THERE CAN BE A LOT OF TWISTS AND TURNS when selecting the appropriate design for a sprinkler system in a storage facility. Properly applying Chapters 12 through 21 of NFPA 13, Installation of Sprinkler Systems, can seem daunting to even the most experienced sprinkler system designer, not to mention a first timer. It is important to remember that designing an appropriate sprinkler system for a given hazard doesn’t start in the storage chapters—it starts in Chapter 5 with the classification of the commodity.
Properly classifying the goods that are being stored is the first and arguably the most critical step in identifying a code-compliant sprinkler system design for a storage facility. In order to identify an appropriate design, you need to consider three important elements to help you avoid common errors in assigning the appropriate commodity classification.
Commodity: It’s not just the product. The first pitfall for many designers is failing to understand how the NFPA technical committees use the term “commodity.” Many designers incorrectly assume that the commodity is simply the item being stored, without any consideration of its packaging. But NFPA 13 defines commodity as the “combination of products, packaging material, and container.” Not considering the packaging material or containers associated with the product being stored can lead to a misclassification of the commodity, and an under-designed sprinkler system. It is not uncommon for a product that would independently be considered a Class I commodity to be packaged with plastics that change how the entire unit load acts during a fire. This is why labs that perform commodity classification testing don’t simply test the product itself, but rather the product in its stored condition with packaging and containers included.
The pallet type matters. Another common error that can lead to under-designed sprinkler systems is failing to consider the type of pallet used for storage. When considering the commodity classification for a storage area, NFPA 13 assumes that wooden pallets are being used. The use of unreinforced plastic pallets or reinforced plastic pallets require an increase in commodity classification. Where unreinforced plastic pallets are used, Class I through Class IV commodities are required to take an increase of one class; a commodity that performed as a Class III commodity when tested with a wood pallet would need to be considered a Class IV commodity if a plastic pallet is used.
Look beyond the Annex tables. For many years NFPA 13 has included tables in the Annex that provide examples of classifications for many commodities. Much of the information in these tables dates back to the NFPA 231 series of standards that dealt with various arrangements of storage. The commodity tests conducted to create these tables are in many cases decades old; advancements in shipping and the packing of goods have changed dramatically, and the Annex data may not be appropriate in all cases. Determining the appropriate commodity classification is in many states the responsibility of the engineer of record. It is important that the engineer of record understands where the information for a storage project is coming from and that it is still valid. The Technical Committee for Sprinkler System Discharge Criteria is currently reviewing the Chapter 5 Annex tables and plans to update them for the 2016 edition of NFPA 13.
Avoiding these common mistakes will help system designers ascertain the appropriate commodity classification—a crucial step towards effective sprinkler performance, reduced risk, and reduced losses.
Matt Klaus is principal fire protection engineer at NFPA and staff liaison for NFPA 13, 13R, & 13D.