Makeup air and ventilation air supply diffusers located within _____ ft. of an exhaust hood shall be directed away from the hood.

Makeup air and ventilation air supply diffusers located within _____ ft. of an exhaust hood shall be directed away from the hood.

• A. 10
• B. 12
• C. 3
• D. 6

Answer: (B)

Makeup air and ventilation air diffusers that are close to an exhaust hood must be directed away from the hood to avoid interfering with the hood’s capture of contaminants. When the diffuser is within 12 feet, a direct jet of makeup air can disrupt the hood’s airflow, potentially drawing contaminants back toward the hood or creating turbulence that reduces exhaust efficiency. Directing the diffuser away helps ensure the makeup air mixes without opposing or short-circuiting the hood’s exhaust flow, preserving effective ventilation. The 12-foot distance is the threshold used to apply this directional requirement.

Makeup air and ventilation air diffusers that are close to an exhaust hood must be directed away from the hood to avoid interfering with the hood’s capture of contaminants. When the diffuser is within 12 feet, a direct jet of makeup air can disrupt the hood’s airflow, potentially drawing contaminants back toward the hood or creating turbulence that reduces exhaust efficiency. Directing the diffuser away helps ensure the makeup air mixes without opposing or short-circuiting the hood’s exhaust flow, preserving effective ventilation. The 12-foot distance is the threshold used to apply this directional requirement.