Open AccessDirect determination of air density in a balance through artifacts characterized in an evacuated weighing chamber
Author(s) -
William F. Koch,
Richard Davis,
V. E. Bower
Publication year - 1978
Publication title -
journal of research of the national bureau of standards
Language(s) - English
Resource type - Journals
eISSN - 2376-5259
pISSN - 0160-1741
DOI - 10.6028/jres.083.026
Subject(s) - density of air , buoyancy , relative humidity , atmospheric pressure , volume (thermodynamics) , air mass (solar energy) , mechanics , environmental science , balance (ability) , constant air volume , materials science , analytical chemistry (journal) , thermodynamics , meteorology , chemistry , air conditioning , physics , chromatography , boundary layer , medicine , physical medicine and rehabilitation
This paper describes a simple device which permits mass comparisons in air without appeal to the correction for air buoyancy. The device consists of a canister which is evacuated and weighed on a laboratory balance with a mass inside. A second weighing of another mass in the evacuated canister provides the desired mass comparison. The method was used to determine the mass difference between two stainless steel weights of widely differing densities. With knowledge of this mass difference and of the volume difference one may, by a simple air weighing of the two objects, determine directly the density of the air in the balance case. Densities of air determined by this method were compared with those calculated from the barometric pressure, the temperature, and the relative humidity of the laboratory air. The experimental and calculated values agree throughout to within 1.0 μ g cm -3 (where the normal air density is about 1.2 mg cm -3 ). The calculated and experimental values of day-to-day fluctuations in air density agree to within 0.5 μ g cm -3 .