☣️ UN 2785 • CLASS 6
UN 2785 — 4-Thiapentanal
Placard: Toxic. ERG Guide 152. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ 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 2785 Quick Details
UN 2785
Product name: 4-Thiapentanal
DOT Class: 6
Placard type: Toxic
ERG Guide: 152 (check current ERG)
Initial isolation: ERG 152: Isolate spill or leak area immediately for at least 25-50 meters in all directions; increase distance if large spill or fire
Common Hazards of UN 2785
- Highly toxic, may be fatal if inhaled, ingested or absorbed through skin.
- Contact with molten substance may cause severe burns to skin and eyes.
- Avoid any skin contact.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental
- Combustible material: may burn but does not ignite readily.
- Containers may explode when heated.
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
Chemical Identity & Physical Properties
| Also known as | 4-Thiapentanal3-(Methylthio)propionaldehyde3-(Methylthio)propanalMethional |
| CAS Number | 1003-10-7 |
| Appearance | Colorless to pale yellow liquid with a strong onion-like or garlic-like odor at room temperature. |
| Flash Point | 54°C (129°F) |
| Boiling Point | 105-106°C (221-223°F) |
| Vapor Density | 2.9 (heavier than air) |
| Water Reactivity | No significant reaction with water under normal conditions |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2785
Extinguishing Media
Alcohol-resistant foam, CO2, dry chemical, water spray
PPE Requirements
⚠️ Level B minimum with SCBA; use full-face respirator and chemical-resistant gloves; avoid all skin contact due to high toxicity
Isolation & Evacuation
ERG 152: Isolate spill or leak area immediately for at least 25-50 meters in all directions; increase distance if large spill or fire
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 152).
First Actions for a UN 2785 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.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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📋 Copy & Share Field Card
UN 2785 — 4-ThiapentanalHAZMAT RADIO NOTE — UN 2785
Product: 4-Thiapentanal
Class 6 / Toxic / ERG 152
PPE: Level B minimum with SCBA; use full-face respirator and chemical-resistant gloves; avoid all skin contact due to high toxicity
ISOLATION: ERG 152: Isolate spill or leak area immediately for at least 25-50 meters in all directions; increase distance if large spill or fire
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 2785 — 4-Thiapentanal
Class: 6 | Placard: Toxic | ERG Guide: 152
Appearance: Colorless to pale yellow liquid with a strong onion-like or garlic-like odor at room temperature.
Water Reactivity: No significant reaction with water under normal conditions
Extinguishing: Alcohol-resistant foam, CO2, dry chemical, water spray
PPE: Level B minimum with SCBA; use full-face respirator and chemical-resistant gloves; avoid all skin contact due to high toxicity
Isolation: ERG 152: Isolate spill or leak area immediately for at least 25-50 meters in all directions; increase distance if large spill or fire
— Key Hazards —
• Highly toxic, may be fatal if inhaled, ingested or absorbed through skin.
• Contact with molten substance may cause severe burns to skin and eyes.
• Avoid any skin contact.
— 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.
• Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
SOURCE: allfirefighter.com/hazmat/un/2785 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2785 4-Thiapentanal Cls6 ERG152 | ERG 152: Isolate spill or leak area immediately for at least 25-50 meters in all | allfirefighter.com/hazmat/un/2785SMS / 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/2785
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Frequently Asked Questions about UN 2785
Highly toxic, may be fatal if inhaled, ingested or absorbed through skin. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental Combustible material: may burn but does not ignite readily. Containers may explode when heated. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
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; use full-face respirator and chemical-resistant gloves; avoid all skin contact due to high toxicity
Water reactivity: No significant reaction with water under normal conditions. Recommended extinguishing: Alcohol-resistant foam, CO2, dry chemical, water spray.
ERG Guide 152 recommendation: ERG 152: Isolate spill or leak area immediately for at least 25-50 meters in all directions; increase distance if large spill or fire
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 152 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.