UN 2012 — Potassium phosphide
Placard: Dangerous When Wet. ERG Guide 139. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2012 is Potassium phosphide, a dangerous-when-wet metal phosphide assigned to ERG Guide 139. Moisture can release flammable and highly toxic phosphine gas.
Hazard overview: DANGEROUS WHEN WET metal phosphide; water or moisture releases flammable and highly toxic phosphine gas. May ignite on contact with water or moist air. Phosphine is heavier than air and may collect in low or confined areas.
Response guidance: For a UN 2012 incident, verify the product with shipping papers, container markings, SDS and ERG Guide 139. Establish incident command, isolate the area, stay upwind, prevent incompatible contact, control runoff or dust spread and base entry/fire-control actions on monitoring and local SOP.
Firefighter training notes: Training for UN 2012 should emphasize phosphine generation, odor unreliability, dangerous-when-wet tactics, dry-agent use, air monitoring, evacuation and medical coordination. Use ERG 139, SDS and local SOP.
Regulatory context: Potassium phosphide is regulated as a hazardous material for transportation and emergency response purposes. Storage, workplace exposure, emergency planning, spill reporting, waste handling and environmental requirements vary by exact product, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, container markings and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Potassium phosphide should be stored dry in compatible sealed containers away from water, moisture, oxidizers, acids where incompatible, ignition sources and unauthorized access. Keep compatible dry extinguishing media available and prevent dust generation.
UN 2012 Quick Details
Common Hazards of UN 2012
- DANGEROUS WHEN WET metal phosphide; water or moisture releases flammable and highly toxic phosphine gas.
- May ignite on contact with water or moist air.
- Phosphine is heavier than air and may collect in low or confined areas.
- Odor is not a reliable warning for phosphine exposure.
- Water, foam or CO2 may worsen reaction or spread toxic gas.
- Fire may produce phosphorus oxides and toxic/corrosive smoke.
- Containers may rupture or fail when heated.
Chemical Identity & Physical Properties
Dark gray to black solid with no characteristic odor. Hygroscopic powder or crystalline material.
| Also known as | Phosphorus potassiumTripotassium phosphideK3P |
| CAS Number | 20770-41-6 |
| Appearance | Dark gray to black solid with no characteristic odor. Hygroscopic powder or crystalline material. |
| Flash Point | Not applicable (water-reactive solid) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Reacts violently with water producing flammable phosphine gas (PH3) and toxic fumes; do not use water |
Fireground Response Guidance — UN 2012
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical protective clothing for dust, fire, spill or phosphine risk. Level A may be needed for close entry, water contact or unknown phosphine concentration.
Isolation & Evacuation
First Actions for a UN 2012 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.
- Avoid breathing dust, vapor, fumes, mist or smoke and avoid skin or eye contact.
- Keep water, foam and moisture away from the material unless incident command confirms a compatible control use.
- Monitor for phosphine gas where available; odor is not a reliable warning.
- Do not touch damaged containers or spilled material unless properly trained and wearing appropriate protective equipment.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or release area and expand the perimeter for fire involvement, water reaction, vapor generation, dust spread or unknown product identity.
- Use ERG Guide 139, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 2012 — Potassium phosphideUse 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.