Reprint--Calibration, verification, calibration and calibration of instruments, difference and connection!

Source: Dinghua Instrument School

Instrument verification, calibration, calibration are static measurement process according to the cycle, daily work, due to the difference in understanding, often cause unnecessary trouble and consequences, Xiaobian today to take you to see, what are the differences and connections between calibration, verification, calibration and calibration.

In the daily work of dealing with instruments and meters, we often come into contact with the four terms calibration, verification, calibration and calibration, what is the difference and connection between the four?

Definition of calibration, verification, calibration, calibration

01 Calibration

Standard measuring instruments are used to test whether the accuracy (precision) of the instruments used meets the standards, and are generally mostly used for instruments with high precision.

Main Benefits:

Determine the input-output relationship of the instrument or measurement system, and assign the instrument or measurement system a graduation value;

Determination of static characteristics of an instrument or measurement system;

Eliminate systematic errors and improve the accuracy of instruments or systems;

Calibration is an important step that should not be overlooked in scientific measurements.

02 Verification

The legal metrology department or the legally authorized organization shall determine the activities in which the indication error of the measuring instrument meets the specified requirements through experiments and certificates provided in accordance with the verification procedures.

03Calibration

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 instrument or reference material, the standard equipment with higher precision verification qualification and the measured equipment are used to test the same measured object respectively, and a group of operations of the error of the measured equipment relative to the standard equipment are obtained, so as to obtain the corrected value of the indication data of the measured equipment.

04 Verification

In the absence of verification or calibration procedures, the self-calibration procedures prepared by the enterprise itself; It is mainly used for special measuring instruments, or hardware or software for measuring instruments and tests with relatively low accuracy.

The main differences between calibration, verification, calibration, and calibration

Calibration is a dynamic process that reviews the accuracy of the test equipment and eliminates the error in time during measurement; Verification, calibration, and calibration are static measurement processes that are carried out in cycles.

Verification and calibration are the two most important means of traceability of metrics, but there are big differences between them:

1. The purpose is different

The purpose of calibration is to evaluate the indication error of the measuring device against the measurement standard to ensure the accuracy of the measurement value, which belongs to a group of operations that trace the value from the bottom up.

The evaluation of this indication error should be made according to the calibration procedures of the organization, and the calibration cycle should be carried out, and the calibration record and calibration mark 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, which specifically guide the operation of the measurement process.

Purpose of Verification:

Mandatory comprehensive assessment of measuring devices. This kind of comprehensive evaluation belongs to the category of value unification, which is a top-down value transfer process. The verification shall assess whether the measuring instrument meets the specified requirements. This requirement is the margin of error specified in the Specification for Measuring Devices. Through verification, it is evaluated whether the error range of the measuring device is within the specified error range.

2. The object is different

The object of calibration is a measuring device that is not subject to mandatory verification. The measuring devices for non-compulsory verification in mainland China mainly refer to the measuring instruments used in large quantities 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 measurement device that is required to be verified by the Continental Metrology Law.

Article 9 of the Metrology Law of the People's Republic of China clearly stipulates: "The metrology administrative departments of the people's governments at or above the county level shall carry out compulsory verification of the public measuring standard instruments, the highest measuring standard instruments used by departments, enterprises and institutions, and the work measuring instruments used in the compulsory inspection catalogue of trade settlement, safety protection, medical and health care, and environmental monitoring." Those who fail to apply for verification in accordance with the provisions or fail to pass the verification shall not use it.

"The verification objects are mainly divided into three categories of measuring instruments:

(1) Measurement standards (including: international [measurement] standards and national [measurement] standards) ISO1OO12-1 "Quality Assurance Requirements for Measurement and Testing Equipment" is defined as: international [measurement] standards: "the measurement standards recognized by international agreements and used as the basis for the determination of all other measurement standards for the relevant quantities in the world." "National [measured] baseline: "A measure benchmark recognized by an official national decision as the basis for the determination of all other measurement standards for the quantity concerned." ”

(2) Metrology Standard The ISO1OO12-1 standard defines a [metrology] standard as: "a physical measure, measuring instrument, reference material, or system used to define, achieve, maintain, or reproduce a unit or one or more known quantities, and to transmit them to other measuring instruments by comparison" (e.g.:

a.1kg quality standard;

b. Standard gauge block;

c. 100Ω standard resistor;

d. Weston standard battery). ”

(3) The Continental Metrology Law and the detailed catalogue 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 care, and environmental monitoring shall be subject to compulsory verification." In this detailed catalog, it has been clearly stipulated that more than 60 kinds of measuring instruments are 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 are used for trade settlement, safety protection, medical and health care, and environmental monitoring, and are subject to compulsory verification." "This is the requirement to list more than 60 kinds of measuring instruments in the compulsory inspection catalog, only used in trade settlement and other four types of measuring instruments, which belong to the scope of compulsory verification. For measuring instruments that are included in the catalogue of more than 60 kinds of measuring instruments, but are not actually used in four types of fields such as trade settlement, they may not fall within the scope of compulsory verification.

