What is the minimum slope required for horizontal grease ducts longer than 75 feet?

The minimum slope required for horizontal grease ducts that are longer than 75 feet is 8.3 percent. This slope is necessary to ensure proper drainage of grease and other liquids that can accumulate in the ductwork. A slope of 8.3 percent, which is approximately 1 inch of rise for every 12 inches of run, facilitates the flow of accumulated grease towards the designated drainage points, preventing blockages that could lead to maintenance issues or fire hazards.

This requirement is consistent with best practices in the design and installation of grease duct systems to promote effective drainage and maintain safe operation within commercial kitchens and food service establishments. The appropriate slope helps in managing the buildup of fats, oils, and greases, which can pose significant safety risks if not properly addressed.