2 replies to this topic

[PTSHeng]

Good morning all,

I would like to know if orifice plates with pipe tappings are indeed restriction orifice plates due to the difference in nomenclature across different countries.

Nicholas

[fallah]

Nicholas,

 

The role of a RO (restriction orifice) is to limit the flow. FO (flow orifice) is a RO that has been sized to limit the flow a little bit just in order to flow measuring. Then it might be said that all FOs could be ROs but not all ROs could be FOs...

 

Therefore the difference is deeper than to be due to the difference in nomenclature...

Edited by fallah, 08 June 2013 - 12:59 AM.

[mansari]

Building on what Fallah has said, Ristriction Orifice (RO) is a device, installed to deliver a known flow for the prevailing pressure differential. For example, kickback flow from discharge of a centrifugal pump, back to suction tank to ensure operation of the pump at minimum flow at all times. Here the RO is sized based on pump required minimum flow and the pressure differential between pump discharge and suction tank. Tapping are not required for an RO

 

On the other hand, Flow Orifice (FO) is a device used for measurement of flow and operates at a pressure differential much lower than that of an RO. Typical pressure drop across a FO is in the range of 100-200 inches of H2O (4-7 psi). Here you need tappings to measure pressure differential for onward calculations of flow rate. Choice of flange or pipe taps is covered under orifice sizing subject