☣️ UN 1636 • CLASS 6
Mercury cyanide
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 1636
Class: 6
Placard type: Toxic
ERG: Guide 154 (check current ERG)
Isolation: ERG 154: Initial isolation 100m all directions; Protective Action Distance 300m daytime, 900m nighttime for large spills
Chemical & Response Details
| Also known as | Mercuric cyanideMercury(II) cyanideCyanure de mercureMercury dicyanide |
| CAS Number | 592-04-1 |
| Appearance | White to colorless crystalline powder or crystals, odorless. Solid at room temperature. |
| Flash Point | Not applicable (non-combustible solid) |
| Boiling Point | Decomposes before boiling at approximately 320C (608F) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Slowly hydrolyzes in water releasing toxic hydrogen cyanide gas; avoid prolonged water contact |
| Extinguishing | Water spray, dry chemical, or CO2 acceptable; avoid direct water streams that promote dissolution |
| PPE | ⚠️ Level A recommended for significant exposure; full-face SCBA, chemical-resistant suit, double gloves; extreme toxicity via all routes |
| Isolation | ERG 154: Initial isolation 100m all directions; Protective Action Distance 300m daytime, 900m nighttime for large spills |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- 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.
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 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 1636 — Mercury cyanide HAZMAT RADIO NOTE — UN 1636
Product: Mercury cyanide
Class 6 / Toxic / ERG 154
PPE: Level A recommended for significant exposure; full-face SCBA, chemical-resistant suit, double gloves; extreme toxicity via all routes
ISOLATION: ERG 154: Initial isolation 100m all directions; Protective Action Distance 300m daytime, 900m nighttime for large spills
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 1636 — Mercury cyanide
Class: 6 | Placard: Toxic | ERG Guide: 154
Appearance: White to colorless crystalline powder or crystals, odorless. Solid at room temperature.
Water Reactivity: Slowly hydrolyzes in water releasing toxic hydrogen cyanide gas; avoid prolonged water contact
Extinguishing: Water spray, dry chemical, or CO2 acceptable; avoid direct water streams that promote dissolution
PPE: Level A recommended for significant exposure; full-face SCBA, chemical-resistant suit, double gloves; extreme toxicity via all routes
Isolation: ERG 154: Initial isolation 100m all directions; Protective Action Distance 300m daytime, 900m nighttime for large spills
— 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/1636 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1636 Mercury cyanide Cls6 ERG154 | ERG 154: Initial isolation 100m all directions; Protective Action Distance 300m | allfirefighter.com/hazmat/un/1636SMS / 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/1636
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FAQ
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 A recommended for significant exposure; full-face SCBA, chemical-resistant suit, double gloves; extreme toxicity via all routes
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.