What's new in LI-8250 firmware v2.1.10?

LI-8250 Multiplexer embedded firmware version 2.1.10 adds support for the 8250-02 Calibration Manifold and the LI-7825 CO2 Isotope/NH3 Trace Gas Analyzer. The 8250-02 Calibration Manifold is an accessory that automatically adjust the baseline readings of the LI-7810, LI-7815, and LI-7825 Trace Gas Analyzers. Daily baseline adjustments are required by the LI-7825. The 8250-02 Calibration Manifold can adjust the baseline automatically on a schedule. It also features a patent-pending sample buffer that can stabilize water vapor in the sample air, which can reduce the need for mathematical corrections for water vapor. The buffer can be used by all Trace Gas Analyzers connected to the LI-8250.

New features

  • Calibration Sequence Status: On the home screen, a new indicator shows the status of the calibration sequence and progress of automatic baseline adjustments (8250-02 Calibration Manifold required). The information is summarized below.

    • Delaying indicates that the calibration schedule has started but the device has added a delay to complete a measurement.
    • Stabilizing indicates that the calibration is underway, but the device is waiting for the measurement to meet stability criteria.
    • Zeroing indicates that the Trace Gas Analyzer baseline (similar to the zero) is being adjusted.
    • Completed YYYYMMDD HHMMSS is the date and time that the calibration was finished.
    • Waiting indicates that the time is outside the scheduled calibration adjustment.
    • Failed YYYYMMDD HHMMSS indicates that the calibration did not succeed.

  • Calibration Sequence blocks: In the Configuration section, the calibration sequence blocks allow you to schedule the time of the calibration (hours past midnight), ports to open, and the gas analyzer to adjust.

  • Calibration Manifold blocks: In the Configuration section, the Calibration Manifold blocks allow you to specify which gases are connected to ports.

  • LI-7825 blocks: In the Configuration section, the LI-7825 CO2 Isotopoe/NH3 Trace Gas Analyzer is supported.

  • Math > Regression blocks: To set parameters for isotopic calculations, you can choose a composition and enter parameters that describe the gas.

Terminology updates

Math > Flux block previously were identified first by the type of flux - mass or area. Now they are identified by chamber or flask, followed by the type of flux.

Configuration panel header items are renamed:

  • Load is now Upload. Click Upload to select a configuration file on your computer and upload it to the LI-8250.

  • Save is now Download. Click Download to save the configuration file that is on the LI-8250 to your computer.

  • Reset and Verify are not changed.

New accessories - 8250-02 Calibration Manifold

Part number 8250-02

An accessory for the LI-8250, the 8250-02 Calibration Manifold provides automated baseline adjustments for connected gas analyzers. This is especially important with the LI-7825 CO2 Isotope/NH3 Trace Gas Analyzer, which requires daily baseline adjustments. It also features a patent-pending water vapor transient buffer that reduces variation in the quantity of water vapor in the air stream. Physically reducing variation in water vapor reduces the need for mathematical corrections, thereby reducing uncertainty in measurements. This reduction in uncertainty is especially important when measuring isotopic species of CO2, where the signals may be very small due to very low concentrations.

What's what

The 8250-02 Calibration Manifold features air inlets and outlets for gas analyzers and the multiplexer, and connector for gas standards.

Main panel

The main panel features a power connector and USB connector. Power, data, and control of the manifold is handled by the LI-8250 Multiplexer.

Gas standards connector panel

The gas standards panel has four swaged connectors for 1/8" tubing. We recommend connecting copper tubing to these ports.

Spares and accessories kit

Part number 9982-106

The 8250-02 Calibration Manifold includes an accessories kit with the cable and tube assembly and 1/8" Swagelok ferrules and nuts.

Description Part Number
Swagelok 1/8" Stainless Steel Ferrule and Nut Set 300-21362
Cable and Tube Assembly 9982-010

LI-870 and 8250-02 cable and tube assembly

Part number 9982-010

The cable assembly includes a 1.2-meter sealed USB-A-to-USB-B cable (part number 392-17654), a 1.2-meter IP68 sealed power cable (9982-008), and two pieces of Bev-a-line tubing with quick-connect fittings.

8250-02 Calibration Manifold measured variables

The Calibration Manifold provides additional parameters related to the automated calibration and adjustments.

Table 1‑2. 8250-02 Calibration Manifold variables. The device for these variables is 8250-02 Calibration Manifold.
Interface variable Units Data file variable Description
Flow L M-1 flow Flow of calibration gas
VSO V vso Control voltage to Voltage Sensitive Orifice (an internal flow controlling valve)
VIN V vin Input voltage
Current A isys Current drawn (amps)

LI-78xx Trace Gas Analyzers measured variables

LI-78xx Trace Gas Analyzers report measurement data and performance information. Measured variables indicate the performance characteristics and status of the Trace Gas Analyzer. Items included depend on the gas analyzer connected.

