ISO International Standard

ISO 4397:2011 specifies information on the nominal outside diameters of rigid or semi-rigid tubing and nominal hose sizes to be used with hydraulic and pneumatic fluid power connectors and associated components: a) nominal outside diameters for rigid or semi-rigid tubes, irrespective of material composition, used in fluid power; b) a list of nominal sizes for hoses made of rubber or plastic used in fluid power.