Determination of the argon concentration in ambient dry air for the calculation of air density

Sutour, Christophe; Stumpf, Christelle; Kosinski, Jean-Pierre; Surget, Ana; Hervouët, G.; Yardin, Catherine; Madec, Tanguy; Gosset, André

doi:10.1088/0026-1394/44/6/003

Cited by 7 publications

(9 citation statements)

References 4 publications

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“…All the argon used in scientific experiments is derived from atmospheric argon. The cosmogenic argon isotopes are 36 Ar and 38 Ar, but currently, these comprise only approximately 1 part in 298 and 1 part in 1580 respectively of 40 Ar, which is entirely derived from the radioactive decay of 40 K. Argon now comprises approximately 0.9330(32)% of atmospheric air [15].…”

Section: Atmospheric Argonmentioning

confidence: 99%

Correction of NPL-2013 estimate of the Boltzmann constant for argon isotopic composition and thermal conductivity

et al. 2015

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In 2013, a team from NPL, Cranfield University and SUERC published an estimate of the Boltzmann constant based on precision measurements of the speed of sound in argon. A key component of our results was an estimate of the molar mass of the argon gas used in our measurements. To achieve this we made precision comparison measurements of the isotope ratios found in our experimental argon against the ratios of argon isotopes found in atmospheric air. We then used a previous measurement of the atmospheric argon isotope ratios to calibrate the relative sensitivity of the mass spectrometer to different argon isotopes. The previous measurement of the atmospheric argon isotope ratios was carried out at KRISS using a mass spectrometer calibrated using argon samples of known isotopic composition, which had been prepared gravimetrically.We report here a new measurement made at KRISS in October 2014, which directly compared a sample of our experimental gas against the same gravimetrically-prepared argon samples. We consider that this direct comparison has to take precedence over our previous more indirect comparison. This measurement implies a molar mass which is 2.73(60) parts in 10 6 lighter than our 2013 estimate, a shift which is seven times our 2013 estimate of the uncertainty in the molar mass.In this paper we review the procedures used in our 2013 estimate of molar mass; describe the 2014 measurement; highlight some questions raised by the large change in our estimate of molar mass; and describe how we intend to address the inconsistencies between them. We also consider the effect of a new estimate of the low pressure thermal conductivity of argon at 273.16 K. Finally we report our new best estimate of the Boltzmann constant with revised uncertainty, taking account of the new estimates for the molar mass and the thermal conductivity of the argon.

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Section: Atmospheric Argonmentioning

confidence: 99%

Correction of NPL-2013 estimate of the Boltzmann constant for argon isotopic composition and thermal conductivity

et al. 2015

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“…In addition, the uncertainty estimate for the CIPM-2007 equation has been established in conformance with [14], whereas the uncertainty statements in [1,2] are ambiguous.…”

Section: Comparison With the Cipm-81/91 Equationmentioning

confidence: 99%

“…This has now been provided by a team from the Laboratoire National de Métrologie et d'Essais (LNE, France) [14]. Their result is x Ar = 9.330(16) mmol mol −1 .…”

Section: Introductionmentioning

confidence: 99%

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Revised formula for the density of moist air (CIPM-2007)

Picard¹,

Davis²,

Gläser³

et al. 2008

Metrologia

321

235

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Measurements of air density determined gravimetrically and by using the CIPM-81/91 formula, an equation of state, have a relative deviation of 6.4 × 10 −5 .This difference is consistent with a new determination of the mole fraction of argon x Ar carried out in 2002 by the Korea Research Institute of Standards and Science (KRISS) and with recently published results from the LNE. The CIPM equation is based on the molar mass of dry air, which is dependent on the contents of the atmospheric gases, including the concentration of argon. We accept the new argon value as definitive and amend the CIPM-81/91 formula accordingly. The KRISS results also provide a test of certain assumptions concerning the mole fractions of oxygen and carbon dioxide in air. An updated value of the molar gas constant R is available and has been incorporated in the CIPM-2007 equation. In making these changes, we have also calculated the uncertainty of the CIPM-2007 equation itself in conformance with the Guide to the Expression of Uncertainty in Measurement, which was not the case for previous versions of this equation. The 96th CIPM meeting has accepted these changes.

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“…In CIPM 1981/91, x Ar value is 9,17 mmol mol-1, based on calculation by Chacket, Paneth, & Wilson (1949). For CIPM 2007 the value of x Ar is changed to 9,332(3) mmol mol-1, based on the recent calculations by KRISS and LNE (Park, Kim, Lee, Esler, Davis, Wielgosz, 2004;Sutour, Stumpf, Kosinski, Surget, Hervouët, Yardin, ... & Gosset, 2007).…”

Section: Molar Mass Of Dry Air (M a )mentioning

confidence: 99%

Application of Cipm 2007 Formula and Its Influence in Determining Uncertainty Due to Variation of Air Density

Mushoddiqoh¹,

Eka²,

Sugiharto³

2017

instrum.

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Air density measurement is an important parameter in standard mass calibration. The value is calculated from four measured components, i.e. temperature, relative humidity, mole fraction of carbon dioxide, and air pressure of environment where the calibration takes place. Empirical formula to calculate air density is recommended by Comité International des Poids et Measures (CIPM) in 1981/91, then updated in 2007. In this paper, there is explanation about the differences between CIPM 1981/91 formula and CIPM 2007, their applications to air density calculation and the effects into uncertainty budget, and uncertainty contribution from air density variation to the standard mass calibration. The data are taken from the environment condition in mass laboratory of RCM LIPI. From the calculation, the average air density obtained from CIPM 1981/91 formula is 0.0001 kgm-3 smaller than that obtained from CIPM 2007 formula. Air density variation in the mass laboratory is calculated as 0.00572 kgm-3 using CIPM 1981/91 formula and 0.00566 kgm-3 using CIPM 2007 formula. Uncertainty contribution to standard mass calibration for both formulas are relatively the same, about 0.031 kgm-3 , with the sensitivity coefficient 3.0 x 10-6 m 3 , making it the third largest contributor after mass standard and instability into the uncertainty budget of mass calibration.

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Determination of the argon concentration in ambient dry air for the calculation of air density

Cited by 7 publications

References 4 publications

Correction of NPL-2013 estimate of the Boltzmann constant for argon isotopic composition and thermal conductivity

Correction of NPL-2013 estimate of the Boltzmann constant for argon isotopic composition and thermal conductivity

Revised formula for the density of moist air (CIPM-2007)

Application of Cipm 2007 Formula and Its Influence in Determining Uncertainty Due to Variation of Air Density

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