Cryogenic liquid level sensing apparatus

Claim 1

A method for measuring the level of a cryogenic liquid in a preselected cryogenic container of a known geometry, comprising the steps of: a) transmitting ultrasonic waves using transducer means at said cryogenic liquid within said container, said transducer means being placed within a block of thermal insulation so as to minimize any potential thermal shock, said insulator having a passage for allowing ultrasonic waves to be transmitted and received from said transducer means; b) monitoring the time interval between the transmitted ultrasonic waves and echoed pulse waves; and c) comparing said time measured with experimentally predetermined time intervals values stored in memory which are characteristic of the level of the cryogenic liquid for said container.

Claim 2

A method for measuring the level of a cryogenic liquid in a preselected cryogenic container of a known geometry, comprising the steps of: a) transmitting ultrasonic waves using transducer means at said cryogenic liquid within said container, said transducer means being placed within a block of thermal insulation so as to minimize any potential thermal shock, said insulator having a passage for allowing ultrasonic waves to be transmitted and received from said transducer means; b) monitoring the time interval between the transmitted ultrasonic waves and echoed pulse waves; and c) comparing said time measured with experimentally predetermined time intervals values stored in memory which are characteristic of the level of the cryogenic liquid for said container.

Claim 5

A device for measuring the level of a cryogenic liquid in a preselected container of a known geometry comprising: a) means for transmitting and receiving ultrasonic waves for a duration of time at least equal to time required to travel to the surface and return, said means for transmitting and receiving ultrasonic waves is placed within a block of insulation so as to minimize any potential thermal shock, said insulation having a passage for allowing ultrasonic waves to be transmitted and received from said transducer; b) measuring means for determining the time interval between the transmitted ultrasonic waves and echoed pulse; and c) means for comparing said time interval measured with a experimentally predetermined stored table of time interval values which are characteristic of the level of a cryogenic liquid in said container.

Claim 6

A device for measuring the level of a cryogenic liquid in a preselected container of a known geometry comprising: a) means for transmitting and receiving ultrasonic waves for a duration of time at least equal to time required to travel to the surface and return, said means for transmitting and receiving ultrasonic waves is placed within a block of insulation so as to minimize any potential thermal shock, said insulation having a passage for allowing ultrasonic waves to be transmitted and received from said transducer; b) measuring means for determining the time interval between the transmitted ultrasonic waves and echoed pulse; and c) means for comparing said time interval measured with a experimentally predetermined stored table of time interval values which are characteristic of the level of a cryogenic liquid in said container.

Claim 15

A device for measuring the level of a cryogenic liquid in a preselected cryogenic container of a known geometry comprising: a) a container vessel for holding a cryogenic liquid, said containment vessel having an access opening; b) a cover for closing said access opening; c) transducer means for transmitting and receiving ultrasonic waves for a duration of time at least equal to the time required to travel to the surface and return, said transducer means being placed within a block of insulation so as to minimize any potential thermal shock, said insulator being secured to said cover for placement within said container, said insulator having a passage for allowing ultrasonic waves to be transmitted and received from said transducer means; d) measuring means for determining the time interval between the transmitted and received ultrasonic waves; e) means for comparing said time interval measured with a predetermined stored table of time interval values which are characteristic of the level of said cryogenic liquid in said container.

Claim 16

A device for measuring the level of a cryogenic liquid in a preselected cryogenic container of a known geometry comprising: a) a container vessel for holding a cryogenic liquid, said containment vessel having an access opening; b) a cover for closing said access opening; c) transducer means for transmitting and receiving ultrasonic waves for a duration of time at least equal to the time required to travel to the surface and return, said transducer means being placed within a block of insulation so as to minimize any potential thermal shock, said insulator being secured to said cover for placement within said container, said insulator having a passage for allowing ultrasonic waves to be transmitted and received from said transducer means; d) measuring means for determining the time interval between the transmitted and received ultrasonic waves; e) means for comparing said time interval measured with a predetermined stored table of time interval values which are characteristic of the level of said cryogenic liquid in said container.