☣️ UN 3474 • CLASS 4
1-Hydroxybenzotriazole, monohydrate
Placard: Flammable Solid. 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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Quick details
UN 3474
Class: 4
Placard type: Flammable Solid
ERG: Guide 113 (check current ERG)
Isolation: ERG 113: isolate spill or leak area immediately for at least 50-100m in all directions; if dried material or large fire, isolate 800m and consider evacuation of 1600m downwind
Chemical & Response Details
| Also known as | HOBt monohydrate1-Hydroxy-1H-benzotriazole monohydrateHydroxybenzotriazole hydrateHOBt·H2O |
| CAS Number | 123333-53-9 |
| Appearance | White to off-white crystalline solid or powder. Odorless or faint characteristic odor. Hygroscopic material that forms monohydrate crystals at room temperature. |
| Flash Point | Not applicable when hydrated; dried material is shock-sensitive and explosive |
| Boiling Point | Decomposes before boiling at approximately 157-160C (315-320F) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Soluble in water; no violent reaction but dissolution releases heat |
| Extinguishing | Water spray, dry chemical, CO2; avoid vigorous application if material is dried out |
| PPE | ⚠️ Level C minimum with full-face respirator; Level B with SCBA if dried material suspected or fire conditions; nitrile gloves, chemical-resistant suit |
| Isolation | ERG 113: isolate spill or leak area immediately for at least 50-100m in all directions; if dried material or large fire, isolate 800m and consider evacuation of 1600m downwind |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Flammable/combustible material.
- May be ignited by heat, sparks or flames.
- DRIED OUT material may explode if exposed to heat, flame, friction or shock; treat as an
- Keep material wet with water or treat as an explosive (GUIDE 112).
- Runoff to sewer may create fire or explosion hazard.
- Some are toxic and may be fatal if inhaled, ingested or absorbed through skin. Specifically,
- Contact may cause burns to skin and eyes.
- Fire may produce irritating, corrosive and/or toxic gases.
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 immediately for at least 100 meters (330 feet) in all directions.
- Consider initial evacuation for 500 meters (1/3 mile) in all directions.
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UN 3474 — 1-Hydroxybenzotriazole, monohydrate HAZMAT RADIO NOTE — UN 3474
Product: 1-Hydroxybenzotriazole, monohydrate
Class 4 / Flammable Solid / ERG 113
PPE: Level C minimum with full-face respirator; Level B with SCBA if dried material suspected or fire conditions; nitrile gloves, chemical-resistant suit
ISOLATION: ERG 113: isolate spill or leak area immediately for at least 50-100m in all directions; if dried material or large fire, isolate 800m and consider evacuation of 1600m downwind
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 3474 — 1-Hydroxybenzotriazole, monohydrate
Class: 4 | Placard: Flammable Solid | ERG Guide: 113
Appearance: White to off-white crystalline solid or powder. Odorless or faint characteristic odor. Hygroscopic material that forms monohydrate crystals at room temperature.
Water Reactivity: Soluble in water; no violent reaction but dissolution releases heat
Extinguishing: Water spray, dry chemical, CO2; avoid vigorous application if material is dried out
PPE: Level C minimum with full-face respirator; Level B with SCBA if dried material suspected or fire conditions; nitrile gloves, chemical-resistant suit
Isolation: ERG 113: isolate spill or leak area immediately for at least 50-100m in all directions; if dried material or large fire, isolate 800m and consider evacuation of 1600m downwind
— Key Hazards —
• Flammable/combustible material.
• May be ignited by heat, sparks or flames.
• DRIED OUT material may explode if exposed to heat, flame, friction or shock; treat as an
— 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/3474 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3474 1-Hydroxybenzotriazole, monohydrate Cls4 ERG113 | allfirefighter.com/hazmat/un/3474SMS / 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/3474
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FAQ
Flammable/combustible material. May be ignited by heat, sparks or flames. DRIED OUT material may explode if exposed to heat, flame, friction or shock; treat as an Keep material wet with water or treat as an explosive (GUIDE 112). Runoff to sewer may create fire or explosion hazard. Some are toxic and may be fatal if inhaled, ingested or absorbed through skin. Specifically, Contact may cause burns to skin and eyes. Fire may produce irritating, corrosive and/or toxic gases.
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 C minimum with full-face respirator; Level B with SCBA if dried material suspected or fire conditions; nitrile gloves, chemical-resistant suit
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 113 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.