This International Standard specifies five methods for determining the ozone resistance of the outer covers of hoses:. method 1, for bore sizes up to and including 25 mm, carried out on the hose itself;. method 2, for bore sizes greater than 25 mm, carried out on a test piece from the hose wall;. method 3, for bore sizes greater than 25 mm, carried out on a test piece from the cover;. method 4, for all bore sizes, carried out on the hose itself;. method 5, for all bore sizes, carried out on hoses that are expandable, for example textile-reinforcedhoses.NOTE For hoses with built-in fittings from which it is not possible to take test pieces, the ozone resista