☣️ UN 3550 • CLASS 6
Cobalt dihydroxide powder
Placard: Toxic. 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 3550
Class: 6
Placard type: Toxic
ERG: Guide 151 (check current ERG)
Isolation: ERG 151: Initial isolation 25m in all directions; spill: 25m day/50m night; fire: isolate 800m if tank/rail car involved
Chemical & Response Details
| Also known as | Cobalt(II) hydroxideCobaltous hydroxideCobalt hydroxideCobalt dihydroxide |
| CAS Number | 1307-96-6 |
| Appearance | Pink to blue-violet powder, odorless. Exists as a solid at room temperature, may vary from rose-red to blue depending on hydration state. |
| Flash Point | Not applicable (non-combustible inorganic solid) |
| Boiling Point | Not applicable (decomposes before boiling at approximately 168°C) |
| Vapor Density | Not applicable (solid, non-volatile) |
| Water Reactivity | Slightly soluble in water, no violent reaction. May slowly dissolve in acidic conditions. |
| Extinguishing | Water spray for dust control, dry chemical, CO2 for surrounding fires. Avoid generating dust clouds. |
| PPE | ⚠️ Level B minimum for spill response; SCBA required in enclosed spaces or fire conditions. Impervious gloves, chemical-resistant clothing to prevent skin contact. Avoid inhalation of dust. |
| Isolation | ERG 151: Initial isolation 25m in all directions; spill: 25m day/50m night; fire: isolate 800m if tank/rail car involved |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Highly toxic, may be fatal if inhaled, ingested or absorbed through skin.
- Avoid any skin contact.
- Fire may 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
- Containers may explode when heated.
- Runoff may pollute waterways.
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.
- 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 3550 — Cobalt dihydroxide powder HAZMAT RADIO NOTE — UN 3550
Product: Cobalt dihydroxide powder
Class 6 / Toxic / ERG 151
PPE: Level B minimum for spill response; SCBA required in enclosed spaces or fire conditions. Impervious gloves, chemical-resistant clothing to prevent skin contact. Avoid inhalation of dust.
ISOLATION: ERG 151: Initial isolation 25m in all directions; spill: 25m day/50m night; fire: isolate 800m if tank/rail car involved
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 3550 — Cobalt dihydroxide powder
Class: 6 | Placard: Toxic | ERG Guide: 151
Appearance: Pink to blue-violet powder, odorless. Exists as a solid at room temperature, may vary from rose-red to blue depending on hydration state.
Water Reactivity: Slightly soluble in water, no violent reaction. May slowly dissolve in acidic conditions.
Extinguishing: Water spray for dust control, dry chemical, CO2 for surrounding fires. Avoid generating dust clouds.
PPE: Level B minimum for spill response; SCBA required in enclosed spaces or fire conditions. Impervious gloves, chemical-resistant clothing to prevent skin contact. Avoid inhalation of dust.
Isolation: ERG 151: Initial isolation 25m in all directions; spill: 25m day/50m night; fire: isolate 800m if tank/rail car involved
— Key Hazards —
• Highly toxic, may be fatal if inhaled, ingested or absorbed through skin.
• Avoid any skin contact.
• Fire may produce irritating, corrosive and/or toxic gases.
— 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.
• Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
SOURCE: allfirefighter.com/hazmat/un/3550 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3550 Cobalt dihydroxide powder Cls6 ERG151 | allfirefighter.com/hazmat/un/3550SMS / 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/3550
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FAQ
Highly toxic, may be fatal if inhaled, ingested or absorbed through skin. Avoid any skin contact. Fire may 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 Containers may explode when heated. Runoff may pollute waterways.
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 B minimum for spill response; SCBA required in enclosed spaces or fire conditions. Impervious gloves, chemical-resistant clothing to prevent skin contact. Avoid inhalation of dust.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 151 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.