Methods and errors in flow measurement

Rad smo započeli pregledom nekoliko metoda za mjerenje masenog ili volumnog protoka. Za mjerenje masenog protoka smo spomenuli Coriolis-ove protokomjere, dok smo za mjerenje volumnog protoka dali opis metoda koje rade na principu prigušivanja, turbinskih mjerila protoka i ultrazvučnih protokomjera. Ultrazvučni protokomjeri su jedini koji se ugrađuju sa vanjske strane na cijevi te nemaju nikakva utjecaja na profil strujanja kroz cjevovod. Dali smo detaljan opis dviju mjernih linija koje rade na principu gravimetrijske metode, kod koje se volumen vode računa preko njezine mase. Proveli smo mjerenja na jednoj liniji pomoću dva kalorimetra, te smo vidjeli da, iako su kalorimetri identični, svaki je pokazao drugačije rezultate. Na kraju smo izračunali mjernu nesigurnost za našu liniju, te smo vidjeli da najviše utjecaja na rezultat mjerenja ima temperatura koja direktno utječe na gustoću vode, pa tako i na njezin volumen.We started our work with overview of few methods for measuring mass or volume flow rate. For measuring mass flow rate we mentioned Coriollis mass flow meter, while for measuring volume flow rate, we gave a description of methods working on reducing the fluid pressure, turbine flow meters and ultrasonic flow meters. Ultrasonic flow meters are the only one which are installed on the outside of pipeline and they have no influence on the flow profile in the pipeline. We gave a detailed description of two measuring lines which work on principle of gravimetric method which gave us a water volume over the water mass. We carry out the measurements on one measuring line with two calorimeters, and we saw, although the calorimeters were identical, we got different results on each one. At the end, we calculate the measurement uncertainty for our line, and we saw that the biggest influence on the result has the water temperature, which directly affect on water density, so it also has a direct effect on her volume