Appendix E TriStar II 3020
E-2 302-42828-01 - Dec 2012
This method may be undesirable if:
• Helium is unavailable; free space determination by the TriStar requires the use of helium
• Analysis speed is a major factor; a helium free space measurement of 10 to 15 minutes is required
• Your sample tends to absorb and retain helium for a prolonged period of time or if it adsorbs helium
Calculate
This method is the most rapid and efficient way of compensating for free space. You must ensure the
following is accomplished:
• Perform a blank analysis on the sample tube
• Load the blank analysis file data into the sample tube file
• Indicate whether a filler rod is being used (found on the Sample Tube dialog)
• Enter the analysis bath temperature (found on the Po and Temperature dialog)
• Enter the sample mass and density (found on the Sample Information dialog)
Enter
This method allows you to enter predetermined values for the warm and cold free spaces. The values to
enter may be obtained in one of two ways:
• A pre-analysis free space calibration of the sample tube containing sample
• The total free space of an empty sample tube is measured and the displacement of the sample
calculated from its mass and density and subtracted from the total free space
In either procedure, ensure that the level (or, in cases where the Isothermal Jacket is used, the effective
level) of the cryogen bath on the sample tube is the same when the analysis is performed as it was
when gathering data for free space calculations.
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