FIELD: contactless inspection of liquid level, applicable in petroleum refining, chemical and other branches of industry, as well as in transport. SUBSTANCE: oscillations in the wall of the vessel are excited and picked up by a piezoelectric transducer installed on its outer surface. The oscillations are transduced into an electric signal. The period of transducer natural oscillations is by on order of magnitude lower that the time between the arrival of the pulses reflected from the inner surface of the vessel wall. The transducer natural oscillations are suppressed with the aid of a damper. The time selection of the picked up electric signal is carried out. Non-linear amplification, square - law detection and accumulation of electric signals corresponding to these pulses are accomplished in the time interval between the fifth and fifteenth reflected pulses. The electric signals that are not within these limits are suppressed. The decision on the presence or absence of liquid behind the wall at the level of installation of the piezoelectric transducer is taken by comparison of voltages of the reflected and reference signals. EFFECT: enhanced truth of inspection of liquid level in a vessel, and simplified procedure of check-up of the results of measurements. 2 cl, 2 dwg
