Tank gauging system and methods

Claim 2

1 . A system for monitoring at least one liquid in a tank comprising : (a) a plurality of ultrasonic reflectors spaced at predetermined distances from each other so that each of said reflectors lies at a different predetermined height in said tank; (b) transducer means, positioned below said reflectors and designed to be located underneath the surface of said liquid in said tank and at a known height above the bottom of said tank, for transmitting ultrasonic energy into said liquid and for forming data signals representing the reflections of said trans mitted energy off of said plurality of reflectors and off of the surface of said liquid; (c) means for causing said transducer means to transmit ultrasonic energy and for receiving said data signals from said transducer means; and (d) the bottom surfaces of at least one of said plurality of ultrasonic reflectors being concave for focusing therefrom reflections of said transmitted energy back to said transducer-

Claim 3

2 . A system as claimed in claim 1, wherein said ultrasonic reflectors are vertically aligned; and the surfaces of said reflectors opposite to the surfaces thereof facing said transducer are beveled for ensuring that ultrasonic waves striking said beveled surfaces are reflected away from said reflectors and said transducer.

Claim 4

A system as claimed in claim 1 or 2 wherein the more distant an ultrasonic reflector is from said transducer, the longer is its horizontal dimension.

Claim 5

A. system as claimed in claim 1, 2 or 3, wherein said transmission causing and data receiving means includes : (i) a data processor (ii) a pulser connected to said data processor for causing said transducer to transmit ultrasonic energy into said liquid; (iii) signal detection circuitry for receiving said data signals from said transducer and for indicating whether a reflection of said transmitted energy was received by said transducer within a predetermined time window; and (iv) a timer connected to said data processor and said signal dictation circuitry to measure the time between the transmission of ultrasonic energy and the receipt within said predetermined time window of reflections of said transmitted energy-

Claim 9

A method as claimed in claim 6, wherein the step of measuring said reflector echo delay times includes the step of measuring a closest reflector echo delay time between the transmission of a second set of pulse bursts and the receipt of the reflections of said second set of pulse bursts in a predetermined window from one of said plurality of reflectors lying closest to said transducer.

Claim 10

A method as claimed in claim 6 or 7, wherein the step of measuring said surface echo delay time includes the steps of : (i) setting an ultrasonic receiver at a predetermined sensitivity; (ii) adjusting the sensitivity of said receiver until a first reflection of said first set of periodic pulse bursts is detected; (iii) setting as a first value for said surface echo delay time the time between the detection of said first reflection and the transmission of the one of said pulse bursts which was reflected to form said first reflection; (iv) adjusting the sensitivity and measuring subsequent echo delay times between the detection of reflections and the transmission of the pulse bursts causing said reflections; (v) measuring an echo delay time difference between the most recently measured echo delay time and the next most recently measured echo delay time; (vi) assigning the most recently measured echo delay time as the new value for said surface echo delay time if said echo delay time difference is equal to one period of said pulses in said burst; (vii) adjusting the sensitivity further if echo delay time difference is less than or equal to one period of said pulses in said burst; (viii) terminating the measurement of said echo delay time if said sensitivity is at a predetermined limit; and (ix) choosing as said surface echo delay time the next most recently measured echo delay time if said echo delay time difference exceeds one period of one of said pulses in said burst.

Claim 12

A method as claimed in claim 9, further including the steps of : determining the average temperature of said liquid in said tank; and normalising the determined volume of said liquid to a reference temperature using said average temperature.