A water bath blackbody for the 5 to 60 degree] temperature range

2014

3 Abstract: Liquid density measurement is an important activity in many laboratories. Usually hydrometers are used to measure the density of liquids in the range from 600 kg/m 3 up to 1850 kg/m 3 . For the purpose of metrological traceability of Hydrometers with the international density reference standards a calibration system has been designed, constructed and validated at the National Institute for Standards, NIS, Egypt. The system covers the range from 500 kg/m 3 up to 2000 kg/m 3 . The system is automatically operated for the intended measurements and calibrations using hydrostatic weighing (Cuckow's method). Distilled water was used as a reference liquid. Finite element analysis using (ABAQUS) software for 3D has been used to check the stress, deformation, rigidity, stability as well, to optimize the design of the system. A laser light source and two linear encoders are used to position the standard liquid surface at the hydrometer scale mark during calibration process. Fo...

PROCEEDING OF THE 1ST INTERNATIONAL CONFERENCE ON STANDARDIZATION AND METROLOGY (ICONSTAM) 2021

A calibration bath designed for clinical thermometer calibration has been developed. The calibration bath developed is a completely operational system which meets the technical requirement for clinical thermometer calibration, compact in size suitable for on-site calibration and at the same time is affordable for calibration laboratories in Indonesia. It is expected that it will encourage calibration laboratories to open calibration services for clinical thermometers belonging to health service facilities (hospitals, clinics, etc.) which by law have to be verified annually. The calibration bath was successfully characterized and proved to meet the requirement with a total uncertainty from spatial uniformity and temporal stability of 10 mK, well below the clinical thermometer tolerance of 100 mK to 200 mK depending on the type of clinical thermometer.

Journal of Atmospheric and Oceanic Technology, 2004

The second calibration and intercomparison of infrared radiometers (Miami2001) was held at the University of Miami's Rosenstiel School of Marine and Atmospheric Science (RSMAS) during May-June 2001. The participants were from several groups involved with the validation of skin sea surface temperatures and land surface temperatures derived from the measurements of imaging radiometers on earth observation satellites. These satellite instruments include those currently on operational satellites and others that will be launched within two years following the workshop. There were two experimental campaigns carried out during the 1week workshop: a set of measurements made by a variety of ship-based radiometers on board the Research Vessel F. G. Walton Smith in Gulf Stream waters off the eastern coast of Florida, and a set of laboratory measurements of typical external blackbodies used to calibrate these ship-based radiometers. This paper reports on the results obtained from the laboratory characterization on blackbody sources. A companion paper reports on the at-sea measurements. Five blackbody sources were intercompared by measurements of their brightness temperature using the National Institute of Standards and Technology (NIST) Thermal-infrared Transfer Radiometer (TXR). Four of these sources are used for calibration of sea surface temperature radiometers. The fifth was a NIST water bath blackbody used for calibration of the TXR. All blackbodies agreed to better than Ϯ0.1ЊC at blackbody temperatures near the ambient room temperature. Some of the blackbodies had reduced effective emissivity relative to the NIST water bath blackbody, and hence they began to disagree at blackbody temperatures far enough away (Ͼ15ЊC) from the ambient room temperature. For these, relative effective emissivity values were determined so that corrections can be applied if they are used in conditions of nonlaboratory ambient temperatures.

IEEE Transactions on Instrumentation and Measurement, 2019

Blackbody cavity temperature sensor, combining the advantages of contact and noncontact thermometry, has been well used for continuously measuring the molten steel temperature in continuous casting. However, the conventional cavity is composed of the opaque wall, and thermal conduction lag from outer to inner wall leads to the relatively slow response speed of the sensor, which impedes its application in the production processes with rapid temperature variation, such as nonferrous and ferrous metal refining. In this article, a novel blackbody cavity temperature sensor is introduced by replacing the blackbody cavity's opaque wall with a transparent wall, thus eliminating the response lag of the temperature sensor. Experiments are conducted on the response speed among the conventional and the novel blackbody cavity temperature sensors as well as two typical thermocouples. The response speed is evaluated by comparing measurements of different temperature sensors after some amount of time when the measured liquid is heated up very fast. Results show that the novel blackbody cavity temperature sensor's response speed is faster than both the traditional one and the thermocouples. Anticipated results indicate the rapidity of the novel sensor and its potential application in an accurate and rapid field with harsh conditions.

International Journal of Thermophysics, 2017

CETIAT's calibration laboratory, accredited by COFRAC, is a secondary thermometry laboratory. It uses overflow and stirred calibration baths (from − 80 • C up to + 215 • C), dry blocks and furnaces (from + 100 • C up to + 1050 • C) and thermostatic chambers (from − 30 • C up to + 160 • C). Typical calibration uncertainties that can be reached for platinum resistance thermometers in a thermostatic bath are between 0.03 • C and 0.06 • C. In order to improve its calibration capabilities, CETIAT is working on the implementation of a gas-controlled heat pipe (GCHP) temperature generator, used for industrial sensor calibrations. This article presents the results obtained during the characterization of water GCHP for industrial applications. This is a new approach to the use of a heat pipe as a temperature generator for industrial sensor calibrations. The objective of this work is to improve measurement uncertainties and daily productivity. Indeed, as has been shown in many studies (Dunn and Reay in Heat Pipes, Pergamon Press, Oxford, 1976; Merlone et al. 2012), the temperature of the system is pressure dependent and the response time, in temperature, follows the pressure accordingly. Thanks to this generator, it is possible to perform faster calibrations with smaller uncertainties. In collaboration with INRiM, the GCHP developed at CETIAT works with water and covers a temperature range from + 30 • C up to + 150 • C. This device includes some improvements such as a removable cover, which allows us to have different sets of thermometric wells adjustable according to the probe to be calibrated, and a pressure controller based on a temperature sensor. Selected Papers of the 13th International Symposium on Temperature, Humidity, Moisture and Thermal Measurements in Industry and Science.

