(under subclass 561) Systems having two or more openings at least one of which functions to vent gases to or from the system or serves as an opening permitting access thereto of persons or of tools other than those contributing to the intended fluid handling operation of the system.
(1) Note. An opening through which a valve actuator extends is not considered an opening in the system.
SEE OR SEARCH THIS CLASS, SUBCLASS:
43, for vent opening or closing on tipping container.
136+, 143 and 144, for vents and air release means for siphons.
154+, especially subclasses 173+, 179+ and 197+, for gas release from diverse fluid containing pressure systems, and 213+ for liquid level responsive gas vents or whistles in systems having gas pressure stored or maintained over liquid. 216+, for back flow prevention by provision of air vents in liquid flow lines.
223+, for means to relieve excess pressure in tires, especially in connection with inflation means.
237+, for devices having openings for the introduction of cleaning fluids or claimed cleaning tools.
283+, for hydrants having removable valves and valve seats.
326, for containers in which a valve in the bottom can be removed through an opening in the top of the container.
327+, for devices having disassembly tool engaging features.
364+, for valve and meter wells.
597, for apparatus having a plurality of inlets with a plurality of outlets.
602+, for apparatus including tanks having a plurality of inlets and a single outlet.
613+, for tanks having an inlet and an outlet.
SEE OR SEARCH CLASS
4, Baths, Closets, Sinks, and Spittoons, 209+, especially subclasses 211, 218 and 219+ for ventilation means for house plumbing or sewers.
222, Dispensing,
442, for dispenser supply container and measuring trap combinations having a vent passage for the trap; subclasses 478+ for dispensers having plural fluid flow openings, including vents.
