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 At a Glance
UN 2509 (Potassium hydrogen sulphate) 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.
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.