Connect 1" NPSH straight hose thread to 3/4" NPSH straight hose thread
How to join 1-11.5NPSH and 3/4-14NPSH, and what stops it leaking.
Needs adapter
End A
1" NPSH straight hose thread (1-11.5NPSH)
Seals on gasket in the coupling
via adapter
End B
3/4" NPSH straight hose thread (3/4-14NPSH)
Seals on flat washer or gasket in the coupling
Adapter needed1 inch to 3/4 NPSH hose reducer
Not a direct fit. Joining 1" NPSH straight hose thread to 3/4" NPSH straight hose thread needs a 1 inch to 3/4 NPSH hose reducer.
The adapter to buy
Search Amazon for 1 inch to 3/4 NPSH hose reduceraffiliate searchFind 1 inch to 3/4 NPSH hose reducer on eBayaffiliate
Reducing a 1 inch NPSH hose to a 3/4 inch NPSH fitting uses a straight hose reducer. Both are gasket-sealed straight threads, so the join is clean once the coupling gasket seats.
Check both ends are NPSH and not NH. A 1 inch NH fire coupling is a completely different pitch and will not thread into an NPSH reducer.
Related connections
1" NPSH straight hose thread1-11.5NPSH3/4" NPSH straight hose thread3/4-14NPSH3/4" NPSH straight hose thread to Garden Hose Thread (GHT / NH)adapter3/4" NPSH straight hose thread to 3/4" NPT (National Pipe Taper)adapter
Sources: NPSH / NH / NHR hose coupling thread table, Fittings.space