In the Russian Federation, work is underway to create a national of the highest accuracy for the unit of volumetric wastewater flow rate. The development of this standard is based on measurement practices for wastewater quantity in both pressurized pipelines and non-pressurized pipelines (open channels). Significant experience has been accumulated in measuring water flow in pressurized pipelines, and a system for the metrological support of measuring instruments has been established. However, measuring water flow in non-pressurized pipelines remains a challenging metrological task due to the hydrodynamic specifics of forming a non-pressurized, non-turbulent water flow and the shortcomings of the existing metrological support system.
The authors of the article examined the results of the first stage in creating the highest-accuracy standard for the unit of volumetric wastewater flow rate – the creation of a model of a prototype initial standard. The development of the prototype began with an analysis of publications (from sources including Rospatent, Espacenet, Scopus, eLIBRARY.RU, and the Federal State Information System of Rosstandart, etc.) on the specified topic. Based on this review, technical and technological solutions were selected for implementation in the prototype’s main systems and were subsequently tested. For example, the study presents approaches that enable the formation of a fully developed non-turbulent flow in an open channel (flume) with a nearly two-dimensional velocity profile in its cross-section. These approaches are designed to ensure the required metrological characteristics across a volumetric flow range Q_V from 1 to 100 m³/h.
The proven promising technical solutions in the prototype standard’s main systems have enabled the following: implementation of non-turbulent flow in an open channel (flume); achievement of the specified metrological characteristics within the declared range of volumetric flow rate Q_V from 1 to 100 m³/h; maintenance of the water temperature in the storage tank and the water circuit within the specified temperature range from 15 to 25 °C; development of engineering recommendations for determining heat influxes to the water in the prototype’s circuit. These recommendations form the basis for defining the capacity requirements of the water cooling system, which is to be based on commercially available refrigeration units (chillers). The results of the experimental research presented in the article will pave the way for the design and development of an initial standard for the unit of volumetric wastewater flow.
The establishment of a national of the highest accuracy for the unit of volumetric wastewater flow rate will strengthen the metrological sovereignty and international standing of the Russian Federation.

The article addresses the challenge of metrological support for phasor measurement unit. It provides an overview of signal processing algorithms designed to calculate parameters of synchronized voltage and current vectors in electrical networks: magnitude, phase, instantaneous frequency, and rate of frequency change. Two algorithms developed and investigated by the authors are presented. The first algorithm follows the structure recommended by international standards for phasor measurement units. It is based on shifting the spectrum of the signal’s fundamental harmonic to a low frequency and extracting the informative signal using a digital low-pass filter. The authors use a specially designed bank of filters in the algorithm, which are dynamically selected depending on the frequency of the fundamental harmonic of the input signal. The second algorithm proposed by the authors is a parametric algorithm applied to an extended signal model that includes, in addition to sinusoidal, linearly frequency-modulated (chirp) components. The mathematical method for obtaining the optimal estimate of the synchrophasor parameters, corresponding to decomposing the signal into a basis of linear frequency-modulated signals, is described. The advantages and limitations of the developed algorithms for application in reference standards and measuring instruments are examined, and practical recommendations for their use are provided. The presented algorithms have been implemented in the software of the State Primary Standard for Electrical Power Quantities.

The metrological support for gas analysis measurements of component content in gas media is facing increasing accuracy requirements as analytical instrumentation advances. Modern demands on analytical instrumentation involve expanding measurement ranges, reducing errors, and enabling the analysis of complex sample matrices. However, not all existing gas mixture generators meet these requirements. The aim of the research described in the article is to evaluate the capabilities of Coriolis flow controllers for creating a reference dynamic installation capable of reproducing and disseminating the unit of molar fraction of components in gas media with high accuracy.
The starting point of the research was an analysis of published results on the preparation of gas mixtures by static and dynamic methods. The analysis identified the strengths and weaknesses of both approaches. An experiment on the preparation of gas mixtures using Coriolis flow controllers was subsequently conducted. It was concluded that Coriolis flow controllers offer significant advantages, primarily their independence from the physicochemical properties of the gas and their high flow measurement accuracy. The main metrological and technical characteristics of the Coriolis controllers were presented. The study demonstrated the feasibility of their application in reference dynamic installation for the preparation of binary and multicomponent gas mixtures.
The study demonstrated the feasibility of using Coriolis flow controllers to create a reference dynamic installation capable of reproducing and disseminating the unit of molar fraction of components in gas media with high accuracy. Furthermore, the results of this work can be used to enhance the metrological support for gas analysis measurements and improve the reliability of analytical results.

