2-1/2-7.5NH vs 2-1/2-8 NPT: specs compared

Updated 05 September 2026.

77.94 mm
2-1/2-7.5NH wins on major diameter

On major diameter, 2-1/2-7.5NH leads: 77.94 mm versus 73.02 mm.

Spec2-1/2-7.5NH2-1/2-8 NPT
Designation2-1/2-7.5NH2-1/2-8 NPT
Major diameter77.94 mm73.02 mm
Threads per inch / pitch7.58
Thread formstraight (parallel), 60 degreetapered, 60 degree
Seals onrubber gasket in the female swivelon the thread flanks with PTFE tape

Questions and answers

Which has the higher major diameter, 2-1/2-7.5NH or 2-1/2-8 NPT?

On major diameter, 2-1/2-7.5NH leads: 77.94 mm versus 73.02 mm.

How do 2-1/2-7.5NH and 2-1/2-8 NPT compare?

On major diameter, 2-1/2-7.5NH leads: 77.94 mm versus 73.02 mm.

Compared here

2-1/2" NH fire hose thread (NST) (2-1/2-7.5NH)2-1/2" NPT (National Pipe Taper) (2-1/2-8 NPT)