Johra, Hicham

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The aim of this technical report is to provide detailed information about the long-term stability of the thermometer ASL F200 (WIKA Instruments Limited [1]) that is used as temperature reference to calibrate other temperature sensors in the Laboratory of Building Energy and Indoor Environment at Aalborg University – Department of the Built Environment [2]. This ASL F200 thermometer is regularly sent for recalibration at the “Temperature Laboratory” of the Danish Technological Institute, which is a National Reference Laboratory [3].In this report, the stability of the thermometer is assessed as the difference in the temperature reading of the instrument at a specific temperature over time. The latter is calculated as the yearly deviation (or stability) in between consecutive recalibrations, which is equivalent to the difference in the calibration correction term in between two consecutive recalibrations divided by the elapsed time in between these two consecutive recalibrations.The long-term stability of the ASL F200 thermometer is only assessed here for the first channel “Chan 1” of the instrument.All calculations of this technical report are based on calibrations reports from the National Reference Laboratory of the Danish Technological Institute [3]. The main results of those calibration reports can be found in the Appendix at the end of this document

    Aalborg UniversitetLong-Term Stability and Calibration of the Reference Thermometer ASL F200Johra, HichamPublication date:2019Document VersionPublisher's PDF, also known as Version of recordLink to publication from Aalborg UniversityCitation for published version (APA):Johra, H. (2019). Long-Term Stability and Calibration of the Reference Thermometer ASL F200. Department ofCivil Engineering, Aalborg University. DCE Technical Reports No. 266General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            ? Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            ? 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You may freely distribute the URL identifying the publication in the public portal ?Take down policyIf you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access tothe work immediately and investigate your claim.Downloaded from vbn.aau.dk on: August 24, 2021                       Long-Term Stability and Calibration of the Reference Thermometer ASL F200    Hicham Johra  ISSN 1901-726X DCE Technical Report No 266 DCE Technical Report No. 266      Long-Term Stability and Calibration of the Reference Thermometer ASL F200  by   Hicham Johra    December 2019          © Aalborg University         Aalborg University Department of Civil Engineering Architectural Engineering             Scientific Publications at the Department of Civil Engineering  Technical Reports are published for timely dissemination of research results and scientific work carried out at the Department of Civil Engineering (DCE) at Aalborg University. This medium allows publication of more detailed explanations and results than typically allowed in scientific journals.  Technical Memoranda are produced to enable the preliminary dissemination of scientific work by the personnel of the DCE where such release is deemed to be appropriate. Documents of this kind may be incomplete or temporary versions of papers—or part of continuing work. This should be kept in mind when references are given to publications of this kind.  Contract Reports are produced to report scientific work carried out under contract. Publications of this kind contain confidential matter and are reserved for the sponsors and the DCE. Therefore, Contract Reports are generally not available for public circulation.  Lecture Notes contain material produced by the lecturers at the DCE for educational purposes. This may be scientific notes, lecture books, example problems or manuals for laboratory work, or computer programs developed at the DCE.  Theses are monograms or collections of papers published to report the scientific work carried out at the DCE to obtain a degree as either PhD or Doctor of Technology. The thesis is publicly available after the defence of the degree.  Latest News is published to enable rapid communication of information about scientific work carried out at the DCE. This includes the status of research projects, developments in the laboratories, information about collaborative work and recent research results.  Published 2019 by Aalborg University Department of Civil Engineering Thomas Manns Vej 23  DK-9220 Aalborg Ø, Denmark  Printed in Aalborg at Aalborg University  ISSN 1901-726X DCE Technical Report No. 266 Contents  1. Foreword ................................................................................................................................................... 6 2. ASL F200 Thermometer Specifications ...................................................................................................... 