☣️ UN 2031 • CLASS 8
Nitric acid, other than red fuming, with not more than 65% nitric 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 2031
Class: 8
Placard type: Corrosive
ERG: Guide 157 (check current ERG)
Isolation: ERG 157: Isolate spill 25-50m all directions; for large spills isolate 800m downwind. Evacuate immediate area if tank/container involved in fire.
Chemical & Response Details
| Also known as | Aqua fortisHydrogen nitrateAzotic acidWhite fuming nitric acidWFNANitric acid solution |
| CAS Number | 7697-37-2 |
| Appearance | Colorless to pale yellow fuming liquid with a suffocating, acrid, pungent odor. Fumes in moist air. Corrosive to metals and tissue. |
| Flash Point | Not applicable (strong oxidizer, non-flammable but supports combustion) |
| Boiling Point | 83C (181F) for concentrated solutions; varies with concentration |
| Vapor Density | 2.2 (heavier than air) |
| Water Reactivity | Highly exothermic reaction with water; generates heat and may increase fuming. Dilute slowly by adding acid to water, never reverse. |
| Extinguishing | Water spray (for cooling), dry chemical. Do not apply water directly to spills; use water spray to reduce vapors from a distance. |
| PPE | ⚠️ Level A or B required; SCBA mandatory; full chemical-resistant suit; butyl or nitrile rubber gloves; face shield and splash goggles minimum. |
| Isolation | ERG 157: Isolate spill 25-50m all directions; for large spills isolate 800m downwind. Evacuate immediate area if tank/container involved in fire. |
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 contact (skin, eyes) with vapors, dusts or substance
- Reaction with water or moist air may release toxic, corrosive or flammable gases.
- Reaction with water may generate much heat that will increase the concentration of fumes in the air.
- Fire will 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
- UN1802, UN2032, UN3084, UN3093, UN1796 (above 50%), UN1826 (above 50%), and UN2031 (above
- Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars, etc.).
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 2031 — Nitric acid, other than red fuming, with HAZMAT RADIO NOTE — UN 2031
Product: Nitric acid, other than red fuming, with not more than 65% nitric acid
Class 8 / Corrosive / ERG 157
PPE: Level A or B required; SCBA mandatory; full chemical-resistant suit; butyl or nitrile rubber gloves; face shield and splash goggles minimum.
ISOLATION: ERG 157: Isolate spill 25-50m all directions; for large spills isolate 800m downwind. Evacuate immediate area if tank/container involved in 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 2031 — Nitric acid, other than red fuming, with not more than 65% nitric acid
Class: 8 | Placard: Corrosive | ERG Guide: 157
Appearance: Colorless to pale yellow fuming liquid with a suffocating, acrid, pungent odor. Fumes in moist air. Corrosive to metals and tissue.
Water Reactivity: Highly exothermic reaction with water; generates heat and may increase fuming. Dilute slowly by adding acid to water, never reverse.
Extinguishing: Water spray (for cooling), dry chemical. Do not apply water directly to spills; use water spray to reduce vapors from a distance.
PPE: Level A or B required; SCBA mandatory; full chemical-resistant suit; butyl or nitrile rubber gloves; face shield and splash goggles minimum.
Isolation: ERG 157: Isolate spill 25-50m all directions; for large spills isolate 800m downwind. Evacuate immediate area if tank/container involved in fire.
— Key Hazards —
• TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
• Reaction with water or moist air may release toxic, corrosive or flammable gases.
• Reaction with water may generate much heat that will increase the concentration of fumes in the air.
— 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/2031 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2031 Nitric acid, other than red fuming, with not more than 65% nitric acid Cls8 ERG157 | allfirefighter.com/hazmat/un/2031SMS / 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/2031
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FAQ
TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance Reaction with water or moist air may release toxic, corrosive or flammable gases. Reaction with water may generate much heat that will increase the concentration of fumes in the air. Fire will 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 UN1802, UN2032, UN3084, UN3093, UN1796 (above 50%), UN1826 (above 50%), and UN2031 (above Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars, etc.).
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 A or B required; SCBA mandatory; full chemical-resistant suit; butyl or nitrile rubber gloves; face shield and splash goggles minimum.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 157 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.