UN 1809 — Phosphorus trichloride
Placard: Toxic. ERG Guide 137. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1809 is Phosphorus trichloride, a toxic corrosive phosphorus halide assigned to ERG Guide 137. Water or moist air can trigger strong heat release and dense corrosive hydrogen halide fumes.
Hazard overview: UN 1809 presents violent water reaction, toxic/corrosive fume, heavy vapor and acidic-runoff hazards. Avoid water and foam on the product unless specialist guidance confirms a safe use.
Response guidance: For a UN 1809 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 1809 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 trichloride 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 trichloride 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 1809 Quick Details
Common Hazards of UN 1809
- TOXIC and CORROSIVE phosphorus halide; inhalation, ingestion or skin/eye contact may cause severe injury.
- Reacts violently with water or moist air, releasing heat, hydrogen chloride and phosphorous acid fumes.
- Vapors or fumes are heavier than air and may collect in low or confined areas.
- Liquid, dust, vapor or fumes can burn eyes, skin and respiratory tissue.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff may spread acidic phosphorus/halide contamination.
- Containers may rupture or fail when heated or contaminated with water.
Chemical Identity & Physical Properties
Colorless to pale yellow fuming liquid with a pungent, irritating odor. Fumes in moist air due to reaction with water vapor.
| Also known as | Phosphorous trichlorideTrichlorophosphinePhosphorus(III) chloridePCl3 |
| CAS Number | 7719-12-2 |
| Appearance | Colorless to pale yellow fuming liquid with a pungent, irritating odor. Fumes in moist air due to reaction with water vapor. |
| Flash Point | Not applicable (non-flammable liquid) |
| Boiling Point | 76C (169F) |
| Vapor Density | 4.75 (heavier than air) |
| Water Reactivity | Reacts violently with water, producing heat and toxic/corrosive hydrogen chloride and phosphorous acid fumes. Do not use water directly on material. |
Fireground Response Guidance — UN 1809
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 1809 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 1809 — Phosphorus trichlorideUse 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.