7 3. Long-Term Stability .................................................................................................................................... 8 4. Current Calibration Correction ................................................................................................................ 11 5. Conclusion ............................................................................................................................................... 12 6. References ............................................................................................................................................... 13 7. Appendix .................................................................................................................................................. 14    1. Foreword The aim of this technical report is to provide detailed information about the long-term stability of the thermometer ASL F200 (WIKA Instruments Limited [1]) that is used as temperature reference to calibrate other temperature sensors in the Laboratory of Building Energy and Indoor Environment at Aalborg University – Department of the Built Environment [2]. This ASL F200 thermometer is regularly sent for recalibration at the “Temperature Laboratory” of the Danish Technological Institute, which is a National Reference Laboratory [3]. In this report, the stability of the thermometer is assessed as the difference in the temperature reading of the instrument at a specific temperature over time. The latter is calculated as the yearly deviation (or stability) in between consecutive recalibrations, which is equivalent to the difference in the calibration correction term in between two consecutive recalibrations divided by the elapsed time in between these two consecutive recalibrations. The long-term stability of the ASL F200 thermometer is only assessed here for the first channel “Chan 1” of the instrument. All calculations of this technical report are based on calibrations reports from the National Reference Laboratory of the Danish Technological Institute [3]. The main results of those calibration reports can be found in the Appendix at the end of this document.   2. ASL F200 Thermometer Specifications The precision thermometer ASL F200 has 2 measurement channels equipped with 2 RTD temperature probes Pt100. This report is only concerning the calibration and stability of the first channel denominated “Chan 1”. In addition, the thermometer is recalibrated and therefore used as a reference, in the temperature range from -20 °C to 100 °C. According to the manufacturer’s specifications, the yearly deviation (stability) of the ASL F200 precision thermometer should be better (lower) than 0.005 °C per year.   3. Long-Term Stability One can see in Figure 1 the different calibration correction curves of the ASL F200 reference thermometer that have been collected over the last years. One can observe that the calibration correction curves do not change much from one calibration to the other.  Figure 1: The different calibration correction curves of the ASL F200 reference thermometer.   One can see in Figure 2 the yearly deviation of the ASL F200 reference thermometer for different temperatures at the different recalibration times. One can observe that, apart from the negative temperatures in 2009 and 2012, and the 100 °C temperature in 2009, the yearly deviation of the ASL F200 thermometer is fairly stable and within the conformity limit of the manufacturer’s documentation (±0.005 °C per year.), for the whole range of temperature measurement.  Figure 2: Yearly deviation of the ASL F200 reference thermometer at the different recalibration times.   One can see in Figure 3 the evolution of the thermometer’s yearly deviation (average of the absolute deviation and maximum of the absolute deviation over the full range of temperature measurement) as a function of time. One can observe that the average of the absolute deviation of the thermometer’s measurement is always below the manufacturer’s conformity limit. However, for the years 2009 and 2012, the maximum deviation over the full range of measurement is larger than the conformity limit. As mentioned before, this is due to some extreme deviations restricted to the far ends of the range of measurement below 0 °C and at 100 °C. Fortunately, since 2018, the yearly deviation of the ASL F200 thermometer over the entire range of temperature measurement is always better than the conformity limit.  