☣️ UN 1556 • CLASS 6
Arsenic compound, liquid, n.o.s.
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 1556
Class: 6
Placard type: Toxic
ERG: Guide 152 (check current ERG)
Isolation: ERG 152: Initial isolation 50m in all directions; protective action distance 150m downwind daytime, 300m nighttime for small spills; 300m downwind daytime, 800m nighttime for large spills
Chemical & Response Details
| Also known as | Arsenic compound liquidLiquid arsenic preparationArsenical liquid n.o.s.Organoarsenic liquid |
| Appearance | Variable appearance depending on specific compound; typically colorless to dark liquid with possible garlic-like odor or odorless. Physical properties vary widely as this is a generic classification. |
| Flash Point | Variable depending on specific compound and solvent carrier |
| Boiling Point | Variable depending on specific arsenic compound |
| Vapor Density | Variable, typically heavier than air if volatile |
| Water Reactivity | Generally no violent reaction with water, but may dissolve or hydrolyze |
| Extinguishing | Water spray, foam, dry chemical, or CO2 appropriate for surrounding fire |
| PPE | ⚠️ Level A or B with SCBA required; full chemical-resistant suit; avoid all skin contact; respiratory protection mandatory even for small releases |
| Isolation | ERG 152: Initial isolation 50m in all directions; protective action distance 150m downwind daytime, 300m nighttime for small spills; 300m downwind daytime, 800m nighttime for large spills |
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.
- 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
- Combustible material: may burn but does not ignite readily.
- Containers may explode when heated.
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
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 1556 — Arsenic compound, liquid, n.o.s. HAZMAT RADIO NOTE — UN 1556
Product: Arsenic compound, liquid, n.o.s.
Class 6 / Toxic / ERG 152
PPE: Level A or B with SCBA required; full chemical-resistant suit; avoid all skin contact; respiratory protection mandatory even for small releases
ISOLATION: ERG 152: Initial isolation 50m in all directions; protective action distance 150m downwind daytime, 300m nighttime for small spills; 300m downwind daytime, 800m 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 1556 — Arsenic compound, liquid, n.o.s.
Class: 6 | Placard: Toxic | ERG Guide: 152
Appearance: Variable appearance depending on specific compound; typically colorless to dark liquid with possible garlic-like odor or odorless. Physical properties vary widely as this is a generic classification.
Water Reactivity: Generally no violent reaction with water, but may dissolve or hydrolyze
Extinguishing: Water spray, foam, dry chemical, or CO2 appropriate for surrounding fire
PPE: Level A or B with SCBA required; full chemical-resistant suit; avoid all skin contact; respiratory protection mandatory even for small releases
Isolation: ERG 152: Initial isolation 50m in all directions; protective action distance 150m downwind daytime, 300m nighttime for small spills; 300m downwind daytime, 800m nighttime for large spills
— Key Hazards —
• Highly toxic, may be fatal if inhaled, ingested or absorbed through skin.
• 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.
• 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/1556 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1556 Arsenic compound, liquid, n.o.s. Cls6 ERG152 | allfirefighter.com/hazmat/un/1556SMS / 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/1556
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FAQ
Highly toxic, may be fatal if inhaled, ingested or absorbed through skin. 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 Combustible material: may burn but does not ignite readily. Containers may explode when heated. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
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 with SCBA required; full chemical-resistant suit; avoid all skin contact; respiratory protection mandatory even for small releases
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 152 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.