How do nominal sizes differ according to DN and NPS?
The nominal size according to DIN (DN) and the Nominal Pipe Size (NPS) differ in their calculation and specification. DN describes the internal diameter of metric systems, while NPS is specified in inches and is primarily used in the USA. Both measurements serve the standardization of pipe sizes and are partially convertible.
Differences of nominal sizes according to DIN and NPS
The nominal size DN is a dimensionless number that defines the internal diameter of a pipeline or the connection size of a fitting. The indication of the nominal size DN specifies the approximate internal diameter of the pipeline in millimeters and is based on the metric measurement system.
The designation Nominal Pipe Size, also known as NPS, also refers to the internal diameter of a pipeline or the connection size of a fitting. In this definition, the approximate internal diameter of the pipeline is mentioned, but the values are provided in inches, which come from the Anglo-American measurement system.
| Nominal size DN | NPS in inches | Pipe connection ISO | Pipe connection EN |
|---|---|---|---|
DN 6 | 1/8“ | Ø 10.2 mm | Ø 10.2 mm |
DN 8 | 1/4“ | Ø 13.5 mm | Ø 13.5 mm |
DN 10 | 3/8“ | Ø 17.2 mm | Ø 17.2 mm |
DN 15 | 1/2“ | Ø 21.3 mm | Ø 21.3 mm |
DN 20 | 3/4“ | Ø 26.9 mm | Ø 26.9 mm |
DN 25 | 1“ | Ø 33.7 mm | Ø 33.7 mm |
DN 32 | 1 1/4" | Ø 42.4 mm | Ø 42.4 mm |
DN 40 | 1 1/2" | Ø 48.3 mm | Ø 48.3 mm |
DN 50 | 2“ | Ø 60.3 mm | Ø 60.3 mm |
DN 65 | 2 1/2" | Ø 76.1 mm | Ø 76.1 mm |
DN 80 | 3“ | Ø 88.9 mm | Ø 88.9 mm |
DN 100 | 4“ | Ø 114.3 mm | Ø 114.3 mm |
DN 125 | 5“ | Ø 139.7 mm | Ø 139.7 mm |
DN 150 | 6“ | Ø 168.3 mm | Ø 168.3 mm |
DN 200 | 8“ | Ø 219.1 mm | Ø 219.1 mm |
DN 250 | 10“ | Ø 273.0 mm | Ø 273.0 mm |
DN 300 | 12“ | Ø 323.9 mm | Ø 323.9 mm |
DN 350 | 14“ | Ø 355.6 mm | Ø 355.6 mm |
DN 400 | 16“ | Ø 406.4 mm | Ø 406.4 mm |
DN 450 | 18“ | Ø 457.0 mm | Ø 457.0 mm |
DN 500 | 20“ | Ø 508.0 mm | Ø 508.0 mm |
DN 600 | 24“ | Ø 610.0 mm | Ø 610.0 mm |
DN 700 | 28“ | Ø 711.0 mm | Ø 711.0 mm |
DN 800 | 32“ | Ø 813.0 mm | Ø 813.0 mm |
DN 900 | 36“ | Ø 914.0 mm | Ø 914.0 mm |
DN 1000 | 40“ | Ø 1016.0 mm | Ø 1016.0 mm |
DN 1200 | 48“ | Ø 1220.0 mm | Ø 1219.0 mm |
DN 1400 | 56“ | Ø 1420.0 mm | Ø 1422.0 mm |
DN 1600 | 64“ | Ø 1620.0 mm | Ø 1626.0 mm |
DN 1800 | 72“ | Ø 1820.0 mm | Ø 1829.0 mm |
DN 2000 | 80“ | Ø 2020.0 mm | Ø 2032.0 mm |
DN 2200 | 88“ | Ø 2220.0 mm | Ø 2235.0 mm |
DN 2400 | 96“ | Ø 2420.0 mm | Ø 2438.0 mm |
DN 2600 | 104“ | Ø 2620.0 mm | Ø 2620.0 mm |
DN 2800 | 112“ | Ø 2820.0 mm | Ø 2820.0 mm |
DN 3000 | 120“ | Ø 3020.0 mm | Ø 3020.0 mm |
DN 3200 | 128“ | Ø 3220.0 mm | Ø 3220.0 mm |
DN 3400 | 136“ | Ø 3420.0 mm | Ø 3420.0 mm |
DN 3600 | 144“ | Ø 3620.0 mm | Ø 3620.0 mm |
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