1/2" BSP tapered (R1/2 / BSPT) (R1/2)
Where R1/2 is used, its real dimensions, and how to connect it to other standards.
R1/2Thread standard
DesignationR1/2
Major diameter20.955 mm
Threads per inch / pitch14
Thread formtapered, 55 degree
Seals onon the thread flanks with PTFE tape or paste
Used on: European pipework, boiler and pump ports, garden pumps.
R1/2 is the tapered 1/2 inch BSP. It self-seals on the thread, so it is the usual male thread on pumps that then adapts out to a hose fitting.
Quick-connect click fittings from Hozelock, Gardena and Karcher are proprietary and do not interchange. They all sit on top of a standard thread underneath, so the reliable way to move between brands is to adapt at the threaded tap or hose-end fitting, then use each brand's own connector above it.
Connect this thread
Connect 1/2" BSP tapered (R1/2 / BSPT) to Garden Hose Thread (GHT / NH)needs an adapter1/8" BSP parallel (G1/8 / BSPP)related standard (G1/8)1/4" BSP parallel (G1/4 / BSPP)related standard (G1/4)3/8" BSP parallel (G3/8 / BSPP)related standard (G3/8)1/2" BSP parallel (G1/2 / BSPP)related standard (G1/2)3/4" BSP parallel (G3/4 / BSPP)related standard (G3/4)1" BSP parallel (G1 / BSPP)related standard (G1)1-1/4" BSP parallel (G1-1/4 / BSPP)related standard (G1-1/4)1-1/2" BSP parallel (G1-1/2 / BSPP)related standard (G1-1/2)1/4" BSP tapered (R1/4 / BSPT)related standard (R1/4)
Sources: BS 21 / ISO 7 (BSPT tapered pipe threads) · BSP thread dimensions chart (ISO 228 / ISO 7), AmesWeb