Flow sensor fitting

Hi, I have a 2000l and 5000l flow meter , am having a hard time to find any thing that will fit , I would like a barb fitting if possible, but I will take any thing at this point.
Was told the thread are G1/2 “and G 1”. I think what I read is G stand for gas.
Anyhow the G1/2 and G 1 are 1/2 “ BSP and 1” BSP, am not sure if that can be converted to mm.
The BSP thread comes in BSPP (British standard pipe parallel) and BSPT( British standard pipe tapered).
Very confusing, anyone can help? I need 2 barb fitting for each, I will buy them from any where if I can find the right one. Hard to find in Canada.
Thanks

Hello,

these all correspond to the defacto world-wide-standard BSW.
Look here for details and also conversions to other units: https://en.wikipedia.org/wiki/Britis...dard_Whitworth

Am lost, can anyone tell me what thread size. Should I be looking to get? I need barb fitting. Any help,
Thank