What is the maximum length, in feet, of the negative air exhaust duct per ICR 56?

What is the maximum length, in feet, of the negative air exhaust duct per ICR 56?

• A. 10 FT
• B. 25 FT
• C. 40 FT
• D. 60 FT

Answer: (B)

Negative air systems are used to keep the work area under negative pressure so asbestos fibers stay contained. The exhaust duct length is limited to 25 feet to ensure the system can maintain the required negative pressure and effective HEPA filtration. Longer runs add friction, drop the exhaust velocity, and raise the risk of leaks or loss of containment, which is why the maximum is set at 25 feet. If you need to go longer, you’d need a higher-capacity setup or multiple ducts to maintain proper containment.

Negative air systems are used to keep the work area under negative pressure so asbestos fibers stay contained. The exhaust duct length is limited to 25 feet to ensure the system can maintain the required negative pressure and effective HEPA filtration. Longer runs add friction, drop the exhaust velocity, and raise the risk of leaks or loss of containment, which is why the maximum is set at 25 feet. If you need to go longer, you’d need a higher-capacity setup or multiple ducts to maintain proper containment.