash fire hazard requires full protective clothing
Isolation: ERG 129: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions
— Key Hazards —
• HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
• Vapors may form explosive mixtures with air.
• Vapors may travel to source of ignition and flash back.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/3056 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3056 n-Heptaldehyde Cls3 ERG129 | ERG 129: isolate spill 50m all directions; if tank/rail car involved in fire, is | allfirefighter.com/hazmat/un/3056SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/3056
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Frequently Asked Questions about UN 3056
HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas Vapor explosion hazard indoors, outdoors or in sewers. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated.
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level B minimum with SCBA; flash fire hazard requires full protective clothing
Water reactivity: No significant reaction with water; slightly soluble. Recommended extinguishing: AFFF foam, alcohol-resistant foam, CO2, dry chemical.
ERG Guide 129 recommendation: ERG 129: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 129 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.