In the Russian Federation, a development type of a state primary special measurement standard for the volumetric flow rate of natural gas at pressures up to 10 MPa has been created on the base of a piston prover with four parallel-connected cylinders with an internal diameter of 500 mm. The design of measurement standard utilizes simultaneous active actuation of the four pistons within the cylinders via piston rods connected to a common hydraulic system piston rod.
In paper the measurement equation compiled that includes more than twenty influencing parameters and determines the value of the volumetric flow rate through a calibrated transfer standard as part of the state primary special standard. Equation takes into account the volumetric flow rate of gas reproduced by the piston prover, the change in the volumetric flow rate as a result of the change in the amount of gas in the attached («dead») volume during the measurement time, and the volumetric flow rate of gas leaks between the cylinder chambers through the piston seals.
Based on the measurement equation, an assessment of the expanded uncertainty (k = 2) of the reproduction of the volumetric gas flow rate carried out and the percentage contribution to this value of individual input parameters under different modes determined.
From the results of the calculations, the accuracy measurements indicators of the state primary special standard declared in the technical specifications for its creation confirmed.

The widespread use of continuous relative humidity sensors has created a need for on-site transfer of the humidity unit. The use of salt-based hygrostats for this purpose is significantly limited by their insufficient range and the requirement for a reference hygrometer. The authors of this article propose a method to expand the range of applicable salt solutions. Through preliminary analysis, they selected salt solutions based on MgNO₃, LiCl, MgCl₂, CsCl, NaCl, KNO₃, MnSO₄. These solutions were then tested for the reproducibility of their relative humidity values after being subjected to various thermal regimes. Modeling confirmed the possibility of maintaining a temperature distribution not exceeding 0.1 °C within the flask’s working zone. The presented results show that the relative humidity value of all salt solutions remains within ±0.6 % after exposure to both lower and higher temperatures. The reproducible relative humidity values for LiCl, MgCl₂, Mg(NO₃)₂, CsCl, MnSO₄, KNO₃ solutions were experimentally established. Based on a synthesis of the obtained data, the use of thermostated salt cells is proposed for reproducing fixed points of relative humidity. This will eliminate the need for reference hygrometers during the unit transfer process. Furthermore, a draft of an extended verification scheme is presented. The presented results may be useful for developers of relative humidity measurement instruments and specialists in the field of environmental parameter assurance or monitoring.

The new regulations for maintaining the Federal State Information System „Grain“ have raised the requirements for the timeliness and reliability of data entered on grain quality measurement results. One of the key parameters for grain acceptance and data submission to the FGIS „Grain“ is the wet gluten content, which is determined using approved IR grain analyzers. These IR analyzers require timely calibration. Therefore, the development of new, accessible calibration tools is a pressing issue.
The goal of the research described in the article is to develop a measurement procedure and reference materials for the wet gluten content in grain and flour, aiming to reduce the time and cost of calibrating IR analyzers and, ultimately, to improve the accuracy of measurements conducted by these analyzers.
To this end, the factors influencing the measurement results were investigated, and the contribution of each influencing factor was evaluated. As a result, a range of approaches has been proposed to enhance measurement accuracy: firstly, the use of distilled water with a regulated temperature for gluten washing; secondly, the replacement of the manual method with a mechanized one, the use of more precise scales, and the employment of a gluten press; thirdly, it is recommended to pre-determine the moisture content of the initial sample of grain (flour) for the subsequent calculation of the sample mass, among other specified conditions. The article presents the characteristics of the measurement procedure FR.1.31.2025.50337, „State System for Ensuring the Uniformity of Measurements (GSI). Procedure for Measuring the Wet Gluten Content in Grain and Flour“, developed by the authors, along with the results of a study of the metrological characteristics of reference materials for wet gluten content in grain and flour, which were certified using this procedure. The application of this procedure will enable the serial production of reference materials for the metrological support of gluten content measurements. The introduction of these reference materials will make calibration tools for IR analyzers accessible to regional metrological centers. Accredited testing laboratories will be able to perform accuracy control independently. Overall, the quality of metrological services for grain processing enterprises will be enhanced.

