This European Standard applies for the design, construction, equipping, marking and testing of air locks and pressure bulkheads, which are to be used in tunnelling work. The oxygen breathing installation used to provide the breathing supply necessary to conduct a safe decompression is also covered by this standard. 1.2 This standard deals with all significant hazards, hazardous situations and events relevant to air locks and pressure bulkheads, when they are used as intended and under the conditions foreseen by the manufacturer (see clause 4). This standard specifies the appropriate technical measures to eliminate or reduce risks arising from the significant hazards. 1.3 This document is not applicable to machinery which is manufactured before the date of publication of this document by CEN.