What is a DN flange ?
A “DN flange” refers to a flange that is designed to match a specific nominal size (DN or “Diamètre Nominal” in French) of a pipe. DN is a metric system for pipe and fitting sizing that is widely used in many parts of the world, especially in Europe and other regions that have adopted the metric system for engineering and construction.
When you encounter a DN flange, it is important to know the DN size of the pipe it is intended to connect to. DN sizes represent the internal diameter of a pipe, and flanges with DN specifications are designed to match that internal diameter for a proper fit and sealing.
For example, a DN150 flange is intended to connect to a pipe with a nominal size of 150 millimeters, and the internal diameter of the flange will match that size.
The DN system is commonly used in Europe for specifying pipe sizes and flanges, and it is similar in concept to the NPS (Nominal Pipe Size) system used in the United States and some other regions. The key difference is that DN sizes are based on the metric system, while NPS sizes are based on inches. When working with DN flanges, it’s important to select flanges that match the DN size of the pipes in your piping system to ensure compatibility and a proper fit.
DN Flange vs NPS Flange
DN (Diamètre Nominal) and NPS (Nominal Pipe Size) are two different systems for specifying pipe sizes, and they are not directly equivalent in terms of exact measurements because they are based on different measurement standards (metric for DN and imperial for NPS). However, there are approximate conversions that can be used for reference:
DN (Diamètre Nominal) and NPS (Nominal Pipe Size) are two different systems for specifying the sizes of pipes and flanges, and they are used in different parts of the world. Here’s a comparison of DN vs. NPS flanges:
1. DN (Diamètre Nominal) System:
– Metric System: The DN system is based on the metric system and is widely used in Europe and many other countries that have adopted the metric system.
– Nominal Diameter: DN represents the nominal diameter of the pipe, which is the internal diameter of the pipe in millimeters. For example, DN100 corresponds to a pipe with an internal diameter of 100 millimeters.
– Flange Matching: DN flanges are designed to match the internal diameter of pipes with corresponding DN sizes for a proper fit and sealing.
2. NPS (Nominal Pipe Size) System:
– Imperial System: The NPS system is based on the imperial system and is primarily used in the United States and a few other countries that use imperial units.
– Nominal Size: NPS represents the nominal size of the pipe, which is based on the outside diameter of the pipe in inches. For example, NPS 4 corresponds to a pipe with an outside diameter of approximately 4.5 inches.
– Flange Matching: NPS flanges are designed to match the outside diameter of pipes with corresponding NPS sizes for a proper fit and sealing.
Key Differences:
– System of Measurement: DN is metric, while NPS is imperial.
– Reference Diameter: DN refers to the internal diameter of the pipe, while NPS refers to the outside diameter of the pipe.
– Geographic Usage: DN is commonly used in Europe and metric-based regions, while NPS is used in the United States and some other countries.
When working with flanges, it’s crucial to choose flanges that match the pipe’s diameter using the appropriate system (DN or NPS) to ensure a proper fit and sealing in the piping system. The choice between DN and NPS typically depends on regional standards and the specifications of the project or application.
DN to NPS Conversion:
– DN15 is roughly equivalent to NPS 1/2.
– DN20 is roughly equivalent to NPS 3/4.
– DN25 is roughly equivalent to NPS 1.
– DN40 is roughly equivalent to NPS 1 1/2.
– DN50 is roughly equivalent to NPS 2.
– DN80 is roughly equivalent to NPS 3.
– DN100 is roughly equivalent to NPS 4.
– DN150 is roughly equivalent to NPS 6.
– DN200 is roughly equivalent to NPS 8.
– DN250 is roughly equivalent to NPS 10.
– DN300 is roughly equivalent to NPS 12.
Please note that these conversions are approximate and may not be exact matches in all cases. The specific dimensions of a flange, fitting, or pipe in a DN or NPS system can vary based on regional standards and manufacturer specifications. When selecting components for a piping system, it’s essential to follow the appropriate standard and ensure compatibility between components.