A Condition Monitor For Liquid Lubricated Mechanical Seals

A recently developed condition monitor for liquid lubricated mechanical seals utilizes actively generated ultrasonic shear waves to determine conditions at the sealing interface. A shear wave transducer is mounted on the backside of the non-rotating seal face, and generates waves that propagate toward the sealing interface. The amplitude of the reflected waves indicates whether or not face contact occurs and, if there is contact, the severity of contact. Thus, this monitor is suitable for use with both non-contacting and partially contacting seals. Laboratory tests on a commercial, unbalanced seal demonstrate the effectiveness of the approach.