CONVERSION TABLE

DN = NPS
DN
(Diameter Nominal)
Milimeters
NPS
(Nominal Pipe Size)
Inches
61/8
81/4
103/8
151/2
203/4
251
321 1/4
401 1/2
502
652 1/2
803
903 1/2
DN
(Diameter Nominal)
Milimeters
NPS
(Nominal Pipe Size)
Inches
1004
1154 1/2
1255
1506
2008
25010
30012
35014
40016
45018
50020
60024
DN
(Diameter Nominal)
Milimeters
NPS
(Nominal Pipe Size)
Inches
70028
80032
90036
100040
105042
110044
120048
130052
140056
150060
160064
170068
DN
(Diameter Nominal)
Milimeters
NPS
(Nominal Pipe Size)
Inches
180072
190076
200080
220088
240096
2600104
2800112
3000120
3200128
3400134
3600142
3800150

Diameters in DN or in NPS

From within the industrial market we find these two systems to size the diameters for pipes, tubes, valve connections and other devices:

  • Nominal pipe size (NPS) , defined by the American standard ANSI / ASME is based on inches .
  • Nominal diameter (DN) , defined by the European standard ISO 6708 is based on millimeters .

We know that to determine the conversion operation from one value to another, we should only perform a simple simple mathematical formula (the value of a inch is 25.4 millimeters and that of 1 millimeter 0.0393701 inches); however we could not apply it to determine these values ​​because each system uses a commercial measure that does not correspond with the real value of the outside diameter of the pipe but with the inside of it. We observe a difference of 0.4 millimeters in the value DN 25 while in larger sizes the difference is even greater , for example: 120 inches is actually 3048 millimeters, 48 ​​millimeters more than the DN 3000 value.

In order to make things easier for you, you have above a conversion table so that you can determine the equivalent value of each measure .

 

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