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Author(s): Matt Klaus. Published on March 1, 2018.

In Compliance | NFPA 13

Commodity classification and the design of sprinkler systems


During the development of the 2016 edition of NFPA 13, Installation of Sprinkler Systems, the technical committee for sprinkler system discharge criteria performed a top-to-bottom review of the often used but often over simplified commodity classification tables in the annex sections for chapter 5. The impetus for this review was that many of the identified classifications were outdated, the result of changes in the raw materials used in today’s products and packaging. Take office furniture, for example—30 years ago, chairs and desks were made primarily of wood and metal, but today many of these products are made of plastics and laminates.

We should first consider the customary overuse of these tables. All of the items listed had undergone a commodity classification test at some point to help determine the hazard they presented and ultimately the appropriate sprinkler protection criteria needed to protect those hazards. Many designers and engineers, when they receive plans from their clients, look at the items stored, go directly to these lists, and pick the closest item they can find in the table. This is dangerous because even the slightest difference in the raw materials used in a commodity, packaging arrangement, or packaging material can cause a change in how the commodity might ultimately be classified based on testing.

For this reason, it’s imperative that the assignment of a commodity class is not based solely on a comparative review of this table, but rather on several factors: an analysis of the materials being stored, a review of product-specific commodity test data (if available), a review of recent and relevant commodity test data, a review of commodity composition by weight and volume, and a review of the annex tables. Simply saying that a commodity is similar to an item listed in the annex is not adequate and can lead to an under-designed sprinkler system.

Combine the importance of the commodity classification assignment with the aforementioned changes in packaging and material selection, and a review of these annex tables was warranted. The results of this review yielded dozens of changes to the commodity classifications for items listed in these tables. For the bulk of these changes, commodities originally considered Class III (or group C plastics) or Class IV (or group B plastics) commodities received a bump in their original classification to either Class IV or group A plastics. This indicates that an increased density of sprinkler protection is needed to control these fires.

For designers and engineers who determine what commodities are present for a given building, a close review of these changes is an important first step. Even if a project is governed by an older edition of NFPA 13, designers would be doing clients a disservice from a risk perspective by not considering the latest edition of the standard. Looking at the common materials found in their clients’ products to determine if these materials have changed commodity class will help determine if design changes are needed going forward. Since they are not in the body of the standard and because NFPA 13 is not set up to require systems to be upgraded to the latest standard, there is no issue of retroactivity with these changes.

That being said, several underwriters have expressed concern for certain existing buildings, used to store/distribute goods, that underwent a change in commodity class in these tables. Consider an existing warehouse that stores products made primarily of polyvinyl fluoride (PVF). The safety system for this warehouse was designed to the 2010 edition of NFPA 13 to protect Class III commodities, which was the assigned commodity class for PVF in Annex A at that time. In 2016, PVF was reclassified to a Group A plastic. While the building and its sprinkler system still comply with NFPA 13, since the building is not required to be upgraded, there is also a stock of products that acts much differently in a fire event than originally anticipated, and the sprinkler system may not be able to handle a fire involving those products. Since there is no mandate to upgrade the systems in these situations, they would need to be decided on by the owner and insurance representatives on a case-by-case basis.

The selection of commodity classification is a critical part of the design. Understanding how the recent changes to the classification tables affects your company and your clients can have a huge impact on the risk being carried.

MATT KLAUS is NFPA technical services lead for fire protection engineering. Top Photograph: AP/Wide World