Where traceability for humidity measuring devices is required, DAkkS (DKD) certification is necessary. Such certification can only be provided by a DAkkS (DKD) accredited calibration laboratory. This accreditation includes not only the calibration, but applies also to the qualified personnel. In addition, the measurement uncertainties are also taken into account. These arise from all influencing variables such as precision of measurement equipment, temperature, type of connection, device-specific parameters and tolerance limits.
ISO certification is a reasonable alternative, provided that traceability is not required. Measurement values of humidity measuring devices are compared against a standard and deviations are documented and can be taken into account accordingly by the user. If the measured values lie outside the specification of the measurement instrument, calibration of the measurement instrument with subsequent recalibration and certification is recommended.