Threadless couplings are permitted only if they are:

Threadless couplings are permitted only if they are:

• A. Not listed for such use
• B. Listed for such use
• C. Required by AHJ but not listed
• D. Always permitted

Answer: (B)

The key idea is that equipment must be listed for the specific use in a foam-water sprinkler system. Threadless couplings can be used only if the listing covers that exact service, meaning the coupling has been tested and approved for foam-water applications, including the materials, pressures, and compatibility with the foam concentrate. If a threadless coupling isn’t listed for foam-water service, it isn’t permitted to be used, even if someone asks the AHJ to approve it. So the correct practice is to rely on listing for such use—only those threadless couplings that are specifically listed for foam-water sprinkler systems may be installed. The other options aren’t valid because unlisted devices aren’t allowed, AHJs can’t authorize unlisted equipment as a blanket rule, and nothing in the code makes such installations always permissible.

The key idea is that equipment must be listed for the specific use in a foam-water sprinkler system. Threadless couplings can be used only if the listing covers that exact service, meaning the coupling has been tested and approved for foam-water applications, including the materials, pressures, and compatibility with the foam concentrate. If a threadless coupling isn’t listed for foam-water service, it isn’t permitted to be used, even if someone asks the AHJ to approve it.

So the correct practice is to rely on listing for such use—only those threadless couplings that are specifically listed for foam-water sprinkler systems may be installed. The other options aren’t valid because unlisted devices aren’t allowed, AHJs can’t authorize unlisted equipment as a blanket rule, and nothing in the code makes such installations always permissible.