Comparison of Air Temperature Calibrations

Heinonen, Martti; Anagnostou, M.; Bartolo, J.; Bell, S A; Benyon, R.; Bergerud, R. A.; Bojkovski, Jovan; Böse, N.; Dinu, Cosmin; Smorgon, D.; Flakiewicz, K.; Martı́n, M. J.; Nedialkov, S.; Nielsen, Michael Bachmann; Aytekin, S. Oğuz; Otych, Jan; Pedersen, M.; Rujan, Mihaela; Testa, N.; Turzo-Andras, E.; Vilbaste, Martin; White, M.

doi:10.1007/s10765-014-1654-9

Cited by 7 publications

(7 citation statements)

References 2 publications

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“…One area of special concern is where two thermometers are compared during calibration. Heinonen [11] has already highlighted the problem of sensors with different emissivities, but this work shows that differences in sensor diameters can also lead to errors where a thin sensor 'inherits' the larger radiation error from a larger calibrated sensor.…”

Section: Precision Measurement In Generalmentioning

confidence: 94%

“…In a comparison of air temperature calibration procedures, Heinonen et al [11] record the diameter of the probes used, deliberately use probes with different emissivities, and analyse their results to study the effects of emissivity. However, they do not analyse the dependence of radiative errors on diameter.…”

Section: Metrologymentioning

confidence: 99%

“…However, they do not analyse the dependence of radiative errors on diameter. Friederici and Tegeler [12] are quoted in [11] as discussing the potential errors arising from thermal radiation in climatic chambers. In [12] they highlight the fact that the heat transfer coefficient of a thermometer in air depends on its diameter, a prediction they confirm qualitatively.…”

Section: Metrologymentioning

confidence: 99%

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Air temperature sensors: dependence of radiative errors on sensor diameter in precision metrology and meteorology

2018

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In both meteorological and metrological applications, it is well known that air temperature sensors are susceptible to radiative errors. However, it is not widely known that the radiative error measured by an air temperature sensor in flowing air depends upon the sensor diameter, with smaller sensors reporting values closer to true air temperature. This is not a transient effect related to sensor heat capacity, but a fluid-dynamical effect arising from heat and mass flow in cylindrical geometries. This result has been known historically and is in meteorology text books. However, its significance does not appear to be widely appreciated and, as a consequence, air temperature can be-and probably is being-widely mis-estimated.In this paper, we first review prior descriptions of the 'sensor size' effect from the metrological and meteorological literature. We develop a heat transfer model to describe the process for cylindrical sensors, and evaluate the predicted temperature error for a range of sensor sizes and air speeds. We compare these predictions with published predictions and measurements. We report measurements demonstrating this effect in two laboratories at NPL in which the air flow and temperature are exceptionally closely controlled. The results are consistent with the heat-transfer model, and show that the air temperature error is proportional to the square root of the sensor diameter and that, even under good laboratory conditions, it can exceed 0.1 °C for a 6 mm diameter sensor.We then consider the implications of this result. In metrological applications, errors of the order of 0.1 °C are significant, representing limiting uncertainties in dimensional and mass measurements. In meteorological applications, radiative errors can easily be much larger. But in both cases, an understanding of the diameter dependence allows assessment and correction of the radiative error using a multi-sensor technique.

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Section: Precision Measurement In Generalmentioning

confidence: 94%

Section: Metrologymentioning

confidence: 99%

Section: Metrologymentioning

confidence: 99%

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Air temperature sensors: dependence of radiative errors on sensor diameter in precision metrology and meteorology

2018

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“…The laboratory was equipped with a two-pressure humidity generator, cooled mirror dew-point meters, a climatic chamber, and hygrometers to perform calibrations from 11 %rh to 95 %rh in an air temperature range from −10 • C to 70 • C, which also covers the dew-point range from −35 • C to 65 • C. The capability of the laboratory was extended down to −60 • C in the dew-point temperature range with the construction of a two-temperature humidity generator in cooperation with MIKES in 2013. The laboratory participated in EURAMET comparison programs in order to assess its technical performance internationally where the final reports can also be found on the EURAMET web site [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

