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Measurement workflow

Use the measurement workflow to bring reference measurements into WS.PEMS. A reference measurement is a file from an analyser that measured the stack, for example a portable gas analyser. The workflow uploads the file, connects its columns to standard tags, and lines up its clock with the process data. At the end, the measurement dataset is ready for a calibration or a validation.

Before you start​

  • You must have the SuperAdmin role.
  • The emission source must have a pipeline.
  • You must have the measurement file or files.
  • You must know the time zone of the analyser clock.
  • The process data for the measurement period must be in WS.PEMS. The workflow compares the measurement with this data.

Start the workflow​

  1. In the menu, open Calibration workflows. The Workflow Manager opens on the Measurement tab.
  2. Click Upload Measurements.
  3. Fill in the Upload Measurement File form:
    • Pipeline: the pipeline of the emission source.
    • Measurement Date: the day of the measurement.
    • Parser: the format of the file.
    • Time Zone: the time zone of the analyser clock.
    • Helper Date Parser (preset) or Date Parser (e.g. yyyy-MM-dd HH:mm:ss): the date format in the file. The form does not show these fields for a Gasmet file, because a Gasmet export always has the same date and time columns.
    • Measurement Files: one file or more. The system merges the files into one dataset. Columns with the same name become one column. Select Dry basis for each file whose values are already on a dry basis. A later step corrects the wet files for water vapour.
  4. Submit the form. The server reads the file, and the new workflow opens.

To use measurements from WS.Project, click Import from WS.Project on the Measurement tab. Each imported dataset goes to the emission source with the same region, asset and source name. The system skips datasets that have no matching emission source.

Steps​

The workflow page shows the Measurement Dataset Overview and the list of steps. Click a step to open it. Each step has a button that validates the step and opens the next step. Click Previous to go back one step.

1. Upload measurements​

This step is complete when the file is uploaded.

2. Add Header-Tag mapping​

  1. For each column in the file, select the Standard Tag that it measures, for example Nitrogen monoxide NO or Carbon dioxide CO2.
  2. Select the Original Unit of the column.
  3. If the file has a water vapour column, select it in H2O Column Name.
  4. Validate the step. You must map one column minimum.

For a large dataset, the system converts the values in the background. The progress shows in the notifications.

3. Validate measurements​

  1. In CO₂ Max Validation, click Calculate CO₂ Max. The system calculates CO₂ Max from the measured CO₂ and O₂. Use the result to check that the analyser measured correctly.
  2. Optional: in Filter Measurement Values, set the limits for a value. Click Apply filter or Apply & exclude the rest. The system excludes the rows outside the limits. It does not delete them. Click Restore all to include them again.
  3. In Request data, select the process tags to plot against the measurement.
  4. Validate the step.

4. Adjust measurements​

  1. Request the process values to plot them with the measurement.
  2. Compare the measured values with the process values on the graph.
  3. If the two curves are not aligned in time, set a Second Offset. The offset moves the measurement timestamps by this number of seconds.
  4. Validate the step.

5. Select measurement dataset​

  1. Request the process values.
  2. On the graph, select a period. Click Remove Selection to exclude the period, or Keep Selection to keep only the period. Exclude the periods that you do not trust, for example when the analyser did a zero check.
  3. Validate the step.

Result​

The measurement dataset is ready for a calibration or a validation. It shows on the Measurement tab of the Workflow Manager. In the Actions column:

  • Overview opens the workflow again.
  • Export shows the measurement values and the process values, and exports them.
  • Delete removes the measurement dataset.

Common problems​

ProblemWhat to do
"Could not read the selected file(s)."Make sure that the file has the format of the selected Parser.
"Map at least one column to a standard tag."In step 2, select a Standard Tag for one column minimum.
The header mapping takes a long time.The system converts large datasets in the background. Look at the notifications.
"Computing CO₂ Max failed"Read the notification for the cause. Make sure that the CO₂ and O₂ columns are mapped.
The measurement and the process data are not aligned.Make sure that the Time Zone was correct at upload. Then set a Second Offset in step 4.
The graph shows no process values.Make sure that the process data for the measurement period is in WS.PEMS.
An error says that the step is not allowed.The workflow is not at that step. Complete the steps before it first.