M. Toromanović, J. Ibrahimpašić, I. Šišić, S. Hotić, “Elements of ultrasonic flowmeter installation...“, Technologica Acta, vol. 15, no. 1, pp. 15-22, 2022. 15 ISSN 1840-0426 (P); ISSN 2232-7588 (E) https://hrcak.srce.hr/ojs/index.php/technologicaacta * http://tf.untz.ba/technologica-acta ELEMENTS OF ULTRASONIC FLOWMETER INSTALLATION, MODEL OMNI TDI 200H WITH TEST WORK RESULTS PROFESSIONAL PAPER Merima Toromanović  , Jasmina Ibrahimpašić, Ifet Šišić, Samira Hotić DOI: 10.5281/zenodo.6913106 RECEIVED 2021-11-09 ACCEPTED 2022-01-25 Faculty of Biotechnology, University of Bihać, Luke Marjanovićabb, 77000 Bihac, Bosnia and Herzegovina  merima.toromanovic@unbi.ba ABSTRACT: Ultrasonic flowmeter works on the principle of transmitting and returning ultrasonic waves that pass through the liquid, ie. fluid, and is used to measure the speed of fluid movement through a pipeline or some other structural form of fluid movement. By knowing the velocity of the fluid and the cross-sectional area of the pipeline or other system, the value of the volumetric or mass flow can be obtained indirectly. Fluid flow measuring device model OMNI TDI 200H owned by the laboratory of the Biotechnical Faculty was used for the first time to measure the flow of purified water at the outlet of the plant device of the training center "Grmeč", built as a pilot plant. The paper will describe the role and importance of flow measurement by the conventional method and present the results of the trial operation of an ultrasonic flow meter, model OMNI TDI 200H. KEYWORDS: ultrasonic meter, installation elements, flow INTRODUCTION Nowadays, due to the greater complexity of technical systems in the manufacturing and process industry, we perform measurements, and the act of measurement itself can be presented as an experimental process of obtaining one or more values of a measured quantity. The measurement aims to determine the value of the measured quantity, while the purpose of each measurement is to obtain the value of the measured quantity. By comparing the measurement results about the given quantities, we control the process quantities, for which we use many information and technical aids. Measurement of non- electric quantities by electrical measuring procedures is realized with the help of measuring transducers, which convert non-electric to electric quantities. Thus, e.g. measures displacement, velocity, angular velocity, acceleration, mechanical power, pressure, flow, fluid level, temperature, volume, time, humidity, flow rate and composition of gases and liquids, pH value, etc. Converting non-electrical quantities into electrical ones is a very important step in process control and regulation systems because in this way different physical quantities can be measured by one method or one type of instrument, very small changes of measured non-electric quantity can be displayed and measured, very fast changes of non-electric size and perform remote measurements (online). FLOW AS A PHYSICAL SIZE Flow measurement, as a variable basic quantity, determines the energy and material balances of process changes (flow chart) based on which the movement of materials and fluids at the inlet, through conversion operations, as well as at the outlet of the process is monitored. The measurement of the flow of fluids, gases, multiphase liquids, and suspensions is complex, subject to numerous errors, and therefore a large number of different measuring procedures have been developed for accurate and reliable measurement. Basic flow values are given through the following expressions [1]: - volume / volume flow QV [m 3 /h], [l/s] - mass flow QM [kg / s], [t/h]), [kg / s] - molar flow Qm [mol/h], [mol/s] Mass flow is the mass of a fluid that passes a point in a unit of time and can be given through the equation: t m Q M   = , [kg/s] .................................................... (1) Otherwise, the mass flow in the pipe is determined by the limit of the ratio of the mass of the fluid flowing through the cross-section of the pipe in the time interval when the interval becomes infinitesimally small: