UN 2509 — Potassium hydrogen sulphate
Placard: Corrosive. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2509 is Potassium hydrogen sulphate, a corrosive acidic salt assigned to ERG Guide 154. Dust or acidic solution can burn tissue and contaminate runoff.
Hazard overview: CORROSIVE acidic salt; dust or solution can burn eyes, skin and respiratory tissue. Dissolves in water to form acidic solution and may release heat or cause splattering. Non-combustible, but heating can produce sulfur oxides and acidic fumes.
Response guidance: For UN 2509, isolate the area, avoid skin contact and use SCBA where dust, vapor, mist or fire is present. Contain toxic/corrosive runoff and verify product controls with SDS and ERG 154.
Firefighter training notes: Training for UN 2509 should emphasize toxic/corrosive exposure routes, skin absorption, SCBA use, decontamination, runoff containment and SDS verification. Use ERG 154, SDS and local SOP.
Regulatory context: Potassium hydrogen sulphate is regulated as a hazardous material for transport and emergency response. Storage, exposure, spill reporting, waste and fire-code duties depend on quantity, concentration and jurisdiction; verify shipping papers, SDS and local authority requirements.
Storage & handling: Potassium hydrogen sulphate should be stored dry in tightly closed compatible containers with secondary containment, restricted access and segregation from bases, metals where incompatible and moisture-sensitive materials.
UN 2509 Quick Details
Common Hazards of UN 2509
- CORROSIVE acidic salt; dust or solution can burn eyes, skin and respiratory tissue.
- Dissolves in water to form acidic solution and may release heat or cause splattering.
- Non-combustible, but heating can produce sulfur oxides and acidic fumes.
- Contact with metals may generate flammable hydrogen under some acidic conditions.
- Runoff may be acidic, corrosive and harmful to waterways.
- Containers may fail when heated or exposed to moisture.
- Avoid dust generation and prevent acidic runoff spread.
Chemical Identity & Physical Properties
White crystalline solid or colorless crystals. Odorless. Hygroscopic (absorbs moisture from air).
| Also known as | Potassium bisulfatePotassium acid sulfateBisulfate of potashKHSO4 |
| CAS Number | 7646-93-7 |
| Appearance | White crystalline solid or colorless crystals. Odorless. Hygroscopic (absorbs moisture from air). |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | Decomposes at approximately 300C (572F) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Dissolves in water producing heat and acidic solution; may cause spattering |
Fireground Response Guidance — UN 2509
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for dust, vapor, mist, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing.
Isolation & Evacuation
First Actions for a UN 2509 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 154, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2509 — Potassium hydrogen sulphateUse 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.