dimensional number(MichaelBurov); nominal diameter(BSP or NPS: British standard pipe or Nominal Pipe Size: British and North American set of standard sizes for pipes used for high or low pressures and temperatures. Pipe size is specified with a non-dimensional number: the nominal pipe size (NPS) for diameter based on inches. NPS is often incorrectly called National Pipe Size, due to confusion with national pipe thread (NPT). The European designation equivalent to NPS is DN (diamètre nominal/nominal diameter/Durchmesser nach Norm), in which sizes are measured in millimetres. The term NB (nominal bore) is also frequently used interchangeably with NPS. Киселев); Dimensional Number(DN can be said to refer to Dimensional Number (DN), as in DN 25 means 25mm ART Vancouver); nominal diameter(akhmed)
