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Pressure disequilibria induced by rapid valve closure in noble gas extraction lines

Leah E. Morgan·Brett Davidheiser-Kroll
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Abstract

Pressure disequilibria during rapid valve closures can affect calculated molar quantities for a range of gas abundance measurements (e.g., K-Ar geochronology, (U-Th)/He geochronology, noble gas cosmogenic chronology). Modeling indicates this effect in a system with a 10 L reservoir reaches a bias of 1% before 1000 pipette aliquants have been removed from the system, and a bias of 10% before 10,000 aliquants. Herein we explore the causes and effects of this problem, which is the result of volume changes during valve closure. We also present a solution in the form of an electropneumatic pressure regulator that can precisely control valve motion. This solution reduces the effect to ∼0.3% even after 10,000 aliquants have been removed from a 10 L reservoir.

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Leah E. Morgan, Brett Davidheiser-Kroll. 2015-06-25. Pressure disequilibria induced by rapid valve closure in noble gas extraction lines. https://doi.org/10.1002/2015gc005823

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