☣️ UN 1038 • CLASS 2

UN 1038 — Ethylene, refrigerated liquid (cryogenic liquid)

Placard: Flammable Gas. ERG Guide 115. 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.

Ethylene, refrigerated liquid, is a highly flammable and toxic substance, classified as a DOT Class 2 gas. It is primarily used as a raw material in the production of plastics and other chemicals. First responders may encounter ethylene in various settings, including industrial facilities, transportation accidents, and residential areas. The scale of production and transport of ethylene is significant, with millions of tons being produced and transported annually. Ethylene is a colorless cryogenic liquid or compressed gas with a faint sweet odor, boiling at -104°C (-155°F) at atmospheric pressure. Its widespread use and potential for accidents make it essential for first responders to be familiar with its hazards and response procedures.

Hazard overview: Ethylene is extremely flammable and can be ignited by heat, sparks, or flames. It can also displace oxygen in confined spaces, leading to asphyxiation, and cause cryogenic burns.

Response guidance: In the event of an ethylene spill or leak, first responders should isolate the area 800m in all directions and evacuate if necessary. The use of dry chemical, CO2, or inert gas is recommended for small fires, while foam is ineffective on cryogenic liquids. It is essential to stop the gas flow if safe to do so. First responders should also be aware of the potential for environmental contamination from runoff water. The isolation distance for a tank or rail car involved in a fire is 800m in all directions, with evacuation of the initial 1600m downwind. CHEMTREC should be contacted in the event of a significant spill or leak.

Firefighter training notes: First responders should be trained to recognize the hazards of ethylene and respond accordingly. A common tactical error is the use of foam on cryogenic liquids, which can exacerbate the situation. First responders should be aware of the potential for environmental contamination and take steps to mitigate it. ICS position needs and mutual aid criteria should be established in advance to ensure a coordinated response. First responders should also be trained to use dry chemical, CO2, or inert gas for small fires and to stop the gas flow if safe to do so.

Regulatory context: Ethylene is classified as a DOT Class 2 gas, with a packing group that is not established. The OSHA PEL for ethylene is 200,000 ppm, and it is not listed on the CERCLA list. However, ethylene can still pose a significant environmental hazard if not handled properly.

Storage & handling: Ethylene should be stored in a well-ventilated area, away from incompatible materials such as oxidizers and flammable liquids. The storage temperature should be limited to prevent overheating, and the container should be designed to withstand the pressure of the gas. The top 3 incompatible materials for ethylene are oxidizers, flammable liquids, and other combustible materials.

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UN 1038 Quick Details

UN 1038
Product name: Ethylene, refrigerated liquid (cryogenic liquid)
DOT Class: 2
Placard type: Flammable Gas
ERG Guide: 115 (check current ERG)
Initial isolation: ERG 115: isolate 800m (1/2 mile) all directions; evacuate 1600m (1 mile) downwind if tank/rail car involved in fire

Common Hazards of UN 1038

  • EXTREMELY FLAMMABLE.
  • Will be easily ignited by heat, sparks or flames.
  • Will form explosive mixtures with air.
  • Vapors from liquefied gas are initially heavier than air and spread along ground.
  • Vapors may travel to source of ignition and flash back.
  • Cylinders exposed to fire may vent and release flammable gas through pressure relief devices.
  • Containers may explode when heated.
  • Ruptured cylinders may rocket.

Chemical Identity & Physical Properties

Ethylene is a colorless cryogenic liquid or compressed gas with a faint sweet odor. It boils at -104°C (-155°F) at atmospheric pressure and has a flash point of -136°C (-213°F). The vapor density of ethylene is 0.98, which is lighter than air as a gas. Ethylene is typically stored in insulated tanks or containers to maintain its cryogenic temperature.

Also known asEtheneEthylene gasRefrigerated liquid ethyleneCryogenic ethyleneLiquid ethylene
CAS Number74-85-1
AppearanceColorless cryogenic liquid or compressed gas with a faint sweet odor. Boils at -104°C (-155°F) at atmospheric pressure. Heavier than air as a liquid, lighter than air as a gas.
Flash Point-136C (-213F)
Boiling Point-104C (-155F)
Vapor Density0.98 (lighter than air as gas)
Water ReactivityNo significant reaction with water
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.

