How often have the calibration filters to be recalibrated?
To check the correctness of the values given on the certificate, the calibration standards should be recalibrated at regular intervals. The periodicity of these intervals should be determined by the user and depends on the laboratory environment and the conditions of use, just like the total lifetime of the filters. To define a statistical basis for establishing the recertification interval it is recommended to have all calibration standards recalibrated every 12 months in the first two years of use. Afterwards an interval of recalibration should be chosen which seems to be suitable based on the values obtained this way.
