UN 1807 — Phosphorus pentoxide
Placard: Corrosive. ERG Guide 137. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1807 is Phosphorus pentoxide, a corrosive water-reactive solid assigned to ERG Guide 137. It rapidly absorbs moisture and can form hot phosphoric acid mist.
Hazard overview: UN 1807 presents corrosive dust, violent water reaction, acid mist and acidic-runoff hazards. Keep the material dry and use compatible dry control agents under incident command.
Response guidance: For a UN 1807 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 137. Establish incident command, isolate the area, stay upwind, prevent incompatible contact, control runoff and choose entry or fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1807 should emphasize violent water reaction, hydrogen halide/phosphoric acid fuming, dry-agent selection, downwind vapor control and decontamination. Use ERG 137, SDS and hazmat SOP.
Regulatory context: Phosphorus pentoxide is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by concentration, formulation, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Phosphorus pentoxide should be stored in tightly closed compatible containers in a cool, dry, well-ventilated area away from water, moisture, bases, oxidizers/reducing agents where incompatible, heat and unauthorized access. Protect containers from corrosion, leakage and contamination.
UN 1807 Quick Details
Common Hazards of UN 1807
- CORROSIVE water-reactive solid; inhalation or contact with dust may cause severe injury.
- Reacts violently with water or moisture, generating intense heat and corrosive phosphoric acid mist.
- Dust and acid mist can burn eyes, skin and respiratory tissue.
- Non-combustible, but contact with moisture can greatly increase fuming and heat.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff may be strongly acidic and corrosive.
- Containers may rupture or fail when heated or contaminated with water.
Chemical Identity & Physical Properties
White, odorless crystalline powder or granular solid. Hygroscopic, readily absorbs moisture from air forming phosphoric acid mist.
| Also known as | Phosphoric anhydrideDiphosphorus pentoxidePhosphorus(V) oxidePhosphoric acid anhydride |
| CAS Number | 1314-56-3 |
| Appearance | White, odorless crystalline powder or granular solid. Hygroscopic, readily absorbs moisture from air forming phosphoric acid mist. |
| Flash Point | Not applicable (non-combustible solid) |
| Boiling Point | 360C (680F) sublimes |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Reacts violently with water generating intense heat and forming corrosive phosphoric acid. Keep dry, do not use water directly. |
Fireground Response Guidance — UN 1807
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, fume, dust, fire or confined-space exposure. Chemical-resistant gloves, boots, eye/face protection and protective clothing should be selected from SDS; Level A may be needed for close entry or unknown concentrations.
Isolation & Evacuation
First Actions for a UN 1807 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 vapors, fumes, dust, mist or spray and avoid skin or eye contact.
- Keep water and moisture away from released product unless incident command confirms a compatible cooling or control use.
- Do not touch or walk through 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 leak area and expand the perimeter if vapor, dust, fire involvement, water reaction or unknown concentration is present.
- Use ERG Guide 137, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1807 — Phosphorus pentoxideUse 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.