NON-INVASIVE SENSORS FOR SHIPBOARD SEWAGE SYSTEMS

An acoustic/ultrasonic sensor development program is proposed for non-invasive determination of the amount of scale in shipboard sewage pipes and fluid level in shipboard sewage tanks. The technology is based on speed, attenuation, and scattering of vibrational waves (acoustic/ultrasonic/elastic) propagating in or through tanks and pipes are sensitive to the materials inside. By measuring the characteristics of certain modes of propagation, we can sense thickness of scale in the pipe, or level of the fluid in a tank. We divide the problem into two: non-invasive tank level and non-invasive pipe scale measurements. A sensor for the former, based on this technology, has already been developed by two of the principle investigators for measuring the fluid level in large petroleum tanks. The proposed Phase I effort consists of four tasks to evaluate the feasibility of the approach, an analytic and an experimental task for each of the problems. The analytical tasks are for determining the optimum modes of propagation and for predicting the wave speeds and attenuatioins under the various conditions. The pipe related experimental task will test several acoustic/ultrasonic methods of measuring scale thickness. The tank experimental task will test the capabilities of the existing sensor for gaging actual shipboard sewage tank levels.