Optimized Volume Determinations and Uncertainties for Accurate and Precise Manometry

• DOI: 10.1017/rdc.2019.43
• Publication Date: 2019-05-27T09:17:41Z
• Authors: Xi Lu; Steven R Beaupré
• Keywords: Diaphragm (acoustics)

ABSTRACT Precise manometric pressure, volume, and temperature (P-V-T) measurements of carbon in samples, standards, blanks are critical for radiocarbon studies. While P T uncertainties depend on instrument choice environmental stability, V their method measurement often overlooked. We used numerical simulations error propagation to find optimum procedures measuring “cold-finger” volumes equipped with capacitance diaphragm gauges (CDGs) by two common application Boyle’s Law: cryogenic transfers serial gas expansions a reference flask known volume. Minimum relative cold-finger comparable these methods (∼0.002), but the expansion is preferred due its convenience. Serial can be performed high precision using dry air, an initial pressure ∼76% full-scale (e.g., 760 Torr), optimal volume based preliminary estimates empirical power function. The cold-fingers ≥ 12 cm 3 determined minimum achievable 0.0021 0.0023. This limit translates 0.0026 0.0027 P-V-T moles simulated here.