Contrec 515 – GN13

Natural Gas Flow Computer (SGERG) - DP Meter (Mass Span)

The 515 GN13 application measures the volume, mass and gross heat content of natural gas. The instrument uses single or stacked differential pressure mass flow inputs and analog temperature and pressure sensor inputs.

The instrument calculates the flow according to generic differential pressure equations and incorporates the conditions at which the flowmeter was calibrated.

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 SGERG (AGA-8 Gross) equations. The calculations are valid for the region:

-8.0°C < t < 62.0°C P < 12MPa

17°F < t < 143.0°F P < 1740psia


Mflow = volume flow• 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