The difference of calibration, verification, calibration and verification of medical metrology
The meaning and difference of calibration, verification, calibration and verification
1、 Meaning of calibration:
The use of standard measuring instruments to test the accuracy (precision) of the instruments used is generally used for instruments with high precision.
The main functions are as follows：
（1）Determine the input-output relationship of the instrument or measuring system, and assign the graduation value of the in）strument or measuring system;
（2）Determine the static characteristic index of the instrument or measuring system;
（3）Eliminate system error and improve the accuracy of instrument or system;
（4） Calibration is an important step in scientific measurement;
2、 Meaning of verification:
When there is no relevant verification regulation or calibration specification, it is a way to implement value transfer traceability according to the method prepared by the organization. It is mainly used for special measuring instruments or measuring instruments with relatively low accuracy and test hardware or software.
3、 Meaning of verification:
According to the verification regulation, the Legal Metrology Department or the legally authorized organization shall provide proof through experiments to determine that the indication error of measuring instruments meets the specified requirements.
4、 Meaning of calibration:
Under the specified conditions, in order to determine the indication value of the measuring instrument or measuring system or the indication value represented by the physical measuring tool or reference material, the standard equipment and the measured equipment with higher accuracy are used to test the same measured object respectively, and a group of operations for the error of the measured equipment relative to the standard equipment are obtained, so as to obtain the correction value of the indication data of the measured equipment.
5、 Main differences between calibration and verification, calibration and calibration
（1） Calibration is a dynamic process of checking the accuracy of test equipment and eliminating the error in time.
（2） Verification, calibration and calibration are static measurement process according to cycle.
6、 Main differences between verification and calibration
（1） Different purposes
The purpose of calibration is to evaluate the indication error of the measuring device according to the measurement standard, so as to ensure the accuracy of the measurement value. It belongs to a group of operations of traceability from bottom to top.
The evaluation of the indication error should be made according to the organization's calibration procedures, according to the calibration cycle, and the calibration records and calibration marks should be made.
In addition to evaluating the indication error of the measuring device and determining the relevant metrological characteristics, the calibration results can also be expressed as correction values or calibration factors to specifically guide the operation of the measurement process. For example, the calipers used by a machining organization are found to be 0.2mm larger than the metrological standards through calibration, which can be used as the correction values, Mark the calibrated value 0.2mm larger than the standard value in the calibration mark and record. In the process of using this measuring instrument (caliper) for physical measurement, subtracting the correction value larger than 0.2mm is the measured value of physical measurement. As long as we can achieve the purpose of traceability and clearly understand the indication error of measuring instruments, that is to say, the purpose of calibration is achieved.
Verification purpose: to carry out compulsory comprehensive evaluation on measuring devices. This kind of comprehensive evaluation belongs to the category of quantity value unification and is a top-down quantity value transfer process. The verification shall assess whether the measuring instruments meet the specified requirements. This requirement is the error range specified in the verification regulation of measuring devices. Through verification, evaluate whether the error range of the measuring device is within the specified error range.
（2） Different objects
The object of calibration is the measuring device which belongs to the compulsory verification. The measuring devices of non compulsory verification in China mainly refer to the measuring instruments widely used in the process of production and service provision, including the measuring instruments used in incoming inspection, process inspection and final product inspection.
The object of verification is the measuring device which is required to be verified by China's metrology law《 Article 9 of the Metrology Law of the people's Republic of China clearly stipulates: "the metrological administrative departments of the people's governments at or above the county level shall carry out compulsory verification on the public standard instruments of measurement, the highest standard instruments of measurement used by departments, enterprises and institutions, as well as the working measuring instruments listed in the catalogue of compulsory inspection for trade settlement, safety protection, medical and health, and environmental monitoring. Those who fail to apply for verification or fail to pass the verification shall not be used. "
Therefore, the objects of verification are mainly three categories of measuring instruments
1. Measurement basis
(including: International [measurement] benchmark and national [measurement] benchmark) ISO10012-1 "quality assurance requirements for measurement and testing equipment" defines international [measurement] benchmark: "the measurement benchmark recognized by international agreement as the basis for setting the value of all other measurement benchmarks of relevant quantities in the world." National [measurement] benchmark: "the measurement benchmark recognized by the national official decision as the basis for setting the value of all other measurement standards of relevant quantities in China.
2. [measurement] standard ISO10012-1 defines "measurement] standard as:" a physical measuring tool, measuring instrument, reference material or system (for example, a.1kg quality standard) used to define, realize, maintain or reproduce a unit or one or more known quantity values, and transfer them to other measuring instruments through comparison; b. Standard gauge block; c.100 Ω Standard resistance; d. Weiss... "Standard battery."
3. China's metrology law and the detailed items of working measuring instruments for compulsory verification of the people's Republic of China stipulate that "all those used for trade settlement, safety protection, medical and health, and environmental monitoring shall be subject to compulsory verification."
