Apparatus for measuring the level of liquid fuel in a tank

Claim 1

An apparatus for measuring a level of liquid in a tank of the type in which there is a hollow space between a surface (P 2 ) of the liquid and a horizontal reference plane (P 1 ) established near an opening that gives access to the tank, comprising: a depth gauge comprising a reference base, a portable, selectively movable rule and a means for measuring a relative displacement of the rule to the base; a means for supporting the reference base of the gauge at the reference plane (P 1 ); an optical probe containing a static means for detection of liquid at a predetermined level (P 4 ), the optical probe being integral with the selectively movable rule and comprising: a light-emitting diode; a photodiode; a prism light-receiving and reflecting communication with the light-emitting diode and photodiode, respectively, such that in a gaseous medium light from the light-emitting diode is reflected off the faces of the prism toward the photodiode, but which reflects little light to the photodiode when the prism is in contact with a liquid; a means for displaying an indication of the immersion of the optical probe into the liquid at the predetermined level (P 4 ) as a function of the signal from the photodiode; a power source providing power to the light-emitting diode, the photodiode, and the means for displaying; and an anti-deflagrant box containing the light-emitting diode, the photodiode, the power source, and the means for displaying; whereby an indication of the depth of the hollow space in the tank is measured by lowering the selectively movable rule into the tank through the opening with the reference base supported at reference plane (P 1 ) to furnish a measurement of the distance between the surface (P 2 ) and the reference base (P 1 ).

Claim 2

An apparatus for measuring a level of liquid in a tank of the type in which there is a hollow space between a surface (P 2 ) of the liquid and a horizontal reference plane (P 1 ) established near an opening that gives access to the tank, comprising: a depth gauge comprising a reference base, a portable, selectively movable rule and a means for measuring a relative displacement of the rule to the base; a means for supporting the reference base of the gauge at the reference plane (P 1 ); an optical probe containing a static means for detection of liquid at a predetermined level (P 4 ), the optical probe being integral with the selectively movable rule and comprising: a light-emitting diode; a photodiode; a prism light-receiving and reflecting communication with the light-emitting diode and photodiode, respectively, such that in a gaseous medium light from the light-emitting diode is reflected off the faces of the prism toward the photodiode, but which reflects little light to the photodiode when the prism is in contact with a liquid; a means for displaying an indication of the immersion of the optical probe into the liquid at the predetermined level (P 4 ) as a function of the signal from the photodiode; a power source providing power to the light-emitting diode, the photodiode, and the means for displaying; and an anti-deflagrant box containing the light-emitting diode, the photodiode, the power source, and the means for displaying; whereby an indication of the depth of the hollow space in the tank is measured by lowering the selectively movable rule into the tank through the opening with the reference base supported at reference plane (P 1 ) to furnish a measurement of the distance between the surface (P 2 ) and the reference base (P 1 ).