Contrec 515 – GN04

Natural Gas Flow Computer (AGA - 8) -DP Meter (ISO/Cone)

The 515 GN04 Natural Gas Flow Computer measures the volume, mass and gross heat content of natural gas.

The instrument uses single or stacked differential pressure meters such as orifice plates, nozzles, venturi tubes or V-Cones as well as temperature and pressure sensor inputs.

This natural gas flow computer calculates the flow according to generic differential pressure equations for the ISO 5167 or V-Cone meters. The flow calculations incorporate the conditions at which the flowmeter was calibrated and accurately account for thermal expansion effect.

The AGA-8 Detail Characterization Method is used to obtain accurate values of density and compressibility factors for the flow calculations.


The gas density and compressibility factor calculations are based on the AGA-8 equations. The calculations are valid for the region:

-130°C < t < 400°C P < 280MPa

-200°F < t < 760°F P < 40000psia


volume flow =Mflow/ρflow

corrected flow = Mflow/ρ ref

Heat flow = Mflow•Hm


Mflow = mass flow

ρflow = density at flow conditions

ρ ref = density at reference conditions

Hm = mass gross heating value