Commercial Kitchen Exhaust System Components Practice Test

In solid-fuel cooking exhaust systems, the residues come from the fuel and cooking process, leading to ash, creosote, and grease deposits. Ash is the solid residue left after burning solid fuels like wood or coal and tends to accumulate in ducts and on surfaces. Creosote forms when wood smoke condenses on cooler duct surfaces, creating a tar-like, flammable buildup that can collect over time. Grease can also deposit from cooking fats and oils, especially where air streams carry particles and vapors from cooking operations, leading to sticky coatings inside the hood, ducts, and fans. This combination of ash, creosote, and grease is distinct from dust and lint, which come from exterior sources, water vapor (which is a normal component of exhaust rather than a buildup), or mold growth (which requires persistent moisture in a different context).