Configure Gas Compressibility Measurement Using Prolink Iii - Emerson Micro Motion SGM Configuration And Use Manual

Configuration and Use Manual
MMI-20020954
7.4 Configure gas compressibility measurement using
ProLink III
ProLink III Device Tools → Configuration → Process Measurement → Compressibility
Gas compressibility measurement is required for the following process variables: line density, calorific value,
Wobbe index, and energy flow. Gas compressibility measurement can also be used to calculate
compressibility as an independent process variable.
Prerequisites
• You must know whether you will measure line compressibility and base compressibility or you will use
fixed values.
• If you will use fixed values, you must know the line compressibility and base compressibility values for your
application.
• If you will measure compressibility, you must be able to supply gas composition data to the meter, for the
following constituents:
— Carbon dioxide (CO2)
— Nitrogen (N2)
— Hydrogen (H2) (required only if you plan to measure compressibility according to SGERG 88)
• Gas composition must be measured in % by volume.
• If you plan to poll an external device for % CO2, % N2, or % H2, ensure that the meter has the required
polling slots available. The meter provides four polling slots, and they may be already in use. You may need
to use a fixed value or digital communications for some external values. To check the current polling
configuration, choose Device Tools → Configuration → Polled Variables.
Procedure
1. Choose Device Tools → Configuration → Process Measurement → Compressibility.
2. Set Compressibility Calculations as desired, and click Apply.
Option Description
Disabled The meter will not calculate compressibility. You must enter fixed values for line
compressibility and base compressibility.
Enabled The meter will calculate line compressibility and base compressibility. You must provide
gas composition data.
3. If you set Compressibility Calculations to Disabled:
a) Set Line Compressibility to the compressibility of your sample gas at line temperature and line
pressure.
The default value is 0. The range is 0.7 to 1.1.
b) Set Base Compressibility to the compressibility of your sample gas at base temperature and
base pressure.
Configuration and Use Manual
Configure process measurement using ProLink III
March 2021
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