What is the nominal diameter (DN)?
Die Nennweite war früher eine ganzzahlige numerische Bezeichnung für den Innendurchmesser einer Rohrleitung oder einer Armatur in Millimeter.
Beispiel: Ein Rohr DN 100 hatte einen Innendurchmesser von 100 mm.
Da inzwischen sehr viele Rohre, insbesondere Stahl- und Kunststoffrohre, mit unterschiedlichsten Wandstärken entstanden sind, wollte man diese Angabe in EN 805 etwas genauer fassen.
Nominal diameter (DN):
The nominal diameter used to be an integer numerical number for the inside diameter of a pipeline or a fitting in mm.
Example: A DN 100 pipe had an inside diameter of (about) 100 mm.
Since a large number of pipes, especially steel and plastic pipes with different wall thicknesses, have been produced in the meantime, this information should be more precise. DIN EN 805 therefore recommends using either the combination DN/OD or DN/ID. These designations are also used, for example, in DIN 11853-1, -2, -3 and DIN 11864-1, -2, -3.
EN 805 now suggests to use either the combination DN/OD or DN/ID. This is also used in DIN 11853-1 ff sowie DIN 11864-1 ff.
Outside Diameter (OD):
Average outer diameter of the pipe.
Inside Diameter (ID):
Average inner diameter of the pipe.
EN ISO 6708 "Pipework components - Definition and selection of DN (nominal size)":
EN ISO 6708 defines DN as follows: "An alphanumeric description of the size of components in a piping system used for reference purposes. It comprises the letters DN followed by a dimensionless integer indirectly related to the physical size of the bore or outside diameter of the connections, expressed in millimeters."
More informations about nominal diameter of valves, pipes and fittings:
- The standards mentioned can be obtained from www.dinmedia.de.
- WIKIPEDIA about nominal diameter.
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