What is the minimum slope requirement for duct systems to prevent grease accumulation?

The correct choice emphasizes that a minimum slope of 1/4 unit vertical in 12 units horizontal is necessary for duct systems to effectively prevent grease accumulation. This requirement is rooted in maintaining proper drainage of condensate and grease that may form within the ductwork, especially in kitchen exhaust systems where oils and grease are more prevalent.

By ensuring a slope of 1/4:12, the design promotes efficient movement of any liquids toward drainage points rather than allowing them to pool within the ducts. This is essential for both maintaining air quality and preventing potential fire hazards associated with grease buildup. Insufficient slope could lead to stagnant areas, which can increase the risk of grease igniting and cause serious safety issues.

Proper slope is crucial not only for functionality but also for compliance with mechanical codes designed to enhance safety in system environments where grease is present.