Teledyne 2020 - Explosion proof thermal conductivity analyzer - Manual (Page 55)

Thermal Conductivity Analyzer Operation 4
4-21 Teledyne Analytical Instruments
automatically shifts to the next higher range. If the concentration falls to
below 85% of full scale of the next lower range, the instrument switches to
the lower range. A corresponding shift in the DC concentration output, and
in the range ID outputs, will be noticed.
The autoranging feature can be overridden so that analog output stays
on a fixed range regardless of the contaminant concentration detected. If the
concentration exceeds the upper limit of the range, the DC output will
saturate at 1 V dc (20 mA at the current output).
However, the digital readout and the RS-232 output of the concentra-
tion are unaffected by the fixed range. They continue to read beyond the
full-scale setting until amplifier saturation is reached. Below amplifier
saturation, the over range readings are accurate UNLESS the application
uses linearization over the selected range.
The concentration ranges can be redefined using the Range function
Manual screen, and the application gases can be redefined using the APPLI-
CATION function, if they are not already defined as necessary.
CAUTION: Redefining applications or ranges might require re-
linearization and/or recalibration.
To setup automatic ranging:
Select range on the MAIN MENU, and ENTER to start the Range
function.
Select range
mode : AUTO
Note: If all three ranges are currently defined for different applica-
tion gases, then the above screen does not display (because
mode must be manual).
If above screen displays, use the UP/DOWN key to Select
AUTO, and
Enter.
Press Escape to return to the previous Analyze Function.