☣️ UN 1581 • CLASS 2
UN 1581 — Chloropicrin and methyl bromide mixture
Placard: Toxic Gas. ERG Guide 123. 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 1581 Quick Details
UN 1581
Product name: Chloropicrin and methyl bromide mixture
DOT Class: 2
Placard type: Toxic Gas
ERG Guide: 123 (check current ERG)
Initial isolation: ERG 123: isolate spill 100m all directions; initial evacuation 300m downwind; if tank/rail car involved in fire, isolate 800m all directions
Common Hazards of UN 1581
- TOXIC; may be fatal if inhaled or absorbed through skin.
- Vapors may be irritating and/or corrosive.
- Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
- Fire will produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may cause environmental contamination.
- Some may burn but none ignite readily.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
- Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief
Chemical Identity & Physical Properties
| Also known as | Chloropicrin-methyl bromide mixturePicfumeTerr-o-gasBromomethane-trichloronitromethane mixtureMethyl bromide-chloropicrin fumigant |
| Appearance | Colorless to pale yellow liquefied gas mixture with a pungent, tear-producing odor. Heavier than air vapor that can accumulate in low-lying areas. |
| Flash Point | Not applicable (non-flammable gas mixture) |
| Boiling Point | Component-dependent: methyl bromide 3.6C (38.5F), chloropicrin 112C (234F) |
| Vapor Density | 3.3-5.7 (heavier than air, depending on mixture ratio) |
| Water Reactivity | Slow hydrolysis in water; chloropicrin component reacts slowly producing corrosive products |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1581
Extinguishing Media
Not applicable for fire control; use water spray to knock down vapors, do not direct water at liquid
PPE Requirements
⚠️ Level A required for spill response; SCBA with full-face positive pressure and chemical-resistant suit; both components are severe respiratory and skin hazards
Isolation & Evacuation
ERG 123: isolate spill 100m all directions; initial evacuation 300m downwind; if tank/rail car involved in fire, isolate 800m all directions
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 123).
First Actions for a UN 1581 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.
- Many gases are heavier than air and will spread along the ground and collect in low or confined areas
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
- 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 1581 — Chloropicrin and methyl bromide mixtureHAZMAT RADIO NOTE — UN 1581
Product: Chloropicrin and methyl bromide mixture
Class 2 / Toxic Gas / ERG 123
PPE: Level A required for spill response; SCBA with full-face positive pressure and chemical-resistant suit; both components are severe respiratory and skin hazards
ISOLATION: ERG 123: isolate spill 100m all directions; initial 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 1581 — Chloropicrin and methyl bromide mixture
Class: 2 | Placard: Toxic Gas | ERG Guide: 123
Appearance: Colorless to pale yellow liquefied gas mixture with a pungent, tear-producing odor. Heavier than air vapor that can accumulate in low-lying areas.
Water Reactivity: Slow hydrolysis in water; chloropicrin component reacts slowly producing corrosive products
Extinguishing: Not applicable for fire control; use water spray to knock down vapors, do not direct water at liquid
PPE: Level A required for spill response; SCBA with full-face positive pressure and chemical-resistant suit; both components are severe respiratory and skin hazards
Isolation: ERG 123: isolate spill 100m all directions; initial evacuation 300m downwind; if tank/rail car involved in fire, isolate 800m all directions
— Key Hazards —
• TOXIC; may be fatal if inhaled or absorbed through skin.
• Vapors may be irritating and/or corrosive.
• Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
— 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.
• Many gases are heavier than air and will spread along the ground and collect in low or confined areas
SOURCE: allfirefighter.com/hazmat/un/1581 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1581 Chloropicrin and methyl bromide mixture Cls2 ERG123 | allfirefighter.com/hazmat/un/1581SMS / 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/1581
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Frequently Asked Questions about UN 1581
TOXIC; may be fatal if inhaled or absorbed through skin. Vapors may be irritating and/or corrosive. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause environmental contamination. Some may burn but none ignite readily. Vapors from liquefied gas are initially heavier than air and spread along ground. Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief
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 required for spill response; SCBA with full-face positive pressure and chemical-resistant suit; both components are severe respiratory and skin hazards
Water reactivity: Slow hydrolysis in water; chloropicrin component reacts slowly producing corrosive products. Recommended extinguishing: Not applicable for fire control; use water spray to knock down vapors, do not direct water at liquid.
ERG Guide 123 recommendation: ERG 123: isolate spill 100m all directions; initial evacuation 300m downwind; if tank/rail car involved in fire, isolate 800m all directions
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 123 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.