UN 3412 — Formic acid, with not less than 10% but not more than 85% acid
Placard: Corrosive. ERG Guide 153. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3412 is Formic acid in a concentration from 10% to 85%, a corrosive organic acid solution. It is encountered in chemical manufacturing, leather processing, cleaning and industrial operations, and the response should be based on acid concentration and container condition.
Hazard overview: UN 3412 can cause severe skin, eye and respiratory injury from liquid, mist or vapor. Concentrated solutions are corrosive to tissue and metals, and dilution with water can release heat. Fire or heating may produce irritating acidic vapors, and higher-concentration solutions may burn under severe fire conditions.
Response guidance: For a UN 3412 spill, isolate the area, keep personnel upwind and stop the release only from a protected position. Use water spray from a distance to reduce vapors and cool containers, but avoid forceful streams that spread concentrated acid. Prevent acid runoff from entering drains and neutralize only under trained hazmat direction.
UN 3412 Quick Details
Common Hazards of UN 3412
- 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
Chemical Identity & Physical Properties
UN 3412 is a colorless liquid with a sharp, penetrating odor. It mixes readily with water, has vapor heavier than air, and the exact boiling point, flash point and corrosivity depend on the acid concentration.
| Also known as | Methanoic acidHydrogen carboxylic acidFormylic acidAminic acid |
| CAS Number | 64-18-6 |
| Appearance | Colorless fuming liquid with a pungent, penetrating odor. Highly corrosive to metals and tissue. Miscible with water in all proportions. |
| Flash Point | 69°C (156°F) for concentrations around 85%; lower concentrations have higher flash points |
| Boiling Point | 100.8°C (213°F) for pure formic acid; varies with concentration |
| Vapor Density | 1.59 (heavier than air) |
| Water Reactivity | Miscible with water; dilution generates heat but no violent reaction. Use water spray to dilute spills. |
Fireground Response Guidance — UN 3412
Extinguishing Media
PPE Requirements
Wear positive-pressure SCBA with acid-resistant chemical protective clothing, gloves, boots and face protection. Splash protection is essential, and glove/suit materials should be selected from the SDS for the concentration involved.
Isolation & Evacuation
First Actions for a UN 3412 Incident
- 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
📋 Copy & Share Field Card
UN 3412 — Formic acid, with not less than 10% butUse 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.