3 times, the book erroneously refers to NPT plumbing fittings as "National Pipe Thread". It is actually "National Pipe Taper". It is helpful to remember that it is "taper" because the thread is tapered! A tapered thread is usually made fast with PTFE "teflon" tape, while other threads are held fast with a gasket, O-ring or other method.
You could write a few paragraphs about the history of why there are quotes around "teflon". In brief, the brand name fell out of trademark. There's quite a bit more to the story but I forget.
3 times, the book erroneously refers to NPT plumbing fittings as "National Pipe Thread". It is actually "National Pipe Taper". It is helpful to remember that it is "taper" because the thread is tapered! A tapered thread is usually made fast with PTFE "teflon" tape, while other threads are held fast with a gasket, O-ring or other method.
You could write a few paragraphs about the history of why there are quotes around "teflon". In brief, the brand name fell out of trademark. There's quite a bit more to the story but I forget.