FIELD: metallurgy, chemical and petroleum refining industries. SUBSTANCE: acoustic radiator with two angles of feed of ultrasonic vibrations into wall of reservoir excites two types of ultrasonic waves: normal wave of needed mode and surface wave that propagate in parallel to plane of surface of checked liquid over perimeter of reservoir inside wall and over its outer surface. Acoustic receiver identical to radiator mounted at definite distance relative to radiator in zone of level check is employed to receive ultrasonic vibrations. Information on presence or absence of liquid medium at checked level is extracted by amplitude of normal wave. Correction of amplitude of normal wave with change of acoustic resistance of contact layer is carried out by amplitude of surface wave. Device for realization of method includes two acoustic converters, generator, measurement stage, two selective stages, two peak detectors, two delay units, two formers of gating pulses, comparator, coincidence circuit, counter, decoder, unit of analog keys, attenuator, summing unit, amplifier, source of reference voltage. EFFECT: increased reliability and precision of check. 2 cl, 2 dwg
