UN 1340 — Phosphorus pentasulphide, free from yellow and white phosphorus
Placard: Dangerous When Wet. ERG Guide 139. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1340 is Phosphorus pentasulphide, free from yellow and white phosphorus, a water-reactive Class 4 material assigned to ERG Guide 139. It can release toxic hydrogen sulfide and acidic products when exposed to water or moisture.
Hazard overview: UN 1340 presents water-reactive, flammable gas and toxic hydrogen sulfide hazards. Moisture can generate heat and H2S, and the material may ignite or re-ignite if water, foam or contaminated runoff reaches it.
Response guidance: For a UN 1340 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 139. Establish incident command, isolate the area, stay upwind, avoid unnecessary disturbance of powder or damaged packaging, and use only extinguishing agents compatible with the specific material.
Firefighter training notes: Training for UN 1340 should emphasize water-reactive sulfide behavior, hydrogen sulfide monitoring, dry-agent selection and downwind toxic gas control. Common errors include using water or foam directly, entering low areas without H2S monitoring and underestimating re-ignition. Use ERG 139, SDS and hazmat SOP.
Regulatory context: Phosphorus pentasulphide, free from yellow and white phosphorus 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 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 pentasulphide, free from yellow and white phosphorus should be stored in tightly closed compatible containers in a cool, dry, well-ventilated area away from water, moisture, acids, oxidizers, heat and ignition sources. Protect containers from damage and keep dry spill-control materials available where required.
UN 1340 Quick Details
Common Hazards of UN 1340
- DANGEROUS WHEN WET; contact with water or moisture can release flammable and toxic hydrogen sulfide gas.
- May ignite on contact with water or moist air.
- Reaction with water may generate heat, phosphoric acid products and toxic/corrosive fumes.
- May be ignited by heat, sparks or flames and may re-ignite after apparent extinguishment.
- Containers may rupture or explode when heated.
- Runoff or water application may spread contamination and increase toxic gas generation.
- Hydrogen sulfide can be rapidly dangerous in low or poorly ventilated areas.
Chemical Identity & Physical Properties
Greenish-yellow to light yellow crystalline solid with a characteristic odor resembling hydrogen sulfide. Hygroscopic material that is sensitive to moisture.
| Also known as | Phosphorus pentasulfidePhosphoric sulfideDiphosphorus pentasulfideThiophosphoric anhydrideP2S5 |
| CAS Number | 1314-80-3 |
| Appearance | Greenish-yellow to light yellow crystalline solid with a characteristic odor resembling hydrogen sulfide. Hygroscopic material that is sensitive to moisture. |
| Flash Point | Not applicable (reacts with moisture before ignition temperature reached) |
| Boiling Point | 514C (957F) - decomposes at 513C |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Reacts violently with water producing toxic hydrogen sulfide gas and phosphoric acid. Produces heat that may ignite combustible materials. Keep dry at all times. |
Fireground Response Guidance — UN 1340
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for any suspected hydrogen sulfide, fire, vapor or confined-space exposure. Chemical-resistant clothing, gloves and eye/face protection should be selected from SDS and incident command; monitoring for H2S is important.
Isolation & Evacuation
First Actions for a UN 1340 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 low areas where hydrogen sulfide or other heavy gases may collect.
- Do not touch spilled material or damaged containers unless properly trained and equipped.
- Keep water, foam and moisture away from the released material unless incident command confirms a compatible cooling or control use.
- Ventilate closed spaces before entering, but only if properly trained, equipped and authorized by incident command.
- Isolate the spill or leak area and expand the perimeter if water contact, fire or H2S detection is suspected.
- Use ERG Guide 139, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1340 — Phosphorus pentasulphide, free from yellUse 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.