UN 3253 — Disodium trioxosilicate
Placard: Corrosive. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 3253 Disodium trioxosilicate is assigned to ERG Guide 154 for initial emergency response. White to grayish-white crystalline powder or granular solid, odorless. Hygroscopic and may form glassy masses when exposed to moisture. Verify the exact product from shipping papers and SDS before selecting tactics.
Hazard overview: Primary hazards: a corrosive hazardous material that can cause severe skin, eye and respiratory injury. 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.
Response guidance: For a UN 3253 incident, isolate the area, keep unauthorized personnel away, stay upwind/uphill and confirm the exact material from shipping papers and SDS. Avoid direct water or foam unless incident command confirms compatibility; use dry agents such as dry chemical, dry sand, lime or soda ash when specified. Follow ERG Guide 154 and local incident command procedures.
UN 3253 Quick Details
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 contamination.
- 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
White to grayish-white crystalline powder or granular solid, odorless. Hygroscopic and may form glassy masses when exposed to moisture.
| 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 |
Fireground Response Guidance — UN 3253
Extinguishing Media
PPE Requirements
Level B minimum; Full face shield, chemical resistant gloves, protective clothing; SCBA if dust/fumes present
Isolation & Evacuation
First Actions for a UN 3253 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper if available.
- 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 25 meters (75 feet) for solids.
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials, increase the initial isolation distance in the downwind direction as needed.
📋 Copy & Share Field Card
UN 3253 — Disodium trioxosilicateUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.