Measurement Science and Technology, 2006

After a brief description of the different methods employed in periodic calibration of hydrometers used in most cases to measure the density of liquids in the range between 500 kg m −3 and 2000 kg m −3 , particular emphasis is given to the multipoint procedure based on hydrostatic weighing, known as well as Cuckow's method. The features of the calibration apparatus and the procedure used at the INRiM (formerly IMGC-CNR) density laboratory have been considered to assess all relevant contributions involved in the calibration of different kinds of hydrometers. The uncertainty is strongly dependent on the kind of hydrometer; in particular, the results highlight the importance of the density of the reference buoyant liquid, the temperature of calibration and the skill of operator in the reading of the scale in the whole assessment of the uncertainty. It is also interesting to realize that for high-resolution hydrometers (division of 0.1 kg m −3), the uncertainty contribution of the density of the reference liquid is the main source of the total uncertainty, but its importance falls under about 50% for hydrometers with a division of 0.5 kg m −3 and becomes somewhat negligible for hydrometers with a division of 1 kg m −3 , for which the reading uncertainty is the predominant part of the total uncertainty. At present the best INRiM result is obtained with commercially available hydrometers having a scale division of 0.1 kg m −3 , for which the relative uncertainty is about 12 × 10 −6 .

This document gives guidance on measurement practices in the specified fields of measurements. By applying the recommendations presented in this document laboratories can produce calibration results that can be recognized and accepted throughout Europe. The approaches taken are not mandatory and are for the guidance of calibration laboratories. The document has been produced as a means of promoting a consistent approach to good measurement practice leading to and supporting laboratory accreditation.

Journal of Analytical Sciences, Methods and Instrumentation, 2012

NASA is developing the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission to provide accurate measurements to substantially improve understanding of climate change. CLARREO will include a Reflected Solar (RS) Suite, an Infrared (IR) Suite, and a Global Navigation Satellite System-Radio Occultation (GNSS-RO). The IR Suite consists of a Fourier Transform Spectrometer (FTS) covering 5 to 50 micrometers (2000 -200 cm -1 wavenumbers) and on-orbit calibration and verification systems. The IR instrument will use a cavity blackbody view and a deep space view for on-orbit calibration. The calibration blackbody and the verification system blackbody will both have Phase Change Cells (PCCs) to accurately provide a SI reference to absolute temperature. One of the most critical parts of obtaining accurate CLARREO IR scene measurements relies on knowing the spectral radiance output from the blackbody calibration source. The blackbody spectral radiance must be known with a low uncertainty, and the magnitude of the uncertainty itself must be reliably quantified. This study focuses on determining which parameters in the spectral radiance equation of the calibration blackbody are critical to the blackbody accuracy. Fourteen parameters are identified and explored. Design of Experiments (DOE) is applied to systematically set up an experiment (i.e., parameter settings and number of runs) to explore the effects of these 14 parameters. The experiment is done by computer simulation to estimate uncertainty of the calibration blackbody spectral radiance. Within the explored ranges, only 4 out of 14 parameters were discovered to be critical to the total uncertainty in blackbody radiance, and should be designed, manufactured, and/or controlled carefully. The uncertainties obtained by computer simulation are also compared to those obtained using the "Law of Propagation of Uncertainty". The two methods produce statistically different uncertainties. Nevertheless, the differences are small and are not considered to be important. A follow-up study has been planned to examine the total combined uncertainty of the CLARREO IR Suite, with a total of 47 contributing parameters. The DOE method will help in identifying critical parameters that need to be effectively and efficiently designed to meet the stringent IR measurement accuracy requirements within the limited resources.

Journal of Atmospheric and Oceanic Technology, 1999

There are many infrared radiometer systems available for the measurement of in situ sea surface skin temperature (SSST). Unfortunately, the marine environment is extremely hostile to optical components, and to ensure the accuracy of SSST measurements, an absolute calibration of instrumentation using an independent calibration reference is required both before and after any sea deployment. During extended deployments it is prudent to have additional regular calibration data to monitor instrument performance characteristics. This paper presents a design for an ambient temperature (278-325 K), wide aperture (100 mm), reference blackbody unit that may be used to calibrate a variety of sea-going infrared radiometer systems both in the laboratory and in the field. The blackbody consists of a spun copper cavity coated with well-characterized high emissivity paint (Mankiewicz Nextel Velvet Coating 811-21) immersed in a water bath that is continuously mixed using a strong water pump. The radiant temperature of the blackbody cavity is determined from the measured water bath temperature. Results derived from validation and intercomparison experiments show this blackbody design to be an accurate and reliable reference blackbody source. However, in order to ensure that the best possible calibration data are obtained, extreme care must be taken to ensure the accurate measurement of the water bath temperature, proper positioning of a radiometer in front of the cavity itself, and prevention of condensation on the cavity surface. Four blackbody units have been specifically built for the European Union combined action for the study of the ocean thermal skin (CASOTS) program. Using these units as reference radiance sources, the authors describe the strategy adopted and present results obtained from the CASOTS radiometer intercalibration experiment. These results highlight the need to obtain independent calibration data both before and after sea-going radiometer deployments and the need to standardize field radiometer calibration protocols.

Experimental Techniques, 2008

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