Radiator Valve Threads

[sammathias]

Oh I must be completely clueless, please forgive my stupidity.

 

[quality]

most imported compression fittings are standard BSP kuterlite is not also zone vale manufacturers have for many years bastardised their threads for some reason, maybe their supplier. I have not read all the posts but 15mm has been 1/2" bsp 14 TPI for over 40 years but there is some stuff out there older. We do refrigeration work also and come across all sizes of pipe thread, BSP, BSPT, NPT and on the odd occasion APT they are not that much different but they are different