In this detailed catalogue, 59 kinds of measuring instruments have been listed in the scope of compulsory verification. It is worth noting that the second paragraph of the "detailed catalogue" clearly emphasizes that "all items in this catalogue, which are used for trade settlement, safety protection, medical and health, and environmental monitoring, are subject to compulsory verification." This is the 59 kinds of measuring instruments required to be listed in the compulsory inspection catalogue. Only the measuring instruments used in four fields, such as trade settlement, belong to the scope of compulsory verification. Although it is listed in the catalogue of 59 kinds of measuring instruments, the measuring instruments that are not actually used in the four fields of trade settlement may not be included in the scope of compulsory verification. Measuring devices other than the above three categories belong to non compulsory verification, that is, the scope of calibration.
（3） Different in nature
Calibration is not mandatory, and it belongs to voluntary traceability. This is a kind of technical activity, according to the actual needs of the organization, the indication error of measuring instruments can be evaluated, which is the process of setting the value of measuring instruments or reference materials. The organization can specify calibration specifications or calibration methods according to actual needs. Self defined calibration cycle, calibration mark and record, etc...
Verification is a compulsory law enforcement behavior, which belongs to the scope of legal metrology management. The agreement period of verification regulation and so on are all carried out according to the legal requirements.
（4） The basis is different
The main basis of calibration is the "calibration specification" formulated by the organization according to the actual needs or in accordance with the requirements of the "National Metrology Technical specification" (JJF). In the calibration specification, the organization shall specify the requirements of calibration procedures, methods, calibration cycle, calibration records and identification. Therefore, the "calibration specification" is a guiding document for the organization to implement calibration.
The main basis of verification is the national metrological verification regulation (JJG), which is the legal technical document that must be observed in the verification of measuring equipment. Among them, the verification period, measurement characteristics, verification items, verification conditions, verification methods and verification results of measurement and detection equipment are usually specified. Metrological verification regulation can be divided into national metrological verification regulation, Department metrological verification regulation and local metrological verification regulation. These procedures belong to the metrological regulatory documents, and the organization has no right to formulate them. They must be formulated by the authorized metrological department.
（5） In different ways
The calibration method can be self calibration, external calibration, or the combination of self calibration and external calibration.
If the organization has the conditions, it can use the self calibration method to calibrate the measuring instruments, so as to save more cost.
The organization should pay attention to the necessary conditions for self calibration, instead of relaxing the requirements for the management of measuring instruments. For example, it is necessary to prepare calibration specifications or procedures, specify the calibration cycle, have the necessary calibration environment and measurement personnel with certain quality, and have at least one level higher standard measuring instruments, so as to reduce the error of calibration as much as possible (in most measurement fields, The measurement error of the standard should not exceed 1 / 3 to 1 / 10 of the error of the confirmed equipment in use).
In addition, the calibration record and identification should also be specified. Through the above provisions, to ensure the accuracy of the measurement value.
The verification must be carried out in a qualified measurement department or a legally authorized unit. According to the current situation in China, most of the production and service organizations do not have the qualification, only a few large organizations or professional metrological verification departments have this qualification.
（6） The cycle is different
The calibration cycle is determined by the organization according to the needs of using measuring instruments. It can be calibrated regularly, irregularly or before use. The principle of determining the calibration cycle should be to minimize the risk of measuring equipment in use while maintaining the minimum cost of calibration. The calibration cycle can be determined according to the frequency or risk degree of measuring instruments.
The verification period must be carried out according to the regulations of verification regulation, and the organization cannot determine by itself. The verification period belongs to the content of compulsory restriction.
（7） The content is different
The contents and items of calibration are only to evaluate the indication error of the measuring device, so as to ensure the accuracy of the measurement value.
The content of verification is the comprehensive evaluation of the measuring device, which requires more comprehensive, in addition to all the contents of calibration, it also needs to verify the relevant items.
For example, the verification content of a certain measuring instrument should include the technical conditions, verification conditions, verification items and methods, verification cycle and disposal of verification results. The content of calibration can be determined by the organization according to its own needs. Therefore, according to the actual situation, verification can replace verification, but calibration cannot replace verification.
（8） The conclusion is different
The conclusion of calibration is only to evaluate the measurement error of the measuring device to ensure the accuracy of the measurement value, and it is not required to give the judgment of qualified or unqualified. The results of calibration can be provided with calibration certificate or calibration report.
The verification must be based on the measurement error range specified in the verification regulation to determine whether the measuring device is qualified or unqualified. It is unqualified if it exceeds the range of measurement error specified in verification regulation, and qualified if it is within the range of measurement error specified. The result of verification is to give the certificate of verification.
（9） The legal effect is different
The conclusion of calibration has no legal effect. The calibration certificate just indicates the measurement error, which belongs to a kind of technical document.
The conclusion of verification has legal effect and can be used as the legal basis for the verification of measuring instruments or measuring devices. The verification certificate is a technical document with legal effect.
7、 The general selection methods of calibration, verification and calibration are as follows:
1. It belongs to the national compulsory verification catalogue and is submitted for inspection;
2. If there is JJG or JJF outside the national compulsory verification catalogue, it can be sent for inspection / calibration, or if the enterprise has standard equipment, apparatus and calibration method, it can conduct self calibration;
3. If there is no JJG and JJF, self check.
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