Teledyne 7300A manual Output Signal Offset, Polarity Reversal

Infrared Gas Analyzer Operation 4

tivity 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.

4.9.1.2Output 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% CO2 in nitrogen, normally zero gas of this application requires 40% CO2 in nitrogen. However, 100% of nitrogen can be used to zero the analyzer. In this case, the output offset is not needed to setup. For linear output the accuracy will access success- fully within +/-1% off. But, if the application is analyzing the sample gas that is not linearly, the accuracy of the analyzer may not meet the specification. There- fore, output offset is required and 40% CO2 in nitrogen is also needed for zero calibrationgas.

To set up the output reversal or output offset, see section 4.8.1-set AP- PLICATION sceen.

NOTE: If the inverting has been setup, “i” shall display on the left bottom corner. Otherwise, the left bottom corner display ”n”.

NOTE: In the example 40% CO2 in N2 is discouraged, because it is hard to produce the exact concentration.

4.9.2 Polarity Reversal

In some special applications, user will find that the display dispalys negative concentration values, even if proper span gas is injected. To correct this problem, TAI has added the Polarity Correction feature. This feature can be set asfollow:

Close S1-5 range 1

Close S1-6 range 2

Close S1-7 range 3

Close S1-8 cal range

Teledyne Analytical Instruments 4-33