Industrial Exhaust System Design

An industrial building owned by a Fortune 500 company in New York state’s Capital Region had an exhaust system in a cleanroom research area that consisted of two parallel scrubbers with downstream exhaust fans that were both rated for 23,000 cubic feet per minute. The fans were located inside the building, and the fan discharge had been routed up several stories to the roof through an enclosed fire-rated shaft that did not have any interior access. 

The building’s owner believed that the discharge ductwork was compromised and in need of replacement, so Erdman Anthony was hired to design a new fan system located on the roof and to design the replacement ductwork while limiting the system shutdown to less than two weeks. A high plume laboratory exhaust system was designed to replace the existing fans.

Reuse of the shaft would have required making openings on each floor to access structural supports and duct anchorages, and leakage from the compromised ductwork would have presented a safety issue for the contractors doing the work and for employees in the areas adjacent to the openings.

Given the concerns related to reusing the existing shaft, our team reviewed alternative routes to get the ductwork to the roof. An alternate route on the exterior of the building was presented to the owner and accepted.

That alternate outside route required erecting a steel frame on the side of the building to support two insulated and jacketed 36-inch-diameter duct risers. 

Because of our team’s careful planning, the shutdown period for this project lasted only 10 days, during which time the old fans and associated ductwork were removed, the new ductwork was connected to the existing scrubbers, and the system was balanced.