What is the minimum duct air velocity in feet per minute?

What is the minimum duct air velocity in feet per minute?

• A. 450
• B. 550
• C. 600
• D. 500

Answer: (D)

Minimum duct air velocity is 500 feet per minute. In kitchen exhaust systems, the grease-laden air moving through the ducts must stay in motion fast enough to prevent grease from condensing and sticking to the duct walls. If the flow drops below 500 fpm, grease can accumulate, increasing fire risk and maintenance needs. Keeping at least 500 fpm ensures the grease-laden air is carried efficiently to the fan and out of the system. Velocities higher than this are possible, but they require more energy and can be noisier; the 500 fpm mark is the tested minimum.

Minimum duct air velocity is 500 feet per minute. In kitchen exhaust systems, the grease-laden air moving through the ducts must stay in motion fast enough to prevent grease from condensing and sticking to the duct walls. If the flow drops below 500 fpm, grease can accumulate, increasing fire risk and maintenance needs. Keeping at least 500 fpm ensures the grease-laden air is carried efficiently to the fan and out of the system. Velocities higher than this are possible, but they require more energy and can be noisier; the 500 fpm mark is the tested minimum.