☣️ UN 2328 • CLASS 6
Trimethylhexamethylene diisocyanate
Placard: Toxic. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ 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 2328
Class: 6
Placard type: Toxic
ERG: Guide 156 (check current ERG)
Isolation: ERG 156: Initially isolate spill 50m in all directions; for large spills isolate 100m and consider evacuation 300m downwind; if tank/rail car involved in fire isolate 800m all directions
Chemical & Response Details
| Also known as | TMDITrimethylhexamethylene-1,6-diisocyanate2,2,4-trimethylhexamethylene diisocyanateTMH diisocyanate1,6-diisocyanato-2,2,4-trimethylhexane |
| CAS Number | 15646-96-5 |
| Appearance | Clear to pale yellow liquid with a sharp, pungent odor characteristic of isocyanates. Liquid at room temperature. |
| Flash Point | 127C (261F) |
| Boiling Point | Approximately 255-270C (491-518F) with decomposition |
| Vapor Density | 8.3 (much heavier than air) |
| Water Reactivity | Reacts slowly with water releasing carbon dioxide gas; may cause foaming and heat generation. Avoid direct water contact. |
| Extinguishing | Alcohol-resistant foam, dry chemical, carbon dioxide; avoid water spray directly on liquid |
| PPE | ⚠️ Level B minimum with full-face SCBA; chemical-resistant suit required. Prevent all skin and eye contact due to severe irritant properties. |
| Isolation | ERG 156: Initially isolate spill 50m in all directions; for large spills isolate 100m and consider evacuation 300m downwind; if tank/rail car involved in fire isolate 800m all directions |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- Combustible material: may burn but does not ignite readily.
- Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
- When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
- Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas
- Vapors may travel to source of ignition and flash back.
- Corrosives in contact with metals may evolve flammable hydrogen gas.
- Containers may explode when heated or if contaminated with water.
- TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
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 2328 — Trimethylhexamethylene diisocyanate HAZMAT RADIO NOTE — UN 2328
Product: Trimethylhexamethylene diisocyanate
Class 6 / Toxic / ERG 156
PPE: Level B minimum with full-face SCBA; chemical-resistant suit required. Prevent all skin and eye contact due to severe irritant properties.
ISOLATION: ERG 156: Initially isolate spill 50m in all directions; for large spills isolate 100m and consider evacuation 300m downwind; if tank/rail car involved in fire isolate 800m all directions
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 2328 — Trimethylhexamethylene diisocyanate
Class: 6 | Placard: Toxic | ERG Guide: 156
Appearance: Clear to pale yellow liquid with a sharp, pungent odor characteristic of isocyanates. Liquid at room temperature.
Water Reactivity: Reacts slowly with water releasing carbon dioxide gas; may cause foaming and heat generation. Avoid direct water contact.
Extinguishing: Alcohol-resistant foam, dry chemical, carbon dioxide; avoid water spray directly on liquid
PPE: Level B minimum with full-face SCBA; chemical-resistant suit required. Prevent all skin and eye contact due to severe irritant properties.
Isolation: ERG 156: Initially isolate spill 50m in all directions; for large spills isolate 100m and consider evacuation 300m downwind; if tank/rail car involved in fire isolate 800m all directions
— Key Hazards —
• Combustible material: may burn but does not ignite readily.
• Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff.
• When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion
— 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/2328 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2328 Trimethylhexamethylene diisocyanate Cls6 ERG156 | allfirefighter.com/hazmat/un/2328SMS / 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/2328
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FAQ
Combustible material: may burn but does not ignite readily. Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion Most vapors are heavier than air. They will spread along the ground and collect in low or confined areas Vapors may travel to source of ignition and flash back. Corrosives in contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water. TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance
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 B minimum with full-face SCBA; chemical-resistant suit required. Prevent all skin and eye contact due to severe irritant properties.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 156 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.