For the first time in Ukraine a primary measurement standard of gas volume and flow rate units in a pressure range of 1 MPa to 5 MPa has been created. The standard is based on realisation of the units by PVTt principle and units dissemination using critical Venturi nozzles. Gas passing through the nozzle during its calibration fills an evacuated collection tank located downstream the nozzle, and the respective time interval is measured. Mass flow rate is calculated by multiplying the volume of the collection tank by the gas density change and dividing by the tank filling time. Density values are determined by the equation of state and the measured initial and final pressure and temperature values. The structural and functional scheme of the measurement standard is shown in Figure 3. The standard consists of two units. The first unit is intended to realise, keep and transfer the units of gas volume and flow rate. The general view of the block is shown in Figure 4. The unit contains high pressure collection tank, precision water thermostat, vacuum pump, piston gas pressure gauge, flow switch, fine filter, a set of seven Venturi nozzles with diameters from 0.1 mm to 3.0 mm. The second unit is designed to form a stationary gas flow and provide a critical gas flow rate (at the speed of sound) at the nozzle throat. In the case of an elementary reversible adiabatic (isoentropic) process at a critical velocity, the mass flow rate of gas passing through the nozzle is maximally possible. The unit consists of equipment for reducing the pressure from 150 bar to 70 bar and from 70 bar to 10 bar, the heat exchanger and the instruments measuring the pressure and temperature of the gas flow. The created measurement standard will assure metrological traceability of the measurements of gas volume and volume flow rate at high pressures for the flow rate up to 100 m3/h and calibration of the primary reference nozzles with a throat diameter from 0.1 mm to 3 mm.

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The article is devoted to the effective system crea­tion for recording liquids and gases flows. There is extremely relevant for creating metering units of fuel and energy resources. The aim of the work is to determine the influence of the flowed body geometric configuration of the sensitive element and its orientation relative to the direction of the flow on the hydrodynamic flow meter metrological characteristics, as well as determining the instruments’ rational location in the technological line Based on the example of the hydrodynamic class measuring transducers factors that have a significant impact on their metrological characteristics are determined, the degree of the transducers sensitivity to the measured medium flows asymmetry is revealed. The flows asymmetry is simulated by hydraulic resistan­ces of different spatial configurations (spatial elbow, elbow, double elbow, contraction, abrupt contraction). Simulation modeling of the operation of such devices is performed. Sensitive elements of different Gaussian curvatures such as zero (cylinder), positive (cone) and negative (hollow hemisphere) were studied. The value of the registration result uncertainty depends on the flow asymmetry and the instrument spatial orientation relative to the vertical axis in the technological network. The obtained results make it possible to clearly determine the instrument installation place in the technological network under conditions of maximum accuracy and minimal impact on the measured medium. This allows effectively using transducers in places of the technological network, taking into account the specific conditions for the metering units creation. There is no ne­cessary to make straight pipeline sections before and after the instruments. The researches results show that measuring instruments with flow bodies in the shape of a cone oriented the apex toward the flow are the best.

SE "Ukrmetrteststandard", Kiev, Metrologichna 4 str., Ukraine R Résumé. L'article est destiné pour expliquer une nouvelle approche de création des installations de sondage combiné pour l'étalonnage des compteurs à gaz. Les auteurs ont analysé les sources principales des erreurs des constructions classiques des gazomètres, en plus ils ont développé les solutions pratiques pour minimiser l'incertitude de mesure. L'utilisation de servo pour le pilotage de mouvement de sondage minimise la durée de processus de transfert aussi bien que donne la possibilité d'obtenir l'utilisation optimale du volume interne de l'installation pendant la reproduction du volume et le débit de gaz volumétriques. Les résultats de la recherche de stabilité de pression dans l'espace sous sondage sont mentionnés dans l'article pour prover la faisabilité de la mise en oeuvre technique.