☣️ UN 1894 • CLASS 6
UN 1894 — Phenylmercuric hydroxide
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 1894 Quick Details
UN 1894
Product name: Phenylmercuric hydroxide
DOT Class: 6
Placard type: Toxic
ERG Guide: 151 (check current ERG)
Initial isolation: ERG 151: isolate spill/leak area 50m in all directions; if tank/rail/tank truck involved in fire, isolate 800m in all directions and consider initial evacuation for 800m
Common Hazards of UN 1894
- 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 | Phenylmercury hydroxideHydroxyphenylmercuryPMHPhenylhydroxymercuryPhenylmercuric acid |
| CAS Number | 100-57-2 |
| Appearance | White to cream-colored crystalline powder or solid. Odorless or slight aromatic odor. Solid at room temperature. |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | Decomposes before boiling |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Slightly soluble in water; no significant reaction |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1894
Extinguishing Media
Dry chemical, CO2, water spray acceptable for fire control
PPE Requirements
⚠️ Level A or B required; SCBA mandatory; impervious suit, gloves, boots to prevent any skin contact with this highly toxic mercury compound
Isolation & Evacuation
ERG 151: isolate spill/leak area 50m in all directions; if tank/rail/tank truck involved in fire, isolate 800m in all directions and consider initial evacuation for 800m
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 151).
First Actions for a UN 1894 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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UN 1894 — Phenylmercuric hydroxideHAZMAT RADIO NOTE — UN 1894
Product: Phenylmercuric hydroxide
Class 6 / Toxic / ERG 151
PPE: Level A or B required; SCBA mandatory; impervious suit, gloves, boots to prevent any skin contact with this highly toxic mercury compound
ISOLATION: ERG 151: isolate spill/leak area 50m in all directions; if tank/rail/tank truck involved in fire, isolate 800m in all directions and consider initial evacuation for 800m
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 1894 — Phenylmercuric hydroxide
Class: 6 | Placard: Toxic | ERG Guide: 151
Appearance: White to cream-colored crystalline powder or solid. Odorless or slight aromatic odor. Solid at room temperature.
Water Reactivity: Slightly soluble in water; no significant reaction
Extinguishing: Dry chemical, CO2, water spray acceptable for fire control
PPE: Level A or B required; SCBA mandatory; impervious suit, gloves, boots to prevent any skin contact with this highly toxic mercury compound
Isolation: ERG 151: isolate spill/leak area 50m in all directions; if tank/rail/tank truck involved in fire, isolate 800m in all directions and consider initial evacuation for 800m
— 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/1894 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1894 Phenylmercuric hydroxide Cls6 ERG151 | allfirefighter.com/hazmat/un/1894SMS / 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/1894
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Frequently Asked Questions about UN 1894
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 A or B required; SCBA mandatory; impervious suit, gloves, boots to prevent any skin contact with this highly toxic mercury compound
Water reactivity: Slightly soluble in water; no significant reaction. Recommended extinguishing: Dry chemical, CO2, water spray acceptable for fire control.
ERG Guide 151 recommendation: ERG 151: isolate spill/leak area 50m in all directions; if tank/rail/tank truck involved in fire, isolate 800m in all directions and consider initial evacuation for 800m
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.