Fireground Response Guidance — UN 1038

Extinguishing Media

Dry chemical, CO2, inert gas; foam ineffective on cryogenic liquid

PPE Requirements

⚠️ Level B minimum; SCBA required; insulated gloves for cryogenic exposure; vapor-protective chemical-resistant clothing

First responders should wear a minimum of Level B PPE, including SCBA, to respond to an ethylene spill or leak. Insulated gloves and vapor-protective chemical-resistant clothing are also recommended to prevent cryogenic exposure. The use of SCBA is essential to prevent inhalation of toxic gases. First responders should also wear protective clothing to prevent skin contact with the cryogenic liquid.

Isolation & Evacuation

ERG 115: isolate 800m (1/2 mile) all directions; evacuate 1600m (1 mile) downwind if tank/rail car involved in fire
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 115).

First Actions for a UN 1038 Incident

  • Keep unauthorized personnel away.
  • Stay upwind, uphill and/or upstream.
  • Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
  • Consider initial downwind evacuation for at least 800 meters (1/2 mile).
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📋 Copy & Share Field Card

UN 1038 — Ethylene, refrigerated liquid (cryogenic
HAZMAT RADIO NOTE — UN 1038 Product: Ethylene, refrigerated liquid (cryogenic liquid) Class 2 / Flammable Gas / ERG 115 PPE: Level B minimum; SCBA required; insulated gloves for cryogenic exposure; vapor-protective chemical-resistant clothing ISOLATION: ERG 115: isolate 800m (1/2 mile) all directions; evacuate 1600m (1 mile) downwind if tank/rail car involved in fire ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO

Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.

SMS WhatsApp
=== IC HAZMAT BRIEFING === UN 1038 — Ethylene, refrigerated liquid (cryogenic liquid) Class: 2 | Placard: Flammable Gas | ERG Guide: 115 Appearance: Colorless cryogenic liquid or compressed gas with a faint sweet odor. Boils at -104°C (-155°F) at atmospheric pressure. Heavier than air as a liquid, lighter than air as a gas. Water Reactivity: No significant reaction with water Extinguishing: Dry chemical, CO2, inert gas; foam ineffective on cryogenic liquid PPE: Level B minimum; SCBA required; insulated gloves for cryogenic exposure; vapor-protective chemical-resistant clothing Isolation: ERG 115: isolate 800m (1/2 mile) all directions; evacuate 1600m (1 mile) downwind if tank/rail car involved in fire — Key Hazards — • EXTREMELY FLAMMABLE. • Will be easily ignited by heat, sparks or flames. • Will form explosive mixtures with air. — First Actions — • Keep unauthorized personnel away. • Stay upwind, uphill and/or upstream. • Isolate spill or leak area for at least 100 meters (330 feet) in all directions. • Consider initial downwind evacuation for at least 800 meters (1/2 mile). SOURCE: allfirefighter.com/hazmat/un/1038 | Always use current ERG + SOP/SOGIC BRIEFING

Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.

SMS (short)
UN1038 Ethylene, refrigerated liquid (cryogenic liquid) Cls2 ERG115 | allfirefighter.com/hazmat/un/1038SMS / 160 CHAR

Use for: Quick text to command or incoming units. Fits in a single SMS.

⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/ethylene-refrigerated-liquid-un-1038

Related UN Numbers in Class 2

Discovery block for training / quick reference. Always consult the current ERG + your SOP/SOG for operations.
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Frequently Asked Questions about UN 1038

Yes, ethylene is extremely flammable and may be easily ignited by heat, sparks, or flames. It can form explosive mixtures with air, and vapors from liquefied gas are initially heavier than air, spreading along the ground and collecting in low or confined areas.

A minimum of Level B PPE, including SCBA, is required to respond to an ethylene spill or leak. Insulated gloves and vapor-protective chemical-resistant clothing are also recommended to prevent cryogenic exposure.

Ethylene is toxic and may cause dizziness, headache, and nausea. Prolonged exposure can cause more severe health effects, including respiratory problems and even death. The IDLH value for ethylene is 200,000 ppm, and respiratory protection is mandatory.

Ethylene is a colorless cryogenic liquid or compressed gas with a faint sweet odor. It boils at -104°C (-155°F) at atmospheric pressure and has a flash point of -136°C (-213°F).

Dry chemical, CO2, or inert gas is recommended for small fires, while foam is ineffective on cryogenic liquids. It is essential to stop the gas flow if safe to do so.
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.