☣️ UN 1790 • CLASS 8
UN 1790 — Hydrofluoric acid
Placard: Corrosive. ERG Guide 157. 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 1790 Quick Details
UN 1790
Product name: Hydrofluoric acid
DOT Class: 8
Placard type: Corrosive
ERG Guide: 157 (check current ERG)
Initial isolation: ERG 157: isolate spill 50m all directions; large spill isolate 800m downwind daytime, 1600m nighttime
Common Hazards of UN 1790
- 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.).
Chemical Identity & Physical Properties
| Also known as | Hydrogen fluoride solutionHydrofluoric acid solutionHF acidFluorhydric acidFluoric acid |
| CAS Number | 7664-39-3 |
| Appearance | Colorless to slightly colored fuming liquid with a pungent, irritating odor. Highly corrosive and fumes strongly in moist air. |
| Flash Point | Not applicable (aqueous solution) |
| Boiling Point | 106-120C (223-248F) depending on concentration |
| Vapor Density | 1.27 (heavier than air) |
| Water Reactivity | Miscible with water; dilution generates heat and increases fuming |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1790
Extinguishing Media
Do not use water directly on acid; use water spray to reduce vapors, CO2 or dry chemical for surrounding fires
PPE Requirements
⚠️ Level A required; full encapsulation with SCBA; acid-resistant suit; HF penetrates skin causing deep tissue damage
Isolation & Evacuation
ERG 157: isolate spill 50m all directions; large spill isolate 800m downwind daytime, 1600m nighttime
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 157).
First Actions for a UN 1790 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 1790 — Hydrofluoric acidHAZMAT RADIO NOTE — UN 1790
Product: Hydrofluoric acid
Class 8 / Corrosive / ERG 157
PPE: Level A required; full encapsulation with SCBA; acid-resistant suit; HF penetrates skin causing deep tissue damage
ISOLATION: ERG 157: isolate spill 50m all directions; large spill isolate 800m downwind daytime, 1600m nighttime
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 1790 — Hydrofluoric acid
Class: 8 | Placard: Corrosive | ERG Guide: 157
Appearance: Colorless to slightly colored fuming liquid with a pungent, irritating odor. Highly corrosive and fumes strongly in moist air.
Water Reactivity: Miscible with water; dilution generates heat and increases fuming
Extinguishing: Do not use water directly on acid; use water spray to reduce vapors, CO2 or dry chemical for surrounding fires
PPE: Level A required; full encapsulation with SCBA; acid-resistant suit; HF penetrates skin causing deep tissue damage
Isolation: ERG 157: isolate spill 50m all directions; large spill isolate 800m downwind daytime, 1600m nighttime
— 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/1790 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1790 Hydrofluoric acid Cls8 ERG157 | ERG 157: isolate spill 50m all directions; large spill isolate 800m downwind day | allfirefighter.com/hazmat/un/1790SMS / 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/1790
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Frequently Asked Questions about UN 1790
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 required; full encapsulation with SCBA; acid-resistant suit; HF penetrates skin causing deep tissue damage
Water reactivity: Miscible with water; dilution generates heat and increases fuming. Recommended extinguishing: Do not use water directly on acid; use water spray to reduce vapors, CO2 or dry chemical for surrounding fires.
ERG Guide 157 recommendation: ERG 157: isolate spill 50m all directions; large spill isolate 800m downwind daytime, 1600m nighttime
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.