Applying Air Buoyancy

1 Page 1 SOP 2 – 2019 Page 1 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 SOP 2 Recommended Standard Operating Procedure for Applying Air Buoyancy Corrections 1 Introducti... Open at page → 2 Page 2 SOP 2 – 2019 Page 2 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Apparatus/Equipment Required 1 Calibrated barometer with sufficiently small resolution, stability... Open at page → 3 Page 3 SOP 2 – 2019 Page 3 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 3 Procedure Record the temperature, pressure, and relative humidity at the start and at the end o... Open at page → 4 Page 4 SOP 2 – 2019 Page 4 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Table 2. Variables not previously defined. Variable Description of Variable d measured difference... Open at page → 5 Page 5 SOP 2 – 2019 Page 5 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Effective density values must be calculated and used for summations of mass standards. The subscr... Open at page → 6 Page 6 SOP 2 – 2019 Page 6 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Appendix A Based on “The Basic Theory of Air Buoyancy Corrections” by Richard S. Davis 4 1 Introd... Open at page → 7 Page 7 SOP 2 – 2019 Page 7 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Chapter 7.3, Handbook 145 1 ). Use of this scale does not indiscriminately eliminate the need for... Open at page → 8 Page 8 SOP 2 – 2019 Page 8 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Sensitivity The response of a balance under load to an additional small weight: 1 sensitivity a s... Open at page → 9 Page 9 SOP 2 – 2019 Page 9 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Table 6. Variables for air density equation. Variable Description ρa density of air, g/cm 3 P bar... Open at page → 10 Page 10 SOP 2 – 2019 Page 10 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Table 7. Variables for CIPM air density equation. Variable Description Ma molar mass of the air... Open at page → 11 Page 11 SOP 2 – 2019 Page 11 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Table 8. Variables not previously defined. Variable Description Mx mass of the unknown object Ms... Open at page → 12 Page 12 SOP 2 – 2019 Page 12 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 If a single-pan balance with built-in weights is used, it is probable that the built- in weights... Open at page → 13 Page 13 SOP 2 – 2019 Page 13 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 The mass of an unknown object weighed on the balance is then 1 1 a R c x a x M M ρ ρ ρ ρ  −... Open at page → 14 Page 14 SOP 2 – 2019 Page 14 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 10 Accuracy Inattention to problems of buoyancy most often results in systematic errors . For a... Open at page → 15 Page 15 SOP 2 – 2019 Page 15 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Appendix B Examples Example 1: The weight set of Table B-1 is used with an equal-arm balance to... Open at page → 16 Page 16 SOP 2 – 2019 Page 16 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 ( ) 3 0.009 998 4 g 0.000 970 72 g/division = 0.970 724 10 g/division 10.3 divisions x − = = ( )... Open at page → 17 Page 17 SOP 2 – 2019 Page 17 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Example 3: Another piece of silicon is measured on a single-pan microbalance. The balance weight... Open at page → 18 Page 18 SOP 2 – 2019 Page 18 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Table B-1. Example of calibration certificate data . Mass (g) Uncertainty (g) Vol at 20 °C (cm 3... Open at page → 19 Page 19 SOP 2 – 2019 Page 19 of 19 This publication is available free of charge from: https://doi.org /10.6028/NIST.IR .6969 - 2019 Table B-2. e s approximation in terms of temperature. Temperature (°C) e s (mmHg) 18 15.48 18.5... Open at page →