Quarter-circle orifice plate

Quarter-circle orifice plate

Recommended for viscous fluids


  • Standard: ISO / TR 15377.
  • Mounting between flanges: ISO PN 2,5 to PN 420, ASME 150 # to 2500 #, others on consultation.
  • Material: Standard: 304L / 316L stainless steel, others according to your application.
  • Fluid: liquid, gas, steam.
  • Diameter of pipes: from 25 to 500 mm.
  • Accuracy: 2% of max flow.
  • Repeatability of the measurement: 0.1%.
  • Pressure taps: in the corners, at the flange.
ISO/TR 15377
ReD Reynolds number in pipework 250 ≤ ReD ≤ 6.104
D Pipe interior diameter 25 mm ≤ D < 500 mm
d Orifice diameter d > 15 mm
β d/D 0,245 ≤ β ≤ 0,6
Ra Upstream face roughness Ra < 10⁴.d
r Quarter circle radius 0,100.d ≤ r ≤ 0,207.d
e Quarter circle hole thickness 2,5 mm ≤ e ≤ 0,1.D
E Plate thickness E ≥ r
α Downstream bevel angle if necessary α = 45° 
t Flatness tolerance Nous consulter

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

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When to use a quarter circle orifice plate?

A quarter-circle orifice plate has a rounded entrance (a bit like a nozzle). It therefore accepts more or less dirty and aggressive fluids since its input radius does not deteriorate. However, for a very aggressive or corrosive fluid, we recommend to apply a resistant coating (deposit of stellite or ceramic projection).

Moreover, it accepts fluids with a low Reynolds number (up to 250) so it is suitable for the measurement of viscous fluids.

To understand and choose from the different orifice plates, refer to the selection table.