☣️ UN 3494 • CLASS 3
UN 3494 — Petroleum sour crude oil, flammable, poisonous
Placard: Flammable. ERG Guide 131. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ Verification required:
Broad or variable material category; verify exact product, SDS and shipping papers.
⚠️ 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.
UN 3494 covers petroleum sour crude oil, a flammable crude oil that may contain hydrogen sulfide and other toxic vapors.
Hazard overview: The major hazards are flammable vapors, flashback, low-area vapor accumulation, toxic hydrogen sulfide exposure, and contaminated runoff during fire control.
Response guidance: Isolate the area, stay upwind, eliminate ignition sources, monitor for H2S, and use alcohol-resistant foam, dry chemical, or CO2. Cool tanks from distance.
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UN 3494 Quick Details
UN 3494
Product name: Petroleum sour crude oil, flammable, poisonous
DOT Class: 3
Placard type: Flammable
ERG Guide: 131 (check current ERG)
Initial isolation: ERG 131: Initial isolation 60m (200 ft) all directions; protective action distance up to 800m (0.5 miles) downwind for large spills; evacuate immediately if H2S concentrations exceed safe limits
Common Hazards of UN 3494
- TOXIC; may be fatal if inhaled, ingested or absorbed through skin.
- Inhalation or contact with some of these materials will irritate or burn skin and eyes.
- Methyl chloroacetate (UN2295) is an eye irritant/lachrymator (causes flow of tears).
- Fire will produce irritating, corrosive and/or toxic gases.
- Vapors may cause dizziness or asphyxiation, especially when in closed or confined areas.
- Runoff from fire control or dilution water may cause environmental contamination.
- HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
- Vapors may form explosive mixtures with air.
Chemical Identity & Physical Properties
Petroleum sour crude oil is a dark brown to black viscous liquid with a strong petroleum odor and characteristic hydrogen sulfide smell.
| Also known as | Sour crude oilHigh sulfur crude petroleumH2S-containing crude oilToxic crude petroleum |
| Appearance | Dark brown to black viscous liquid with a strong petroleum odor and characteristic hydrogen sulfide (rotten egg) smell. Flammable liquid at ambient temperature. |
| Flash Point | -35°C to 35°C (-31°F to 95°F) depending on composition |
| Boiling Point | Wide boiling range 30°C to 400°C+ (86°F to 752°F+) |
| Vapor Density | 3-4 (heavier than air due to hydrocarbon vapors and H2S) |
| Water Reactivity | No significant reaction with water; floats and spreads on water surface |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3494
Extinguishing Media
Alcohol-resistant AFFF foam, dry chemical, CO2; water spray for cooling only
PPE Requirements
⚠️ Level A or B with SCBA mandatory due to H2S toxicity; chemical-resistant suit and gloves required; H2S monitoring essential
Level B with SCBA is recommended. Use gas monitoring and chemical-resistant/flame-resistant protection when vapor, fire, or spill exposure is possible.
Isolation & Evacuation
ERG 131: Initial isolation 60m (200 ft) all directions; protective action distance up to 800m (0.5 miles) downwind for large spills; evacuate immediately if H2S concentrations exceed safe limits
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 131).
First Actions for a UN 3494 Incident
- CALL 911. Then call the emergency response number on the shipping paper, if available.
- 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 for at least 50 meters (150 feet) in all directions.
- For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.
- For non-highlighted materials, increase the downwind precautionary distance as conditions require.
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📋 Copy & Share Field Card
UN 3494 — Petroleum sour crude oil, flammable, poiHAZMAT RADIO NOTE — UN 3494
Product: Petroleum sour crude oil, flammable, poisonous
Class 3 / Flammable / ERG 131
PPE: Level A or B with SCBA mandatory due to H2S toxicity; chemical-resistant suit and gloves required; H2S monitoring essential
ISOLATION: ERG 131: Initial isolation 60m (200 ft) all directions; protective action distance up to 800m (0.5 miles) downwind for large spills; evacuate immediately if H2S concentrations exceed safe limits
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 3494 — Petroleum sour crude oil, flammable, poisonous
Class: 3 | Placard: Flammable | ERG Guide: 131
Appearance: Dark brown to black viscous liquid with a strong petroleum odor and characteristic hydrogen sulfide (rotten egg) smell. Flammable liquid at ambient temperature.
Water Reactivity: No significant reaction with water; floats and spreads on water surface
Extinguishing: Alcohol-resistant AFFF foam, dry chemical, CO2; water spray for cooling only
PPE: Level A or B with SCBA mandatory due to H2S toxicity; chemical-resistant suit and gloves required; H2S monitoring essential
Isolation: ERG 131: Initial isolation 60m (200 ft) all directions; protective action distance up to 800m (0.5 miles) downwind for large spills; evacuate immediately if H2S concentrations exceed safe limits
— Key Hazards —
• TOXIC; may be fatal if inhaled, ingested or absorbed through skin.
• Inhalation or contact with some of these materials will irritate or burn skin and eyes.
• Methyl chloroacetate (UN2295) is an eye irritant/lachrymator (causes flow of tears).
— First Actions —
• CALL 911. Then call the emergency response number on the shipping paper, if available.
• 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/petroleum-sour-crude-oil-un-3494 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN3494 Petroleum sour crude oil, flammable, poisonous Cls3 ERG131 | allfirefighter.com/hazmat/un/petroleum-sour-crude-oil-un-3494SMS / 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/petroleum-sour-crude-oil-un-3494
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Frequently Asked Questions about UN 3494
Yes. It is flammable and vapors may ignite or flash back.
No significant reaction is expected, but runoff can spread oil contamination and toxic residues.
Level B with SCBA, flame-resistant clothing, and gas monitoring is recommended.
Isolate at least 50 m, remove ignition sources, stay upwind, and monitor for hydrogen sulfide.
UN 3494 is assigned to ERG Guide 131 for initial emergency response guidance.
Sour crude may contain hydrogen sulfide, a highly toxic gas that can be fatal at elevated concentrations.
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.