☣️ UN 1787 • CLASS 8
UN 1787 — Hydriodic acid
Placard: Corrosive. ERG Guide 154. 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 1787 Quick Details
UN 1787
Product name: Hydriodic acid
DOT Class: 8
Placard type: Corrosive
ERG Guide: 154 (check current ERG)
Initial isolation: ERG 154: isolate spill 25-50m all directions; if tank/rail car involved in fire, isolate 800m all directions and consider evacuation
Common Hazards of UN 1787
- TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
- 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
- Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive
- Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.).
- Corrosives in contact with metals may evolve flammable hydrogen gas.
Chemical Identity & Physical Properties
| Also known as | Hydrogen iodide solutionHydroiodic acidHI solutionIodhydric acid |
| CAS Number | 10034-85-2 |
| Appearance | Colorless to pale yellow aqueous solution with a pungent, acrid odor. Fumes strongly in moist air. Typically supplied as 47-57% solution in water. |
| Flash Point | Not applicable (aqueous solution) |
| Boiling Point | 127C (261F) for azeotropic mixture |
| Vapor Density | 4.4 (heavier than air) |
| Water Reactivity | Miscible with water; generates heat on dilution |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1787
Extinguishing Media
Water spray to reduce vapors, soda ash or lime to neutralize, avoid direct water contact with concentrated acid
PPE Requirements
⚠️ Level B minimum; SCBA required; full face shield; acid-resistant gloves and suit; rubber boots
Isolation & Evacuation
ERG 154: isolate spill 25-50m all directions; if tank/rail car involved in fire, isolate 800m all directions and consider evacuation
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 154).
First Actions for a UN 1787 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 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 1787 — Hydriodic acidHAZMAT RADIO NOTE — UN 1787
Product: Hydriodic acid
Class 8 / Corrosive / ERG 154
PPE: Level B minimum; SCBA required; full face shield; acid-resistant gloves and suit; rubber boots
ISOLATION: ERG 154: isolate spill 25-50m all directions; if tank/rail car involved in fire, isolate 800m all directions and consider evacuation
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 1787 — Hydriodic acid
Class: 8 | Placard: Corrosive | ERG Guide: 154
Appearance: Colorless to pale yellow aqueous solution with a pungent, acrid odor. Fumes strongly in moist air. Typically supplied as 47-57% solution in water.
Water Reactivity: Miscible with water; generates heat on dilution
Extinguishing: Water spray to reduce vapors, soda ash or lime to neutralize, avoid direct water contact with concentrated acid
PPE: Level B minimum; SCBA required; full face shield; acid-resistant gloves and suit; rubber boots
Isolation: ERG 154: isolate spill 25-50m all directions; if tank/rail car involved in fire, isolate 800m all directions and consider evacuation
— Key Hazards —
• TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
• 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.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/1787 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1787 Hydriodic acid Cls8 ERG154 | ERG 154: isolate spill 25-50m all directions; if tank/rail car involved in fire, | allfirefighter.com/hazmat/un/1787SMS / 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/1787
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Frequently Asked Questions about UN 1787
TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury 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 Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Corrosives in contact with metals may evolve flammable hydrogen gas.
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; SCBA required; full face shield; acid-resistant gloves and suit; rubber boots
Water reactivity: Miscible with water; generates heat on dilution. Recommended extinguishing: Water spray to reduce vapors, soda ash or lime to neutralize, avoid direct water contact with concentrated acid.
ERG Guide 154 recommendation: ERG 154: isolate spill 25-50m all directions; if tank/rail car involved in fire, isolate 800m all directions and consider evacuation
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 154 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.