To keep the building comfortable, the exhaust fans had to provide enough air flow to extract the heat produced by the turbine. However, noise management was the primary constraint. The owner’s primary concern was to ensure the fans met local codes for noise levels at the property boundary.
Because the exhaust fans would be installed on the roof, wind loading was another concern. According to the owner’s specification, the roof ventilators were to withstand wind speeds of 100 mph. In addition, the fans had to be self-supporting meaning the owner required the fan/silencer to meet this wind load criteria without the use of guy wires. Typically, fans that extend more than 8 feet above the roof deck must be secured with guy wires. However, fans that satisfy the owner’s design specifications would extend nearly 12' above the roof.
To meet the fan performance criteria and satisfy the sound, wind loading, and structural design requirements, Easton supplied several direct-drive VJ Vane-axial fans with patented weatherproof silencers. The VJ fan is quiet, which is why it was chosen. The “J” type propeller is the heart of this Vane-axial fan. A unique feature of this fan is that the angle of the blades can be adjusted manually or by using a blade adjusting tool allowing for future flow changes. Easton’s engineers designed the fans—the largest of which was 42 inches—to withstand wind speeds of up to 110 mph without guide wires.