| 摘要 |
To detect the liquid level in a container, a plurality of ultrasonic detection units are arranged at various heights on the outside of the container, each unit comprising a transmitter 7, a receiver 8 arranged to receive sound pulses transmitted through the container by the transmitter, and a device 9 for producing the pulses and for converting the signal received by the receiver to an indication of whether liquid is present in the part of the container through which the sound pulses were transmitted. The positions of the detection units are adjustable. The final output from the unit can be used to switch on or off pumps, safety devices or valves controlling the liquid feed to the container. <IMAGE> |
