DN50 means a pipe or fitting has a Nominal Diameter (DN) of 50 millimeters, a standard European metric measurement for classifying pipe sizes, indicating its approximate internal diameter for compatibility with other components. While '50' suggests 50mm, it's a reference number, not the exact internal or external diameter; a DN50 pipe typically has an outer diameter around 60.3mm and corresponds to a 2-inch NPS (Nominal Pipe Size) in the US system, ensuring fittings match up.
DN50 is a common standard specification, which represents the inner diameter of the steel pipe. DN is the abbreviation of Deutsches Institut für Normung (German Standardization Institute), which means "German Standard". 50 means that the inner diameter of the steel pipe is 50 mm.
What Do DN and NPS Stand For? DN stands for diametre nominal, which denotes the size of a pipe (specifically, its inside diameter) in millimeters (mm). NPS, or nominal pipe size, is merely the non-metric equivalent in which the diameter is measured in inches (in.).
Conversion of DN diameters to inches
25.4 is the number of millimetres in one inch. The result shows that the diameter of DN 50 is approximately 1.97 inches.
Valve would have 2" on it. DN50 on the valve means the nominal diameter of the valve is 50 millimeters. DN (Nominal Diameter) is a measurement that indicates the internal diameter of the valve in millimeters.
Nominal Diameter (DN)
DN is defined by the European standard ISO 6708 and is based on millimeters. It represents the approximate internal diameter of a pipe. DN values are typically expressed as whole numbers (e.g., DN 50).
The DN system of conversions simplifies these measurements by ignoring the demical point and rounding down to the nearest zero or five. Using the above example, 1 inch equals 25.4 milimetres but rendered as DN25; 8 inch equals 203.2 milimeters but rendered as DN200; while, a 14 inch flange will be termed as DN350.
Definition of nominal diameter (DN)?
Defining this term in the simplest terms, we can say that the nominal diameter DN roughly defines the diameter inside the pipe given in millimetres. It is therefore given in the metric system, rather than in the commonly used imperial system.
DN does not exactly correspond to a size in millimeters, because ISO 6708 defines it as being a dimensionless specification only indirectly related to a diameter.
DIN Tri-Clamp fittings are denoted with a number that indicates their size in millimeters. For example, a DIN50 fitting would be 50mm in size.
In other words, for every NPS number there is a DN number; for example NPS 3/4" is equivalent to DN20. This means that a pipe having NPS 3/4" can also be defined as DN20, where 3/4 (0.75 inches) approximates the nearest standard size in millimeters which is DN20 since there is no DN19.
To convert a DN value into inches, simply divide it by 25.4, since one inch equals 25.4 millimeters. This means a DN50 pipe corresponds to roughly 1.97 inches in diameter.
DN = Diameter Nominal
The term Diameter Nominal refers to the internal diameter of a pipe. Together with the nominal pressure rating and the materials class, all dimensions of a piping line, e. g. flange dimensions, are defined by indicating the nominal diameter. Steel is often not specified, but assumed as material.
This pipe is often called 50mm, note that this refers to the internal diameter of the pipe and not the external. External diameter of 2" pipe is 55mm.
The DN50 means the valve belongs to the nominal diameter class 50 mm. That is to say, the internal bore is intended to match other DN50 piping components, although the true internal diameter may be slightly different (depending on wall thickness or design).
The nominal dimension for pipe is the ID. So, 1½ inch pipe is NOT 1½ inch outside diameter, but instead is nominally, (approximately) 1½ inch inside diameter. Pipe is typically manufactured to looser tolerances and less expensive to purchase.
Nominal Diameter (DN)
Nominal diameter is a typical term used to specify the size of pipes and pipe fittings in the UK and Europe. It is actually often abbreviated to DN from the French term diamètre nominal. DN is based on the metric system, using millimetres to denote pipe sizes.
DN80 (3 inch) Flanged Cast Iron Y Strainer PN16.
The specific conversion between inches and DN can vary slightly depending on the standards used, but in most cases, 1 inch is considered equivalent to DN 25 in the metric system.
CONVERSION OF DN DIAMETERS TO INCHES
Diameter Nominal (DN)
As with the NPS system, the DN system is dimensionless, although it is based on the millimetre (mm) unit. A DN 80 pipe relates to a pipe having an outside diameter of 88.90 mm, not 80.00 mm.
The DN150 designation means the valve has a nominal bore size of 150 mm, which is equivalent to 6 inches (NPS 6) in the imperial system.