☣️ UN 3253 • CLASS 8
UN 3253 — Disodium trioxosilicate
Placard: Corrosive. ERG Guide 154. 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 3253 Quick Details
UN 3253
Product name: Disodium trioxosilicate
DOT Class: 8
Placard type: Corrosive
ERG Guide: 154 (check current ERG)
Initial isolation: ERG 154: Isolate spill 25m all directions; for large spills isolate 50m and deny entry
Common Hazards of UN 3253
- TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
- 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
- Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive
- Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.).
- Corrosives in contact with metals may evolve flammable hydrogen gas.
Chemical Identity & Physical Properties
| Also known as | Sodium metasilicateSodium silicateWater glassSilicic acid disodium saltDisodium metasilicate |
| CAS Number | 6834-92-0 |
| Appearance | White to grayish-white crystalline powder or granular solid, odorless. Hygroscopic and may form glassy masses when exposed to moisture. |
| Flash Point | Not applicable (inorganic solid) |
| Boiling Point | Not applicable (decomposes above 1088C/1990F) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Dissolves in water forming strongly alkaline solution (pH 12-13), generates heat |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3253
Extinguishing Media
Water spray, dry chemical, CO2, sand; avoid water contact with molten material
PPE Requirements
⚠️ Level B minimum; Full face shield, chemical resistant gloves, protective clothing; SCBA if dust/fumes present
Isolation & Evacuation
ERG 154: Isolate spill 25m all directions; for large spills isolate 50m and deny entry
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 154).
First Actions for a UN 3253 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.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- 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 3253 — Disodium trioxosilicateHAZMAT RADIO NOTE — UN 3253
Product: Disodium trioxosilicate
Class 8 / Corrosive / ERG 154
PPE: Level B minimum; Full face shield, chemical resistant gloves, protective clothing; SCBA if dust/fumes present
ISOLATION: ERG 154: Isolate spill 25m all directions; for large spills isolate 50m and deny entry
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 3253 — Disodium trioxosilicate
Class: 8 | Placard: Corrosive | ERG Guide: 154
Appearance: White to grayish-white crystalline powder or granular solid, odorless. Hygroscopic and may form glassy masses when exposed to moisture.
Water Reactivity: Dissolves in water forming strongly alkaline solution (pH 12-13), generates heat
Extinguishing: Water spray, dry chemical, CO2, sand; avoid water contact with molten material
PPE: Level B minimum; Full face shield, chemical resistant gloves, protective clothing; SCBA if dust/fumes present
Isolation: ERG 154: Isolate spill 25m all directions; for large spills isolate 50m and deny entry
— Key Hazards —
• TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
• 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.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/3253 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3253 Disodium trioxosilicate Cls8 ERG154 | allfirefighter.com/hazmat/un/3253SMS / 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/3253
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Frequently Asked Questions about UN 3253
TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury 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 Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Corrosives in contact with metals may evolve flammable hydrogen gas.
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; Full face shield, chemical resistant gloves, protective clothing; SCBA if dust/fumes present
Water reactivity: Dissolves in water forming strongly alkaline solution (pH 12-13), generates heat. Recommended extinguishing: Water spray, dry chemical, CO2, sand; avoid water contact with molten material.
ERG Guide 154 recommendation: ERG 154: Isolate spill 25m all directions; for large spills isolate 50m and deny entry
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 154 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.