A fuel tanker crash or fire requires a 40-50 m radius response zone on highways. NFPA 385 (Tank Vehicles for Flammable and Combustible Liquids) defines tanker construction and transport, while NFPA 11 covers foam attack. The biggest threat: LPG/LNG tankers prone to BLEVE (Boiling Liquid Expanding Vapor Explosion) producing a 300 m fireball.
Tanker Types and Risk
- MC-306 / DOT-406: Diesel, gasoline (atmospheric)
- MC-307 / DOT-407: Chemical (3 psi)
- MC-331: LPG, ammonia (pressurized)
- MC-338: Cryogenic (LNG, N2, O2)
MC-331 LPG tankers are the highest BLEVE risk.
BLEVE Mechanism
BLEVE stages:
- External fire heats tank wall
- Liquid exceeds boiling point (superheat)
- Tank wall metallurgically weakens (>650 C)
- Crack propagates; sudden pressure drop flashes liquid
- Ignited vapor cloud creates 300-500 m fireball
Time window is 10-30 min depending on tank insulation. Water cooling delays BLEVE.
Response Strategy
- Isolation zone: 800 m (LPG tanker)
- Water cooling: 10 L/min/m2 on tank shell (NFPA 11)
- Foam: AFFF or F3 3-6 percent, 6.5 L/min/m2
- Escape route: Perpendicular to wind, avoid downhill
- PRV sound: Loud venting is an early BLEVE warning
In-Tunnel Tanker Scenarios
Mont Blanc 1999 and Frejus 2005 tunnel fires measured tanker HRR >200 MW. NFPA 502 requires for in-tunnel tanker fires:
- FFFS deluge 10-15 mm/min
- Longitudinal ventilation 3 m/s (critical velocity)
- Cross-passage every 200 m
- Foam concentrate storage at portal
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Download MEP Calc on the App StoreNFPA 385, NFPA 11, NFPA 502, DOT 49 CFR 178, CDI/ICI BLEVE Guidelines. NFPA 385 Tank Vehicles standard.