Sprinkler Age A Publication of the American Fire Sprinkler Association
The Right Fit for Fire Protection
Over the last 100 years, the methods to store water for fire protection have evolved and become more sophisticated, resulting in superior fire suppression. Modern tanks that store water used for fire protection are very specific and are governed by NFPA 22, Standard for Water Tanks for Private Fire Protection. The size of the tank is determined by the amount of water required, based on fire suppression calculations.
For greater efficiency, potable water storage can also be combined with fire protection requirements as one larger tank replaces two smaller tanks. In addition, as water is continuously drawn from the tank for domestic use, the water in the tank does not become stagnant as it would if the tank was used for fire protection alone. However, when a tank is used for dual purposes, the tank must include considerations to ensure sufficient fire suppression water is always available. For example, the tank will usually include two outlets: one at a higher level for potable water and a second one at the bottom of the tank for fire protection. Also, fire protection tanks will include a special larger anti-vortex outlet nozzle to ensure an adequate and solid flow of water to fire pumps. Depending on how the tank will be utilized, additional inlets with automatic fill valves may be required to rapidly refill the tank as the tank is being drained. If multiple water supply sources are available, the tank may include several inlets to refill the tank faster and increase the water available for fire suppression.
Tanks for fire suppression are frequently constructed of steel or concrete. The material and design of the tank is commonly determined by the size and location of the project. Typically, concrete tanks are larger in size due to the high cost to set up the required equipment on the job site. This high cost makes smaller tanks cost prohibitive relative to other designs, which require considerably less equipment on site. Steel tanks for fire protection are commonly either bolted or welded design. Bolted tanks range in size from 5,000 to 3,500,000 gallons compared to welded steel tanks, which can be extremely large.
Of the various tank designs, bolted tanks have proven to be a cost effective solution for fire protection tanks. Bolted steel tanks are prefabricated in the factory and complete kits arrive to the jobsite ready to install, therefore the amount of manual labor on site is significantly reduced. As extensive and expensive site work required is very minimal, the tank cost is decreased, making bolted steel tanks more affordable compared to other tanks of the same size range. For most mid-sized projects, storage tanks for fire protection range in capacity from 25,000 to 250,000 gallons, which is well-suited for a bolted steel tank. As welding, grinding and other hot work is not required to erect a bolted steel tank, the risk of fire is dramatically reduced. In addition, bolted steel tanks are prefinished in the factory, therefore sandblasting and painting in the field are eliminated and negative environmental impact is significantly reduced.
Commonly, bolted steel tanks are used to supplement existing infrastructure and increase water storage close to the area where fire protection is needed. For example, when a new warehouse or large retail store is built and the current water supply will not support the requirements of the project, a new bolted steel tank will be installed on site. Alternatively, bolted tanks work well for remote and rural areas to provide water for fire suppression. In addition to closed-top tanks, open-top “scoop” tanks are also available to provide helicopters with easy access to water when fighting wildfires.
With the advances in the tank manufacturing process, quality of raw materials and design standards have improved the durability of bolted steel tanks, ensuring modern bolted tanks are extremely durable and will stand the test of time. For instance, most bolted steel tanks manufactured in the U.S. are comprised of high-strength steel, which is fastened together using higher grade bolts and hardware. State-of-the-art factories produce the tanks and frequently utilize CNC machinery, turret punch presses, and hydraulic press brakes to ensure tank components meet exact specifications to make assembly at the job site hassle free and prevent leaks. Specially formulated epoxy powder coating provides outstanding corrosion protection, and synthetic rubber gaskets fabricated of heavy-duty EPDM, Viton or Buna-N are used to provide decades of maintenance-free service.
As customers are discovering, a bolted steel tank can provide the perfect solution for both potable water storage as well as storage of water for fire protection.
ABOUT THE AUTHOR: Brandon Alexander currently serves as marketing coordinator for Superior Tank Co., Inc. located in Southern California. Alexander has worked in heavy manufacturing and construction since 2000 with projects ranging up to $20,000,000. Superior Tank Co., Inc. manufactures and installs bolted steel tanks throughout the United States, Mexico and Canada. STCI tank kits have also been shipped to countries throughout the world.
