Test algorithm to confirm the type of modern measuring devices for low absolute pressures and vacuum

The article provides information on the normative documentation applicable in the Russian Federation on the approval procedure of measuring devices, explains the procedure for carrying out tests for approval of the type of vacuum measuring devices at D. I. Mendeleyev Institute for Metrology VNIIM, summarized information about modern high-precision thermal (measuring range (1⋅10-2… 1.08⋅105) Pa, maximum permissible error of a measuring ±(10…50) %) and ionization (specified measuring range (1⋅10-7…1.3) Pa, maximum permissible error of a measuring ±(20…50) %) of vacuum gauges that have been tested for type approval since 2016. The information on the vacuum gauges contained in this article was published in the Federal Information Fund for Ensuring the Uniformity of Measurements.

F-THETA LENS DISTORTION

The features of F-Theta lenses, the values of the characteristics of the most common models are considered. The conditions for achieving the F-Theta law and the telecentric run of the main rays in the optical scheme of the lens are identified. A formula for the distortion required to provide a linear law, depending on the angle of the inclined beam of rays relative to the optical axisis given. The criteria for the permissible error of deviation from the exact compliance with the linear law are formulated. The relevance of the development of new optical systems for F-Theta lenses is justified.

Diagnosis of the rheological properties of oil emulsions considering watercut and temperature factors

It is well known that one of the factors adversely affecting the operational efficiency of infield technological oil pipelines is persistent oil emulsions formed due to the oils watercut. These hardly demulsifible emulsions with abnormal rheological features show non-Newtonian properties. Depending on the temperature and watercut degree, the viscosity of these emulsions varies widely. The specification of viscosity and other physical-chemical properties in oil-field experience is carried out via laboratory testing of oil samples according to the standards. Based on the roto-viscosimetric studies of oil samples with various temperatures, an empiric formula for the specification of oil emulsions viscosity depending on watercut degree is offered. It was defined that the offered formula enables with permissible error to specify the viscosity of abnormal emulsions considering the changing watercut and temperature aspects.

IDENTIFICATION OF CONDITION OF LINEAR DISPLACEMENT SENSOR

Urgency of the research. There are several types of displacement sensor available on market. Displacement sensor investigated in this work is based on optical encoder principle. Condition of sensors changes with using of it. Periodically it is necessary to check its condition, if it is within the declared limits. Target setting. Displacement linear sensor is mounted in comparator stand for the verifying of its condition using the set of length gauge blocks. Length gauge blocks allows to set up the etalon of length with various dimension in interval from 0.5mm to 100 mm. The systematic errors of used set of length gauge blocks of grade “0” are very small in comparing with measured dimension and measured deviations. Actual scientific researches and issues analysis. It is necessary to check actual status of sensor. It means that verification process will obtain the information about maximum permissible error and information about reliability. Uninvestigated parts of general matters defining. The main problem was to identify condition of sensor. The question of the probability distribution of measured values and uncertainty balance are uninvestigated, because the next research will be focused to this are. The research objective. The aim is to obtain maximum permissible error of explored sensor. On the base of deviation of measurement made on length gauges could be expressed. The optimal number of measurement is problem to know, because the low number will cause big uncertainty of measurement and large number of measurement will cause the large cost of measurement. The statement of basic materials. Gauge length blocks have been used for verification of investigated sensor. The set of gauge length blocks of grade “0” has been used, which are preferred mainly for calibration or verification purposes. Maximum permissible error has been estimated as math model for next using. Also optimal number of measurement is identified from analysis of standard deviation of measurements made one hundred times on selected dimensions. Conclusions. The investigated sensor meets the maximum permissible error limits set by the manufacturer with a large margin, and so the maximum permissible error limits have been tightened so that the measurement uncertainty is better. The sensor can be used in dimensional measurement applications, even in industrial conditions.

REPEATABILITY AND VALIDITY OF THE MEASUREMENTS MADE ON TOOLMAKERS MICROSCOPE

Urgency of the research. There are several problems with resulting of measurement result related to validity and repeatability of measurement device. Toolmaker microscope has been verified for these characteristics. Target setting. Toolmakers microscope is as target device which is currently used for fast testing of manufactured prototype. Currently, it is necessary to know information about repeatability and validity of obtained results. Actual scientific researches and issues analysis. Producer did not provide the maximum permissible error MPE, so the aim of this work was to establish the actual MPE for this microscope. Also there is no mention about repeatability of this machine. Normally in accordance with standards, it is required to express results with also with measurement error or uncertainty of measurement. Uninvestigated parts of general matters defining. The main problem is with expressing of validity and repeatability of measurement process. The minimum number of measurement has been established and also maximum permissible error has been identified. Producer provides own microscope etalon as calibration ruler and multiscale micrometer glass slide for microscope. The question of the validity of these etalons are uninvestigated, because the next research will be focused to this problem. The research objective. Too log measurement process will unnecessarily over-price overall costs for measurement process. But insufficient number of measurements will decrease accuracy of measurement and overall uncertainty of measurement. Verification process of microscope has been executed for obtaining the information about maximum error of microscope. This information is also necessary for balance of the uncertainty of measurement made on this microscope. The statement of basic materials. The probability distribution of measured values and number of minimum required number of measurement has been obtained from mentioned analysis. Conclusions. Validity and repeatability of measurement device bring the information how we can believe to measurement process with specified measurement device. Every measurement device should be verified for these metrological properties. Repeatability obtained for examined microscope shows information about the number of measurement needed for effective measurement from the viewpoint of optimized inaccuracy and also from the viewpoint of economic costs. Measurement process is very expensive, so it is necessary to do economy optimization because of ability to be competitive on the market.

IDENTIFICATION OF MAXIMUM INACCURACY OF TOOLMAKERS MICROSCOPE

Urgency of the research. There are several types of measurement devices. Industrial practice needs simple, fast and cheap measurement system for inspection of produced parts. There is a need for system like toolmakers microscope. Target setting. Toolmakers microscope is very popular because of its simplicity, but producer often do not provide information about the errors during the measurements. Actual scientific researches and issues analysis. Toolmakers microscope uses two methods of measurements – micrometer head slides in two axes XY and CCD camera for measurements of very small dimensions. Uninvestigated parts of general matters defining. The main problem is with expressing of uncertainty of measurements for both methods of measurements. There is no regulations and recommendation for using of both methods. The question of the probability distribution of measured values and number of minimum required measurements are uninvestigated, because the next research will be focused to this are. The research objective. The aim is to obtain maximum permissible error of explored toolmakers microscope. On the base of this the uncertainty of measurement could be expressed. Uncertainty measurement is non-separable parts of measurement results. The statement of basic materials. Gauge length blocks have been used for calibration of both measurement systems. Maximum permissible error has been estimated as math model for next using. Conclusions. The toolmakers microscope is suitable device for fast and cheap measurement right in industry condition. The producer did not provide information about the accuracy of measurement on this device. Calibration process can be used for estimation of this maximum error achieved during the measurement via using this device. Also this approach can be used for estimation of actual condition of measuring device.