Teledyne 2020 - Explosion proof thermal conductivity analyzer - Manual (Page 63)

Thermal Conductivity Analyzer Operation 4
4-29 Teledyne Analytical Instruments
6. Repeat step 5 for each of the special calibration gases, from the
lowest to the highest concentrations. Escape when done.
To end the session, send:
st
st
to the analyzer from the computer.
4.9 Special Function Setup
CAUTION: The programming functions of the output signal
reversal, polarity reversal and gain preset are con-
figured at the factory to the users application speci-
fication. These functions should only be repro-
grammed by trained, qualified personnel.
4.9.1 OFFSET OUTPUT/Reversal Output
4.9.1.1 Output Signal Reversal
Some applications require a reversal of the output signals in order
for the 4-20mA and 0-1 V DC output signals to correspond with the low
and high end of the concentration range. For example, if an application
involves the analysis of 85-100% oxygen in a background of argon by
measuring the thermal conductivity of the binary gas, the analyzer would
normally be set up so that the 100% oxygen (0% argon) concentration
would correspond to the zero level (4mA 0 V) of the output signal. Then,
85% oxygen (15% argon) would correspond to 20mA (1 V) in the signal
output.
It may be convenient for the user to have the outputs reversed so that
the 85-100% oxygen level outputs a 4-20mA (0-1 V) signal respectively.
This can be accomplished by reversing the data input to the custom settings.
Not all applications will require a reversing function, however, if this is
desirable. This can be programmed by allowing the user to set the analyzer
to read reversal output. Contact the factory for further information.
4.9.1.2 Output Signal Offset
TAI has provided the output offset feature in the software for the
accuracy purpose. In many cases, the analyzer does not require this feature.
For exmple, if the analyzer has setup to analyze the sample gas of 40-50%