What is the minimum height requirement for ducts conveying flammable vapors above adjoining grade?

The minimum height requirement for ducts conveying flammable vapors to be positioned above adjoining grade is established to mitigate the risk of fire hazards. At 10 feet, this height is considered sufficient to ensure that any flammable vapors are adequately elevated above potential ignition sources at ground level. The regulation takes into account safety considerations, including potential sources of flame or spark, the movement of personnel, and the general environment where such ducts may be installed.

Maintaining this height is critical in preventing accidental ignition, promoting safe work environments, and ensuring compliance with fire safety standards. This requirement serves as a precautionary measure to enhance operational safety in areas where flammable materials are present, thus safeguarding occupants and property.