Metrological instruments are an important means of assessing various indicators. Measuring instruments that are used in everyday life and in production are able to reflect accurate readings only under condition of serviceability. Moreover, the state of the measuring tool can not always be estimated by simple technical methods. As a rule, metrological verification is performed for this, as a result of which experts determine the main indicator of the health of such devices - the error.
Who carries out the verification?
To carry out such activities, metrological services are assigned, the list of tasks of which includes ensuring the uniformity of measurements. They organize and provide services in the form of verification studies at the expert level. The regions have structural units of the central metrological apparatus. These bodies accept applications for examinations or carry out planned activities aimed at ensuring the unity of measurement parameters. For example, metrological calibration of meters is one of the most common. This operation is carried out jointly with utilities without fail at intervals determined by local service organizations. Representatives of services in expert analyzes rely on a single base of standards, in accordance with which the quality of work of measuring instruments is evaluated.
What tools are subject to examination?
Metrological services work in all areas covered by modern measuring instruments. The most common are instruments for measuring the physical characteristics of a person, optical data, radiation, etc. Instruments should be included in the register provided for by the state metrological supervision. At the same time, metrological verification is often carried out jointly or with the support of other departmental bodies or administrative services and departments.
It has already been said about utilities, which can organize and regulate the verification procedures of meters, but similar cooperation also takes place in other industries. For example, a whole segment of measuring instruments is used in environmental surveillance. Another thing is that different characteristics are evaluated. So, the correctness of measuring the delivery volumes of a liquid carrier is an object that is evaluated by the verification of water meters. The metrological service dealing with sound level meters, in turn, evaluates the quality of measurement of acoustic waves. That is, each device has its own specifics for evaluating the characteristics.
Verification procedure
The rules for organizing verifications are regulated by the executive authority. The order of the event is fixed in the regulatory documentation and serves as a kind of instruction for compliance by metrological supervision authorities. Moreover, in each case, the commission itself can establish the best verification methods. For example, metrological verification of water meters involves the implementation of several stages. First of all, the representative of the service performs an external inspection, identifying possible external or visible defects of the device. Next, the meter is tested in working condition. After that, the specialist proceeds to assess the error of the device. At this stage, various auxiliary tools may be used. For example, it can be measuring stations with optimal accuracy indicators. Against the background of the indications of the reference settings, the error of the estimated counter is recorded.
Verification Method Requirements
State regulation of the unity of measuring units also approves a list of methods that are allowed for examination. The only exceptions are those calculated for direct measurements using instruments of an approved type, which have also been verified. Regardless of the measurement method, the final result should be expressed in quantities that are approved for use in the field of state metrological regulation. In fact, any method that meets established requirements can be used. For this kind of confirmation of conformity, controls are subject to certification. In the future, using the certification methodology, metrological verification can be performed by specialized organizations and private entrepreneurs.
Types of Verification
The Interstate Council for the Development of Metrological Standards provides for two classifications of calibrations - by the time and type of instrumentation. In accordance with the first classification, the following types of verifications are distinguished:
- Primary It is carried out before the first use or after the repair work.
- Periodic. This procedure affects measuring instruments in use. The need for its implementation is due to the timing of the planned verification recommended by the manufacturer.
- Extraordinary. For technical reasons established by the manufacturer, it may be necessary to conduct a preventive check outside the planned schedule.
There is also expert metrological calibration of measuring instruments, the basis of which is the presence of disagreement on the health of the device. However, such events are less common. As for the classification according to the type of measuring instruments, the following categories are distinguished: counters, weight control devices , cash registers and thermometers.
Calibration of measuring instruments
If verification shows that even if there is an error, the deviation is within the acceptable coefficient, then the device is allowed to operate. In reverse cases, there may be two final decisions - either assigning the tool the status of unsuitable for use or making recommendations for correcting defects. For this, calibration measures may be used, which are often performed by the metrological service itself. Calibration of meters, for example, may show deviations in the readings of accounting for water volumes. To restore the correct operation of the device, a standard installation is also used, which allows you to correctly configure the serviced device to accurately account for water flow.
Conclusion
Despite the technological development of metrological instruments, the need for technical maintenance of the function of such devices remains as relevant as it was decades ago. Another thing is that metrological verification is performed at a higher technological level. Modern methods and analysis tools allow you to evaluate the work of the same water meters even without removal. Of course, to obtain the correct data and the verification itself, this procedure must be performed by a specialist.