A Comparison of Climatic Chamber Hygrothermal Characterization Techniques as Described in IEC60068.

Techniques for the evaluation of the spatial temperature and humidity performance criteria of climatic chambers are described within the various sections of the International Electrotechnical Commission (IEC) Standard IEC60068 applicable to environmental testing. This paper involves the comparison of three common measurement systems used to assess the performance of climatic chambers, as well as the development of methods for determination of uncertainty contributions, and subsequent propagation into an uncertainty analysis for each method. Methods for validating the performance of these chambers should include specific uncertainty contributions, such as fluctuations, homogeneity, radiation, sampling, and loading effects. These effects are discussed and evaluated as part of this work. The procedure, as detailed in IEC60068, was followed using a chilled-mirror dew-point hygrometer with nine platinum resistance thermometers, nine calibrated RH (relative humidity) and temperature probes, and nine calibrated RH and temperature wireless data logger modules. Loading effect and dew-point uniformity were evaluated empirically and the results discussed. A summary of the results obtained and the associated uncertainty calculations are described and compared. All three systems have their merits, and lower uncertainties in both temperature and %rh were obtained for the chilled-mirror system. [ABSTRACT FROM AUTHOR]