Rudjer Boskovic Institute
International standards for flow measurements - active network objects


ISO-5167 calculations
ISO -5167 online calculations are in accordance with:

ISO-5167/2003-03-01: Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full -
  Part1: General principles and requirements
  Part2: Orifice plates
  Part3: Nozzles and Venturi nozzles
  Part4: Venturi tubes
ISO-5167 specifies the geometry and method of use of the primary devices (pressure differential devices) when they are inserted in a conduit running full to determine the flowrate of the fluid in the conduit. ISO-5167 considers single-phase fluids only and supposes subsonic and non-pulsating flow throughout the measuring section. The following are the differential devices covered by ISO-5167:
  1. Orifice with flange tappings
  2. Orifice with corner tappings
  3. Orifice with D and D/2 tappings
  4. Classical Venturi tube with a machined inlet
  5. Classical Venturi tube with a rough cast inlet
  6. Classical Venturi tube with a rough-welded sheet-iron inlet
  7. Long radius nozzle
  8. ISA 1932 nozzle
  9. Venturi nozzle (ISA inlet)
ISO-5167 details the following calculations:
  1. Flow-rate calculation
  2. Differential pressure calculation
  3. Orifice diameter calculation
  4. Pipe diameter calculation
ISO-5167 also specifies an 'upstream' and 'downstream' pressure measurements for gaseous fluids and for liquids. We used PHP a general-purpose scripting language and our COM object 'iso5167' to implement the ISO-5167 interactive flow-rate calculations for all nine differential devices using either upstream or downstream pressure measurements. In each calculation a user can choose the corresponding flow measurement options and conditions. To enter the calculation click on the corresponding left side link.

International standards for flow measurements - active network objects
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