Venturi as cast

For a better precision


  • Standards: ISO 5167-1 & 4, ASME MFC-3M.
  • Solder (BW) or flanged connection
  • Material: Standard: carbon steel, stainless steel, others according to your application.
  • Fluid: liquid, gas, steam.
  • Diameter of pipes: from 100 to 1,200 mm.
  • Accuracy: 0.7% of max flow.
  • Repeatability of the measurement: 0.1%.
  • Upstream and neck pressure points: annular chamber or individual plugs connected in "triple T".

ISO 5167-1&4 ASME MFC-3M
ReD Reynolds number in pipework 2.105 ≤ ReD ≤ 2.106 2.105 ≤ ReD ≤ 6.106
D Pipe interior diameter    100 mm ≤ D ≤ 800 mm 100 mm ≤ D ≤ 1 200 mm
β d/D 0,30 ≤ β ≤ 0,75
Ra Roughness at the throat Ra ≤ 10⁴.d
Roughness input and convergent cylinder Ra ≤ 10⁴.D
l Minimum inlet cylinder length l = D ou (0,25.D + 250 mm)
l' Convergent input length l' = 2,7.(D - d)
α Convergent angle of entry α = 21° ± 1°
lc Throat length lc = d ± 0,03.d (minimum value = d/3)
R1 Radius of curvature 1 between the input cylinder and the convergent  R1 = 1,375.D ± 0,275.D
R2 Radius of curvature 2 between the convergent and the throat R2 = 3,625.d ± 0,125.d
R3 Radius of curvature 3 between the throat and the divergent 5.d < R3 < 15.d
φ Diverging angle of exit 7° ≤ φ ≤ 15°

You can find below our most frequently asked questions / answers.

If you do not find the answer you are looking for, please contact us either by phone at +33 (0) or via the contact form. We will respond as soon as possible.

When to choose a venturi tube "as cast"?

A venturi tube "as cast" is the least used model in favor of machined or rolled-welded venturi. However, there are cases and especially when it comes to seeking a measuring accuracy of the order of 1% for diameters greater than DN250 and up to DN800 mm where it should be used.

What about the venturi "as cast" with machined convergent?

The convergent of a venturi "as cast" is normally poured into a sand mold to obtain an ideal surface finish and the intersections between the cylinder and the cones are rounded. It is thus possible to obtain a measurement accuracy of about 0.7% of the maximum flow rate. However, for reasons of quantity (the molds are generally made for large series), we often realize venturis "as cast" with a machined convergent. The measurement accuracy obtained is then of the order of 1% of the max flow.