Common specifications for small diameters
Size range: DN20, DN25, DN40, DN50, DN65, DN80
Applications: Small-diameter piping and pipeline connections for precision equipment
Common specifications for medium-diameter fire protection systems
Size range: DN100, DN125, DN150, DN200
Corresponding outer diameters: 108/114mm, 133/140mm, 159/165mm, 219mm; these are the standard choices for fire protection piping
Specifications for large-diameter engineering projects
Size range: DN250, DN300, DN400, DN500, DN600
Corresponding outer diameters: 273mm, 325mm, 508–609mm; primarily used in large-scale projects such as HVAC systems and water supply mains