☣️ UN 1786 • CLASS 8
Hydrofluoric acid and sulphuric acid mixture
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 1786
Class: 8
Placard type: Corrosive
ERG: Guide 157 (check current ERG)
Isolation: ERG 157: isolate spill 25-50m in all directions; initial evacuation 100m downwind; if tank/rail car involved in fire, isolate 800m all directions
Chemical & Response Details
| Also known as | HF-H2SO4 mixturehydrofluoric-sulfuric acid mixturefluorosulfuric acid mixtureHF/sulfuric acid blend |
| Appearance | Clear to slightly colored fuming liquid mixture with a sharp, pungent, irritating odor. Highly corrosive and generates toxic vapors. |
| Flash Point | Not applicable (non-flammable corrosive liquid) |
| Boiling Point | Variable depending on mixture ratio, typically 100-160C (212-320F) |
| Vapor Density | Heavier than air (vapors sink and concentrate in low areas) |
| Water Reactivity | Reacts with water generating heat and increasing toxic vapor concentration; violent spattering may occur |
| Extinguishing | Do not use water directly; use water spray from distance to cool containers; soda ash or lime to neutralize small spills |
| PPE | ⚠️ Level A required for spill response; full encapsulation with SCBA; acid-resistant suit, gloves, and boots mandatory; hydrofluoric acid requires specialized medical treatment protocols |
| Isolation | ERG 157: isolate spill 25-50m in all directions; initial evacuation 100m downwind; if tank/rail car involved in fire, isolate 800m all directions |
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 1786 — Hydrofluoric acid and sulphuric acid mix HAZMAT RADIO NOTE — UN 1786
Product: Hydrofluoric acid and sulphuric acid mixture
Class 8 / Corrosive / ERG 157
PPE: Level A required for spill response; full encapsulation with SCBA; acid-resistant suit, gloves, and boots mandatory; hydrofluoric acid requires specialized medical treatment protocols
ISOLATION: ERG 157: isolate spill 25-50m in all directions; initial evacuation 100m downwind; if tank/rail car involved in fire, isolate 800m all directions
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 1786 — Hydrofluoric acid and sulphuric acid mixture
Class: 8 | Placard: Corrosive | ERG Guide: 157
Appearance: Clear to slightly colored fuming liquid mixture with a sharp, pungent, irritating odor. Highly corrosive and generates toxic vapors.
Water Reactivity: Reacts with water generating heat and increasing toxic vapor concentration; violent spattering may occur
Extinguishing: Do not use water directly; use water spray from distance to cool containers; soda ash or lime to neutralize small spills
PPE: Level A required for spill response; full encapsulation with SCBA; acid-resistant suit, gloves, and boots mandatory; hydrofluoric acid requires specialized medical treatment protocols
Isolation: ERG 157: isolate spill 25-50m in all directions; initial evacuation 100m downwind; if tank/rail car involved in fire, isolate 800m all directions
— 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/1786 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1786 Hydrofluoric acid and sulphuric acid mixture Cls8 ERG157 | allfirefighter.com/hazmat/un/1786SMS / 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/1786
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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 required for spill response; full encapsulation with SCBA; acid-resistant suit, gloves, and boots mandatory; hydrofluoric acid requires specialized medical treatment protocols
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.