UN 2693 — Bisulphites, aqueous solution, n.o.s.
Placard: Corrosive. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2693 At a Glance
UN 2693 (Bisulphites, aqueous solution) is listed as DOT Class 8 Corrosive and is assigned to ERG Guide 154. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
Bisulphites, aqueous solution, n.o.s. is a variable corrosive solution that may release sulfur dioxide. Concentration and additives must be confirmed from shipping papers and SDS.
Hazard overview: Bisulphites, aqueous solution, n.o.s. is a variable corrosive solution. Sulfur dioxide release is the key inhalation concern, especially if the product is heated or mixed with incompatible acids.
Response guidance: Isolate the spill, control downwind exposure and contain runoff. Use water spray or fog only from a safe distance for vapor reduction or exposure protection as SDS permits.
Firefighter training notes: Train crews to identify Bisulphites, aqueous solution, n.o.s. by UN number, placard, ERG guide and SDS before choosing entry, isolation or extinguishment tactics.
Regulatory context: Use UN 2693, ERG 154, SDS, container labels and shipping papers to confirm the exact hazard profile and protective action distances.
Storage & handling: Store in closed, compatible containers away from heat, ignition sources and incompatible materials; keep the area ventilated and protected from damage.
UN 2693 Quick Details
Common Hazards of UN 2693
- Corrosive solution; skin or eye contact can cause burns or severe irritation.
- May release sulfur dioxide, especially when heated, acidified or disturbed.
- Sulfur dioxide vapors can irritate eyes, throat and lungs and may collect downwind.
- Non-flammable solution, but fire exposure can release toxic corrosive gases.
- Runoff can be acidic or toxic and may contaminate waterways.
- Reaction severity depends on concentration and exact formulation.
- Containers heated by fire may rupture or vent.
Chemical Identity & Physical Properties
Clear to yellowish aqueous liquid with sharp sulfur dioxide odor and acidic pH.
| Also known as | Bisulfites aqueous solutionHydrogen sulfite solutionAcid sulfite solutionBisulphite liquorHSO3- solution |
| Appearance | Clear to yellowish aqueous solution with a pungent, sharp sulfur dioxide odor. Liquid at room temperature with acidic pH. |
| Flash Point | Not applicable (non-flammable aqueous solution) |
| Boiling Point | Approximately 100C (212F), similar to water depending on concentration |
| Vapor Density | Not applicable (aqueous solution; vapors if any are SO2) |
| Water Reactivity | Miscible with water; dilution or heating may release sulfur dioxide gas |
Fireground Response Guidance — UN 2693
Extinguishing Media
PPE Requirements
Use SCBA with chemical-resistant suit, gloves, boots and full face/eye protection when vapor or splash exposure is possible.
Isolation & Evacuation
First Actions for a UN 2693 Incident
- Call 911 and the emergency response number shown on shipping papers or container documents.
- Keep unauthorized personnel away and establish an initial isolation perimeter.
- Stay upwind, uphill and upstream; avoid low areas where vapors or runoff may collect.
- Avoid breathing vapors, dust, smoke or mist and prevent skin and eye contact.
- Do not touch damaged containers or spilled material without appropriate chemical PPE.
- Ventilate confined spaces only when personnel are trained, monitored and properly equipped.
- Use ERG guidance, SDS, shipping papers and air monitoring before committing crews.
📋 Copy & Share Field Card
UN 2693 — Bisulphites, aqueous solution, n.o.s.Use 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.