ULTRASONIC PROBES FOR USE IN HARSH ENVIRONMENTS

摘要

An ultrasonic device for detectingconcentrations of solids or positions ofsolid/liquid interfaces in liquid media,particularly Bayer process liquids. Thedevice comprises at least one piezoelec-tric element provided with electrodes;electrical circuit elements connected tothe electrodes for conveying electricalsignals, in use, to and from control ap-paratus; an ultrasound-transparent win-dow, made of glassy carbon, positionedadjacent to the or each piezoelectric ele-ment; a protective matrix, preferably ofepoxy resin, embedding and surround-ing said the or each piezoelectric elementand the electrodes while allowing ultra-sonic waves to pass through the or eachadjacent window to or from the piezo-electric element; and an external pro-tective cover, preferably comprising anelastomer that is resistant to caustic al-kali and has a smooth and non-poroussurface, forming an exterior of the de-vice except at the or each window. Theuse of glassy carbon for the windowsmakes the probes resistant to corrosionand scaling without impeding the effec-tiveness of the device. Further improvedscaling resistance is provided by an elas-tomeric material preferably used as the external protective cover.