Teledyne gfc 7000ta Physical Range versus Analog Output Reporting Ranges, Reporting Range Modes

Operating Instructions Model GFC7000TA Carbon Dioxide Analyzer

6.8.1. Physical Range versus Analog Output Reporting Ranges

Functionally, the Gas Filter Correlation CO2 Analyzer has one hardware Physical Range that is capable of determining CO2 concentrations between 50 ppm and 2,000 ppm. This architecture improves reliability and accuracy by avoiding the need for extra, switchable, gain-amplification circuitry. Once properly calibrated, the analyzer’s front panel will accurately report concentrations along the entire span of its 50 ppm and 2,000 ppm physical range.

Because, most applications use only a small part of the analyzer’s physical range, the width of the Model GFC 7000TA’s physical range can create data resolution problems for most analog recording devices. For example, in an application where the expected concentration of CO2 is typically less than 500 ppm, the full scale of expected values is only 25% of the instrument’s 2,000 ppm physical range. Unmodified, the corresponding output signal would also be recorded across only 25% of the range of the recording device.

The GFC 7000TA solves this problem by allowing the user to select a scaled reporting range for the analog outputs that only includes that portion of the physical range relevant to the specific application. Only the reporting range of the analog outputs is scaled, the physical range of the analyzer and the readings displayed on the front panel remain unaltered.

6.8.2. Reporting Range Modes

The GFC 7000TA provides three analog output range modes to choose from.

∙Single range (SNGL) mode sets a single maximum range for the analog output. If single range is selected (See Section 6.78.3) both outputs are slaved together and will represent the same measurement span (e.g. 0-50 ppm), however their electronic signal levels may be configured for different ranges (e.g. 0-10 VDC vs. 0-.1 VDC – See Section 6.9.4.1).

Dual range (DUAL) allows the A1 and A2 outputs to be configured with different measurement spans (See Section 6.8.4) as well as separate electronic signal levels (See Section 6.9.4.1).

∙Auto range (AUTO) mode gives the analyzer to ability to output data via a low range and high range. When this mode is selected (See Section 6.8.5) the GFC 7000TA will automatically switch between the two ranges dynamically as the concentration value fluctuates.

Range status is also output via the external digital I/O status outputs (See Section 6.15.1.1).

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