Fire hose fittings are simply adapters designed to connect hoses and pipes of incompatible diameter, thread, or gender. Examples include reducers, increasers, male x male, and female x male configurations. There are three primary threads in use nationally today as well as a number of regional custom threads. There are some cases where different threads may be compatible, for the most part they are not and it is critical that the correct thread is specified.
- GH = Garden Hose Thread
- NST or NH = Fire Hose Thread
- NPT = Tapered Pipe Thread
- NPSH = Straight Pipe Thread
