☣️ UN 1685 • CLASS 6
UN 1685 — Sodium arsenate
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 1685 Quick Details
UN 1685
Product name: Sodium arsenate
DOT Class: 6
Placard type: Toxic
ERG Guide: 151 (check current ERG)
Initial isolation: ERG 151: isolate spill area immediate 25m all directions; if tank/rail car involved in fire, isolate 800m all directions
Common Hazards of UN 1685
- 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 | Disodium arsenateArsenate of sodaDisodium hydrogen arsenateSodium acid arsenate |
| CAS Number | 7778-43-0 |
| Appearance | White or colorless crystalline powder or granular solid. Odorless. Hygroscopic, readily absorbs moisture from air. |
| Flash Point | Not applicable (non-flammable inorganic solid) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Soluble in water, no significant reaction. Forms toxic arsenate solutions. |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1685
Extinguishing Media
Not applicable for extinguishing; use water spray, dry chemical, or CO2 for surrounding fires
PPE Requirements
⚠️ Level A or B minimum; SCBA required; full chemical-resistant suit; avoid all skin contact due to high toxicity
Isolation & Evacuation
ERG 151: isolate spill area immediate 25m all directions; if tank/rail car involved in fire, isolate 800m all directions
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 151).
First Actions for a UN 1685 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 1685 — Sodium arsenateHAZMAT RADIO NOTE — UN 1685
Product: Sodium arsenate
Class 6 / Toxic / ERG 151
PPE: Level A or B minimum; SCBA required; full chemical-resistant suit; avoid all skin contact due to high toxicity
ISOLATION: ERG 151: isolate spill area immediate 25m all directions; if tank/rail car involved in fire, isolate 800m all directions
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 1685 — Sodium arsenate
Class: 6 | Placard: Toxic | ERG Guide: 151
Appearance: White or colorless crystalline powder or granular solid. Odorless. Hygroscopic, readily absorbs moisture from air.
Water Reactivity: Soluble in water, no significant reaction. Forms toxic arsenate solutions.
Extinguishing: Not applicable for extinguishing; use water spray, dry chemical, or CO2 for surrounding fires
PPE: Level A or B minimum; SCBA required; full chemical-resistant suit; avoid all skin contact due to high toxicity
Isolation: ERG 151: isolate spill area immediate 25m all directions; if tank/rail car involved in fire, isolate 800m all directions
— 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/1685 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1685 Sodium arsenate Cls6 ERG151 | ERG 151: isolate spill area immediate 25m all directions; if tank/rail car invol | allfirefighter.com/hazmat/un/1685SMS / 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/1685
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Frequently Asked Questions about UN 1685
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 minimum; SCBA required; full chemical-resistant suit; avoid all skin contact due to high toxicity
Water reactivity: Soluble in water, no significant reaction. Forms toxic arsenate solutions.. Recommended extinguishing: Not applicable for extinguishing; use water spray, dry chemical, or CO2 for surrounding fires.
ERG Guide 151 recommendation: ERG 151: isolate spill area immediate 25m all directions; if tank/rail car involved in fire, isolate 800m all directions
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.