GOST 1497–2023 «Metals. Methods of tension test» establishes a certified reference material as the reference for evaluating the strength and plasticity parameters of steel’s mechanical properties. However, prior to the development in 2024 of the certified reference material GSO 12792–2024 for mechanical properties of 12Cr18Ni10Ti steel, metrological services had no certified reference material for plasticity evaluation. The only available certified reference material for mechanical properties of 20 steel (GSO 11854–2021) before 2024 was certified only for strength characteristics.
The study aims to develop and certify a reference material for the steel mechanical properties, certified for plasticity parameters – percentage elongation after fracture (δ₅) and percentage contraction after fracture (ψ).
The source material for preparation of the reference material is a hot-rolled round bar of circular cross-section according to GOST 2590–2006, made of 12Cr18Ni10Ti steel according to GOST 5632–2014. The material homogeneity study was conducted in accordance with GOST 1497–2023, simultaneously with determination of the certified values and the absolute expanded uncertainties of the certified values of the reference material. The measurements were performed at the Ural Branch of the D. I. Mendeleyev Institute for Metrology (VNIIM) according to the measurement procedure for percentage elongation after fracture during static tension testing of steel samples M.265.002/RA.RU.311866/2024, and the measurement procedure for percentage contraction of the cross-sectional area during static tension testing of steel samples M.265.003/RA.RU.311866/2024. The following measuring instruments were used: the State Standard of the Unit of Force, 1st category, in the range from 2 to 200 kN; the standard of the unit of length, 4th category – video measuring microscope series MBZ, model MBZ-500TT CNC. The homogeneity assessment of the reference material complies with Section 7 of GOST ISO Guide 35–2015.
The article presents a description of the development process of the certified reference material for the mechanical properties of 12Cr18Ni10Ti steel (GSO 12792–2024); the application methodology; and a practical example of using the reference material for accuracy control of mechanical property measurement results during static tensile testing of metals.
The certified reference material for the mechanical properties of 12Cr18Ni10Ti steel (GSO 12792–2024) is intended for certification and validation of measurement methods for mechanical properties during static tensile testing of metals, control of the accuracy of measurement results for plasticity parameters during static tensile testing of metals, and monitoring tensile testing machines regarding inspection of software according to GOST 1497–2023.

The review analyzes the current state and prospects for the development of high-temperature dilatometry. Basic definitions and concepts are given. The main types of dilatometers using contact (mechanical) and remote (optical) measurement methods are considered; some specific installations are described. Limiting factors of known methods are analyzed. Technological progress, which produces materials with new properties, requires the creation of approaches to study the characteristics and application possibilities of such materials, as well as, possibly, forecasting the directions of materials science. Techniques that can ensure further progress in high-temperature dilatometry technology are analyzed. This review is addressed to researchers – metrologists, material scientists, physicists working in the field of dilatometry, as well as specialists who create measuring instruments.

Mobile metrological complexes operate primarily outdoors, under high-intensity operational loads and constantly changing application conditions. A key factor in ensuring their functionality is the well-founded determination of their residual service life.
However, the criteria for assessing the limiting state of the working standards and measuring instruments within them are not always fully evident for justifying the residual service life of mobile metrological complexes. While a significant number of scientific publications address the metrological reliability of such measuring instruments, the issues of defining their limiting state and assessing the residual service life of mobile metrological complexes are not fully resolved and require further development.
The presented study aimed to justify the criteria for the limiting state of mobile metrological complexes based on a risk-oriented approach.
Risks were identified through an analysis of the design and functional features of mobile metrological complexes across the triad of subsystems: transport, measurement, and support. Mathematical calculations of the indicators and criteria for the limiting state of mobile metrological complexes were performed. These indicators and criteria are based on accounting for the level of risk from latent metrological failures of measuring instruments during inter-verification intervals.
An approach to determining risk indicators has been substantiated, taking into account the dynamic variations in the metrological characteristics of working standards and measuring instruments during operation. Indicators and criteria for the onset of the limiting state of mobile metrological complex subsystems have been established, along with indicators for assessing their service life and residual resource. The core mathematical relationships for calculating these indicators have been defined, considering potential risks from latent metrological failures.
The conclusions presented in the article are intended for metrologists involved in the daily operation of mobile metrological complexes. The indicators, criteria, and characteristics established in this study can be used to assess the condition, justify decisions, and extend the service life of mobile metrological complexes, while considering potential risks from latent metrological failures.

As the architecture and functionality of measuring systems grow increasingly complex, there is a corresponding and steady rise in the need to enhance their metrological support. This necessitates the development of new methods for verification, calibration, and measurement uncertainty assessment under conditions of dynamic and intelligent interaction between elements.
Analysis of the literature has identified the key stages and current trends in the development of measurement systems, which are driven by informatization, automation, and the growth of their multifunctional capabilities. The article demonstrates how modern digital technologies, predictive analytics, and artificial intelligence are transforming the role of measurement systems in process control. It ensures not only precise parameter monitoring but also active participation in their regulation and optimization.
The study highlights how these transformations enhance product quality by enabling more in-depth and real-time analytics.
The study also examines the emerging terminological inconsistencies caused by the convergence of IT and measurement technologies, highlighting the need for a unified conceptual framework across metrology and related areas.
The study underscores the necessity of an interdisciplinary approach to ensure measurement reliability, reproducibility, and comparability within modern digital production settings.
The work aims to establish the foundation for the further development of the metrological infrastructure in the context of the digital transformation of industry.