☣️ UN 2655 • CLASS 6
Potassium fluorosilicate
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 2655
Class: 6
Placard type: Toxic
ERG: Guide 151 (check current ERG)
Isolation: ERG 151: isolate spill 25m all directions; if large spill isolate 50m and evacuate immediate area
Chemical & Response Details
| 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 |
| 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 |
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.
- 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.
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 2655 — Potassium fluorosilicate HAZMAT 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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FAQ
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
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.