When applying water to a highway tanker or railway tank car with flame impingement, the minimum amount of water to be used is ________ gpm at the point of flame impingement

• A. 250
• B. 750
• C. 500
• D. 1000

Answer: (C)

Cooling the tank surface is essential when flame impingement occurs on a highway or railway tank car. You need enough water to absorb the intense heat and slow the temperature rise of the tank wall and its contents, which helps prevent failure that could lead to a BLEVE. The minimum you should apply at the point of flame contact is 500 gallons per minute. This rate provides enough cooling capacity to remove heat quickly from the exposed surface and keep internal pressure from spiking too rapidly. Using less water won’t remove heat fast enough, while larger flows (750 or 1000 gpm) can be used in more severe conditions, but 500 gpm is recognized as the minimum. Direct the water as a wide spray to maximize cooling coverage and continue until the fire is under control and the tank is cooled.