• Please to View Article

    Restaurant Systems: Sealing Penetrations with Grease-Tight Fittings Keeps Fire from Spreading

    By Mark Conroy


    Whenever a penetration is made in a hood or duct to accommodate extinguishing system piping, detection cable conduit, or a corner pulley, the area around the penetration needs to be sealed. That is to help prevent a fire from spreading beyond the hood and duct. It also keeps the combustible cooking grease within the hood and duct system. Sometimes changes to accommodate new cooking appliances results in penetrations that are no longer needed. Those penetrations need to be plugged for the same reasons. Here is what you need to know to make sure all hood and duct penetrations are safe and code compliant.


    NFPA requires penetrations in hoods to be welded or sealed by listed devices [96: 5.1.5].

    NFPA requires any holes that result from the removal of conduit or piping to be plugged and sealed with listed or equivalent liquid-tight sealing devices [96: 10.2.7.2].

    Piping and Conduit Penetrations

    Jiffy “Grease-Tite” Adaptors are UL listed mechanical fittings (threaded) that form a liquid-tight seal around distribution piping or detection cable conduit. They are installed wherever a penetration is made to accommodate the piping or conduit in a restaurant hood or duct.

    Corner Pulley Penetrations

    Corner Pulley “Grease-Tite” Adaptors are needed for installing high-temperature corner pulleys. The adaptor creates a liquid-tight seal, connecting the corner pulley to ½ inch EMT conduit. These adapters are installed for corner pulleys that make a 90° change in direction from a detector bracket through the top of a hood.

    Penetration Plugs

    Jiffy Patch "Grease-Tite" Seals are installed when cooking appliances are replaced or changes are made to the extinguishing system, causing piping or conduit to be removed or redirected. The penetrations that are no longer needed leave holes in the hood. Those holes are required to be plugged. UL listed Jiffy Patch "Grease-Tite" Seals are threaded fittings that are used to plug unwanted holes.

    Your knowledge of the NFPA requirements and the importance of these fittings will help you make the right safety decisions for every penetration in restaurant hoods and ducts. The restaurant owner can rest assured that your knowledge and compliance with the national standards will keep his property, employees, and patrons safe.



    Click Here to view a PDF version


    Mark Conroy is an engineer in our Boston office, specializing in fire extinguishers and their applications.

    Disclaimer: The opinions expressed in the above Tech Series article are the author’s only and provide limited information. Although the information is believed to be reliable, Brooks Equipment Company, LLC expressly disclaims any warranty with respect to the information and any liability for errors or omissions. The user of this article or the product(s) is responsible for verifying the information’s accuracy from all available sources, including the product manufacturer. The authority having jurisdiction should be contacted for code interpretations.