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Whether the unit that purchased the verification/calibration certificate issued by the instrument is a qualified supplier;
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Whether the instrument supplier has done supplier evaluation;
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The purchased instrument should communicate the certificate requirements with the user unit, such as range, accuracy, etc.;
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To check the authenticity of the certificate, you can quickly locate each institution through the menu in the URL query of the measurement forum;
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Whether all of the above problems occur, the process of our measurement confirmation is as follows:
(1) Confirmation of the capability of metrology technical institutions
The qualifications of calibration/verification institutions should be reviewed before equipment traceability to ensure that they meet the requirements. After the equipment is returned, verify again according to the standard technical indicators (parameters and their uncertainty, accuracy level or maximum allowable error), calibration/verification method, measurement result uncertainty and whether the standard is within the validity period as reflected in the certificate. its calibration capability.
(2) Confirmation of the basic information of the traceability certificate
First check whether the agreed source tracing method is adopted. The commonly used traceability methods mainly include calibration and verification. Equipment users should understand the difference between calibration and verification and choose the correct method.
Secondly, check the basic information of the certificate. The basic information of the certificate includes the certificate unit name, address, basic equipment information (name, specification, serial number, manufacturing unit, etc.), equipment receiving date, calibration date, certificate issuance date, calibration location, contact information, etc. The information should be consistent with reality and be complete and correct.
(3) Confirmation of environmental conditions and technical basis for calibration/verification
Environmental conditions for calibration/verification, such as temperature, humidity or other special requirements, whether the information is reasonable. Whether the technical basis is applicable and the latest valid version.
(4) Confirmation of traceability certificate verification or calibration results
In the case of a certificate of verification, the conclusion shall be a conforming or reporting device's accuracy rating. The user of the equipment should judge whether it meets the intended use according to the equipment use requirements; if it is a certificate of unqualified verification or a notification of verification result, it is necessary to choose debugging, repair and recalibration/re-verification according to the specific situation.
The calibration certificate does not give a conclusion of whether it is qualified or not. The user should make a judgment on whether the results meet the expected use requirements, that is, whether the calibration parameters, calibration points and calibration results meet the expected use requirements. Measurement uncertainty may need to be considered at this point. When the indication error of each point does not exceed the maximum allowable error, the equipment can be used within this range. In addition, other metrological characteristics reflected in the calibration results, such as resolution, detection limit, repeatability, etc., should also meet the requirements for use. The uncertainty of the calibration result should be reported separately for different calibration parameters and different measurement points, and the number of significant digits should not be more than two.
(5) Confirmation of calibration/verification cycle
The verification cycle on the traceability certificate must comply with the corresponding verification regulations. Generally, the calibration does not give the next recommended calibration date. If the customer has a demand, the proposed next calibration date generally does not exceed the time limit required by the corresponding technical specifications. For the confirmation of the calibration certificate, the calibration cycle is recommended to be presented on the confirmation record, which is convenient for the implementation of the next calibration plan, and the user can also adjust the calibration cycle according to the conditions of the equipment.
