Monitoring instruments in any application such as turbidity measurement require a periodical check for assuring correct measurement. Instruments with lower performance show significant drift that requires a regular calibration procedure, high quality monitors such as the AquaScat from SIGRIST-PHOTOMETER operate virtually drift free. However for quality assurance reasons there is often the need for checking of the performance as certified ISO 9001 operators typically prescribe mandatory verifications of their metering equipment.
More (PDF)...