Presents three methods for determining resistance of outer covers of hoses to ozone: Method 1 - for bore sizes up to 25mm carries out on hose itself; Method 2 - for bore sizes above 25mm carried out on piece from hose wall; Method 3 - for bore sizes above 25 mm carried out on a piece from cover. Method 1 or 2 shall normally be used. Method 3 shall be used only if Method 2 cannot be employed. Results from Method 1 may not be comparable with results from Methods 2 and 3.