☣️ UN 1704 • CLASS 6
Tetraethyl dithiopyrophosphate
Placard: Toxic. 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.
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Quick details
UN 1704
Class: 6
Placard type: Toxic
ERG: Guide 153 (check current ERG)
Isolation: ERG 153: Initial isolation 25m in all directions; protective action distance 100m downwind (small spill day), up to 600m for large spills at night; highly toxic by all routes
Chemical & Response Details
| Also known as | SulfotepTEDPDithiopyrophosphoric acid tetraethyl esterEthyl thiopyrophosphateDithioneBladafum |
| CAS Number | 3689-24-5 |
| Appearance | Pale yellow to colorless oily liquid with a garlic-like or sulfurous odor. Denser than water and poorly soluble in water. |
| Flash Point | Not available, but likely >93°C (>200°F) due to high boiling point |
| Boiling Point | 136-139°C (277-282°F) at 2 mmHg; decomposes above 150°C (302°F) |
| Vapor Density | Approximately 9.7 (much heavier than air) |
| Water Reactivity | Hydrolyzes slowly in water; no violent reaction but degrades over time producing toxic breakdown products |
| Extinguishing | Dry chemical, CO2, water spray for cooling; alcohol-resistant foam acceptable |
| PPE | ⚠️ Level A or B with SCBA required; full chemical-resistant suit due to extreme dermal toxicity; this is a highly toxic organophosphate cholinesterase inhibitor |
| Isolation | ERG 153: Initial isolation 25m in all directions; protective action distance 100m downwind (small spill day), up to 600m for large spills at night; highly toxic by all routes |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
- Methyl bromoacetate (UN2643) is an eye irritant/lachrymator (causes flow of tears).
- Contact with molten substance may cause severe burns to skin and eyes.
- Avoid any skin contact.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental
- Combustible material: may burn but does not ignite readily.
- When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind
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UN 1704 — Tetraethyl dithiopyrophosphate HAZMAT RADIO NOTE — UN 1704
Product: Tetraethyl dithiopyrophosphate
Class 6 / Toxic / ERG 153
PPE: Level A or B with SCBA required; full chemical-resistant suit due to extreme dermal toxicity; this is a highly toxic organophosphate cholinesterase inhibitor
ISOLATION: ERG 153: Initial isolation 25m in all directions; protective action distance 100m downwind (small spill day), up to 600m for large spills at night; highly toxic by all routes
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 1704 — Tetraethyl dithiopyrophosphate
Class: 6 | Placard: Toxic | ERG Guide: 153
Appearance: Pale yellow to colorless oily liquid with a garlic-like or sulfurous odor. Denser than water and poorly soluble in water.
Water Reactivity: Hydrolyzes slowly in water; no violent reaction but degrades over time producing toxic breakdown products
Extinguishing: Dry chemical, CO2, water spray for cooling; alcohol-resistant foam acceptable
PPE: Level A or B with SCBA required; full chemical-resistant suit due to extreme dermal toxicity; this is a highly toxic organophosphate cholinesterase inhibitor
Isolation: ERG 153: Initial isolation 25m in all directions; protective action distance 100m downwind (small spill day), up to 600m for large spills at night; highly toxic by all routes
— Key Hazards —
• TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
• Methyl bromoacetate (UN2643) is an eye irritant/lachrymator (causes flow of tears).
• Contact with molten substance may cause severe burns to skin and eyes.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/1704 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1704 Tetraethyl dithiopyrophosphate Cls6 ERG153 | allfirefighter.com/hazmat/un/1704SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/1704
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FAQ
TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury Methyl bromoacetate (UN2643) is an eye irritant/lachrymator (causes flow of tears). Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental Combustible material: may burn but does not ignite readily. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level A or B with SCBA required; full chemical-resistant suit due to extreme dermal toxicity; this is a highly toxic organophosphate cholinesterase inhibitor
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 153 and your department SOP/SOG for incident-specific protective actions.
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.