What is the minimum nominal diameter required for a test connection pipe in an NFPA 13 R system?

In an NFPA 13R system, the minimum nominal diameter required for a test connection pipe is established as 1 inch to ensure effective performance during system testing. A test connection plays a crucial role in evaluating the water supply and pressure available for the sprinkler system. By specifying a minimum diameter of 1 inch, the standard ensures that the flow of water can be adequately measured and that any tests conducted on the system reflect realistic operating conditions.

Using a larger diameter pipe for the test connection, such as 2 inches or above, might lead to excessive flow that can complicate testing, while smaller diameters, such as 3/4 inch, could restrict flow and result in inaccurate test results. The chosen nominal diameter ensures a balance between ensuring sufficient flow for accurate testing without unnecessary complications during the process.