Appendix II: Sampling from a Jar

The following photos utilize a glass jar customized with the addition of a Vacutainer® septum.

The F-950 can draw and analyze a headspace gas sample from a rigid jar by incorporating an input probe and output flow into the septum to compensate for removed airspace, thus preventing a vacuum from occurring.

Instructions:

1. With the F-950 in Fixed Volume Mode, allow the instrument to purge and stabilize in ambient air before inserting the fixed volume probe into the sample jar septum.
2. Once stabilization is complete, insert the fixed volume needle probe connected to the F-950 inlet into the jar septum.
3. To prevent a vacuum, insert another probe from the outlet (bottom) of the F-950 into the septum. There are now two needle probes inserted into the septum.
4. Press the square button above the name of the instrument to initiate the Fixed Volume measurement. The pump inside of the F-950 will activate and draw headspace gas into the unit.
5. Remove both needle probes during each purge to allow the instrument to properly purge the internal tubing in the F-950.

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*If you receive a Clogged probe? error, check that your needle is not bent and that the needle has penetrated through the septum and into the sampling space.

For larger sampling jars, consider incorporating an internal fan to improve circulation within the sample space. Carbon dioxide gas can sink to the bottom portion of the jar, rendering a non-representative reading to occur. Placing the jar on a long side helps to mitigate this from affecting the sample draw and more evenly distributes the internal gas.