Multiple Calibrations; Purge And Purge-Cycle The Sgm Device - Emerson Micro Motion SGM Series Configuration And Use Manual

5.2.5

Multiple calibrations

The SGM can store calibrations for up to four different process gases or ranges. Each
calibration is generated by an independent calibration procedure and contains an
independent set of calibration coefficients. This feature allows you to switch between
process gases or ranges without recalibrating the device.
If you plan to use more than one calibration:
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Important
It is possible to use a different control pressure for each calibration. If you do, change the control
pressure in the meter whenever you change the active calibration. If you do not change the control
pressure to match the active calibration, measurement accuracy will be affected.
Calibration ranges
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5.3

Purge and purge-cycle the SGM device

Purging the SGM device prepares it for calibration by ensuring that the reference chamber
is filled to the desired control pressure and that the reference gas is pure.
Prerequisites
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Configuration and Use Manual
Perform all calibrations using the same measurement option: specific gravity,
molecular weight, or relative density.
Set calibrations as either two-point calibrations or three-point calibrations.
Complete each calibration before beginning the next calibration.
Choose to add calibrations at a later time. You do not need to perform all
calibrations at the same time.
If you have a specific gravity meter, the meter will automatically calculate the
specific gravity output variable for all four ranges during operation.
If you have a molecular weight meter, the meter will automatically calculate the
molecular weight output variable for all four ranges during operation.
If you have a relative density meter, only one calibration is applied at a time. A
control selects the active calibration.
For specific gravity and molecular weight meters — energy, energy flow,
compressibility, and Wobbe index are calculated only from the active calibration.
Gas purity is automatically calculated for the associated calibration (for example,
Gas Purity Concentration for curve 4 automatically uses calibration range 4).
Damping is applied only to the active variable.
You must be able to flow process gas through the device.
You must know the working pressure of your system and the desired control
pressure (the pressure to be used in the reference chamber).
Purging and calibration
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