☣️ UN 1779 • CLASS 8
Formic acid, with more than 85% acid
Placard: Corrosive. 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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Quick details
UN 1779
Class: 8
Placard type: Corrosive
ERG: Guide 153 (check current ERG)
Isolation: ERG 153: isolate spill 50m all directions; for large spill isolate 800m downwind; evacuate immediate area if fire or major leak
Chemical & Response Details
| Also known as | Methanoic acidFormylic acidHydrogen carboxylic acidAminic acid |
| CAS Number | 64-18-6 |
| Appearance | Colorless fuming liquid with a pungent, penetrating odor. Corrosive and miscible with water. Fumes in moist air. |
| Flash Point | 69C (156F) closed cup |
| Boiling Point | 101C (214F) |
| Vapor Density | 1.6 (heavier than air) |
| Water Reactivity | Miscible with water; exothermic dilution generates heat but no violent reaction |
| Extinguishing | Alcohol-resistant foam, CO2, dry chemical; water spray for cooling |
| PPE | ⚠️ Level B minimum; SCBA required; acid-resistant suit, gloves, and boots; avoid all skin contact |
| Isolation | ERG 153: isolate spill 50m all directions; for large spill isolate 800m downwind; evacuate immediate area if fire or major leak |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
- Methyl bromoacetate (UN2643) is an eye irritant/lachrymator (causes flow of tears).
- 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.
- When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
First actions (field-minded)
- 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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UN 1779 — Formic acid, with more than 85% acid HAZMAT RADIO NOTE — UN 1779
Product: Formic acid, with more than 85% acid
Class 8 / Corrosive / ERG 153
PPE: Level B minimum; SCBA required; acid-resistant suit, gloves, and boots; avoid all skin contact
ISOLATION: ERG 153: isolate spill 50m all directions; for large spill isolate 800m downwind; evacuate immediate area if fire or major leak
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 1779 — Formic acid, with more than 85% acid
Class: 8 | Placard: Corrosive | ERG Guide: 153
Appearance: Colorless fuming liquid with a pungent, penetrating odor. Corrosive and miscible with water. Fumes in moist air.
Water Reactivity: Miscible with water; exothermic dilution generates heat but no violent reaction
Extinguishing: Alcohol-resistant foam, CO2, dry chemical; water spray for cooling
PPE: Level B minimum; SCBA required; acid-resistant suit, gloves, and boots; avoid all skin contact
Isolation: ERG 153: isolate spill 50m all directions; for large spill isolate 800m downwind; evacuate immediate area if fire or major leak
— Key Hazards —
• TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
• Methyl bromoacetate (UN2643) is an eye irritant/lachrymator (causes flow of tears).
• Contact with molten substance may cause severe burns to skin and eyes.
— 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/1779 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1779 Formic acid, with more than 85% acid Cls8 ERG153 | allfirefighter.com/hazmat/un/1779SMS / 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/1779
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FAQ
TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury Methyl bromoacetate (UN2643) is an eye irritant/lachrymator (causes flow of tears). 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. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
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; acid-resistant suit, gloves, and boots; avoid all skin contact
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 153 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.