Open AccessPressure disequilibria induced by rapid valve closure in noble gas extraction lines
Author(s) -
Morgan Leah E.,
DavidheiserKroll Brett
Publication year - 2015
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2015gc005823
Subject(s) - noble gas , geochronology , geology , closure (psychology) , volume (thermodynamics) , geochemistry , thermodynamics , physics , law , atomic physics , political science
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.