☣️ UN 2698 • CLASS 8
UN 2698 — Tetrahydrophthalic anhydrides
Placard: Corrosive. ERG Guide 156. 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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UN 2698 Quick Details
UN 2698
Product name: Tetrahydrophthalic anhydrides
DOT Class: 8
Placard type: Corrosive
ERG Guide: 156 (check current ERG)
Initial isolation: ERG 156: isolate spill 25m all directions; for large spill isolate 50m, evacuate 300m downwind if fire or water-reactive release occurs
Common Hazards of UN 2698
- 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
Chemical Identity & Physical Properties
| Also known as | THPATetrahydrophthalic acid anhydride1,2,3,6-Tetrahydrophthalic anhydride3,4,5,6-Tetrahydrophthalic anhydrideHexahydrophthalic anhydride (isomer)HHPA |
| CAS Number | 85-43-8 |
| Appearance | White to pale yellow crystalline solid or viscous liquid (depending on isomer). Acrid, irritating odor. Combustible at room temperature. |
| Flash Point | 153°C (307°F) |
| Boiling Point | 195-200°C (383-392°F) |
| Vapor Density | 5.2 (heavier than air) |
| Water Reactivity | Reacts with water releasing corrosive acidic fumes and heat; reaction can be vigorous with large quantities |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 2698
Extinguishing Media
Dry chemical, CO2, water spray (use cautiously from distance); avoid direct water contact with bulk material
PPE Requirements
⚠️ Level B minimum with chemical-resistant suit; SCBA required in confined spaces or fire; skin/eye protection mandatory due to severe irritant properties
Isolation & Evacuation
ERG 156: isolate spill 25m all directions; for large spill isolate 50m, evacuate 300m downwind if fire or water-reactive release occurs
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 156).
First Actions for a UN 2698 Incident
- 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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📋 Copy & Share Field Card
UN 2698 — Tetrahydrophthalic anhydridesHAZMAT RADIO NOTE — UN 2698
Product: Tetrahydrophthalic anhydrides
Class 8 / Corrosive / ERG 156
PPE: Level B minimum with chemical-resistant suit; SCBA required in confined spaces or fire; skin/eye protection mandatory due to severe irritant properties
ISOLATION: ERG 156: isolate spill 25m all directions; for large spill isolate 50m, evacuate 300m downwind if fire or water-reactive release occurs
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 2698 — Tetrahydrophthalic anhydrides
Class: 8 | Placard: Corrosive | ERG Guide: 156
Appearance: White to pale yellow crystalline solid or viscous liquid (depending on isomer). Acrid, irritating odor. Combustible at room temperature.
Water Reactivity: Reacts with water releasing corrosive acidic fumes and heat; reaction can be vigorous with large quantities
Extinguishing: Dry chemical, CO2, water spray (use cautiously from distance); avoid direct water contact with bulk material
PPE: Level B minimum with chemical-resistant suit; SCBA required in confined spaces or fire; skin/eye protection mandatory due to severe irritant properties
Isolation: ERG 156: isolate spill 25m all directions; for large spill isolate 50m, evacuate 300m downwind if fire or water-reactive release occurs
— 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/2698 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2698 Tetrahydrophthalic anhydrides Cls8 ERG156 | allfirefighter.com/hazmat/un/2698SMS / 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/2698
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Frequently Asked Questions about UN 2698
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 chemical-resistant suit; SCBA required in confined spaces or fire; skin/eye protection mandatory due to severe irritant properties
Water reactivity: Reacts with water releasing corrosive acidic fumes and heat; reaction can be vigorous with large quantities. Recommended extinguishing: Dry chemical, CO2, water spray (use cautiously from distance); avoid direct water contact with bulk material.
ERG Guide 156 recommendation: ERG 156: isolate spill 25m all directions; for large spill isolate 50m, evacuate 300m downwind if fire or water-reactive release occurs
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.