Dew Point Measurement Error due to Tube Length in a Calibration Instrumentation and the Evaluation of Measurement Uncertainty

Abstract:

The purpose of this paper is to analyze the effect of tube length in calibration instrumentation on dew point measurement of dew point sensors (DPS) and evaluation of measurement uncertainty. When measuring dew point temperature, various tube lengths between dew point generator and dew point sensor (DPS) cause a significant error due to moisture absorption of inner tube. The measurement is carried out to analyze the variation on measured dew point temperature for four cases of tube lengths with 300 mm, 1200 mm, 2500 mm and 5000 mm. The dew point temperature measurements were performed in the range from-60 °C to 10 °C by using calibrated standard chilled mirror hygrometer as reference standard. In order to investigate contribution to the standard uncertainty for the tube length variation as an uncertainty source, expanded uncertainties were evaluated for the cases including the effect of tube length variation as an uncertainty source and excluding it at each measurement point. The measurement was conducted according to standard calibration procedure of Korea Testing Laboratory which assures suitability and traceable results. It is also based on international standards.

• Periodical: Applied Mechanics and Materials (Volumes 789-790)
• Pages: 519-525
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.789-790.519
• Online since: September 2015
• Authors: Yun Kyung Bae*, Dong Hoon Hyun
• Keywords: Dew Point Sensor, Dew Point Temperature, Measurement Uncertainty, Tube Length

References

[1] Andy Benton, Walter Segovia, Dew point measurement in natural gas, Report of Michell (2012).

[2] Standard Test Methods for Water Vaper Content of Electrical Insulating Gases by Measurement of Dew Point, ASTM, D2029-97 (2008).

[3] Tzehung Lu, Chiachung Chen, Uncertainty evaluation of humidity sensors calibrated by saturated salt solutions, Measurement, vol 40 (2007), p.591–599.

DOI: 10.1016/j.measurement.2006.09.012

[4] Essam EL-Din, Mostafa Mahmoud, Realization of humidity standard facility using two-pressure humidity generator and humidity chamber, Metrologia (2009), Index 330930.

[5] B. Cretinon, The CETIAT Standard Humidity Generator Operating in dew point temperature, Third International Symposium on Humidity & Moisture, UK (1998).

[6] H. Venzke, A. Melling, Papers and Abstracts from Third International Symposium on Humidity & Moisture, vol. 1 (1998), pp.476-477.

[7] H. G. Liedberg, M.R. Mnguni, D. Jonker, A Simple Humidity Generator for Relative Humidity Calibrations, Int J Thermophys, vol 29 (2008), p.1660–1667.

DOI: 10.1007/s10765-008-0423-z

[8] J. Lovell-Smith, The propagation of uncertainty for humidity calculations, Metrologia, vol 46 (2009), p.607–615.

DOI: 10.1088/0026-1394/46/6/001

[9] Yun-Kyung Bae, Dong-Hoon Hyun, Effect of purging rate on the calibration of dew point sensor and the estimation of measurement uncertainty, Applied Mechanics and Materials, vol 627 (2014), pp.161-167.

DOI: 10.4028/www.scientific.net/amm.627.161

[10] Martti Heinonen, A humidity generator with a test chamber system, Measurement (1998), pp.307-313.

[11] "Expression of the Uncertainty of Measurement in Calibraition, EA-4/02 (1999).

[12] Standard Test Methods for Water Vaper Content of Electrical Insulating Gases by Measurement of Dew Point, ASTM, D2029-97 (2008).

[13] Standard Test Method of Measuring Humidity with Cooled-Surface Condensation Hygrometer, ASTM, D4230-02 (2012).