C280 – ISO 5167 Orifice Plate Calculations


This calculation can be set to calculate the flow rate through an orifice plate metering system, the differential pressure setting of the metering system or the orifice size to use for specified flowing conditions according to the ISO 5167 standard.


ISO 5167 – Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full

ISO TR9464 – Guidelines for the use of ISO 5167

ISO TR15377: Measurement of fluid flow by means of pressure differential devices – Guidelines for the specification of orifice plates, nozzles and venturi tubes beyond the scope of ISO 5167

BS 1042: Part 1. Pressure differential devices – Section 1.2 Specification for square-edged orifice plates and nozzles (with drain holes, in pipes below 50mm diameter, as inlet and outlet devices) and other orifice plates and Borda inlets (1984)

Kelton calculation reference C280

KIMS calculation reference K215

Kelton calculation reference C270 – ISO 5167 Orifice Mass Flow Calculation

Kelton calculation reference C273 – ISO 5167 Differential Pressure Calculations

Kelton calculation reference C274 – ISO 5167 Sizing Calculation

Kelton calculation reference C261 – Gas Flowrate Conversion from Qm

Kelton calculation reference C262 – Liquid Flowrate Conversion


Solve for

  • Flow Rate
  • Orifice Size
  • Differential Pressure

This option is used to select what kind of calculation the user wishes to implement.

The rest of the options that can be encountered in this calculation can be found in the calculations referenced above.


Mass Flow Rate

The mass flow rate is calculated using the formula shown in C270. Further flow rate outputs, if required, are calculated using one of the flow rate converters using this value of mass flow rate.

Orifice Size

The orifice size is calculated according to the process described in C274.

Differential Pressure

The differential pressure is solved as described in C273.



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