Methods of and/or means for indicating the levels of liquids

Claim 3

A method as claimed in claim 1 wherein step (a) is carried out by using a wire wound resistor having between three and eight turns per mm and a resistance of between one and four ohms per turn of resistance wire and so that the liquid interconnects adjacent turns of the resistor.

Claim 4

A method as claimed in claim 1 wherein the change of impedance in step (b) is measured by applying an alternating current to the terminals of the resistor and measuring the change in alternating current flowing through the resistor.

Claim 5

Apparatus for indicating the level of an electrically conducting liquid milk in a vessel, said apparatus comprising (a) a rod type resistor disposed vertically in use in said vessel, said resistor having an average cross sectional dimension between twenty and forty-five mm and a resistor of between three and thirty-two ohms per mm of length of the resistor, the resistor being arranged so that increase in the level of liquid in the vessel causes some of the liquid in the vessel to interconnect adjacent lengths of the resistor to change the impedance thereof, (b) means for measuring such change in impedance and (c) display means on which change in level of liquid in the vessel is indicated.

Claim 6

Apparatus for indicating the level of an electrically conducting liquid milk in a vessel, said apparatus comprising (a) a rod type resistor disposed vertically in use in said vessel, said resistor having an average cross sectional dimension between twenty and forty-five mm and a resistor of between three and thirty-two ohms per mm of length of the resistor, the resistor being arranged so that increase in the level of liquid in the vessel causes some of the liquid in the vessel to interconnect adjacent lengths of the resistor to change the impedance thereof, (b) means for measuring such change in impedance and (c) display means on which change in level of liquid in the vessel is indicated.

Claim 7

Apparatus as claimed in claim 4 wherein said resistor is a former wound with wire having between three and eight turns per mm and a resistance of between one and four ohms per turn and being arranged so that increase in the level of liquid in the vessel causes some of the liquid to interconnect adjacent turns of said wire.

Claim 8

Apparatus for indicating the level of an electrically conducting liquid in a vessel, said vessel comprising (a) a rod type resistor disposed vertically in use in said vessel, said resistor having an average cross sectional dimension between twenty and forty-five mm and a resistance of between three and thirty-two ohms per mm of length of the resistor, the resistor being arranged so that increase in the level of liquid in the vessel causes some of the liquid in the vessel to interconnect adjacent lengths of the resistor to change the impedance thereof, (b) means for measuring such change in impedance and (c) display means on which change in level of liquid in the vessel is indicated, wherein said resistor is a former wound with wire having between three and eight turns per mm and a resistance of between one and four ohms per turn and being arranged so that increase in the level of liquid in the vessel causes some of the liquid to interconnect adjacent turns of said wire, wherein said former is made of a softenable material such as polysulfone or polycarbonate and said resistance wire is embedded in said softenable material of the former with only a portion thereof exposed, whereby said dimension enables the total area of the wire in contact with the liquid to be sufficiently great to allow a good resistance connection to the liquid in contact with it and enables extremely small changes of impedance to be measured.

Claim 9

Apparatus for indicating the level of an electrically conducting liquid in a vessel, said vessel comprising (a) a rod type resistor disposed vertically in use in said vessel, said resistor having an average cross sectional dimension between twenty and forty-five mm and a resistance of between three and thirty-two ohms per mm of length of the resistor, the resistor being arranged so that increase in the level of liquid in the vessel causes some of the liquid in the vessel to interconnect adjacent lengths of the resistor to change the impedance thereof, (b) means for measuring such change in impedance and (c) display means on which change in level of liquid in the vessel is indicated, wherein said resistor is a former wound with wire having between three and eight turns per mm and a resistance of between one and four ohms per turn and being arranged so that increase in the level of liquid in the vessel causes some of the liquid to interconnect adjacent turns of said wire, wherein said former is made of a softenable material such as polysulfone or polycarbonate and said resistance wire is embedded in said softenable material of the former with only a portion thereof exposed, whereby said dimension enables the total area of the wire in contact with the liquid to be sufficiently great to allow a good resistance connection to the liquid in contact with it and enables extremely small changes of impedance to be measured.

Claim 10

Apparatus as claimed in claim 5 wherein separately spaced studs or terminals are provided on said former and whereby the conductance of the liquid the level of which is being measured, can be measured by a conductance measuring device.

Claim 11

Apparatus as claimed in claim 5 wherein said vessel is provided with a plurality of frusta of cones at the lower end thereof, the lowermost of said plurality having a lesser slope than the next frustum for the purpose of assisting in giving a linear scale during the commencement of filling of the vessel.