1.1 This part of this European Standard applies to the design and manufacture of simple unfired serially made pressure vessels, hereinafter referred to as vessels, designed for air breaking equipment and auxiliary systems for motor vehicles and their trailers, and which: a) include fabrication by welding; b) have a simple geometry enabling simple-to-use production procedures. This is achieved by either: 1) a cylindrical shell of circular cross section closed by outwardly dished and/or flat ends having the same axis of revolution as the shell; or: 2) two dished ends having the same axis of revolution. c) have branches not larger in diameter than 0,5 of the diameter of the cylinder to which they are welded. 1.2 It applies to vessels which are intended to contain only compressed air, and which operate within the following constraints: a) subjected to an internal pressure greater than 0,5 bar; b) the parts and assemblies contributing to the strength of the vessel under pressure to be made either of non-alloy quality steel or of non-alloy aluminium or non-age hardening aluminium alloys; c) maximum working pressure 30 bar. The product of that pressure and the capacity of the vessel (PS.V) is greater than 50 bar.litre and not exceeding 1500 bar.litre; d) minimum working temperature - 50 øC and maximum working termperature not higher than 100 øC. It does not apply to vessels specifically designed for nuclear use, to vessels specifically intended for installation in or the propulsion of ships and aircraft, or to fire extinguishers. 1.3 The essential safety requirements are given in annex G.