FM Approved Cooling Towers
Cooling towers are a critical infrastructure element for commercial and public facilities the world over. These important heat removal systems are used in conjunction with chillers as part of a building’s heating, ventilation and air conditioning (HVAC) system and as a direct cooling system for machinery or heat generating processes in industry.
For instance, cooling towers help remove heat from the cooling water used in power plants, petrochemical plants, paper production, semiconductor fabrication, food processing, and many other industries.
A widely held misconception is that cooling towers are inherently safe from fire hazards because water flows through them. In fact, cooling towers are not only vulnerable to fire risks, but can contain combustible materials, including:
- Polyvinyl Chloride (PVC) fill, most commonly in the form of corrugated sheets, or extruded splash bars
- Fiberglass Reinforced Plastic (FRP) walls, fan stacks, fan decks, fan blades, louvers, partitions and catch basins
- Acrylonitrile Butadiene Styrene (ABS) and Polypropylene nozzles
- Wood used as structural members as well as fill material
There are not only dry areas within a functioning cooling tower that can catch on fire, even with water flowing through the system, but also periods when water flow must be temporarily turned off for repairs or regular maintenance. During these high- risk periods, hot work accidents, smoking or electrical arcing sometimes trigger fires.
Even a fire in a cooling tower that is not directly attached to a structure can result in substantial loss, not just from the physical damage to the tower, but as a result of the business interruption that follows. Automatic sprinkler systems provide the best protection for combustible cooling towers, reducing the impact of fire and associated downtime.
Testing Required for FM Approval
The best solution to address the fire risks associated with cooling towers is to install an FM Approved cooling tower. These towers have undergone FM Approval testing in accordance with Approval Standard 4930, Approval Standard for Cooling Towers. An engineering evaluation of the structural design to determine resistance to live loads, including wind and seismic, is a requirement of Approval Standard 4930.
While some other organizations provide certifications or guidelines relating to cooling towers, only FM Approvals offers a comprehensive standard that covers all tower designs including single cell, multi-cell and rooftop-mounted cooling towers. The addition in 2009 of natural hazard evaluation and testing—seismic and wind loads, windborne debris and cyclic air pressure—to the pre-existing combustibility and flammability tests have made the FM Approval standard for cooling towers truly unique in the industry. Under Approval Standard 4930, cooling towers must be designed to withstand seismic and wind load stresses in accordance with FM Global Loss Prevention Data Sheet 1-6, Cooling Towers. The cooling tower design must be certified by a Professional Engineer and calculations submitted to verify compliance with design requirements for the range of towers for which FM Approval is sought.
Every cooling tower submitted for FM Approval testing is subjected to a full-scale fire test. Both single cell and multi-cell cooling towers must be able to operate with at least 75 percent of design capacity after the test fire. In addition to this requirement, roof-top mounted cooling towers must demonstrate the ability to prevent burning debris from falling onto the roof surface.
Benefits and Availability
FM Approved cooling towers and towers equipped with FM Approved fill materials and FM Approved components are considered to be either noncombustible or of limited combustibility (equivalent to Class 1) such that they do not require automatic sprinkler protection. This saves the building owner the cost of sprinkler installation—either in new construction or as a retrofit—as well as the cost of required periodic maintenance and repairs.
Only FM Approved cooling towers have also been evaluated for seismic and wind loading, cyclic air pressure and windborne debris, making them the best choice for regions susceptible to earthquake, hurricane and other natural hazards.
In addition, the selection of an FM Approved single or multi-cell cooling towers ensures that, even in the event of a fire, the system will continue to function. The intent is to avoid costly business interruption, which typically follows a serious cooling tower fire.
Value? The FM Approved certification program is an investment that demonstrates a manufacturer’s confidence in their products. While FM Approval testing is considered among the most rigorous in the world, it is also a quality indicator that will help differentiate a product from the competition.
FM Approvals provides its customers insights at an early stage that can strengthen product design and, later, by providing ongoing support. FM Approved products are listed in the online Approval Guide and FM Approved products are specified and accepted by building owners, designers and code authorities, and regularly recommended to FM Global insureds in nearly 200 countries by 1,700 FM Global field engineers.