Measuring devices outside the above three categories are subject to non-mandatory verification, i.e. calibration.

3. Different in nature

Calibration is not mandatory, it is a voluntary traceability behavior of the organization. This is a kind of technical activity, which can evaluate the indication error of measuring instruments according to the actual needs of the organization, and determine the process of determining the value of measuring instruments or reference materials. Organizations can prescribe calibration specifications or calibration methods based on actual needs. Define calibration cycles, calibration markings, records, etc. Verification is a mandatory law enforcement act, which belongs to the scope of legal measurement management, in which the verification procedures and agreement cycle are all carried out in accordance with the statutory requirements.

4. Depending on the basis

The main basis of calibration is the "Calibration Specification" formulated by the organization according to the actual needs, or refer to the requirements of the "Verification Regulations". In the "Calibration Specification", the organization stipulates its own requirements for calibration procedures, methods, calibration cycles, calibration records and identification. Therefore, the Calibration Specification is a guiding document for the organization and implementation of calibration.

The main basis for verification is the "Metrological Verification Regulations", which is a statutory technical document that must be complied with for the verification of measuring equipment. Among them, the verification cycle, measurement characteristics, verification items, verification conditions, verification methods and verification results of measurement and testing equipment are usually stipulated. Metrological verification regulations can be divided into three types: national metrological verification regulations, departmental metrological verification regulations and local metrological verification regulations. These regulations are metrology regulatory documents, which the organization does not have the authority to develop and must be developed by an approved authorized metrology department.

5. In different ways

The calibration can be carried out in the form of internal calibration, external calibration, or a combination of internal and external calibration. If conditions are available, the organization can use the internal calibration method to calibrate the measuring instruments, so as to save a large cost. Organizations should pay attention to the necessary conditions for internal calibration (internal calibration is very strict!). For example, calibration specifications or procedures must be prepared, calibration cycles must be specified, the necessary calibration environment and metrology personnel with a certain quality must be available, and the standard measuring instruments at least one level higher must be available, so that the calibration error can be reduced as much as possible. In most measurement areas, 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, calibration records and labeling should be regulated, among other things. The verification must be carried out at a qualified metrology department or a legally authorized unit. According to the current situation in the mainland, most production and service organizations do not have the qualification of verification, and only a few large organizations or professional metrology verification departments have this qualification.

6. The cycle is different

The calibration interval is determined by the organization itself according to the needs of the measuring instrument used. It can be calibrated periodically, irregularly, or before use. The calibration interval should be determined in such a way as to minimize the risk of the measurement equipment in use while keeping the calibration costs to a minimum. The calibration interval can be determined based on the frequency of use of the measuring instrument or the degree of risk. The verification cycle must be carried out in accordance with the provisions of the "Verification Regulations", and the organization cannot determine it by itself. The verification cycle is a mandatory constraint.

7. The content is different

The content and items of calibration are only to evaluate the indication error of the measuring device to ensure that the measurement value is accurate. The content of the verification is a comprehensive evaluation of the measuring device, which requires a more comprehensive and comprehensive assessment, in addition to including the entire content of the calibration, it is also necessary 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 verification methods of the measuring instrument, the verification cycle and the disposal of the verification results. The content of the calibration can be determined by the organization as needed.

8. Conclusions differ

The conclusion of the calibration is only to evaluate the measurement error of the measurement device to ensure that the measurement value is accurate, and does not require a pass or fail judgment. The results of the calibration can be given as a "Calibration Certificate" or "Calibration Report". The verification rules must be based on the "verification regulations" specified in the value error range, to give the measurement device qualified or unqualified judgment. Exceeding the limit of error specified in the "Verification Regulations" is unqualified, and within the specified range of error is qualified. The result of the verification is to give the "Certificate of Verification".

9. Legal efficiency is different

The conclusion of the calibration has no legal effect, and the "calibration certificate" given only indicates the error of the measurement value, which is a kind of technical document. The conclusion of the verification has legal effect and can be used as the legal basis for the verification of measuring instruments or measuring devices, and the "Certificate of Conformity" is a technical document with legal effect.

The connection of calibration, verification, calibration and calibration

Generally applicable principles of calibration, verification and calibration:

1. It belongs to the national compulsory verification catalogue and is submitted for inspection. Generally, to determine whether the instruments and equipment of the laboratory are to be verified, the following two conditions need to be met:

a. Instruments and equipment in the detailed catalogue of working measuring instruments for compulsory verification of the People's Republic of China;

b. The fields used are: trade settlement, security protection, medical and health care, and environmental monitoring.

2. If there is a JJG or JJF outside the national compulsory verification catalog, it can be submitted for inspection/calibration, or the enterprise has standard equipment, instruments and calibration methods, and can be calibrated by itself.

3. If there is no JJG and JJF, it will be verified by itself.