DIN EN ISO 1452-4 is the German version of EN ISO 1452-4. EN ISO 1452-4 defines for the first time internationally uniform specifications regarding the characteristics of valves made of unplasticized poly(vinyl chloride) (PVC-U) for piping systems intended for water supply and for buried and above-ground sewerage under pressure. The currently parallel applicable standards ISO 4422-4 and EN 1452-4 on PVC-U on valves for water supply have now been combined in a common standard which also contains the corresponding specifications of EN 1456-1 on buried and above-ground sewerage under pressure which are made of PVC-U. The standard addresses the manufacturers, test equipment and users of piping systems made of unplasticized poly(vinyl chloride) (PVC-U). It has the character of a delivery standard. In particular, the standard contains aspects of quality and product safety. The standard has been prepared by Technical Committee ISO/TC 138 "Plastics pipes, fittings and valves for the transport of fluids", in collaboration with CEN/TC 155 "Plastics piping systems and ducting systems". The responsible German Committee is Working Committee NA 054-05-03 AA "Fittings für Druckrohre aus Thermoplasten" ("Fittings for pressure pipelines made of thermoplastic materials") at FNK.