M. M. Isaev, E. K. Mehdizade, T. S. Abbaszade

Support of automatic measurement of density of a stream with high accuracy in the conditions of the raised impurity, vibrations, pulsations of the expense and pressure of environment, temperature and viscosity fluctuations demands much of metrological indicators of a measuring instrument of density in systems of measurement of mass expenses of mineral oil. Qualitatively new direction of creation of high-precision and reliable measuring instruments of density was working out of gauges, reformative controllable parameters in a frequency-modulated signal. The high noise stability of the frequency-modulated signal allows to raise accuracy of measurement by frequency gauges in comparison with analogue and to transfer the information to the big distances. Action of vibration-frequency measuring instruments of density is based on dependence of own frequency of fluctuations of mechanical resonators on density of the liquid which are in them or outside. As sensitive element of the vibration-frequency gauge of density of flowing type the tube-resonator fixed by one end or both ends in the motionless basis and resulted in a mode of fluctuations by system of excitation serves. Frequency of fluctuations of a tube is a target frequency signal. As the receiver and the activator of self-oscillations the polarisation electromagnets are used. Now is about hundred patents and the copyright certificates received on various designs of vibrating measuring instruments of density in the different countries of the world. Working frequency of vibrating gauges many times over exceeds frequency of mains voltage that allows to avoid influence of external hindrances on the basic signal. As a data carrier at a frequency signal it is possible to consider a time interval between impulses. The algorithm of processing of results of measurement of density of a stream of mineral oil with use of the combined methods of an estimation of errors and accompanying Algorithmic correction of an error in the vibro-frequency converter of density of mineral oil.