☣️ UN 2799 • CLASS 8
UN 2799 — Benzene phosphorus thiodichloride
Placard: Corrosive. ERG Guide 137. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
Benzene phosphorus thiodichloride is a corrosive organophosphorus thiochloride. It can fume in moist air and should be treated as moisture-reactive until the SDS confirms handling details.
Hazard overview: The key hazards are corrosive liquid contact, toxic vapor inhalation and heat/fume generation from water or humidity. Fire conditions can produce more hazardous decomposition products.
Response guidance: Isolate the area, stay upwind and prevent water from contacting the product. Use dry chemical, carbon dioxide or dry sand where compatible, and keep runoff contained for specialist cleanup.
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UN 2799 Quick Details
UN 2799
Product name: Benzene phosphorus thiodichloride
DOT Class: 8
Placard type: Corrosive
ERG Guide: 137 (check current ERG)
Initial isolation: ERG 137: isolate spill 50m in all directions; for large spills isolate 100m and consider evacuation 300m downwind
Common Hazards of UN 2799
- Corrosive liquid and vapors can injure skin, eyes and respiratory tissue.
- Moisture contact can release acidic and sulfur/phosphorus-containing fumes.
- Fire may produce irritating, corrosive and toxic decomposition gases.
- Vapors may settle in low areas and confined spaces.
- Containers may rupture when heated or contaminated with water.
- Runoff can remain acidic and harmful to waterways.
- Product identity and concentration should be verified before neutralization.
Chemical Identity & Physical Properties
This material is generally a colorless to pale yellow liquid with a pungent odor. Vapor behavior depends on temperature, but vapors can collect in low areas.
| Also known as | Phenylphosphonothioic dichlorideBenzenephosphonothioic dichloridePhenylthiophosphonic dichlorideThiophosphonic dichloride phenyl ester |
| CAS Number | 3497-00-5 |
| Appearance | Colorless to pale yellow liquid with a pungent, irritating odor. Fumes in moist air due to reaction with atmospheric moisture. |
| Flash Point | Not readily available; presumed combustible but not classified as flammable liquid |
| Boiling Point | Approximately 250-260°C (482-500°F) with decomposition |
| Vapor Density | Heavier than air (vapor density >1); vapors will settle in low areas |
| Water Reactivity | Reacts with water producing hydrochloric acid and other toxic/corrosive fumes; generates heat |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2799
Extinguishing Media
Dry chemical, CO2, or dry sand; avoid water due to reactivity
PPE Requirements
⚠️ Level B minimum with full face SCBA; chemical-resistant suit, gloves, and boots required for liquid contact
Use chemical-resistant clothing, gloves, boots and SCBA. Level B is a minimum for controlled spill entry; upgrade if concentrations are unknown or heavy vapor is present.
Isolation & Evacuation
ERG 137: isolate spill 50m in all directions; for large spills isolate 100m and consider evacuation 300m downwind
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 137).
First Actions for a UN 2799 Incident
- Call 911 and the emergency response number shown on the shipping papers or container documents.
- Keep unauthorized personnel away and establish an isolation perimeter before entry.
- Stay upwind, uphill and upstream; keep responders out of vapors, dusts and runoff.
- Avoid breathing vapors, dust, mist or smoke and avoid skin or eye contact.
- Do not touch damaged containers or spilled material unless properly trained and protected.
- Ventilate confined spaces only when personnel are trained, equipped and monitored.
- Use ERG guidance, SDS, shipping papers and air monitoring to confirm protective actions.
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📋 Copy & Share Field Card
UN 2799 — Benzene phosphorus thiodichlorideHAZMAT RADIO NOTE — UN 2799
Product: Benzene phosphorus thiodichloride
Class 8 / Corrosive / ERG 137
PPE: Level B minimum with full face SCBA; chemical-resistant suit, gloves, and boots required for liquid contact
ISOLATION: ERG 137: isolate spill 50m in all directions; for large spills isolate 100m and consider evacuation 300m downwind
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 2799 — Benzene phosphorus thiodichloride
Class: 8 | Placard: Corrosive | ERG Guide: 137
Appearance: Colorless to pale yellow liquid with a pungent, irritating odor. Fumes in moist air due to reaction with atmospheric moisture.
Water Reactivity: Reacts with water producing hydrochloric acid and other toxic/corrosive fumes; generates heat
Extinguishing: Dry chemical, CO2, or dry sand; avoid water due to reactivity
PPE: Level B minimum with full face SCBA; chemical-resistant suit, gloves, and boots required for liquid contact
Isolation: ERG 137: isolate spill 50m in all directions; for large spills isolate 100m and consider evacuation 300m downwind
— Key Hazards —
• Corrosive liquid and vapors can injure skin, eyes and respiratory tissue.
• Moisture contact can release acidic and sulfur/phosphorus-containing fumes.
• Fire may produce irritating, corrosive and toxic decomposition gases.
— First Actions —
• Call 911 and the emergency response number shown on the shipping papers or container documents.
• Keep unauthorized personnel away and establish an isolation perimeter before entry.
• Stay upwind, uphill and upstream; keep responders out of vapors, dusts and runoff.
• Avoid breathing vapors, dust, mist or smoke and avoid skin or eye contact.
SOURCE: allfirefighter.com/hazmat/un/benzene-phosphorus-thiodichloride-un-2799 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN2799 Benzene phosphorus thiodichloride Cls8 ERG137 | allfirefighter.com/hazmat/un/benzene-phosphorus-thiodichloride-un-2799SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/benzene-phosphorus-thiodichloride-un-2799
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Frequently Asked Questions about UN 2799
Water or humidity can drive hydrolysis, producing heat and acidic toxic fumes.
The main response concern is corrosive and toxic exposure, with added fire decomposition hazards if heated.
Dry chemical, carbon dioxide or dry sand are preferred when they can be used without spreading the liquid.
The SDS and shipping papers should confirm composition, concentration and any product-specific incompatibilities.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.