Juliano Augusto Dillenburg - dill@mecanica.ufrgs.br
Universidade Federal do Rio Grande do Sul, Departamento de Engenharia Nuclear
Av. Osvaldo Aranha 99, 4º andar, CEP: 90460-900 Porto Alegre, RS, Brasil.

Milton Antonio Zaro - zaro@mecanica.ufrgs.br
Universidade Federal do Rio Grande do Sul, Departamento de Engenharia Mecânica
Rua Sarmento Leite, 425, CEP: 90050-170, P. Alegre, RS, Brasil.

Horácio Antonio Vielmo - vielmoh@mecanica.ufrgs.br
Universidade Federal do Rio Grande do Sul, Departamento de Engenharia Mecânica
Rua Sarmento Leite, 425, CEP: 90050-170, P. Alegre, RS, Brasil.

Calibration and characterization procedures for single waveband infrared pyrometers are proposed. Regardling the fact that doesn't exist a brazilian normatization and  the fact that the international normatization ASTM E1256-95 is incomplete, it's expected that these considerations will produce a discussion about the creation of a brazilian normatization for the use of such technique.

Keywords: Calibration, Temperature, Pyrometry, Emissivity, Radiation.
 
 

HELBER S.HUAQUIPACO - e-mail sucah@hotmail.com
ALCIR F.ORLANDO - e-mail afo@mec.puc-rio.br
Pontifícia Universidade Católica do Rio de Janeiro - PUC-Rio
Departamento de Engenharia Mecânica
R.Marquês de S. Vicente 225, Gávea, 22453-900, Rio de Janeiro, Brasil

ALBERTO J.F.Orlando - e-mail albfrida@directnet.com.br
Instituto Tecnológico de Aeronáutica
Departamento de Engenharia Eletrônica

LUIZ C.CIPRIANO -
INMETRO

The water content in air or in other gases is important for controlling biological, chemical and physical processes, Measurements are made in industry within a wide range of humidity. They contribute to the composition of the final cost and quality of products, health and safety. The present work deals with a measurement technique for the water content in air. The resonance frequency of a rectangular cavity, designed for a fundamental frequency of 2,45 GHz (dry air), was measured by a spectrum analyser for different values of the water content. A standard dew point apparatus was used in INMETRO for measuring the partial pressure of water vapor in air inside the cavity. The partial pressure of water vapor in air was calculated by na existing theory as a function of temperature and resonance frequency of the cavity, and it was compared to the measured one. The resulting second degree polynomial curve fit between the two values reflects the deviation from ideality of the real cavity, suggesting that all cavities should be calibrated before being used. The uncertainty of measurement was estimated together with the influence of several parameters on the equipment response, which was compared to the available ones. This completes the metrological qualification of the device. As a result, it was demonstrated that the uncertainty of the dew point measurement by the standard apparatus is the parameter that mostly affects the overall uncertainty of the calibration.