The Contrec 515 GN05 is a reliable natural gas flow computer designed for measuring the volume, mass, and gross heat content of natural gas. This advanced instrument utilizes single or stacked differential pressure inputs, along with temperature and pressure sensor inputs, to provide accurate flow measurements.
This natural gas flow computer performs flow calculations based on the AGA-3 differential pressure equations. It takes into account the calibration conditions of the flowmeter and accurately adjusts for thermal expansion effects, ensuring precise results.
To achieve accurate density and compressibility factors for flow calculations, the AGA-8 Detail Characterization Method is employed. For other gas properties, such as viscosity and isentropic exponent, the recommended values from AGA-3 are utilized.
CALCULATIONS
The calculations for gas density and compressibility factors are based on the AGA-8 equations, which are valid within the following conditions:
-130°C < t < 400°C P < 280MPa
-200°F < t < 760°F P < 40000psia
FORMULAS
Volume flow = Mflow / ρflow
Corrected flow = Mflow / ρ ref
Heat flow = Mflow • Hm
Where:
Mflow = mass flow
ρflow = density at flow conditions
ρ ref = density at reference conditions
Hm = mass gross heating value
Displayed Information
The front panel display provides real-time values of input variables and the results of the calculations. A comprehensive list of these variables, along with their types (total or rate), is included at the end of this document.
The instrument can also be equipped with a real-time clock for logging over 1000 entries of the displayed variables.
Isolated Outputs
The opto-isolated outputs can retransmit any variable from the main menu. The output type depends on the assigned variable: totals are output as pulses, while rates are output as 4-20 mA signals. One output is standard, with an additional output available as an option.
Relay Outputs
Relay alarms can be configured for any of the main menu variables of a rate type. These alarms are fully customizable, including hysteresis settings. The standard configuration includes two relays, with an option for two additional relays. All setup parameters, totals, and logged data are stored in non-volatile memory, ensuring at least 30 years of data retention.
Software Configuration
The instrument can be customized to meet specific application needs, including measurement units, custom tags, additional languages, or access levels. A distributor can configure these options before delivery.
Instrument parameters, including measurement units, can also be programmed in the field based on user access levels assigned by the distributor.
Temperature and Pressure Input Types
Temperature sensor inputs can be PT100, PT500, or signals of 4-20 mA, 0-5 V, or 1-5 V. Pressure sensor inputs can also be 4-20 mA, 0-5 V, or 1-5 V signals.
