The nominal diameter is the size of all the pipe accessories in the piping system expressed by numbers. The nominal diameter is a convenient round integer for reference, and it has only a non-strict relationship with the processing size. The nominal diameter is identified by the letter "DN" followed by a number.
Nominal diameter (nominal diameter), also known as the mean outside diameter (mean outside diameter).
This is due to the thin tube of the metal pipe, the outer diameter of the pipe and the inner diameter of the pipe are almost the same, so the average value of the outer diameter of the pipe and the inner diameter of the pipe is taken as the pipe diameter.
DN is the nominal diameter. The nominal diameter (or nominal diameter) is the universal diameter of various pipes and pipe accessories. Pipes and pipe accessories of the same nominal diameter can be connected to each other and have interchangeability. It is not the outer diameter or inner diameter of the pipe in the actual sense, although its value is close to or equal to the inner diameter of the pipe; in order to make the connection dimensions of the pipes and fittings uniform , Using the nominal diameter (also known as the nominal diameter, nominal diameter). For example, welded steel pipes can be divided into thin-walled steel pipes, ordinary steel pipes and thickened steel pipes according to their thickness. Its nominal diameter is not the outer diameter or the inner diameter, but a nominal size that approximates the inner diameter of ordinary steel pipes. Each nominal diameter corresponds to an outer diameter, and the value of the inner diameter varies with thickness. The nominal diameter can be expressed in metric mm, or in inch. The pipe accessories are also expressed by the nominal diameter, which has the same meaning as the sewn pipe.
