Type a line (100 m3/h DN100 Sch 40, 400 l/min 2" Sch 80, 50 m3/h ID 80 mm, 100 m3/h 2 m/s) or fill in the fields: the line and the fields stay in step.
Enter the flow rate (m3/h, l/min, l/s, US gpm or Imp gpm) and the pipe: a size with its schedule (DN100 Sch 40, 2" Sch 80), an outside diameter with the wall, or the inside diameter. The calculator gives the inside diameter used, the flow area and the mean velocity in m/s and ft/s, shows the working with your numbers and draws the section to scale. Enter a velocity as well, and it gives the smallest inside diameter for it and the smallest ASME pipes that keep the velocity at or below it.
This is geometry and unit conversion: v = Q / A. It gives no recommended or limiting velocities, no pressure loss and no pump sizing; the velocity a system is designed for is set by its designer or by class rules. The pipe outside diameters and ASME walls come from the pipe size identifier on this site, where two published tables agree on them.
For a standard pipe it is the outside diameter less two nominal walls: for DN100 Sch 40, 114.3 - 2 x 6.02 = 102.26 mm. A real wall differs within the mill tolerance, and scale or a lining makes the inside smaller: when it matters, measure it and enter it.
A = 3.1416 x D x D / 4. For 102.26 mm it is 8213 mm2, or 0.008213 m2.
v = Q / A, with Q in m3/s: 100 m3/h is 0.02778 m3/s, which gives 3.38 m/s in DN100 Sch 40. The reverse: D = square root of (4 x Q / (3.1416 x v)); for 100 m3/h at 2 m/s it is 133.0 mm.
| Size | Outside diameter, mm | Sch 10, mm | Sch 40, mm | Sch 80, mm | Sch 160, mm | XXS, mm |
|---|---|---|---|---|---|---|
| DN15 / NPS 1/2 | 21.3 | 17.08 | 15.76 | 13.84 | 11.74 | 6.36 |
| DN20 / NPS 3/4 | 26.7 | 22.48 | 20.96 | 18.88 | 15.58 | 11.06 |
| DN25 / NPS 1 | 33.4 | 27.86 | 26.64 | 24.3 | 20.7 | 15.22 |
| DN32 / NPS 1 1/4 | 42.2 | 36.66 | 35.08 | 32.5 | 29.5 | 22.8 |
| DN40 / NPS 1 1/2 | 48.3 | 42.76 | 40.94 | 38.14 | 34.02 | 27.98 |
| DN50 / NPS 2 | 60.3 | 54.76 | 52.48 | 49.22 | 42.82 | 38.16 |
| DN65 / NPS 2 1/2 | 73.0 | 66.9 | 62.68 | 58.98 | 53.94 | 44.96 |
| DN80 / NPS 3 | 88.9 | 82.8 | 77.92 | 73.66 | 66.64 | 58.42 |
| DN90 / NPS 3 1/2 | 101.6 | 95.5 | 90.12 | 85.44 | — | 69.3 |
| DN100 / NPS 4 | 114.3 | 108.2 | 102.26 | 97.18 | 87.32 | 80.06 |
| DN125 / NPS 5 | 141.3 | 134.5 | 128.2 | 122.24 | 109.54 | 103.2 |
| DN150 / NPS 6 | 168.3 | 161.5 | 154.08 | 146.36 | 131.78 | 124.4 |
A dash: NPS 3 1/2 has no Sch 160. At these sizes Sch 10 is also the 10S wall, Sch 40 the STD wall and Sch 80 the XS wall. EN 10220 and JIS G3452 (SGP) walls are not in this data: for such a pipe, enter the wall or the inside diameter. Units: 1 in = 25.4 mm, 1 ft = 0.3048 m, 1 US gallon = 3.785411784 l and 1 Imperial gallon = 4.54609 l, all exact by definition.
Outside diameters and ASME walls: the data of the pipe size identifier on this site, from the EN 10220, ASME B36.10 and JIS G3452 tables of pipe makers and standards references, kept where two agree; the ASME walls from two published schedule tables that agree to within 0.03 mm. Units: the international inch and foot of 1959, the US gallon of 231 cubic inches and the Imperial gallon, as national measurement institutes list them.
About 3.38 m/s, or 11.10 ft/s. The inside diameter is 114.3 - 2 x 6.02 = 102.26 mm, the flow area 0.008213 m2, and 100 m3/h is 0.02778 m3/s: v = Q / A = 0.02778 / 0.008213 = 3.38 m/s.
For an ASME pipe, the outside diameter less two nominal walls of the schedule, from ASME B36.10. For an EN 10220 or JIS pipe, the outside diameter of the standard less two walls you enter. Or the inside diameter you enter. A real pipe can differ: the wall varies within the mill tolerance, and scale, deposits or a lining make the inside smaller.
This page does not say. The velocity a system is designed for is set by its designer or by class rules. The calculator gives only the geometry: the velocity for a flow rate and an inside diameter, or the smallest inside diameter for a velocity you enter.
By exact definitions: 1 US gallon = 3.785411784 l, 1 Imperial gallon = 4.54609 l, 1 in = 25.4 mm and 1 ft = 0.3048 m; gpm is gallons per minute. So 1 US gpm is about 0.2271 m3/h and 1 Imp gpm about 0.2728 m3/h. A bare gpm is read as US gpm.
The pipe size and schedule or wall (DN100 Sch 40, or OD 114.3 mm, wall 6.02 mm), the standard, the material, the length or number of lengths, the ends and a photograph of the pipe marking. The flow rate and the velocity worked out here show the supplier what the pipe is for.
The calculator works from nominal sizes and the figures you enter. Attach a photograph of the pipe marking or the certificate, and Vessel Core checks the size, schedule and material before an offer goes back.
