R2-1/2 vs 2-1/2-7.5NH: 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 75.184 mm.

SpecR2-1/22-1/2-7.5NH
DesignationR2-1/22-1/2-7.5NH
Major diameter75.184 mm77.94 mm
Threads per inch / pitch117.5
Thread formtapered, 55 degreestraight (parallel), 60 degree
Seals onon the thread flanks with PTFE tape or pasterubber gasket in the female swivel

Questions and answers

Which has the higher major diameter, R2-1/2 or 2-1/2-7.5NH?

On major diameter, 2-1/2-7.5NH leads: 77.94 mm versus 75.184 mm.

How do R2-1/2 and 2-1/2-7.5NH compare?

On major diameter, 2-1/2-7.5NH leads: 77.94 mm versus 75.184 mm.

Compared here

2-1/2" BSP tapered (R2-1/2 / BSPT) (R2-1/2)2-1/2" NH fire hose thread (NST) (2-1/2-7.5NH)