First, send the instrument manufacturer's calibration requirements to a third-party calibration agency so that the third-party calibration agency can confirm whether it has calibration capabilities (required by ISO/IEC 17025:2005 standard 4.4). Whether the calibration certificate of an authoritative third-party metrology calibration institution is recognized by the auditor depends on whether the defined calibration requirements comply with the definition of the testing standard/method, and whether the results of the calibration parameters comply with the specifications defined in the testing standard/method. If they are both satisfied, the on-site auditor will not question their traceability activities, but will at most confirm the evaluation activities of the selected calibration body (the supplier's evaluation activities). Since the calibration institution is a laboratory and is also bound by the CNAS accreditation rules, the calibration institution will not take the risk of issuing a calibration report that does not comply with the accreditation rules. Calibration Certificate Secondly, when determining whether the calibration supplier's range meets the laboratory's requirements, common practice is to compare the equipment name and measurement parameters with the calibration supplier's CNAS range. If the equipment being calibrated is outside the scope of the calibration laboratory, measurements are usually made according to the properties to which the equipment belongs. For example: digital multimeter, the scope of the calibration laboratory is current, voltage, etc. But the supplier only wanted to measure the pen tip of the digital multimeter, and the pen tip was not within the parameters of the calibration laboratory's digital multimeter. Generally, if the calibration laboratory has the ability to measure pen tips, then the other party will choose the corresponding pen tip measurement rules to measure the equipment, so there will be no problem. What qualifications are required for a third-party calibration organization? The important qualification of a third-party calibration organization is CNAS, which is also the basis of a third-party calibration organization. There are two types of laboratories accredited by CNAS. One is the calibration laboratory, which issues calibration certificates. The seal on the certificate is the "Special Calibration Seal". The other is a testing laboratory, which issues a test report or test report with a "special seal for testing". Both CNAS accredited laboratories can perform instrument calibration, and their reports are approved by auditors.