Practical Study of Psychrometer Calibrations

Kentved, Anders Bonde; Heinonen, Martti; Hudoklin, Domen

doi:10.1007/s10765-012-1212-2

Cited by 8 publications

(7 citation statements)

References 10 publications

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“…This value is coming from the result of peer review in 2014 due to achieving secure uncertainty for former calibration systems which were using climatic chamber as the media and liquid in glass thermomers as the sensors. On the other hand, some authors stated that uncertainty requirements for calibration of such psychrometers are typically around 1-2% rh, close to the best calibration and measurement uncertainties claimed by national metrology institutes (NMIs) (Kentved, Heinonen, & Hudoklin, 2012). Hence, the existing CMC should be improved.…”

Section: A Introductionmentioning

confidence: 81%

“…A method for calibrating psychrometers gives important role in the uncertainty analysis, as long as authors know that there are three ways to calibrate psychrometers. First, the calibration process yields relative humidity correction values where the psychrometer coefficient A is already given (Kentved et al, 2012). The drawback of this method is that if the applied psychrometer coefficient A does not match the characteristic of the calibrated psychrometer, then it will result in big correction values.…”

Section: A Introductionmentioning

confidence: 99%

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Improving Calibration and Measurement Capability (Cmc) of Psychrometer Calibration

Tistomo¹,

Purwowibowo²,

Soleh³

et al. 2019

instrum.

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Peningkatan calibration measurement capability (CMC) untuk kalibrasi psychrometer telah dilakukan melalui kalibrasi sebuah psychrometer buatan sendiri yang memiliki dua buah sensor tahanan platina sebagai termometer kering dan basahnya. Rentang kalibrasi mencakup 15% rh 90% rh dalam kisaran suhu dari 25° C hingga 65° C. Ketidakpastian pengukuran dievaluasi dari ketidakpastian besaran individu mengikuti persamaan Ferrel. Sebagai hasilnya, tidak hanya CMC yang ada meningkat tajam dari 5% rh menjadi 1,8% rh, tetapi juga ketidakpastian kalibrasi pada setiap set point sesuai dengan nilai kriteria ketidakpastian untuk mengusulkan CMC kelembaban relatif ke Lampiran C dari Biro Internasional untuk Ukuran dan Timbangan (BIPM).

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Section: A Introductionmentioning

confidence: 81%

Section: A Introductionmentioning

confidence: 99%

Improving Calibration and Measurement Capability (Cmc) of Psychrometer Calibration

Tistomo¹,

Purwowibowo²,

Soleh³

et al. 2019

instrum.

View full text Add to dashboard Cite

show abstract

“…Environmental conditions in the laboratory should be checked. Not only temperature, pressure and humidity [26], but also extraneous electromagnetic fields have to be estimated. Regarding unwanted extraneous magnetic fields, one should take into consideration increasing the distance from the magnetic field source, removing or reducing the power of the magnetic field or introducing high permeability magnetic shielding, e.g.…”

Section: Discussionmentioning

confidence: 99%

Magnetic effects on thermocouples

Beguš¹,

Bojkovski²,

Drnovšek³

et al. 2014

Meas. Sci. Technol.

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Thermometers in laboratory environment and industrial applications are often subject to extraneous, usually unwanted and uncontrolled magnetic fields. Magnetic field influence can be minimized, but cannot be fully cancelled out. Even more, in most cases, there is no awareness of the existence of magnetic fields, let alone their effect on measurement instrumentation. In the past, sensitivity to high dc magnetic fields has been investigated in cryogenics and at high temperatures. More recently, the magnetic effect on weak dc magnetic fields was presented. The goal of this paper was to analyse and empirically and experimentally prove the magnetic sensitivity of thermocouples exposed to low magnetic fields: both dc and ac. Precision and uniform alternating and direct magnetic flux densities were generated by means of permanent magnets and power amplifiers with air-cored coils. The magnetic effect on ferromagnetic and non-ferromagnetic thermocouples at liquid-nitrogen-boiling point (−196 °C), ice point (0 °C), in water (17 °C) and at melting point of gallium fixed point cell (29.7646 °C) was investigated. Magnetic-field-dependent temperature errors of up to 700 mK (at 5.3 mT: dc) and up to 1 °C (at 10 mT: ac 50 Hz magnetic fields) were detected. From the results, it can be concluded that, ideally for temperature measurements of the highest accuracy in the above-cryogenic temperature range, magnetic sensitivity should be estimated and taken into account either as the correction of an error and/or as an additional source of measurement uncertainty. Special consideration should be given to thermocouple orientation relative to the magnetic field direction, influence of metal enclosures and magnetization effects on ferromagnetic components of thermocouples.

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“…Humidity can especially become an issue when vapor condenses during temperature shocks or uneven temperature/humidity distribution. Namely, a change in temperature by 1 • C can cause a relative humidity change, as high as 7 %, which could result in unwanted condensation for extended periods [54].…”

Section: Temperature and Humidity Measurementmentioning

confidence: 99%

“…Regarding the case in Table 5, the values exp(β k+1,k τ k+1,k ) and exp(β k+1 τ k+1 ) are given in the column VI, the values of −β are written in column VII for unperturbed transportation and other logistics, and in column X in the perturbed case. Source of the basic data before perturbations: [54] and authors' calculations of the perishability dynamics β.…”

Section: The Example Where the Only Path On The Graph Is A Chainmentioning

confidence: 99%

Risk Mitigation in a Meat Supply Chain with Options of Redirection

et al. 2020

Self Cite

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The aim of this paper is to present how a higher income can be achieved by developing a broader and more accurate planning framework and control perishability from stable to fork if it is possible to redirect the shipments in the case of increasing perishability dynamics or longer time delays on the roads. It also gives the answer to the question of how such a Supply Chain (SC) can be evaluated using Net Present Value (NPV) approach. The procedures include a real-time calculation and communication about the remaining shelf life (RSL) during transportation and other logistic manipulations from one chain node to another if the time to exceed the contractually stipulated Customer Remaining Shelf Life (CRSL) is distributed by known distribution. Planning and control on the skeleton of the extended material requirements planning (MRP) model are advised, where time delays and their impact on the CRSL can be easily calculated. The changes in the NPV at contractually stipulated CRSL are calculated dynamically in real-time. Smart devices, tracking temperature, humidity, and gas concentration enable such reports immediately after detecting a high probability that CRSL, as stipulated in a contract, will not be achieved, based on the known parameters of the exponential distribution of the remaining shelf life as a time to failure at each node of the graph. The model includes possibilities to deliver the meat to the local market or to the reverse logistics plants in the nodes of the remaining route, if the expected contractually stipulated CRSL becomes too high. On this way, shortening unnecessary routes further contributes to less pollution.

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Practical Study of Psychrometer Calibrations

Cited by 8 publications

References 10 publications

Improving Calibration and Measurement Capability (Cmc) of Psychrometer Calibration

Improving Calibration and Measurement Capability (Cmc) of Psychrometer Calibration

Magnetic effects on thermocouples

Risk Mitigation in a Meat Supply Chain with Options of Redirection

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