Verification of vacuum pressure gauge and calibration of pressure gauge
1. Similarities between pressure gauge verification and pressure gauge calibration
Pressure gauge verification and pressure gauge calibration ⑴ are both the evaluation forms of measuring instruments and the two most important ways to ensure the correct indication of instruments.
Pressure gauge verification and pressure gauge calibration (2) are activities to achieve unity of units and accurate and reliable values, that is, they belong to the measurement category.
Pressure gauge verification and pressure gauge calibration ⑶ In most cases, both are conducted according to the same measurement procedure.
2. Differences between pressure gauge verification and pressure gauge calibration
Pressure gauge verification and pressure gauge calibration ⑴ The legal constraints of pressure gauge verification and pressure gauge calibration are different. Verification is legal and belongs to the law enforcement of metrological management. The object of verification is measuring instruments within the scope of legal management. The personnel shall obtain the verifier's certificate issued by the relevant metrological administrative department. The fees collected shall comply with the provisions of national laws and regulations. Both compulsory verification and non compulsory verification belong to legal verification. Compulsory verification is mandatory. However, calibration is not mandatory. It is a voluntary act of users. The scope of services and service charges are determined by mutual agreement.
Pressure gauge verification and pressure gauge calibration ⑵ The basis for pressure gauge verification and pressure gauge calibration is different. The verification must be carried out in accordance with the verification regulations, and the verification institution must make a conclusion on whether the tested instruments are qualified or not. Calibration standards, calibration methods or other technical documents agreed by both parties can be technical rules, specifications or customer requirements, or can be formulated by the calibration agency itself. Generally, the calibration agency does not need to make a declaration of conformity. The user of the measuring instrument will evaluate the calibrated object according to the calibration results, and if necessary, determine whether a certain performance of the calibrated object meets the expected requirements.
Pressure gauge verification and calibration (3) Pressure gauge verification and pressure gauge calibration are to ensure the accuracy and consistency of the measurement values. Verification is to transfer the measurement values reproduced by the national measurement standards to the measurement standards at all levels and ordinary measuring instruments level by level from the top to the bottom. Calibration is to trace the measurement values to the national standards from the bottom to the top, which can be bypassed. Users can choose the laboratory, time and method for providing traceability services according to their needs.
Pressure gauge verification and pressure gauge calibration (4) The items verified are more than those calibrated. The verification consists of qualitative test and quantitative test, which is a comprehensive assessment of the measurement characteristics of measuring instruments and the compliance with technical requirements. Generally, calibration only involves quantitative test and only evaluates the indication error.
Pressure gauge verification and pressure gauge calibration (5) The form of result report is different. Verification certificate or verification result notice shall be issued for verification, and calibration certificate is usually issued for calibration. According to the provisions of ISO/IEC17025:1999, the uncertainty of measurement results may not be given for technical basis such as regulations, so the verification certificate generally only provides the maximum allowable error or error limit, and does not give the measurement uncertainty of measurement results. In order to provide a quantitative statement on the correctness of the measurement results obtained by the measuring instrument, calibration needs to enable users to establish the reliability of the measurement results obtained by calibration by establishing measurement traceability and providing measurement uncertainty.
