Cooling Towers

Cooling towers are among the heaviest pieces of equipment typically located on the roof. Their change in operating weight (wet vs. dry) poses a challenge when isolating cooling towers for vibration and restraining them for wind or seismic activity. Noise control is frequently missed. Cooling towers are often close to the property line or office windows, where noise from the fans can cause a problem.

Environmental Noise

Problem	Solution
click image to view larger Environmental Noise Sound levels at the property line are required to be 45 to 60 dBA, depending on the local municipal bylaw. Noise above this level often results in complaints from neighboring offices or residents and even lawsuits. Extremely low static capabilities of the cooling tower fans, coupled with moisture and corrosion issues, makes the noise control solution a challenge.	click image to view larger An acoustic calculation is required to determine whether noise control is required and, if so, how much insertion loss is needed. Special inlet and discharge silencers are good solutions. Material choice is important depending on the geographic location and aesthetic needs. Possible materials include stainless steel, powder coating and many other options. Fiberglass cloth is sometimes recommended to avoid trapping moisture in the acoustic media. Due to the low static fans, flow shaping silencer internals are necessary for reduced pressure drop. Other solutions include enclosures and acoustic barriers. Projects: 403/421 Bloor Office Building, Guggenheim Museum Storage Building, York Administration Center

Problem

Solution

click image to view larger

Environmental Noise

Sound levels at the property line are required to be 45 to 60 dBA, depending on the local municipal bylaw. Noise above this level often results in complaints from neighboring offices or residents and even lawsuits.

Extremely low static capabilities of the cooling tower fans, coupled with moisture and corrosion issues, makes the noise control solution a challenge.

click image to view larger

An acoustic calculation is required to determine whether noise control is required and, if so, how much insertion loss is needed.

Special inlet and discharge silencers are good solutions. Material choice is important depending on the geographic location and aesthetic needs. Possible materials include stainless steel, powder coating and many other options. Fiberglass cloth is sometimes recommended to avoid trapping moisture in the acoustic media. Due to the low static fans, flow shaping silencer internals are necessary for reduced pressure drop.

Other solutions include enclosures and acoustic barriers.

Projects: 403/421 Bloor Office Building, Guggenheim Museum Storage Building, York Administration Center

Seismic & Wind Loading

Problem	Solution
click image to view larger Seismic & Wind Loading Overturn and anchorage calculations as well as the installation of proper restraint systems are required for code compliance. Failure to adhere to the local code can result in a delay in occupancy of the building and unnecessary liability.	click image to view larger Seismic vertically-restrained isolators are recommended with a minimum of 2-inch deflection. Anchorage and overturn calculations as well as PE stamping of the calculations and restraint locations are required for code compliance. A structural base might be required even if the cooling tower structure has been designed to withstand point loading. Exact calculations can determine if a structural base is necessary.

Problem

Solution

click image to view larger

Seismic & Wind Loading

Overturn and anchorage calculations as well as the installation of proper restraint systems are required for code compliance. Failure to adhere to the local code can result in a delay in occupancy of the building and unnecessary liability.

click image to view larger

Seismic vertically-restrained isolators are recommended with a minimum of 2-inch deflection. Anchorage and overturn calculations as well as PE stamping of the calculations and restraint locations are required for code compliance. A structural base might be required even if the cooling tower structure has been designed to withstand point loading. Exact calculations can determine if a structural base is necessary.

Structure-borne Noise

Problem	Solution
click image to view larger Structure-borne Noise This is noise traveling through the structure instead of the air. Vibration from the fans is transferred to the structure and can create noise problems in different areas of the building. Unlike airborne noise, structure-borne noise is very difficult to diagnose post design.	click image to view larger Due to the potential change in the operating weight of the cooling tower, restrained isolators are recommended. A minimum of 2-inch deflection is suggested so that the springs are operating at a high efficiency. For cooling towers that are not designed to withstand point loading, a structural base could be required.

Cooling Towers

Environmental Noise

Environmental Noise

Seismic & Wind Loading

Seismic & Wind Loading

Structure-borne Noise

Structure-borne Noise

Other problems

Other problems