Lines with other classes and within this class
The class is divided into two groups, subclasses 1+ for processes,
and subclasses 38 to 616 for automatic or condition change responsive
devices, special types and combinations of the necessary elements
of the class with the subject matter of other classes or with features
added to perfect the operation of the material handling means, and
the more complex devices of the class generally grouped under the
title "systems." Class 251, Valves and Valve
Actuation, provides for valves and valve actuation not otherwise
classified. Subclasses 777 to 802 comprise subcombinations and elements
pertaining to fluid handling not particularly related to any of
the special types and not otherwise classified. Automatic or condition change responsive systems and devices
of this class are discussed more at length in (1) Automatic Control
below, (2) Plural Valves, and (3) Valve Actuation. (1) AUTOMATIC CONTROL Devices and systems in which the presence or absence of, or
a change in, a condition is sensed and control exercised as a result
thereof are commonly called automatic, and in this class form the
basis of a number of "special type" and general
categories. Line condition change response refers to control exercised
over the material being handled in the system as a result of a change
in the condition of that material, as temperature, quantity, pressure
or rate of flow. Condition change response does not include the
mere fact of flow or those fluid pressure operated devices where change
does not affect the operation of the device, nor those where the
flow is changed by external means for the purpose of causing operation
of the control means or with that result. Combinations of an automatic valve with a nonautomatic valve
have been excluded for line condition change responsive groupings
because the system comprising such combinations is not primarily
automatic. Fluid actuated or retarded valves which have not been considered
automatic even though they depend on the presence of fluid flowing
in the line, and have been classified in the following subclasses
in Class 251; are (1) fluid actuated valves with compulsory cut-off
after a flow period (subclasses 15+), (2) dash-pot or fluid
controlled timers and retarders for valves, operating fluid for
which is derived from the line controlled (subclasses 50+). The following groups of subject matter in this class are wholly
or partly of automatic or closely related types. In each instance
the search notes in the definitions of the particular subclasses
referenced in Subclass References of the Current Class, below, should
be consulted for related art. Atmospheric Boiler (see temperature) Combustion (see temperature) Discriminating Valves (see level response). Failure Responsive and Testing Devices Freeze (see Temperature). Heating (see Temperature) Inertia or Position Change Level Response or Maintenance, Floats, Gravitating Tanks,
including: (A) By pressure connection at liquid level; (B) By gravitating
vessel; and (C) By floats - This class is the generic place for
floats, per se, and systems controlled by floats are classified
in various appropriate groups, the subclasses in Subclass References
to the Current Class provide especially for float control or operation. Line Condition Change Response - See the definition, second
paragraph of this section, and listings under Plural heading below Periodic or Cyclic Plural - For a discussion of plural valves as such, see following
section (4). In this category, plural flow controllers, valves,
or condition responsive means may be (A) plural valves controlling
different flows, (B) plural valves controlling the same flow, (C)
one valve responding to changes in plural conditions, or (D) plural
valves each responding to a different condition change. Subclass
References to the Current Class includes subclasses references to
the following: (1) Plural Flows; (2) Plural Condition Responses;
(3) Plural Controls, One Condition Responsive -Where the controls
are separate valves controlling the same flow and one is not automatic
or line condition responsive the patent is excluded from line condition
responsive categories. See section 2, definitions. Such patents
may appear in the earlier special type groups of subclasses, however: Pressure Modulating Pump Safety cut-offs - For resetting operations see (3) Manual Control,
Resetting, and Adjusting Devices, especially the subclass references
to Cut-offs With Resetting. Speed Responsive Control Temperature. (See Boiler, Combustion) (2) PLURAL VALVES Control means for plural flow paths comprising a single movable
body having plural seats or plural port obstructing positions have
been classified as multiway valve units in subclasses 625+.
Valves associated with dispensers have been classified in Class
222, Dispensing. See especially the Search Notes in the appropriate subclasses
of these classes and in the main class definitions, as well as the
Search Notes to the subclasses listed below. In Class 137 devices for controlling plural flows have been
regarded as comprising a system (1) if additional flow confining
means was claimed to a greater extent than as a mere mounting for
the valves, (2) if some definite significant relation between fact
of flow and/or the direction of flow in the plural flow
paths exists, or (3) if one or more conduits or passages have two
or more valves or cut-off devices which function to control the flow
of the fluid by means of the valves. Some plural flow path controls
of various automatic or condition change responsive types are also
found in the earlier subclass groups, but on that basis rather than
as systems in and of themselves. Plural valves having a common means for simultaneous or alternating
actuation, are for the most part in appropriate subclasses under
subclass 561. Some valves, because of motor or complex mechanical
actuation, have been classified in Class 251, Valves and Valve Actuation,
under the type of actuation. For plural automatic or condition responsive valves, see (1)
Automatic Control, "Plural Condition Responses", above
and the associated references in Subclass References to the Current
Class. For plural valves, one automatic or condition responsive and
one or more mechanically or manually actuated, see section for Automatic
Control, Plural Controls, "One Condition Responsive",
above and the associated references in Subclass References to the
Current Class. (3) MANUAL CONTROL, RESETTING AND ADJUSTING DEVICES See section for Automatic Control, Plural Controls, One Condition
Responsive, above for notes on manual control of valves which are
also condition responsive and for manual valves combined with automatic
or condition responsive valves. The term "manual" in some instances includes
nonautomatic valve actuation of other types, as by mechanical movements
or even motors. The term "control" or "actuation" as
applied to the operation of valves does not include the resetting
of valves which are either condition responsive or trip actuated
to move from a preset position and which do not return to that position
when the operating force is removed or reversed, but require intervention
of an external independent agency to restore them to their set position.
Mere adjustment of bias, spacing, seating or actuator connection
of a valve is not included in these terms. (A) Flow Control or Valve Actuation - See references to (1)
Automatic Control, "Plural Controls, One Condition Responsive",
for manual and automatic actuation of valves, and also (2) "Plural
Valves," for plural valves, including actuation. (B) Cut-Offs with Resetting - Also see references to (1) Automatic
Control, "Safety Cut-offs." (C) Adjustment |
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