On the control of the measurement characteristics of calibration laboratory instruments - Database & Sql Blog Articles

<9.0pt> Instrument Calibration Lab is passed

CNAS (

China National Conformity Assessment Committee

)

It is recognized that the calibration reports or data issued by accredited laboratories are subject to international mutual recognition. With the development of laboratory accreditation, the instrument as an important tool for conducting calibration activities is the material basis for the operation of the entire calibration laboratory system. Whether the management of the instrument is scientific and effective directly affects the smooth development of the instrument calibration work and the laboratory system. The normal operation. And the instruments in the instrument calibration laboratory are all measuring instruments or measuring instruments. As a standard measuring tool, they are widely used in various fields of production and scientific research.

Instrument measurement

In order to achieve accurate and reliable measurement results, the measuring instrument must have the required metering characteristics.

1

Measurement characteristics and quantity transfer of measuring instruments

The metering characteristic of the instrument is to carry out the quantity transfer activity.

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Mainly including instrument verification or

Instrument calibration

The basic characteristics of the measurement are important characteristics that affect the measurement results, including the sensitivity, stability, resolution, measurement uncertainty, and accuracy level of the instrument. The following is a combination of practical work, talk about the relationship between the measurement characteristics of the measuring instrument and the value transfer.

1.1

Measurement uncertainty and accuracy level

The measurement uncertainty of an instrument is the component of the measurement uncertainty caused by the measuring instrument or measurement system used. The magnitude of the uncertainty is determined by the measuring instrument itself. The uncertainty of a general measuring instrument can be obtained by passing the value of the previous standard. The accuracy level, as the name implies, reflects the accuracy of the measuring instrument and refers to the level or level of the measuring instrument or system that keeps the measurement error or instrument uncertainty within specified limits. In the technical specifications on which the volume transfer activities are carried out, the accuracy level of the measuring instruments is generally clearly defined, and the accuracy level is also an indispensable technical indicator in the traceability table.

1.2

Indication error and maximum allowable error

The indication error is one of the most important measurement characteristics of the measuring instrument. It indicates the difference between the output value of the measuring instrument and the standard value of the input quantity. It reflects the accuracy of the measuring instrument, the indication error is large, and its accuracy is low. If the indication error is small, its accuracy is high, and its size is usually given by the upper standard value. The maximum allowable error refers to the allowable error limit value specified in the technical specification. The indication error is compared with the maximum allowable error to determine whether the maximum allowable error is met. It is the indication error of the measuring instrument in the instrument verification certificate. Qualified standards.

2

Control and maintain the metering characteristics of the instrument

2.1

Strengthen the quality of personnel

As the main body of the operation of the entire calibration laboratory system, personnel act on the equipment from the aspects of equipment purchase, acceptance, use and maintenance, directly or indirectly affecting the state of the instrument.

First of all, to strengthen the management of personnel, the calibration organization must clarify the qualifications and responsibilities of personnel, and the personnel must have the corresponding capabilities and conditions, especially as laboratory calibrators and instrument administrators. The performance, measurement characteristics and related measurement of the instrument itself should be performed. Management knowledge, etc. should have an in-depth understanding

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Secondly, the study and assessment of relevant systems and operational norms are also important measures to improve the professional quality of technical management personnel and reduce negligence in the operation process.

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In addition, relevant personnel should continue to improve their knowledge and adaptability through continuing education and training to meet the needs of equipment renewal and technology development.

2.2

Control environmental conditions

The environment is one of the main factors affecting the metering characteristics of the instrument, mainly reflected in the two aspects of the use and storage of measuring instruments. The amount of recurrence of many measuring standard instruments must be guaranteed in a certain environment to achieve the specified accuracy. Some calibration results are corrected according to the parameters of the environmental conditions. Sometimes, if the environmental impact is not controlled, it will directly affect the measurement characteristics of the measuring instrument, resulting in inaccurate calibration results. Therefore, the calibration site must be monitored according to the calibration specifications for environmental conditions such as temperature and humidity, air pressure, noise, vibration, etc., and equipped with environmental monitoring equipment, such as temperature and humidity meter, barometer, sound level meter, etc.

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Sometimes there are situations in which different experimental project conditions conflict with each other. For example, when calibrating the vibration test rig, severe vibrations are generated. Strong vibrations will have a great influence on the balance, and measures must be taken to effectively isolate them. Compared with the environmental control during the use of the measuring instrument, the storage state of the instrument is in a relatively stable indoor environment, which is more conducive to the maintenance of the metering characteristics of the instrument. It is also essential for indoor environmental monitoring. First, the hardware configuration must be guaranteed. Environmental control requirements, such as equipped with necessary monitoring equipment, some moisture-proof, dust-proof, anti-vibration isolation treatment for some high-precision instruments

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Improve environmental monitoring procedures, develop different environmental control procedures for different measurement instruments' own performance and measurement characteristics, and form a document record

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Equipped with a full-time instrument administrator, and the administrator must have the necessary expertise and quality. The transportation of the instrument is often a neglected part of the instrument's measurement management. When carrying out the outbound calibration activities, the transportation of the instrument is inevitable. The storage of the instrument during transportation, in addition to eliminating some interference factors such as temperature and humidity, electromagnetic, etc. Taking into account the impact of bumps on the instrument during driving, such as some high-precision balances, platform scales, etc., anti-vibration treatment should be done in advance.

2.3

Perfect system

Management is inseparable from the management system.

CNAS-CLO1

The Test and Calibration Laboratory Capability Recognition Guidelines are currently internationally tested.

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The general guidelines for calibration laboratories, so any relevant management system must be based on the requirements and requirements of the guidelines. On this basis, the complete quality management system should also determine the objectives and requirements of the instrument management in each link. From the purchase to the final scrap, all the links may have uncertain factors affecting the metering characteristics of the instrument, so the sound system documents

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Quality manual, program documentation, and various work instructions, etc.

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To determine the measures for supervision and control of each stage and each link, the operation of the system and the management of the instrument cannot be relied upon, and there are systems to follow, to achieve the purpose of instrument management, and to control and maintain the metering characteristics of the instrument.

2.4

Technical means control

In addition to the above several control elements, maintaining the metering characteristics of the instrument must also be controlled by effective technical means. The management of the calibration laboratory instruments mainly includes

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Periodic verification

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Calibration, measurement instrument verification, interlaboratory comparison, measurement review, and capability verification.

In summary, the control elements that maintain the metering characteristics of the instrument mainly include personnel, documents, environment, and technology. The four elements are independent and related to each other.

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Shown.

2.5

Other means of supervision

In addition to the measurement management of measuring instruments, the necessary supervision means are also indispensable.

CNI15

Regular or irregular capacity assessment by the review team

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Supervisory review, review, etc.

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Regular internal audits of the laboratory. Through the internal supervision and external supervision complement each other, the problems found in the management and use of the instrument during the audit are promptly rectified and improved, so as to achieve the purpose of effectively controlling and maintaining the metering characteristics of the instrument.

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Conclusion

As an important tool for the calibration laboratory to carry out calibration activities, the reliability of the measurement characteristics affects the credibility of the calibration results. Once the measurement characteristics are changed and lost, the accuracy of the calibration results will be directly affected. Therefore, strengthening the metering management of the instrument and effectively controlling and maintaining the metering characteristics of the instrument are necessary prerequisites for the laboratory to carry out the calibration work. All in all, a correct understanding of the measurement characteristics of the measuring instrument, a comprehensive analysis of the factors affecting its measurement characteristics, combined with effective means to control, can not eliminate the unfavorable factors, keep the metering characteristics of the instrument constant and reliable.