Loop Calibration

Use to calibrate the gas injection loop’s volume under current conditions so that precise volume injections can be made in analyses that perform loop injections, such as Pulse Chemisorption experiments. During a loop calibration, the operator repeatedly injects a known volume of gas through the analyzer septum using a syringe, then the analyzer repeatedly injects gas from the loop. This results in a series of recorded peaks in the TCD signal. After the operation completes, the operator can adjust the peaks in the peak editor and make a loop calibration report. This calculates the loop volume by comparing the average area of the manual injection peaks to the average area of the automatic injection peaks. The operator then enters the calculated loop volume under Unit [n] > Unit Configuration for use in subsequent analyses.

1. Install the correct injection loop.
2. Prepare and install a clean, empty sample tube.
3. Ensure the correct gases are connected.
4. Create the sample file:

5. Select the Analysis Conditions tab.
6. Click Insert and select Loop Calibration.
7. Click OK.

8. Complete the dialog box entering the appropriate information for the sample being used.

Specific selections and entries shown in this table are only applicable when using Micromeritics samples. Make the necessary adjustments when using non-Micromeritics samples.

Selections	Description
Carrier Gas [drop‑down box]	Select Helium and enter 50 for the flow rate.
Description [text box]	Enter a description for this calibration.
Filament temperature [selection]	Enter the temperature between 20 to 250 degrees for the filament.
Loop Gas [drop‑down box]	Select Argon and enter 50 for the flow rate.
Number of injections [text box]	Enter the number of automatic injections (3-10) to be done with the loop during calibration.
Temperature [group box]	Enter a value between 20.0 and 150.0 degrees for the Valves and Detector block.

9. Click OK again to close the Calibration window.
10. Click Save As, provide a new file name, then click Close.
11. Go to Unit [n] > Sample Analysis.
12. Click Browse to locate sample file previously created.
13. Click Start to start the analysis. Use the other views of the analysis window to observe the progress of the analysis. During the first half of the analysis, the analyzer displays a prompt before each manual injection. Enter the syringe's physical injection volume (which should be approximately 80% of the nominal loop volume), click Continue, then inject gas through the analyzer septum from the syringe. During the second half of the analysis, the analyzer automatically injects gas from the loop. The resultant data should appear as a series of peaks in the TCD signal.

14. When the analysis ends, close the Analysis window.

15. When the displayed sample temperature reaches the ambient temperature, open the furnace and remove the sample tube.

Use the cotton gloves provided in the accessory kit when handling heated surfaces. These cotton gloves are not intended to protect hands when heated surfaces are above 60 °C.

16. Go to File > Open > [.SMP]. Open the .SMP file containing the calibration experiment. Verify the defined peaks are properly marked (or correct them) using the Peak Editor.
17. On the Reports tab, select only the Loop Calibration report option. Click Preview to view the results, including the Loop Volume.
18. Go to Unit [n] > Unit Configuration. In the Loop Volume field, enter the Loop Volume.