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CO2 Flow Module

CO2 Flow DIN rail mounted processor (prelim.)Flow Module: CO2 Flow DIN rail mounted processor (prelim.)

Automation and Electronics, Inc. has developed a CO2 flow module that uses turbine meter and NIST 14 (National Institute of Standards and Technology) to calculate flow rate and totals that are accessible via MODBUS registers. Density is calculated for a Hydrocarbon mixture of up to 17 pure compounds with an emphasis on CO2 rich mixtures as a function of temperature and pressure. The PLC transfers the flow temperature and pressure to the module and reads back the flow rate and totals.


Automation and Electronics, Inc. developed the embedded NIST 14 Density Calculation based on the NIST 14 Mixture Property Database which is an interactive program written in standard FORTRAN 77. The original purpose of this interactive database program was to provide accurate calculations of the density, phase equilibrium, enthalpy, entropy, heat capacity and sound velocity for mixtures composed of a variety of well studied fluids. Our implementation of NIST 14 is used to calculate only the density of the CO2 rich mixture for use in the flow calculation.


Our NIST module...

  • has a customer supplied default injection mixture for use until overwritten by a new mixture downloaded from the PLC or laptop computer.
  • calculates the density of a mixture in a super-critical state. This does not have to be in a gaseous state, which is a requirement for some flow calculations.
  • calculates a standard density for the given mixture at 60 Degrees Fahrenheit and 14.696 PSIA. This calculation is performed whenever the mixture changes.
  • analyzes mixtures formed from any of the 17 pure compounds listed (including Hydrocarbons, Nitrogen, Oxygen, Argon, Carbon Monoxide, Carbon Dioxide, and Hydrogen Sulfide).
    CH4 C1: Methane
    C2H4 C2-: Ethylene
    C2H6 C2: Ethane
    C3H8 C3: Propane
    C4H10 C4: Butane
    C4H10 IC4: Iso-Butane
    C5H12 C5: Pentane
    C5H12 IC5: Iso-Pentane
    C6H14 C6: Hexane
    C6H14 IC6: Iso-Hexane
    C7H16 C7: Heptane
    Ar Argon
    O2 Oxygen
    N2 Nitrogen
    CO Carbon Monoxide
    CO2 Carbon Dioxide
    H2S Hydrogen Sulfide

Technical Specifications

  • Direct turbine meter input
  • Dry contact pulse output
  • RS-232/RS485 serial communications port
  • MODBUS communications protocol
  • Fast density calculation (typically less than one second, varies depending on mixture)
  • Low power ( < 100 mA)
  • Operates on 9-30 VDC
  • DIN Rail mount

This product brief contains preliminary information.