☣️ UN 1634 • CLASS 6
UN 1634 — Mercury bromides
Placard: Toxic. ERG Guide 154. 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 1634 Quick Details
UN 1634
Product name: Mercury bromides
DOT Class: 6
Placard type: Toxic
ERG Guide: 154 (check current ERG)
Initial isolation: ERG 154: Isolate spill area at least 25m in all directions; for large spills isolate 50m and consider evacuation; do not touch or walk through material
Common Hazards of UN 1634
- TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
- Contact with molten substance may cause severe burns to skin and eyes.
- 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
- Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.).
- Corrosives in contact with metals may evolve flammable hydrogen gas.
Chemical Identity & Physical Properties
| Also known as | Mercuric bromideMercury(II) bromideMercurous bromideMercury(I) bromideHgBr2 |
| Appearance | White to yellowish crystalline powder or solid. Odorless. Exists in two forms: mercuric bromide (HgBr2) is white/colorless and mercurous bromide (Hg2Br2) is pale yellow. |
| Flash Point | Not applicable (inorganic solid) |
| Boiling Point | Approximately 322C (612F) for mercuric bromide; decomposes at high temperature |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Slightly soluble in water; no violent reaction but may release toxic vapors |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1634
Extinguishing Media
Dry chemical, CO2, or dry sand; water spray may be used to keep containers cool
PPE Requirements
⚠️ Level B minimum; SCBA required; chemical-resistant suit and gloves mandatory; avoid all skin contact due to high toxicity
Isolation & Evacuation
ERG 154: Isolate spill area at least 25m in all directions; for large spills isolate 50m and consider evacuation; do not touch or walk through material
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 154).
First Actions for a UN 1634 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 1634 — Mercury bromidesHAZMAT RADIO NOTE — UN 1634
Product: Mercury bromides
Class 6 / Toxic / ERG 154
PPE: Level B minimum; SCBA required; chemical-resistant suit and gloves mandatory; avoid all skin contact due to high toxicity
ISOLATION: ERG 154: Isolate spill area at least 25m in all directions; for large spills isolate 50m and consider evacuation; do not touch or walk through material
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 1634 — Mercury bromides
Class: 6 | Placard: Toxic | ERG Guide: 154
Appearance: White to yellowish crystalline powder or solid. Odorless. Exists in two forms: mercuric bromide (HgBr2) is white/colorless and mercurous bromide (Hg2Br2) is pale yellow.
Water Reactivity: Slightly soluble in water; no violent reaction but may release toxic vapors
Extinguishing: Dry chemical, CO2, or dry sand; water spray may be used to keep containers cool
PPE: Level B minimum; SCBA required; chemical-resistant suit and gloves mandatory; avoid all skin contact due to high toxicity
Isolation: ERG 154: Isolate spill area at least 25m in all directions; for large spills isolate 50m and consider evacuation; do not touch or walk through material
— Key Hazards —
• TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
• Contact with molten substance may cause severe burns to skin and eyes.
• Avoid any skin contact.
— 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/1634 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1634 Mercury bromides Cls6 ERG154 | ERG 154: Isolate spill area at least 25m in all directions; for large spills iso | allfirefighter.com/hazmat/un/1634SMS / 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/1634
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Frequently Asked Questions about UN 1634
TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury Contact with molten substance may cause severe burns to skin and eyes. 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 Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Corrosives in contact with metals may evolve flammable hydrogen gas.
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; SCBA required; chemical-resistant suit and gloves mandatory; avoid all skin contact due to high toxicity
Water reactivity: Slightly soluble in water; no violent reaction but may release toxic vapors. Recommended extinguishing: Dry chemical, CO2, or dry sand; water spray may be used to keep containers cool.
ERG Guide 154 recommendation: ERG 154: Isolate spill area at least 25m in all directions; for large spills isolate 50m and consider evacuation; do not touch or walk through material
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 154 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.