US PATENT SUBCLASS 73 / 323
.~ Sight glass

Current as of: June, 1999
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73 /   HD   MEASURING AND TESTING

290 R  DF  LIQUID LEVEL OR DEPTH GAUGE {13}
323.~ Sight glass {5}
324  DF  .~.~> With cleaner
325  DF  .~.~> With guard or casing {1}
327  DF  .~.~> Reflector or magnifier
328  DF  .~.~> Boiler type {3}
334  DF  .~.~> Transparent closure plate type

DEFINITION

Classification: 73/323

(under subclass 290) Gauges whereby the liquid level may be directly viewed. The gauges may comprise either a transparent plate fastened over an opening in the reservoir wall or a tube transparent at least in part and so communicating with the reservoir that the liquid in the reservoir and tube may assume a common level. The term "glass", as employed in these definition, is intended to include any transparent material.

(1) Note. Similar devices employed for determining the level of dry fluent materials are here included.

(2) Note. For structures similar to sight glasses, such as tubular ullage rods or sampling tubes, insertable into a liquid to determine depth or to take a sample, but not permanently attached to the reservoir, see Class 33, Geometrical Instruments, subclasses 717+ and this class (73) subclasses 864+.

SEE OR SEARCH THIS CLASS, SUBCLASS:

299, for hydrostatic pressure type gauges.

747+, for U-tube pressure gauges. 864+, see (2) Note.

SEE OR SEARCH CLASS

33, Geometrical Instruments, see Note 2.

138, Pipes and Tubular Conduits, for glass tube structure, per se, not limited to use as a gauge glass.

184, Lubrication,

96+, for similar structures employed with sight feed lubricators.

220, Receptacles,

82, and see the notes thereto, for structures wherein a transparent panel is mounted in a wall.

359, Optics: Systems (Including Communication) and Elements,

894+, for transparent closures, in general.