☣️ UN 2655 • CLASS 6
UN 2655 — Potassium fluorosilicate
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 2655 Quick Details
UN 2655
Product name: Potassium fluorosilicate
DOT Class: 6
Placard type: Toxic
ERG Guide: 151 (check current ERG)
Initial isolation: ERG 151: isolate spill 25m all directions; if large spill isolate 50m and evacuate immediate area
Common Hazards of UN 2655
- 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 | Potassium hexafluorosilicatePotassium silicofluorideDipotassium hexafluorosilicatePSF |
| CAS Number | 16871-90-2 |
| Appearance | White to colorless crystalline powder or granular solid. Odorless. Insoluble in water but slightly soluble in dilute acids. |
| Flash Point | Not applicable (non-combustible inorganic salt) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid with negligible vapor pressure) |
| Water Reactivity | No significant reaction with water, but slightly soluble forming acidic solution |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2655
Extinguishing Media
Water spray for dust control, dry chemical, CO2 - avoid generating dust clouds
PPE Requirements
⚠️ Level B minimum; SCBA and chemical-resistant suit; avoid skin contact and inhalation of dust
Isolation & Evacuation
ERG 151: isolate spill 25m all directions; if large spill isolate 50m and evacuate immediate area
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 151).
First Actions for a UN 2655 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 2655 — Potassium fluorosilicateHAZMAT RADIO NOTE — UN 2655
Product: Potassium fluorosilicate
Class 6 / Toxic / ERG 151
PPE: Level B minimum; SCBA and chemical-resistant suit; avoid skin contact and inhalation of dust
ISOLATION: ERG 151: isolate spill 25m all directions; if large spill isolate 50m and evacuate immediate area
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 2655 — Potassium fluorosilicate
Class: 6 | Placard: Toxic | ERG Guide: 151
Appearance: White to colorless crystalline powder or granular solid. Odorless. Insoluble in water but slightly soluble in dilute acids.
Water Reactivity: No significant reaction with water, but slightly soluble forming acidic solution
Extinguishing: Water spray for dust control, dry chemical, CO2 - avoid generating dust clouds
PPE: Level B minimum; SCBA and chemical-resistant suit; avoid skin contact and inhalation of dust
Isolation: ERG 151: isolate spill 25m all directions; if large spill isolate 50m and evacuate immediate area
— 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/2655 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2655 Potassium fluorosilicate Cls6 ERG151 | allfirefighter.com/hazmat/un/2655SMS / 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/2655
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Frequently Asked Questions about UN 2655
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; SCBA and chemical-resistant suit; avoid skin contact and inhalation of dust
Water reactivity: No significant reaction with water, but slightly soluble forming acidic solution. Recommended extinguishing: Water spray for dust control, dry chemical, CO2 - avoid generating dust clouds.
ERG Guide 151 recommendation: ERG 151: isolate spill 25m all directions; if large spill isolate 50m and evacuate immediate area
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.