DN-公稱直徑Ф－外徑大外徑系列DN15-ф22mmDN20-ф27mmDN25-ф34mmDN32-ф42mmDN40-ф48mmDN50-ф60mmDN65-ф76(73)mmDN80-ф89mmDN100-ф114mmDN125-ф140mmDN150-ф168mmDN200-ф219mmDN250-ф273mmDN300-ф324mmDN350-ф360mmDN400-ф406mmDN450-ф457mmDN500-ф508mmDN600-ф610mm 小外徑系列DN15-ф18mmDN20-ф25mmDN25-ф32mmDN32-ф38mmDN40-ф45mmDN50-ф57mmDN65-ф73mmDN80-ф89mmDN100-ф108mmDN125-ф133mmDN150-ф159mmDN200-ф219mmDN250-ф273mmDN300-ф325mmDN350-ф377mmDN400-ф426mmDN450-ф480mmDN500-ф530mmDN600-ф630mm一般來說，管子的直徑可分為外徑、內徑、公稱直徑。