The NH fire hose coupling, also known as NST (National Standard Thread) or NHT (National Hose Thread), is a widely used standard coupling system for fire hoses in the United States. It is designed to provide a secure and reliable connection between fire hoses and firefighting equipment, such as hydrants, nozzles, and pumps.
The NH coupling utilizes a quarter-turn thread connection with a male and female component. The male coupling has external threads with a diameter of 2.5 inches, while the female coupling has corresponding internal threads. The thread pitch is 8 threads per inch (TPI), which allows for quick and efficient attachment and detachment of hoses.