ULTRASONIC INTERFERENCE DIFFERENCE FLOW RATE MEASURING INSTRUMENT AND ULTRAFILTRATION QUANTITY MEASURING INSTRUMENT USING SAID INSTRUMENT

摘要

PURPOSE:To measure a difference flow rate simply, at a low cost and with high accuracy by providing no special duct line constitution, and also, by using a measuring circuit and an arithmetic circuit which are used in common. CONSTITUTION:Transmitters 14a, 14b and receivers 16a, 16b are placed at the same clearance by setting the flow directions of each fluid to the same against two duct lines 10, 12 whose inside diameters are the same. Subsequently, from each transmitter 14a, 14b, ultrasonic signals of the same frequency are sent out by the same phase, the ultrasonic signals which have been received, 16a, 16b are synthesized 22 and a peak value or a zero value of its amplitude is detected. Next, a frequency of an oscillation output of the ultrasonic signals sent out of the transmitters 14a, 14b is adjusted so that the amplitude of the synthesized wave becomes the peak value or the zero value, and based on the oscillation frequency at this time, a difference flow rate of each fluid can be measured simply and with high accuracy. Also, in case the difference flow rate is extremely small, the generation of a measurement error can be avoided by varying only the inside diameter of the duct lines 10, 12.