Parsjahd Products - Restriction Orifice Plates

The purpose of the restriction orifice can be:

 - To reduce the flow rate
 - To create a pressure drop
 - To decrease temperature

The restriction orifice plates are some times placed downstream of a turbine meter to guard against over-spin. A restriction orifice is denoted by “RO” or “FO”.

When specifying a restriction orifice, plate thickness “E” should be large enough to keep the plate from deflection. As a rule, the maximum pressure drop across a single orifice for a gas is 50%. For greater drops, multistage orifices may be used.



  • 304/304L or 316/316L Stainless Steel; ASTM A240 (the most common)
  • Stainless Steel 316Ti; DIN 1.4571()
  • Hastelloy® C-276; ASTM B575
  • Copper
  • Cupronickle 30%
  • Aluminum bronze
  • K-Monel
  • Monel 400
  • Haynes Stellite 25
  • Yellow Brass