This document specifies three methods for the determination of the volume of gas diffusing through a rubber or plastics hose or length of tubing used for gas applications in a specified time. Method 1: For determining the volume of gas diffusing through the complete hose or length of tubing, excluding end fittings in a specified time. This method is suitable for textile reinforced hose with either pricked cover or textile cover or both, although this method is not suitable for textile reinforced hose with unpricked cover. The permeability is calculated with respect to the length of the hose or tubing and to the surface area of the hose lining or the tubing. Method 2: For determining the volume of gas diffusing at the hose and fitting interface. This method is used when determining the permeability characteristics of textile reinforced 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 and to the surface area of the hose lining. Method 3: For precisely determining the volume of gas diffusing through the complete hose or length of tubing including end fittings in a specified time. This method is not suitable for textile reinforced hose with unpricked cover. The permeability is calculated with respect to the length of the hose or tubing and to the surface area of the hose lining or the tubing. NOTE 1 Guidance on test methods are provided in Annex C, Table C.1. NOTE 2 Explanation of permeability is provided in Annex A, where the concept of trapped air and permeation is explained in Figure A.1.