• Guideline DAkkS-DKD-R 5-7 lays down minimum requirements for the calibration procedure and for the determination of measurement uncertainties when calibrating climatic chambers. • This guideline describes inter alia the objectives, procedures, and methods of calibration, and the uncertainty components involved. • The full text of this guideline is available as a PDF document on the home page of the Physikalisch-Technische Bundesanstalt (www.ptb.de --> Metro-logische-Dienstleistungen --> DKD --> Publikationen) and can be downloaded free-of-charge. Calibration of relative atmospheric humidity at nine points in the climatic chamber using precision measuring instrument ALMEMO® 710 11/2025 • We reserve the right to make technical changes. The ALMEMO® measuring system, comprising precision measuring instrument ALMEMO® 710, one humidity sensor, and eight temperature sensors, can be used to acquire all relevant measurable variables prevalent in the climatic chamber. The relative atmospheric humidity at the nine points in the climatic chamber is calculated in the ALMEMO® 710 itself. Climatic chambers can thus be calibrated in full and on site quickly and easily. Humidity is calculated in the ALMEMO® 710 on the basis of formulae as per Dr. Sonntag and the enhancement factor as per W. Bogel (correction factor Fw(t,p)) for real mixed gas systems). This substantially widens the measuring range and improves the accuracy of humidity variable calculations. The determination of the radiation influence on the air temperature measurement is done with 2 temperature sensors with different sensor surface (different emissivity e.g. stainless steel and PTFE). With an ALMEMO® double sensor the 2 temperatures can be measured simultaneously (additionally) with the 8 temperatures of the corner points. All values, both measured and calculated, are shown in a clear and easy-to-understand way on the ALMEMO® 710‘s large touch display. The ALMEMO® 710 also operates as a data logger. Measuring series can be saved either to the internal memory (capacity for over 400,000 measured values) or via the ALMEMO® memory connector to an SD card (capacity for several millions of measured values). WinControl can be used to display and document values e.g. as a line graphic - either online those measured values actually being acquired during a measuring operation or offline after a measuring operation those measured values previously saved. It also provides various evaluation and statistical functions.

Calibrating climatic chambers 11/2025 • We reserve the right to make technical changes. The ALMEMO® measuring system comprises: Precision measuring instrument ALMEMO® 710 10 inputs for any ALMEMO® sensors, atmospheric pressure sensor integrated in the measuring instrument. Precision measuring instrument ALMEMO® 710 including USB cable, mains unit, instrument case, and configuration software ALMEMO® Connect Precision measuring instrument ALMEMO® 510 Data acquisition system, PC control. 20 measuring inputs for any ALMEMO® sensors (expandable). ALMEMO® 510, data logger, data acquisition system with...

Calibrating climatic chambers Digital Pt100 psychrometer with DAkkS accredited calibration certificate Operative range 0 (no ice formation) to 90 °C, 10 to 100 % RH Built-in digital air pressure sensor: 700 to 1100 mbar The psychrometer is positioned at the center of the useful volume. From the measured values - dry temperature (t) and wet temperature (tw) - and atmospheric pressure (p) (atmospheric pressure sensor integrated in the ALMEMO® connector) we can calculate the relative humidity (Uw) at the center and the dewpoint (td). Digital Pt100 psychrometer FPAD 36-3 with ALMEMO® D6 connector,...

11/2025 • We reserve the right to make technical changes. Guideline DAkkS-DKD-R 5-7 The following section includes extracts from the guideline. Guideline DAkkS-DKD-R 5-7 Calibration of climatic chambers (...) The calibration of a climatic chamber determines any deviation between the values displayed by the chamber indicators and the climatological variables, air temperature and relative humidity, measured in those parts of the chamber volume provided for use or at individual points in the chamber volume. (...) The objectives of calibration are thus the following: Calibration of the indicators...