Buildings with high-piled storage pose significant fire protection challenges due to building layouts and ceiling heights, the type of storage configuration used, and the types of commodities they store. While typically associated with warehouses, high-piled storage is used in a variety of other settings, including manufacturing facilities, shipping and receiving areas of businesses, storage facilities rented to individuals, and consumer-related businesses such as wholesale clubs and big-box home building supply stores.
High-piled storage provides a number of benefits to businesses because it allows more goods to be stored in a smaller area and increases efficiency in product handling. However, because it involves such large quantities of goods, fire losses can be huge, sometimes even greater than the loss of the building in which they are stored.
Sprinklers are a critical component of warehouse fire protection and can significantly reduce the direct property loss resulting from a fire if they are properly designed.
Commodity Classifications and Their Importance in Sprinkler System Design
High-piled storage is defined as any solid-piled, palletized, rack storage, bin box, and shelf storage greater than 12 feet in height. The NFPA 13 Standard for the Installation of Sprinkler Systems specifies the design requirements for sprinkler systems for the protection of high-piled storage areas, which are based on the type of commodities to be stored in the area. Because an area can have a significant impact on the characteristics of a fire, especially in terms of how hot it will burn and how quickly it might spread.
According to NFPA 13, commodity classifications are based not only on the goods stored but the packing materials and containers they are stored in. The following list summarizes the different commodity classes you need to be aware of if your business uses high-piled storage. For ordinary combustibles, there are four basic commodity classes:
- Class I: Commodities that are noncombustible products on wood pallets.
- Class II: Commodities that are noncombustible in slatted wood crates, or multiple layered corrugated cartons.
- Class III: Commodities that are fashioned from wood, paper, or natural fibers. Class III commodities may also be Class C plastics, or have less than 5% (by weight or volume) of Group A or Group B plastics.
- Class IV: Commodities that are Group B plastics; consist of free-flowing Group A plastic materials; or contains an appreciable amount of Group A plastics.
It is important for building owners and facility managers to understand these classifications because if the types of commodities or storage configurations within the space change, the sprinkler system may no longer provide sufficient protection. If you change what you store in your high-piled storage, you also need to look at your sprinkler design to determine if it needs to be re-designed to offer the necessary protection.
Key Design Considerations for Sprinkler Systems to Protect High-Piled Storage Areas
In addition to the commodity classification, there are a number of other factors that will determine the type and number of sprinklers needed, their orientation, and their spacing within a building. Providing adequate sprinkler protection requires a comprehensive analysis of the commodities to be stored, as well as the following additional factors:
- Storage Height — Storage height, which is measured from the floor to the top of the storage, is important because the sprinkler system design must take into account the amount of clearance between the storage and the ceiling. According to NFPA 13, fire tests of high-piled storage have shown that sprinklers are generally more effective if located 1.5 to 4.5 feet above the storage height.
- Storage Configuration — Most storage configurations fall into one of two groups, piled storage in which goods are piled one on top of the other, and rack storage, which uses a system of racks to facilitate the movement of materials stored in bins or pallets. Fire risk is generally greater with rack storage because the open air space around the racks can enhance the growth and spread of fire through the stored goods once ignited. Bin boxes can introduce additional design challenges because they can capture water from sprinklers preventing its even distribution down through the racks.
- Aisle Width — Aisles can help slow the spread of fire from one group of materials to an adjacent group by creating a fire break between storage racks or piles. They also allow open areas for the sprinklers to fill with water spray.
- Ceiling Slope — The slope of the ceilings in the storage area can significantly impact average activation time for sprinklers. The higher the slope, the longer it can take for the heat of the fire to activate the sprinkler.
- Building Height — Building height, which is measured from the floor to the underside of the roof deck or ceiling, is important because fire spreads faster vertically than horizontally. Therefore, when designing a sprinkler system, the amount of force at which water is released must be sufficient to reach the base of the fire.
The Most Common Sprinklers for High-Piled Storage Areas
Wet pipe sprinkler systems should always be used in high-piled storage areas unless the storage is located in an area where freezing or other special conditions prevent their use. In these cases, dry pipe or pre-action sprinkler systems may be used, but the area of operation will have to be increased significantly to compensate for the additional time it takes for the water to reach the sprinkler heads.
Some of the most common sprinklers used in storage occupancies include:
- Standard Upright and Pendent Spray Sprinklers — Because they can be used in all occupancy hazard classifications and building types, these are one of the most common types of sprinklers used for high-piled storage. For example, dry pendent sprinklers can be used even in areas subject to freezing. This type of sprinkler extends from a wet pipe system and is fed from a drop that is sealed to prevent water from entering the sprinkler head until it is activated.
- Early Suppression Fast-Response Sprinklers (ESFR) — This type of sprinkler is becoming very popular for use with high-piled storage because it eliminates the need for in-rack sprinklers, which are costly and easily damaged during the movement of goods in and out of the storage rack. Unlike most other sprinkler systems intended to control the growth of a fire, ESFR sprinklers are designed to suppress the fire with large volumes of water, up to 100 gallons per minute flowing through each sprinkler head.
- Large Drop Sprinklers — As the name implies, these sprinklers produce large water droplets and are designed to address high challenge fire hazards typical of high-piled storage of combustibles or certain high-hazard commodities, such as rubber tires, Group A plastics, flammable liquids, etc. Mounted on the ceiling, they deliver a higher percentage of large droplets to more effectively penetrate a high-velocity fire plume.
Is Your Sprinkler System Designed for Your Current Storage Needs?
Based on the most recent NFPA data, the average direct property loss resulting from warehouse fires exceeds $138,000 even with sprinklers present. In warehouses and other settings that use high-piled storage, such losses can be devastating and underscore the need to ensure your sprinklers are appropriate for your facility.
If your storage area has changed in any significant way since your sprinkler system was installed — in particular, the types of commodities you store, their packaging, and/or the configuration or size of the storage — it is important to have the system re-evaluated to ensure it is in compliance with NFPA 13 and providing the protection you need.
Talk with a Koorsen expert today to find out if the sprinklers in your storage facilities are providing the protection your business needs.
