Calibration of climatic chambers according to DAkkS-DKD-R 5-7

The newly revised guideline DAkkS-DKD-R 5-7 serves to define minimum requirements for the calibration procedure and for the determination of measurement uncertainty in the calibration of climatic chambers. Among other things, it describes the aim of the calibration, the calibration methods, the calibration procedure and the uncertainty contributions. With the ALMEMO® data logger system, AHLBORN offers the optimum measurement technology for calibrations.

Calibration of the relative humidity at 9 points in the climatic chamber

With the ALMEMO® 710 data logger, a digital psychrometer and 8 temperature sensors, all relevant measured variables are recorded in the climatic chamber. The climatic chamber can be conveniently calibrated on site, as the relative humidity of the 9 points is calculated in the ALMEMO® measuring device itself. The latter is based on the formulas according to Dr. Sonntag, taking into account the enhancement factor according to W. Bögel (correction factor Fw(t,p) for real mixed gas systems). This significantly increases the measuring range and the accuracy of the humidity values.

The influence of radiation on the measurement of the air temperature is determined using 2 temperature sensors. These have different emissivities due to their different sensor surfaces. With an ALMEMO® double sensor, the 2 temperatures can be measured simultaneously (additionally) with the 8 temperatures of the corner points.

A digital Pt100 psychrometer is placed in the center of the useful volume. The relative humidity and dew point are determined from the measured values of dry temperature and wet bulb temperature together with the air pressure. All measured values and calculated values can be displayed directly on the user-friendly touch display of the ALMEMO® 710. At the same time, the ALMEMO® 710 works as a data logger, i.e. the measurement series are stored in the device. Either the internal memory with more than 400,000 measured values or an ALMEMO® memory plug (SD card) with several million measured values are available for this purpose.

The WinControl software is used to document and display the measured values (e.g. as a line graph) - online during the measurement or offline after the measurement. Various evaluation and statistical functions can also be selected. As an option, there is an assistant for calibrating climatic chambers with automatic, convenient evaluation and protocol generation.