Multi-hole restriction orifice

Multi-hole restriction orifice

Suitable for reducing noise when passing the orifice


  • Standards: Element based on ISO 5167, ASME MFC-3M or R.W. MILLER.
  • 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: all sizes.
  • Orifices: dimensioned according to the fluid, the pressure drop or the flow to be achieved going through the restriction.
  • Plate thickness: calculated taking into account the pressure drop generated by the plate and the diameter of the pipework in order to avoid a deformation of the plate. For more details, see our Frequently Asked Questions.
  • Noise: the number of orifices is determined according to the level of noise not to be exceeded.
    The maximum noise level depends on the operating conditions: limited to 85 dB(A) by the regulatory body for an average daily exposure in continuous operation. Intermittent or emergency operation - acceptable upper values ​​(see corresponding regulations).
    If the noise level is still too high, it is possible to switch to a multi-stage restriction orifice.
  • Cavitation: the cavitation level is checked for each plate and the orifices are calculated to avoid cavitation. For more information on cavitation, see our Frequently Asked Questions.
  • Critical flow or choked flow: the orifices are calculated at the critical flow limit for a maximum pressure drop. For more information on critical flow, see our Frequently Asked Questions.
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.

In which case does a multi-hole restriction orifice is used?

The fluid passing a restriction is accelerated and this can cause an increase in sound level. Multiplying the number of holes in the plate can significantly reduce noise.

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