UN 1611 — Hexaethyl tetraphosphate
Placard: Toxic. ERG Guide 151. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1611 is Hexaethyl tetraphosphate, a highly toxic organophosphate liquid assigned to ERG Guide 151. Skin absorption is a major concern, and exposed responders may need medical evaluation for cholinesterase inhibitor effects.
Hazard overview: UN 1611 presents organophosphate poisoning, skin absorption and contaminated-runoff hazards. Fire or decomposition may produce toxic phosphorus-containing gases and contaminated equipment must be handled carefully.
Response guidance: For a UN 1611 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 151. Establish incident command, isolate the area, stay upwind, prevent dust or vapor exposure, control runoff and choose entry or cleanup actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1611 should emphasize organophosphate toxicity, skin absorption, cholinesterase inhibitor recognition, decontamination, medical coordination and contaminated runoff control. Use ERG 151, SDS and local SOP.
Regulatory context: Hexaethyl tetraphosphate is regulated as a toxic organophosphate hazardous material. Transportation, occupational exposure, medical surveillance, spill reporting, pesticide/waste handling and environmental requirements may vary by jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Hexaethyl tetraphosphate should be stored in tightly closed compatible containers in a secure, cool, well-ventilated toxic-material area away from heat, food/feed, oxidizers and unauthorized access. Storage should include spill containment, decontamination supplies and medical/emergency planning appropriate to the SDS.
UN 1611 Quick Details
Common Hazards of UN 1611
- HIGHLY TOXIC organophosphate liquid; inhalation, ingestion or skin absorption may be fatal.
- Can inhibit cholinesterase; exposure may require specialized medical evaluation.
- Low volatility does not eliminate skin absorption or contaminated clothing risk.
- Fire may produce phosphorus oxides and other toxic gases.
- Runoff and contaminated equipment may carry toxic pesticide residue.
- Containers may rupture or fail when heated.
- Avoid all skin contact and prevent spread of contaminated liquid.
Chemical Identity & Physical Properties
Colorless to amber-colored liquid with a faint, pleasant odor. Oily consistency at room temperature.
| Also known as | HETPTetraphosphoric acid hexaethyl esterBladanHexaethyl tetraphosphate |
| CAS Number | 757-58-4 |
| Appearance | Colorless to amber-colored liquid with a faint, pleasant odor. Oily consistency at room temperature. |
| Flash Point | Not readily flammable under normal conditions |
| Boiling Point | Decomposes before boiling at approximately 150C (302F) |
| Vapor Density | Not applicable (low volatility liquid) |
| Water Reactivity | Hydrolyzes slowly in water; no violent reaction but produces toxic degradation products |
Fireground Response Guidance — UN 1611
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical protective clothing selected by hazmat specialists. Level A may be needed for close entry or unknown concentrations; avoid skin absorption and use decontamination and medical coordination for possible cholinesterase inhibitor exposure.
Isolation & Evacuation
First Actions for a UN 1611 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 or mist and avoid all skin or eye contact.
- 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 or unknown concentration is present.
- Use ERG Guide 151, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1611 — Hexaethyl tetraphosphateUse 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.