DN, NPS & DN vs NPS

DN & NPS

What is DN in Pipes?

  1. “DN” is an abbreviated form of Diameter Nominal (DN).
  2. It is a dimensionless number that denotes the pipe size in the metric unit system.
  3. The DN pipe size designator is developed by the International Standards Organization or ISO.
  4. The pipe sizes are designated by DN followed by a number to indicate standard pipe size. For example, DN50 indicates a 2″ NPS pipe; Similarly, DN80 indicates a 3″ NPS pipe.

Attempt Question on DN in Pipe

DN Pipe Size Quiz

1. What does "DN" stand for in piping?

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2. Who developed the DN pipe size designator?

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3. What does DN80 indicate?

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What is PN in Pipes

  1. NPS or Nominal pipe size is also a dimensionless pipe size designator.
  2. A specific pipe size is indicated by NPS followed by a number. For example, NPS 2 indicates a pipe having an outside diameter of 2.375 inches.
  3. The pipe outside diameter is more than its NPS designator for NPS 12 and smaller pipes. However, NPS 14 and larger pipes have the same pipe OD in inches as the NPS designator. This means an NPS 24 pipe has an OD of 24 inches.

Attempt Questions on DN & NPS

DN vs NPS Quiz

1. What does DN indicate for pipe dimensions?

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2. How is DN calculated for pipes larger than NPS 3.5?

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3. What does NPS indicate for pipe dimensions?

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DN vs NPS

  • So, the main difference between DN and NPS is that DN indicates the approximate pipe dimensions in mm whereas the NPS indicates the pipe dimension in inches.
  • For pipes larger than NPS 3.5, the DN number is calculated by multiplying the NPS size designation number by 25. For example, NPS 4 is the same as DN 100.

FAQs

  • What is DN (Nominal Diameter) in pipes? DN, or Nominal Diameter, is a numeric designation used to indicate the approximate internal diameter of pipes. It is standardized and commonly used in Europe and other parts of the world.

  • What is NPS (Nominal Pipe Size) and how does it differ from DN? NPS, or Nominal Pipe Size, is a North American standard that specifies the nominal size of the pipe based on its approximate inside diameter. It is expressed in inches, unlike DN which is often metric-based.

  • How are DN and NPS related? While both DN and NPS serve similar purposes of indicating pipe size, they are based on different measurement systems (metric vs. imperial). Conversion tables are available to equate DN to NPS and vice versa.

  • What does PN (Pressure Nominal) indicate in piping? PN, or Pressure Nominal, refers to the nominal pressure rating of a pipe or fitting. It indicates the maximum allowable operating pressure at a given temperature.

  • How is PN different from pressure ratings like ANSI class ratings? PN and ANSI class ratings serve similar functions but are based on different standards. PN is typically used in European and international systems, while ANSI class ratings are common in North America.

  • How do DN and PN influence pipe selection? DN influences the physical size of the pipe, affecting flow capacity and installation requirements, while PN determines the pressure rating, affecting the suitability of the pipe for different applications.

  • What are the common DN sizes used in piping? Common DN sizes range from DN 15 (0.5 inches) to DN 1200 (48 inches) or larger, depending on the application and industry standards.

  • How are PN ratings designated and what do they signify? PN ratings are designated by a number which represents the pressure rating in bars at 20°C. For example, PN 16 indicates a maximum pressure of 16 bar at 20°C.

  • Can NPS be converted to DN and vice versa? Yes, conversion tables exist to convert NPS to DN and DN to NPS. These conversions are useful in international projects or when dealing with equipment and standards from different regions.

  • What considerations are important when selecting pipes based on DN and PN? When selecting pipes, consider factors such as fluid type, temperature, pressure requirements, material compatibility, and standards compliance to ensure safety and efficiency in operations.

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