☣️ UN 1644 • CLASS 6
UN 1644 — Mercury salicylate
Placard: Toxic. ERG Guide 151. 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 1644 Quick Details
UN 1644
Product name: Mercury salicylate
DOT Class: 6
Placard type: Toxic
ERG Guide: 151 (check current ERG)
Initial isolation: ERG 151: isolate spill area at least 25m in all directions; for large spills isolate 50m and consider evacuation; if fire, evacuate 800m downwind
Common Hazards of UN 1644
- 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.
Chemical Identity & Physical Properties
| Also known as | Mercuric salicylateMercury(II) salicylateSalicylic acid mercury saltMercurisalicylate |
| Appearance | White to pale pink crystalline powder or granules. Odorless or faint characteristic odor. Solid at room temperature. |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Slightly soluble in water; no violent reaction expected but may release toxic mercury compounds |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1644
Extinguishing Media
Dry chemical, CO2, water spray for cooling containers; standard firefighting agents acceptable
PPE Requirements
⚠️ Level B minimum with SCBA required; avoid all skin contact, use chemical-resistant gloves and full protective clothing due to high toxicity
Isolation & Evacuation
ERG 151: isolate spill area at least 25m in all directions; for large spills isolate 50m and consider evacuation; if fire, evacuate 800m downwind
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 151).
First Actions for a UN 1644 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.
- 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 1644 — Mercury salicylateHAZMAT RADIO NOTE — UN 1644
Product: Mercury salicylate
Class 6 / Toxic / ERG 151
PPE: Level B minimum with SCBA required; avoid all skin contact, use chemical-resistant gloves and full protective clothing due to high toxicity
ISOLATION: ERG 151: isolate spill area at least 25m in all directions; for large spills isolate 50m and consider evacuation; if fire, evacuate 800m 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 1644 — Mercury salicylate
Class: 6 | Placard: Toxic | ERG Guide: 151
Appearance: White to pale pink crystalline powder or granules. Odorless or faint characteristic odor. Solid at room temperature.
Water Reactivity: Slightly soluble in water; no violent reaction expected but may release toxic mercury compounds
Extinguishing: Dry chemical, CO2, water spray for cooling containers; standard firefighting agents acceptable
PPE: Level B minimum with SCBA required; avoid all skin contact, use chemical-resistant gloves and full protective clothing due to high toxicity
Isolation: ERG 151: isolate spill area at least 25m in all directions; for large spills isolate 50m and consider evacuation; if fire, evacuate 800m downwind
— 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/1644 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1644 Mercury salicylate Cls6 ERG151 | ERG 151: isolate spill area at least 25m in all directions; for large spills iso | allfirefighter.com/hazmat/un/1644SMS / 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/1644
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Frequently Asked Questions about UN 1644
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 with SCBA required; avoid all skin contact, use chemical-resistant gloves and full protective clothing due to high toxicity
Water reactivity: Slightly soluble in water; no violent reaction expected but may release toxic mercury compounds. Recommended extinguishing: Dry chemical, CO2, water spray for cooling containers; standard firefighting agents acceptable.
ERG Guide 151 recommendation: ERG 151: isolate spill area at least 25m in all directions; for large spills isolate 50m and consider evacuation; if fire, evacuate 800m downwind
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.