what is nh thread
âNHâ, or National Hose, thread is the thread that has become the standard thread used in firefighting today. The threads specified in NFPA 1963 are âNHâ. This thread was previously known as âNSTâ or National Standard Thread. âNPSHâ, or National Pipe Straight Hose, is slightly smaller in diameter and has more threads per inch than the same nominal diameter âNHâ thread.