Hose-to-pipe fittings, also called adapters, allow a plumber to connect the threads of a hose spigot or water hose to the threads of standard, National Pipe Thread-type pipes.
Difference Between Hose Threads and NPT Threads
Hose threads and NPT threads differ in pitch, or angle, and size. Whereas pipe-thread fittings require a coating of pipe-thread sealant to create a leak-proof joint, hose-thread fittings seal connections with a small rubber washer seated within the interior portion of the fitting, called the "female" side.
Parts of Hose-to-Pipe Fittings
Hose-to-pipe fittings are typically made of PVC. The hose-thread portion of the fitting always has exterior threads, also called "male" threads.
The pipe-thread portion of the fitting may have exterior threads or interior threads.
Where to Find the Fittings
The average home improvement store typically stocks several hose-to-pipe fittings, but the fittings are not usually located with the garden hoses; look for hose-to-pipe fittings in the plumbing department alongside PVC irrigation components. Many retailers label hose-to-pipe fittings with "Hose X NPT," wherein the size of the pipe thread precedes the acronym NPT.
For example: 1/2-inch NPT. Hose fittings do not vary in size.