☣️ UN 2851 • CLASS 8
UN 2851 — Boron trifluoride, dihydrate
Placard: Corrosive. ERG Guide 157. 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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UN 2851 Quick Details
UN 2851
Product name: Boron trifluoride, dihydrate
DOT Class: 8
Placard type: Corrosive
ERG Guide: 157 (check current ERG)
Initial isolation: ERG 157: Initial isolate 50m all directions; spill: 300m downwind day/800m night; fire: evacuate 800m radius
Common Hazards of UN 2851
- 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 | Boron trifluoride hydrateBF3 dihydrateTrifluoroborane dihydrateBoron fluoride dihydrate |
| CAS Number | 13319-75-0 |
| Appearance | Colorless to pale yellow liquid with a pungent, irritating odor. Fuming liquid that releases white vapors in moist air. |
| Flash Point | Not applicable (non-flammable corrosive liquid) |
| Boiling Point | Approximately 106C (223F) with decomposition |
| Vapor Density | Greater than 1 (heavier than air) |
| Water Reactivity | Reacts with water releasing heat and corrosive/toxic hydrogen fluoride (HF) and boric acid; exothermic reaction increases vapor concentration |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2851
Extinguishing Media
Dry chemical, soda ash, lime; avoid water streams that cause violent reaction and splashing
PPE Requirements
⚠️ Level A or B required; SCBA mandatory; full acid-resistant suit, boots, gloves; protect against corrosive vapors and liquid contact
Isolation & Evacuation
ERG 157: Initial isolate 50m all directions; spill: 300m downwind day/800m night; fire: evacuate 800m radius
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 157).
First Actions for a UN 2851 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 2851 — Boron trifluoride, dihydrateHAZMAT RADIO NOTE — UN 2851
Product: Boron trifluoride, dihydrate
Class 8 / Corrosive / ERG 157
PPE: Level A or B required; SCBA mandatory; full acid-resistant suit, boots, gloves; protect against corrosive vapors and liquid contact
ISOLATION: ERG 157: Initial isolate 50m all directions; spill: 300m downwind day/800m night; fire: evacuate 800m radius
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 2851 — Boron trifluoride, dihydrate
Class: 8 | Placard: Corrosive | ERG Guide: 157
Appearance: Colorless to pale yellow liquid with a pungent, irritating odor. Fuming liquid that releases white vapors in moist air.
Water Reactivity: Reacts with water releasing heat and corrosive/toxic hydrogen fluoride (HF) and boric acid; exothermic reaction increases vapor concentration
Extinguishing: Dry chemical, soda ash, lime; avoid water streams that cause violent reaction and splashing
PPE: Level A or B required; SCBA mandatory; full acid-resistant suit, boots, gloves; protect against corrosive vapors and liquid contact
Isolation: ERG 157: Initial isolate 50m all directions; spill: 300m downwind day/800m night; fire: evacuate 800m radius
— 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/2851 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2851 Boron trifluoride, dihydrate Cls8 ERG157 | allfirefighter.com/hazmat/un/2851SMS / 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/2851
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Frequently Asked Questions about UN 2851
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 acid-resistant suit, boots, gloves; protect against corrosive vapors and liquid contact
Water reactivity: Reacts with water releasing heat and corrosive/toxic hydrogen fluoride (HF) and boric acid; exothermic reaction increases vapor concentration. Recommended extinguishing: Dry chemical, soda ash, lime; avoid water streams that cause violent reaction and splashing.
ERG Guide 157 recommendation: ERG 157: Initial isolate 50m all directions; spill: 300m downwind day/800m night; fire: evacuate 800m radius
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.