National Interlaboratory Comparison in Scope of Relative Humidity in the Range from 11 %rh to 95 %rh at 23 $${}^{\circ }\hbox {C}$$ ∘ C

Aytekin

Kalemci

2015

Int J Thermophys

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The goal of interlaboratory comparisons is to verify the competence of accredited or non-accredited laboratories, including verification of the reported measurement uncertainties, whenever possible. An interlaboratory comparison consists of measurement results of a laboratory and a reference laboratory which is competent to run the comparison and provides traceability at the required uncertainty level. In Turkey, the demand for an interlaboratory comparison in the humidity field increased drastically in parallel to an increasing number of accredited laboratories in this field. Therefore, a national interlaboratory comparison in the scope of relative humidity in the range between 11 %rh and 95 %rh at 23 • C was initiated by TUBITAK UME in 2011. Two hygrometers were calibrated at TUBITAK UME in the above-mentioned range and characterized in terms of long-term stability, temperature dependence, and hysteresis. One of the hygrometers is used throughout this comparison. The second one was kept aside as a backup device in case of a malfunction of the first device. Organization and evaluation of the interlaboratory comparison in the scope of relative humidity were performed according to the EN ISO/IEC 17043:2010 "Conformity assessment-general requirements for proficiency testing" among thirteen national laboratories. Evaluation of comparison results are performed by normalized error analysis. It was found that among the 95 realized points of comparison, 85 (89 %) had E n ≤ 1 and only 10 (11 %) had E > 1.

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“…(Žužek & Pušnik, 2017;van Geel, Bosma, van Wensveen, & Peruzzi, 2015; (DKD, 2004) (Engineers, 2003). Akan tetapi fasilitas yang digunakan di dalam contoh masingmasing dokumen sangat mahal yaitu menggunakan sensor suhu Pt-100 (Heinonen, et al, 2014)…”

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Penggunaan Termokopel Dalam Kalibrasi Climatic Chamber

Tistomo¹,

Fajria²,

Soleh³

et al. 2020

instrum.

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Penggunaan climatic chamber sebagai media kalibrasi untuk proses kalibrasi termohigrometer banyak digunakan oleh laboratorium kalibrasi di Indonesia. Kalibrasi climatic chamber dapat mengacu kepada dokumen acuan DKD-R 5-7 yaitu menggunakan 9 sensor suhu berupa Resistance Thermometer Devices (RTD) dan 1 sensor kelembapan berupa chilled mirror hygrometer. Makalah ini memaparkan kalibrasi cilimatic chamber berdasar acuan tersebut dengan mengganti sensor suhu dan kelembapan.Sensor suhu yang digunakan berupa termokopel tipe T dan sensor kelembapan berupa probe termohigrometer.Pemilihan termokopel sebagai sensor suhu mengacu pada kondisi di lapangan dimana termokopel masih banyak digunakan oleh laboratorium kalibrasi dalam pengukuran suhu.Titik uji metode dilakukan pada kelembapan relatif 90 %rh pada 25 °C dengan luas daerah kerja lebih kecil daripada volume totalnya yaitu sebesar 0,25 m × 0,24 m × 0,4 m. Sebagai hasilnya, nilai inhomogenitas dan stabilitasnyaadalah sebesar 0,95 %rh dan 0,35 %rh. Nilai tersebut masih berada di dalam spesifikasi pabrik yaitu sebesar3,0%rh dan 2,5 %rh.

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Comparison of Air Temperature Calibrations

Cited by 7 publications

References 2 publications

Air temperature sensors: dependence of radiative errors on sensor diameter in precision metrology and meteorology

Air temperature sensors: dependence of radiative errors on sensor diameter in precision metrology and meteorology

National Interlaboratory Comparison in Scope of Relative Humidity in the Range from 11 %rh to 95 %rh at 23 $${}^{\circ }\hbox {C}$$ ∘ C

Penggunaan Termokopel Dalam Kalibrasi Climatic Chamber

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