| Inch | DN | ISO rör | Metric rör | ANSI rör |
|---|---|---|---|---|
| mm | mm | mm | ||
| 1/4 | 8 | 13.5 | 13.72 | |
| 3/8 | 10 | 17.2 | 17.15 | |
| 1/2 | 15 | 21.3 | 21.34 | |
| 3/4 | 20 | 26.9 | 26.67 | |
| 1 | 25 | 33.7 | 33.40 | |
| 1 1/4 | 32 | 42.4 | 42.16 | |
| 1 1/2 | 40 | 48.3 | 48.26 | |
| 2 | 50 | 60.3 | 60.33 | |
| 2 1/2 | 65 | 76.1 | 73.03 | |
| 3 | 80 | 88.9 | 80 | 88.90 |
| 4 | 100 | 114.3 | 100 | 114.30 |
| 5 | 125 | 139.7 | 125 | 141.30 |
| 6 | 150 | 168.3 | 150 | 168.28 |
| 8 | 200 | 219.1 | 200 | 219.08 |
| 10 | 250 | 273.0 | 250 | 273.00 |
| 12 | 300 | 323.9 | 300 | 323.90 |
| 14 | 350 | 355.6 | 350 | 355.60 |
| 16 | 400 | 406.4 | 400 | 406.40 |
Tum is an older unit of length that is still used in some area such as pipe diameter. The origin of an inch is equivalent to the length of a man's thumb, measured from the first knuckle of the thumb to the uttermost. This fact means that this is a measure that can vary between countries, making it an inappropriate entity to use internationally.
The DN is the European standard unit of measurement for pipe diameters.
The measure refers to the dimensions of the pipe, the estate built inside the pipe.
The measure refers to the internal dimension of the pipe, the goods are based outside of the pipe.
The measure refers to the dimensions of the pipe, the estate built inside the pipe.
ANSI (American National Standards Institute) is the American standard dimensions. The difference from the ISO standard pipe is insignificant and is covered in most cases within the pipe tolerances.