Figure 3: Evolution of the yearly deviation (average of the absolute deviation and maximum of the absolute deviation) as a function of time.   4. Current Calibration Correction In order to perform an accurate temperature measurement with the ASL F200 reference thermometer, it is necessary to correct the readings of the instrument with the adequate correction term. This correction term depends on the temperature reading of the thermometer. The temperature-dependent correction terms (calculated from the recalibration report) are shown in Figure 4 and can be found in Appendix Table 5. The correction term corresponding to the instrument’s reading must be added to the instrument’s reading: 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑚𝑚𝐶𝐶𝑎𝑎𝑎𝑎𝑎𝑎𝐶𝐶𝐶𝐶𝑚𝑚𝐶𝐶𝑎𝑎𝐶𝐶 = 𝐼𝐼𝑎𝑎𝑎𝑎𝐶𝐶𝐶𝐶𝑎𝑎𝑚𝑚𝐶𝐶𝑎𝑎𝐶𝐶 𝐶𝐶𝐶𝐶𝑎𝑎𝐶𝐶𝑟𝑟𝑎𝑎𝑟𝑟 + 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝑟𝑟𝐶𝐶𝑎𝑎 Because the recalibration report comprises only correction terms at every 10 °C, it is recommended to use a linear interpolation or a cubic Hermite spline interpolation function to calculate the correction term at the specific temperature corresponding to the reading of the instrument. Alternatively, for very smooth and regular calibration correction curves such as the one from the 2020 recalibration (see Figure 4), one can use a polynomial fitting function on the entire set of recalibration data to interpolate the correction term at the specific temperature.  Figure 4: Current calibration correction curve for the ASL F200 reference thermometer to be used from 2020 onwards.   5. Conclusion From the evolution of the thermometer’s yearly deviation presented in Figure 3, one can conclude that the ASL F200 thermometer presents a very good long-term stability over the last 2 years and can thus be trusted as a reference thermometer for the calibration of other temperature sensors.   6. References [1] WIKA Instruments Limited https://www.wika.co.uk/ [2] Aalborg University, Department of Built Environment, Aalborg, Denmark. https://www.build.aau.dk/ [3] Danish Technological Institute (DTI), The Temperature Laboratory. https://www.dti.dk/testing/temperature/37566   7. Appendix Table 1: Results of the calibration report of 2005. Reference temperature [°C] Instrument reading [°C] Error [°C] Correction [°C] -20.0042 -20.0050 -0.0008 0.0008 -10.0089 -10.0075 0.0014 -0.0014 0.0000 -0.0100 -0.0100 0.0100 10.0100 10.0060 -0.0040 0.0040 20.0060 20.0080 0.0020 -0.0020 30.0070 30.0130 0.0060 -0.0060 40.0057 40.0155 0.0098 -0.0098 50.0078 50.0205 0.0127 -0.0127 60.0008 60.0145 0.0137 -0.0137 70.0037 70.0180 0.0143 -0.0143 80.0016 80.0160 0.0144 -0.0144 90.0127 90.0100 -0.0027 0.0027 100.0048 100.0060 0.0012 -0.0012   Table 2: Results of the calibration report of 2009. Reference temperature [°C] Instrument reading [°C] Error [°C] Correction [°C] -20.1026 -20.0795 0.0231 -0.0231 -10.0195 -10.0080 0.0115 -0.0115 0.0000 -0.0040 -0.0040 0.0040 9.9906 9.9905 -0.0001 0.0001 20.0370 20.0430 0.0060 -0.0060 29.9930 30.0020 0.0090 -0.0090 39.9760 39.9870 0.0110 -0.0110 50.0159 50.0280 0.0121 -0.0121 60.0720 60.0835 0.0115 -0.0115 69.9874 70.0025 0.0151 -0.0151 80.0050 80.0170 0.0120 -0.0120 89.9920 90.0100 0.0180 -0.0180 99.9900 100.0190 0.0290 -0.0290    Table 3: Results of the calibration report of 2012. Reference temperature [°C] Instrument reading [°C] Error [°C] Correction [°C] -20.0005 -20.0295 -0.0290 0.0290 -10.0583 -10.0760 -0.0177 0.0177 0.0000 -0.0080 -0.0080 0.0080 9.9981 9.9970 -0.0011 0.0011 19.9940 20.0010 0.0070 -0.0070 30.0330 30.0450 0.0120 -0.0120 39.9830 40.0000 0.0170 -0.0170 49.9774 49.9970 0.0196 -0.0196 59.9770 59.9985 0.0215 -0.0215 69.9764 69.9985 0.0221 -0.0221 79.9927 80.0155 0.0228 -0.0228 90.0480 90.0740 0.0260 -0.0260 100.0620 100.0860 0.0240 -0.0240   Table 4: Results of the calibration report of 2018. Reference temperature [°C] Instrument reading [°C] Error [°C] Correction [°C] -20.6814 -20.6995 -0.0181 0.0181 -10.6286 -10.6350 -0.0064 0.0064 0.0000 0.0030 0.0030 -0.0030 10.3294 10.3365 0.0071 -0.0071 20.2992 20.3095 0.0103 -0.0103 30.2714 30.2845 0.0131 -0.0131 40.0836 40.1010 0.0174 -0.0174 50.0565 50.0780 0.0215 -0.0215 60.0318 60.0535 0.0217 -0.0217 70.0103 70.0325 0.0222 -0.0222 79.9909 80.0105 0.0196 -0.0196 90.0043 90.0245 0.0202 -0.0202 100.0124 100.0290 0.0166 -0.0166   Table 5: Results of the calibration report of 2020. Reference temperature [°C] Instrument reading [°C] Error [°C] Correction [°C] -20.0117 -20.0310 -0.0193 0.0193 -10.0040 -10.0150 -0.0110 0.0110 0.0000 -0.0050 -0.0050 0.0050 10.0098 10.0130 0.0032 -0.0032 19.9999 20.0085 0.0086 -0.0086 29.9913 30.0045 0.0132 -0.0132 39.9901 40.0060 0.0159 -0.0159 50.0033 50.0220 0.0187 -0.0187 59.9993 60.0190 0.0197 -0.0197 69.9973 70.0170 0.0197 -0.0197 79.9885 80.0080 0.0195 -0.0195 89.9954 90.0120 0.0166 -0.0166 100.0025 100.0165 0.0140 -0.0140      Recent publications in the DCE Technical Report Series Hicham Johra. Thermal properties of common building materials. DCE Technical Reports No. 216. Department of Civil Engineering, Aalborg University, 2019. Hicham Johra. Project CleanTechBlock 2: Thermal conductivity measurement of cellular glass samples. DCE Technical Reports No. 263. Department of Civil Engineering, Aalborg University, 2019. Hicham Johra. Cleaning Procedure for the Guarded Hot Plate Apparatus EP500. DCE Technical Reports No. 265. Department of Civil Engineering, Aalborg University, 2019.  ISSN 1901-726X DCE Technical Report No. 266 

Long-Term Stability and Calibration of the Reference Thermometer ASL F200

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Long-Term Stability and Calibration of the Reference Thermometer ASL F200

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