Historical
ISO 11191:1997
Gas cylinders -- 25E taper thread for connection of valves to gas cylinders -- Inspection gauges
This International Standard specifies types, dimensions and principles of use of gauges, to be used in conjunction with the taper thread specified in ISO 10920.
Annex A provides examples of calculations for thread gauge dimensions on the large end diameter.
Annex B draws attention to the limitations of the gauging system specified.
International Organization for Standardization [iso]