Connect 3/4" NPSH straight hose thread to 3/4" NPT (National Pipe Taper)
How to join 3/4-14NPSH and 3/4-14 NPT, and what stops it leaking.
Needs adapter
End A
3/4" NPSH straight hose thread (3/4-14NPSH)
Seals on flat washer or gasket in the coupling
via adapter
End B
3/4" NPT (National Pipe Taper) (3/4-14 NPT)
Seals on on the thread flanks with PTFE tape
Adapter needed3/4 NPSH to 3/4 NPT adapter
Not a direct fit. Joining 3/4" NPSH straight hose thread to 3/4" NPT (National Pipe Taper) needs a 3/4 NPSH to 3/4 NPT adapter.
The adapter to buy
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NPSH is a straight hose thread and NPT is tapered, so a 3/4 NPSH hose will not seal into a 3/4 NPT pipe port despite the close size. An NPSH-to-NPT adapter presents a tapered male for the pipe and a straight female for the hose.
The straight-into-tapered mistake weeps because the flanks never fully mate. Use the adapter rather than forcing the hose coupling onto a pipe thread.
Related connections
3/4" NPSH straight hose thread3/4-14NPSH3/4" NPT (National Pipe Taper)3/4-14 NPT3/4" NPT (National Pipe Taper) to 3/4" BSP parallel (G3/4 / BSPP)adapter3/4" NPT (National Pipe Taper) to Garden Hose Thread (GHT / NH)adapter3/4" NPSH straight hose thread to Garden Hose Thread (GHT / NH)adapter1" NPSH straight hose thread to 3/4" NPSH straight hose threadadapter
Sources: NPSH / NH / NHR hose coupling thread table, Fittings.space · ANSI/ASME B1.20.1 (NPT pipe threads) · NPT thread dimensions chart (ASME B1.20.1), Machining Doctor