Characterisation of the vacuum pressure chamber

U uvodnom dijelu rada dan je pregled mjerila atmosferskog tlaka, odnosno barometara, za njihovo područje mjerenja (grubi vakuum i mali tlakovi), princip rada, te konstrukcija uređaja. Također su opisane i metode generiranja grubog vakuuma i malih tlakova (stapne, rotacijske i molekularne pumpe). U eksperimentalnom dijelu rada prvo su provjerene karakteristike nove vakuumsko tlačne komore ispitivanjem najvišeg i najnižeg tlaka. Nakon toga je sastavljen mjerni sustav za ispitivanje barometara kojem je komora glavni dio. Provedena su mjerenja i napravljena analiza rezultata za dva mjerna instrumenta. Mjerna linija za izradu ovog rada je sastavljena od pumpe, vakuumsko tlačne komore, barometra za umjeravanje, etalonskog barometra i uređaja za mjerenje okolnih uvjeta zraka. Napravljena je shema i dan opis spajanja mjerne linije. Umjeravana su dva barometra istog proizvođača Testo 176 P1 koji imaju raspon mjerenja od 600 – 1100 mbar. Za etalonsko mjerilo je uzet barometar Vaisala PTB 220. Napravljena su mjerenja za raspon od 860 – 1060 mbar te su tablično prikazani rezultati. Opisan je postupak procjene mjerne nesigurnosti te je napravljen proračun mjernih nesigurnosti koji je prikazan tablično i grafički kao dodatak odstupanjima.In the introductory part of the paper, an overview of atmospheric pressure gauges, i.e. barometers, for their measurement area (rough vacuum and low pressures), the principle of operation, and the construction of the device is given. Methods of generating rough vacuum and low pressures (step, rotary and molecular pumps) are also described. In the experimental part of the paper, the characteristics of the new vacuum pressure chamber were first checked by testing the highest and lowest pressure. After that, a measuring system was put together to test the barometer, the main part of which is the chamber. Measurements were carried out and the results were analyzed for two measuring instruments. The measuring line for this work is composed of a pump, a vacuum pressure chamber, a measuring barometer, a reference barometer and a device for measuring the surrounding air conditions. A diagram was created and a description of the connection of the measuring line was given. Two barometers of the same manufacturer, Testo 176 P1, which have a measurement range of 600-1100 mbar, were measured. The Vaisala PTB 220 barometer was used as the standard. Measurements were made for the range of 860 - 1060 mbar and the results are tabulated. The procedure for estimating the measurement uncertainty is described and the calculation of the measurement uncertainty is made, which is shown in tables and graphics as an addition to the deviations