☣️ UN 1835 • CLASS 8
UN 1835 — Tetramethylammonium hydroxide aqueous solution with more than 2.5% but less than 25% tetramethylammonium hydroxide
Placard: Corrosive. ERG Guide 153. 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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UN 1835 Quick Details
UN 1835
Product name: Tetramethylammonium hydroxide aqueous solution with more than 2.5% but less than 25% tetramethylammonium hydroxide
DOT Class: 8
Placard type: Corrosive
ERG Guide: 153 (check current ERG)
Initial isolation: ERG 153: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions and evacuate accordingly
Common Hazards of UN 1835
- 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
Chemical Identity & Physical Properties
| Also known as | TMAHTetramethylammonium hydroxide solutionHydroxide de tetramethylammoniumTetramethylammonium hydroxide pentahydrate |
| CAS Number | 75-59-2 |
| Appearance | Clear to slightly yellow liquid with an ammonia-like or fishy odor. Strong alkaline solution that is highly corrosive and toxic. |
| Flash Point | Not applicable (aqueous solution, non-flammable) |
| Boiling Point | Approximately 100C (212F), varies with concentration |
| Vapor Density | Not applicable (aqueous solution) |
| Water Reactivity | Miscible with water; generates heat when diluted but does not react violently |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1835
Extinguishing Media
Water spray, dry chemical, CO2 for small fires; avoid direct water streams on spills
PPE Requirements
⚠️ Level B minimum; full chemical-resistant suit, butyl rubber gloves, face shield, SCBA required; extremely corrosive to skin and eyes
Isolation & Evacuation
ERG 153: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions and evacuate accordingly
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 153).
First Actions for a UN 1835 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 1835 — Tetramethylammonium hydroxide aqueous soHAZMAT RADIO NOTE — UN 1835
Product: Tetramethylammonium hydroxide aqueous solution with more than 2.5% but less than 25% tetramethylammonium hydroxide
Class 8 / Corrosive / ERG 153
PPE: Level B minimum; full chemical-resistant suit, butyl rubber gloves, face shield, SCBA required; extremely corrosive to skin and eyes
ISOLATION: ERG 153: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions and evacuate accordingly
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 1835 — Tetramethylammonium hydroxide aqueous solution with more than 2.5% but less than 25% tetramethylammonium hydroxide
Class: 8 | Placard: Corrosive | ERG Guide: 153
Appearance: Clear to slightly yellow liquid with an ammonia-like or fishy odor. Strong alkaline solution that is highly corrosive and toxic.
Water Reactivity: Miscible with water; generates heat when diluted but does not react violently
Extinguishing: Water spray, dry chemical, CO2 for small fires; avoid direct water streams on spills
PPE: Level B minimum; full chemical-resistant suit, butyl rubber gloves, face shield, SCBA required; extremely corrosive to skin and eyes
Isolation: ERG 153: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions and evacuate accordingly
— 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/1835 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1835 Tetramethylammonium hydroxide aqueous solution with more than 2.5% but less than 25% tetramethylammonium hydroxide Cls8 ERG153 | allfirefighter.com/hazmat/un/1835SMS / 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/1835
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Frequently Asked Questions about UN 1835
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 B minimum; full chemical-resistant suit, butyl rubber gloves, face shield, SCBA required; extremely corrosive to skin and eyes
Water reactivity: Miscible with water; generates heat when diluted but does not react violently. Recommended extinguishing: Water spray, dry chemical, CO2 for small fires; avoid direct water streams on spills.
ERG Guide 153 recommendation: ERG 153: isolate spill 50m all directions; if tank/rail car involved in fire, isolate 800m all directions and evacuate accordingly
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.