Accredited calibration laboratory no. 2298

- Accredited calibration

Accredited calibration is conducted by a laboratory with valid certification issued by the appropriate accreditation authorities, such as ČIA. Calibration is then conducted in accordance with the calibration procedures approved by ČIA. The methods used are regularly validated, and interlaboratory comparisons with ČMI are conducted. Accredited laboratories are subject to certain control mechanisms, which are described and specified in detail in the Quality Guide. They are also annually assessed by accreditation authorities. Accredited laboratories comply with all the requirements and conditions in accordance with ČSN EN ISO/IEC 17025. Customers therefore obtain accurate, clear and reproduceable results.

- Unaccredited calibration

Unaccredited calibration is conducted in accordance with internal regulations only and the calibration laboratory incorporates only those control elements it considers necessary. No other control mechanisms are in place and the results may differ from the calibration conducted by an accredited laboratory.

Calibration of a measuring device is a set of procedures that compare the values from a measuring device and the known values of an etalon. 

Adjustment is a process that sets the output values of a measuring system to correspond to the etalon’s values with a defined accuracy. For example, device calibration can determine the error in a measuring device’s measurements. The adjustment process (using, for example, calibration constants) sets the device to indicate the real values at any given point.

Measurement deviation is the difference between the real value of the measured quantity and the value determined by measurement (etalons).

Measurement uncertainty is a parameter attached to a measurement result. It characterizes the dispersion of the values that could be justifiably assigned to a measured quantity. Measurement uncertainty is affected by individual sources that move the measured value away from the real value (unsuitable device selection, poor procedure, linearization, approximation, impact of the surrounding environment, etc.). The final uncertainty therefore consists of several partial uncertainties.

Calibration at a single spatial point

This type of calibration is the most commonly executed. The sensor is placed at the centre of a device’s space, and the result represents the deviation of the parameters entered on the displaying device from the value measured using the etalon and has a certain measurement uncertainty.    

Calibration in homogenous space

Homogeneous measurements explore the temperature and humidity distribution in a previously defined space. The measurement result is a temperature and humidity map of the device’s space, where the deviations at individual spatial locations are clearly visible. Measurements in homogeneous space are based on the standard ČSN EN 60068-3-5, which specifies not only the distances between individual sensors, but also their number (depending on the chamber size).

Yes, one person may conduct calibration and adjustment in a single test, provided they have been sufficiently trained. However, the device adjustment procedure requires additional time, which means a higher price (calibration of each unit – adjustment – recalibration of the given value).

The temperature stabilization time interval is very important and has a fundamental impact on the final measurement result. Devices that generate heat and humidity do not maintain their values linearly but oscillate instead according to a sinusoid. The difference between the min. and max. measured values is greater at the beginning than after a longer time interval. A longer stabilization time and therefore a reduction of the difference strongly influences the corresponding measurement uncertainty and the entire calibration result = a more accurate and better result.

Each calibration interval is selected by the user according to their conventions. Only when the measuring device is designated as a specific measuring device is the verification time defined by Regulation No. 345/2002 Coll.

Generally, this interval is recommended at one year for devices that are used often and two years for devices used less often.

It depends on the device’s manner of use. If it is not necessary to know individual deviations in a given space, you can opt for calibration at a single point in the centre of the given space. If it is necessary to know the individual deviations in a device’s space, calibration using a homogeneous space is recommended. Homogeneous calibration is generally recommended for chambers with a volume of more than 2000 litres.