Does Avk supply Gas Valves?

Yes,Avk Valves is known for various types of gas valves in the world, for more info please contact marius@avkvalves.co.za

what does 23/30 (top right corner of page) stand for ?

The top right corner of a data sheet refers to the internal series of that particular product... eg, 43/60 Refers to the SABS 664 spec Flanged RSV Valve.