Section 5: Calibration
5.1 Section contents
Overview .......................................................................................................................page 65
Fully Automatic Calibration ...........................................................................................page 65
Operator - Initiated Autocalibration ...............................................................................page 66
Manual Calibration ........................................................................................................page 67
D/A Trim Procedures - LOI .............................................................................................page 75
D/A Trim Procedures - HART ..........................................................................................page 77
5.2 Overview
During a calibration, two calibration gases with known O
2
concentrations and one calibration
gas with a known COe concentration are applied to the Hazardous Area OCX 8800. Slope and
constant values are calculated to determine if the Hazardous Area OCX 8800 is correctly
measuring net concentrations of O
2
and combustibles in the industrial process.
Before calibrating the Hazardous Area OCX 8800, verify that the calibration gas parameters are
correct by setting the test gas values used when calibrating the unit. Refer to Section 3,
Configuration and Startup.
There are three calibration methods available to the Hazardous Area OCX 8800; automatic,
operator-initiated automatic, and manual. Calibration commands and menus can be accessed
by 375 Field Communicator or by the optional LOI.
5.3 Fully Automatic Calibration
If the Hazardous Area OCX 8800 is equipped with calibration solenoids, the unit can be
programmed to automatically calibrate without any operator action. Refer to the following
paragraphs for using the LOI or 375 Field Communicator to set up the OCX 8800 for fully
automatic calibration.
5.3.1 Autocalibration Setup using HART
NOTE:
Automatic calibration is only available on units equipped with calibration solenoids.
Use the following procedure to specify a time interval (in hours) at which the OCX 8800 will
automatically calibrate.
1. From the DEVICE SETUP screen, select DETAILED SETUP.
2. From the DETAILED SETUP screen, select O2 CALIB PARAMS or COE CALIB PARAMS.
3. If the unit is equipped with calibration solenoids and timed automatic calibrations are
desired, select Solenoids, then select Yes. Select No to disable the calibration solenoids.
4. Select O2 CalIntrvl (O2 calibration interval) and enter the desired time in hours
between automatic O2 calibrations. Select COE Callintrvl and enter the desired time
Section contents 65
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