Table 1‑3. LI-78xx Trace Gas Analyzer data definitions. The DEVICE for these variables is LI-7810, LI-7815, LI-7820, or LI-7825.
Interface variable Units Data file variable Description
Diagnostic   DIAGNOSTIC Diagnostic value indicating the quality of the data and state of the instrument
CO2 Dry μmol mol-1 CO2_DRY Carbon dioxide dry mixing ratio (LI-7810, LI-7815, or LI-7825)
H2O mmol mol-1 H2O H2O vapor mole fraction
CH4 Dry nmol mol-1 CH4_DRY CH4 dry mixing ratio (LI-7810 only)
N2O Dry nmol mol-1 N2O_DRY N2O dry mixing ratio (LI-7820 only)
16O12C16O μmol mol-1 16O12C16O_DRY C12 CO2 mixing ratio (LI-7825 only)
16O13C16O μmol mol-1 16O13C16O_DRY C13 CO2 mixing ratio (LI-7825 only)
16O12C18O μmol mol-1 16O12C18O_DRY O18 CO2 mixing ratio (LI-7825 only)
16O12C17O μmol mol-1 16O12C17O_DRY O17 CO2 mixing ratio (LI-7825 only)
δ13CCO2 ‰ CO2C13 C12:13 isotopic ratio of CO2 (LI-7825 only)
δ17OCO2 ‰ CO2O17 O16:17 isotopic ratio of CO2 (LI-7825 only)
δ18OCO2 ‰ CO2O18 O16:18 isotopic ratio of CO2 (LI-7825 only)
NH3 Dry nmol mol-1 NH3_DRY NH3 dry mixing ratio (LI-7825 only)
Cavity Temperature C T_CAVITY Optical cavity temperature
Cavity Pressure kPa PA_CAVITY Optical cavity pressure
Laser Pressure kPa PA_LASER_PHASE Pressure used to control the laser phase
Laser Temperature C T_LASER Temperature of the laser
Residual   RESIDUAL Residual of absorption spectrum fit
Ring Down μs RING_DOWN Ring down time
Enclosure Temperature C T_THERMAL_ENCLOSURE Temperature of the optical cavity enclosure
Phase Error   PHASE_ERROR Error between setpoint and actual laser phase in counts
Shift Temperature C T_LASER_SHIFT Difference between factory set laser temperature and operating laser temperature
Voltage V VIN Input voltage to the LI-78xx

8250-02 Calibration Manifold metadata

Metadata includes information about the device.

Table 1‑4. 8250-02 Calibration Manifold metadata definitions.
Interface variable Units Data file variable Description
Serial Number   SERIAL_NUMBER String indicating the serial number
Firmware   FIRMWARE String indicating the device firmware version number
Tube Length cm TUBE_LENGTH Length of tubing connecting the Calibration Manifold to the LI-8250. Contributes to the total system volume.
Volume cm3 VOLUME Volume of internal components.

LI-78xx Trace Gas Analyzer metadata

Metadata includes information about the device.

Table 1‑5. LI-78xx metadata definitions. The DEVICE for these variables is LI-7810, LI-7815, LI-7820, or LI-7825.
Interface variable Units Data file variable Description
Volume cm3 VOLUME Device volume
Tube Length cm TUBE_LENGTH Length of tubing associated with the analyzer used to calculate total volume
Serial Number   SERIAL_NUMBER Device serial number
Firmware   FIRMWARE Device firmware version

LI-7825 isotope metadata group definitions

Isotope metadata includes information about the computations.

Table 1‑6. Isotope metadata group includes variables that are provided with isotopologue measurements.
Interface variable Units Data file variable Description
Regression   REGRESSION Regression method: Keeling or Slope
Deadband s DEADBAND Deadband length (default is 0)
Stop Time s STOP_TIME Length of data used for the regression
Major Gas   MAJOR_GAS Name of the major gas species the regression was computed from (Keeling is CO2; Slope is 12CO2)
Major Gas Source   MAJOR_GAS_SOURCE Name of instrument representing the source of the major gas for the regression (defaults to LI-7825)
Minor Gas   MINOR_GAS Name of the minor gas species the regression was computed from (Keeling is DELTA_13C; Slope is 13CO2)
Minor Gas Source   MINOR_GAS_SOURCE Name of instrument representing the source of the minor gas for the regression (defaults to LI-7825)
Standard ‰ STANDARD Isotopic standard value (default is 0.0112372)