| 摘要 |
<p>A fluid level monitor (14) for monitoring the level of fluid (13) in a vessel (10) comprises an inverted U-shaped propagation member (16) which allows the propagation of stress waves therethrough. A first limb (15) of the propagation member (16) is immersed in the fluid in the vessel (10) and a second limb (17) is positioned outside the vessel (10). A transmitter transducer (18) and a receiver transducer (20) are acoustically coupled to the second limb (17) of the propagation member (16). The transducer (18) transmits stress wave pulses into the propagation member (16), the stress wave pulses produce a diffuse stress wave field in the propagation member which is damped by any fluid contacting the first limb (15) of the propagation member (16). The transducer (20) detects the stress waves propagating in the propagation member (16) and produces an electrical signal corresponding to the level of the diffuse stress wave field. An analyser (24) measures the decay rate of the diffuse stress wave field which is indicative of the level of fluid in the vessel (10) contacting the propagation member (16).</p> |
