This International Standard specifies three methods for the determination of the volume of gas diffusing through a rubber or plastics hose or length of tubing in a specified time. Method 1: For determining the permeability of the complete hose or length of tubing, excluding end-fittings, to the test gas. The permeability is calculated with respect to the length of the hose or tubing. Method 2: For determining the permeability at the hose/fitting interface. This method is used when determining the permeability characteristics of hoses with an unpricked cover, when the gas usually issues from the textile reinforcement at the cut ends. The permeability is calculated with respect to the length of the hose. Method 3: For determining precisely the permeability of a hose or hose assembly to the test gas. The permeability is calculated with respect to the surface area of the hose lining. The methods are applicable only to gases which are insoluble in water. NOTE 1 Although the results are expressed in the same units for methods 1 and 2, the results obtained will not necessarily be comparable in the case of unpricked and pricked hoses intended for the same application as the test times specified are different and the permeability could therefore vary. NOTE 2 Method 3 is the preferred method.