☣️ UN 2853 • CLASS 6
Magnesium 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 2853
Class: 6
Placard type: Toxic
ERG: Guide 151 (check current ERG)
Isolation: ERG 151: isolate spill/leak area 25m in all directions; evacuate immediate area if large spill; protect from moisture
Chemical & Response Details
| Also known as | Magnesium hexafluorosilicateMagnesium silicofluorideSilicic acid magnesium saltMagnesium fluosilicate |
| CAS Number | 16949-65-8 |
| Appearance | White to off-white crystalline powder or granular solid. Odorless. Soluble in water. |
| Flash Point | Not applicable (inorganic solid, non-flammable) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid, no vapor pressure) |
| Water Reactivity | Soluble in water, forms acidic solution; releases hydrogen fluoride gas upon heating in moist conditions |
| Extinguishing | Water spray to reduce dust, dry chemical, CO2 for surrounding fires |
| PPE | ⚠️ Level B minimum; SCBA and full protective clothing; prevent any skin contact; chemical-resistant gloves and boots required |
| Isolation | ERG 151: isolate spill/leak area 25m in all directions; evacuate immediate area if large spill; protect from moisture |
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 2853 — Magnesium fluorosilicate HAZMAT RADIO NOTE — UN 2853
Product: Magnesium fluorosilicate
Class 6 / Toxic / ERG 151
PPE: Level B minimum; SCBA and full protective clothing; prevent any skin contact; chemical-resistant gloves and boots required
ISOLATION: ERG 151: isolate spill/leak area 25m in all directions; evacuate immediate area if large spill; protect from moisture
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 2853 — Magnesium fluorosilicate
Class: 6 | Placard: Toxic | ERG Guide: 151
Appearance: White to off-white crystalline powder or granular solid. Odorless. Soluble in water.
Water Reactivity: Soluble in water, forms acidic solution; releases hydrogen fluoride gas upon heating in moist conditions
Extinguishing: Water spray to reduce dust, dry chemical, CO2 for surrounding fires
PPE: Level B minimum; SCBA and full protective clothing; prevent any skin contact; chemical-resistant gloves and boots required
Isolation: ERG 151: isolate spill/leak area 25m in all directions; evacuate immediate area if large spill; protect from moisture
— 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/2853 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2853 Magnesium fluorosilicate Cls6 ERG151 | allfirefighter.com/hazmat/un/2853SMS / 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/2853
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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 full protective clothing; prevent any skin contact; chemical-resistant gloves and boots required
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.