Calibration Sequence blocks

The Calibration Sequence supports the automated zero calibration of LI-COR Trace Gas Analyzers and analyzers from other manufacturers. This is essential when using the LI-7825 CO2 Isotope/NH3 Trace Gas Analyzer, but may also be useful with other gas analyzers.

The calibration is configured in two parts: A Calibration Sequence, which controls the sequence and timing, and a Calibration Manifold block that is added to the Multiplexer block. The Calibration Sequence is always part of the Configuration workspace (if you don't use it, just ignore it). The Calibration Manifold block is added under the LI-8250 Multiplexer block to establish communication between the 8250-02 Calibration Manifold and the LI-8250.

When configured, the Calibration Sequence will pause a measurement sequence, flow a zero gas through one or more gas analyzers, adjust the zero, and then resume the measurement sequence. The software allow you to schedule the zero adjustment, specify which analyzers to zero, and set other related parameters. The Calibration Sequence block uses instrument time of 00:00 [hh:mm] as the start time for calibration delays.

  • Displays: The start time for the calibration sequence.
  • Fits into: As a root block, the Calibration Sequence block does not fit into any other blocks.
  • Accepts: Calibration Delay block (optional) with time and Open Cal Port # block with the port # as a configurable setting.
  • Requires: The sampling sequence requires the Execute Zero On block.

Calibration Delay block

The optional Calibration Delay is useful if you want to specify the time of day for the calibration. Typically, the calibration should be carried out at a time when the measurements are not critical because measurements are stopped during the calibration. The Duration is configurable - enter the number of hours to wait.

Open Cal Port #

Specifies which port on the 8250-02 Calibration Manifold should be opened to deliver the calibration gas (this is the port that the tank is connected to). Options are 1 to 4.

Execute Zero On

A display block that shows how long the calibration is expected to take. The Estimated Duration [hh:mm] is a fixed in the software. It is the maximum time allowed for the calibration. It is set to 30 minutes or 60 minutes, depending on the gas analyzer.

Gas Analyzer

To specify the gas analyzer to adjust. Select one from the list. The interface will display the calibration time, which is not adjustable. Only one gas analyzer can be selected, but multiple gas analyzer blocks can be added. You can select LI-COR Trace Gas Analyzers or Generic for a gas analyzer from another manufacturer.

Calibration Manifold blocks

This block represents the hardware - the 8250-02 Calibration Manifold.

  • Displays: The serial number and firmware of the 8250-02 Calibration Manifold..
  • Fits into: LI-8250 block.
  • Accepts: Cal port # block.
  • Requires: All nested blocks must be present and configured.

Cal Port # Block

Allows you to select the Cal Port # to open. Features a free-entry description field for notes.

  • Displays: The Cal Port # that is selected.
  • Fits into: Calibration Manifold block.
  • Accepts: Calibration Gas block.
  • Requires: One or more calibration gas blocks.

CO2 Gas, CH4 Gas blocks

Parameters of the calibration gas. For zero gases, the concentration is zero. For CO2 isotopologues, enter the permil (‰) concentration of δ13C, δ17O, and δ18O in the fields.