| 摘要 |
<p>A fluid level monitor (110) for monitoring the fluid level (56) in a tank (50) comprises a first pair of transducers (66,70) arranged in a vertically upper horizontal plane and a second pair of transducers (68,72) arranged in a vertically lower horizontal plane. Pulse generators (62,64) send electrical pulses to the transmitter transducers (66,68) which transmit stress waves into the wall of the tank (50). The stress waves propagating peripherally are detected by the receiver transducers (70,72) and processors (78,80) analyse the amplitude of the detected stress waves to determine if the fluid is present or absent at the upper and lower horizontal planes. The pulse generators (62,64) are arranged to send pulses out of phase so that stress waves propagating axially can be detected to determine alterations of the fluid level (56) between the upper and lower horizontal planes. The processors (78,80) may be arranged to operate alarms (82,84) or to operate valves (102,104) to control the fluid level (56) in the tank (50).</p> |
