R1-1/2 vs 1-1/2-11.5NPSH: specs compared

Updated 05 September 2026.

47.803 mm
R1-1/2 wins on major diameter

On major diameter, R1-1/2 leads: 47.803 mm versus 47.7 mm.

SpecR1-1/21-1/2-11.5NPSH
DesignationR1-1/21-1/2-11.5NPSH
Major diameter47.803 mm47.7 mm
Threads per inch / pitch1111.5
Thread formtapered, 55 degreestraight (parallel), 60 degree
Seals onon the thread flanks with PTFE tape or pastegasket in the coupling

Questions and answers

Which has the higher major diameter, R1-1/2 or 1-1/2-11.5NPSH?

On major diameter, R1-1/2 leads: 47.803 mm versus 47.7 mm.

How do R1-1/2 and 1-1/2-11.5NPSH compare?

On major diameter, R1-1/2 leads: 47.803 mm versus 47.7 mm.

Compared here

1-1/2" BSP tapered (R1-1/2 / BSPT) (R1-1/2)1-1/2" NPSH straight hose thread (1-1/2-11.5NPSH)