What is the thread count per inch for 2½ inch coupling threads?

What is the thread count per inch for 2½ inch coupling threads?

• A. 7.5 threads per inch
• B. 5.0 threads per inch
• C. 9.0 threads per inch
• D. 6.5 threads per inch

Answer: (A)

Thread count per inch is the standard pitch of the threads on a hose coupling. For a 2½ inch fire hose coupling, the accepted pitch is 7.5 threads per inch. That means there are seven and a half ridges in every inch of the threaded portion, which equals about 0.133 inches per thread. This specific pitch is standardized so hoses and couplings from different manufacturers fit together properly. The other numbers don’t match this size’s standard pitch, so they wouldn’t thread correctly for a 2½ inch coupling.

Thread count per inch is the standard pitch of the threads on a hose coupling. For a 2½ inch fire hose coupling, the accepted pitch is 7.5 threads per inch. That means there are seven and a half ridges in every inch of the threaded portion, which equals about 0.133 inches per thread. This specific pitch is standardized so hoses and couplings from different manufacturers fit together properly. The other numbers don’t match this size’s standard pitch, so they wouldn’t thread correctly for a 2½ inch coupling.