Which statement about termination distances for ducts conveying explosive or flammable vapors, fumes or dusts is correct?

Which statement about termination distances for ducts conveying explosive or flammable vapors, fumes or dusts is correct?

• A. All of the above apply
• B. 30 feet from a property line
• C. 10 feet from openings into the building
• D. 6 feet from exterior walls and roofs

Answer: (D)

When ducts carry explosive or flammable vapors, fumes, or dusts, the termination point must be kept at a safe distance from the building structure to prevent vapors from lingering near exterior surfaces or being drawn back into the building. The standard you’re looking for is a minimum six-foot clearance from exterior walls and roofs. This spacing helps ensure that any vapors venting outdoors disperse quickly away from potential ignition sources and from openings that could lead back inside. Distances such as thirty feet from a property line or ten feet from openings into the building aren’t the universal rule for this particular requirement, and they can vary by jurisdiction or specific code section. So, six feet from exterior walls and roofs is the best, most consistent criterion for safe duct termination in this context.

When ducts carry explosive or flammable vapors, fumes, or dusts, the termination point must be kept at a safe distance from the building structure to prevent vapors from lingering near exterior surfaces or being drawn back into the building. The standard you’re looking for is a minimum six-foot clearance from exterior walls and roofs. This spacing helps ensure that any vapors venting outdoors disperse quickly away from potential ignition sources and from openings that could lead back inside. Distances such as thirty feet from a property line or ten feet from openings into the building aren’t the universal rule for this particular requirement, and they can vary by jurisdiction or specific code section. So, six feet from exterior walls and roofs is the best, most consistent criterion for safe duct termination in this context.