Development of the ultrasonic buffer rod for the molten glass measurement

•Trailing echo was strongly affected by the frequency.•There was the characteristic frequency depending on the rod geometry.•Yttria-stabilized zirconia was suitable material for molten glass measurement.•Sound velocities were almost constant in a temperature range of 1000–1200 °C.•Attenuation coefficients were roughly estimated and proportional to the viscosity.

Design and demonstration of an ultrasonic buffer rod for high temperature fluid especially for the molten glass were studied. Material selection guide for glass melts was established focusing on high temperature strength, attenuation and acoustic impedance. Durability and wettability of ultrasonic buffer rod have been tested for several materials. Frequency of the ultrasound was chosen considering the transmission characteristic of the buffer rod which was investigated employing three dimensional FEM code. The buffer rod tested has tapered shape and cladding on the side wall as a further suppression of trailing echo. Sound velocity and attenuation coefficient measurements in a temperature range of 1000–1200 °C were then demonstrated utilizing the designed buffer rod. Signal processing technique to eliminate remained trailing echoes was also performed. Applicability of the ultrasonic measurement using the buffer rod is discussed.