PWTAG recommend that photometers should be calibrated on a annual basis. Here at PASA were provide this service with independent calibration certification. We will collect the unit by a tracked courier and then deliver it back as part of the service. All major models of Palintest and Lovibond of photometers can be calibrated. Your instrument will be calibrated against laboratory standards whose values are traceable to National Standards. These tests are carried out in accordance with BS EN ISO 17025 : 2017 and a certificate of calibration will be sent on the return of each unit. For further information please contact.