Abstract: A liquid petroleum gas (LPG) gauge sensor unit fits between the units of an existing magnetically-coupled LPG gauge and includes a magnetic field sensing switch, a mechanism to variably position the switch and an intermediate magnet. The intermediate magnet is positioned upon an axle-like mechanism upon which it is free to rotate and magnetically couples to the existing gauge base magnet which is, in turn, connected to a float that measures the liquid level. The existing indicator magnet in the gauge assembly magnetically couples with the intermediate magnet so that the gauge unit visually indicates the level of LPG within the LPG tank, despite the increased distance between the base and indicator magnets caused by the sensor unit. The magnetic field sensing switch is used to sense the position of the base or intermediate magnet and thereby sense the liquid level.

Abstract: An apparatus for protecting and optically isolating the optical element of the probe used for sensing liquid levels includes a tubular body formed from a rigid, non-reflective material which slides over the optical probe. The probe is mounted within the tubular body to create a gap between the shield and the probe in which liquid collects. An open end of the tubular body is cut at an angle and tapers to a point at the widest part of the gap. The tapered point and gap width are arranged so that, when the liquid level falls below the probe end, the surface tension of liquid running down the tapered point overcomes the surface tension of the liquid in the gap and draws the fluid out of the shield.

Abstract: A gage glass assembly can be mounted in a standard pipe joint flange and has a sleeve with an inturned flange at the outer end and an outwardly extending flange at the inner end. A pair of cylindrical lenses inside the sleeve are interspaced by a plastic sheet that also extends axially between the inner lens and the sleeve and outwardly over the outwardly extending flange. Both lenses and the sheet are bonded together and to the sleeve by a transparent, plastic material. A liquid level gage has a cover extending over a body having an elongated central chamber and the cover has a similarly elongated recess facing the chamber. A pair of glass lenses are stacked in the recess and a transparent plastic sheet extends between the lenses, along the side of the inner lens and outwardly over the inner side of the cover, where it serves as a gasket between the cover and the body. A plastic bonding material fills the space between the plastic sheet, the two lenses, and the cover recess.

Abstract: A liquid level gauge having a body defining a liquid receiving chamber, a transparent reflex glass at an open face of the body chamber for maintaining liquid within the chamber while providing visual access into the chamber, a removable cover plate maintaining the reflex glass in sealing engagement with the chamber body, the reflex glass including on its inner face a plurality of longitudinally extending prisms adapted to be contacted by liquid in the chamber, a background plate within the walls of the chamber, and means to space the background plate from the reflex body to permit circulation of liquid therebetween, the background plate displaying through the reflex glass a high visual contrast, e.g., a bright color, between wetted and nonwetted areas of the reflex glass. As disclosed, the reflex glass may be formed of a transparent plastic material and be arranged with a relatively thin cross section to permit its use as an insert for assembly with an outwardly disposed primary pressure-retaining glass.