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CLASS 137,	FLUID HANDLING
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SECTION I - CLASS DEFINITION

This is the residual class for fluid material handling, and takes processes, systems, combinations, subcombinations and certain elements pertaining thereto not otherwise classified.

Fluid materials include gas and liquids primarily, but the handling of other flowable materials, as fluent granular solids, is also found.

Handling for this class comprises the transfer of fluent material by flow, as by confining, directing, causing and/or controlling the flow, and includes making the material available for flow or separating a smaller from a larger body of fluid material, as by tanks, containers, receivers, traps, etc., or pipes or conduits, with or without siphons, pumps, pressure or displacing fluids or other flow imparting means.

SECTION II - 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

SECTION III - SUBCLASS REFERENCES TO THE CURRENT CLASS

SEE OR SEARCH THIS CLASS, SUBCLASS:

SECTION IV - REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:

SECTION V - GLOSSARY

SPECIAL TYPE CATEGORIES

Those comprising a group of related patents directed toward solving a problem in one specific field of activity, which have been classified on the basis of and under a title reflecting that activity rather than on a generalized basis. Examples of special type categories are 94, Fuel controlled by boiler or water system condition; 108, Pump unloader type (indented under Self-proportioning or correlating systems).

SYSTEM

A term applied to any apparatus of the class which comprises more than a single flow path and/or a single valve unit. It may include only an unvalved branched flow path or a single flow path having two or more valve units. In some instances subcombinations or elements having special utility in the combination and having no other classification have been included in the group of subclasses pertaining to the system, as subclasses 777-802, Expansible Chamber Devices.

VALVES AND VALVE ACTUATION

The term "valve unit," as used above, is applied to either a single or multiway valve. In the multiway type plural passages are controlled by valve means having plural flow closing areas or points, but the entire means is housed in a single casing or organized as a body or unit. Valve units as such are classified in subclasses 625+. The class also provides for some valve units under the special titles. Radiator vent check valves, Reversing cokes and valves, Flush or water closet valves, Drain valves, Float valves, Temperature operated cut-off valves, Safety valves, and certain analogous types. The class also takes valves combined with other structure, as the tire inflation type combined with or adapted for connection with inflation means and/or the inflatable article. Class 251, Valves and Valve Actuation provides for valves combined with certain actuators, particularly the fluid and electric motors and the more complex mechanical movement actuators.

The term "Valves" includes variable restrictors, which frequently cannot be distinguished as claimed, and have been set apart only in certain subclasses having the term restrictor or choke in the title, as subclasses 436+, and 475+, primarily because of their special function as silencers. Closures are also frequently indistinguishable from valves, particularly as used and claimed in fluid handling systems. In some instances they have been classified with valves, as in subclasses 613+, Single flow path with plural serial valves and/or closures and Class 251, Valves and Valve Actuation, provides for restrictors or flow guides in subclasses 118.01+.

SUBCLASSES

1	PROCESSES:
	This subclass is indented under the class definition.  Processes. (1) Note. All patents containing method claims drawn to the method of operation of any of the systems or parts thereof involved in the class are included in this and the indented subclasses, but methods of making parts of the system are not included. They will be found in the subclass providing for the system or part. (2) Note. This subclass includes, for example, methods of operation of speed regulators for prime movers, valves, fluid motors; methods of developing fluid pressures by series parallel combinations of pumps, tanks or pipes; methods for affecting fluid flow by using pipe sections of varying diameter or joined at critical angles, or by slugging. SEE OR SEARCH CLASS: 166,  Wells,   subclasses 244.1+ for process of flowing or treating a well; and particularly subclasses 373+ for a method of operating a valve, closure, or changeable restrictor in a well wherein some significant manipulative step regarding the well is recited. 210,  Liquid Purification or Separation,   subclasses 606 , 631, 632, 639, 663+, 696+, 702+, and 749+ for a process comprising the step of adding a chemical to a liquid with treatment of the liquid. 222,  Dispensing,   subclass 1 for processes of dispensing. 399,  Electrophotography,   subclasses 237+ for liquid developer applied to a latent image within an electrophotographic device. 414,  Material or Article Handling,   subclasses 800+ for a process of material or article handling.

2	With control of flow by a condition or characteristic of a fluid:
	This subclass is indented under subclass 1.  Processes in which one or more conditions or characteristics of a fluent material are determined and used to control the system in such a manner as to cause delivery of controlled quantities of a fluent material at a part of the system. (1) Note. See the main class definition, for collected search notes on automatic fluid handling devices of this and related classes. SEE OR SEARCH THIS CLASS, SUBCLASS: 455+, for line condition change responsive valves, and see the search notes to subclass 455.

3	Mixing of plural fluids of diverse characteristics or conditions:
	This subclass is indented under subclass 2.  Processes in which two or more fluent materials of different conditions or characteristics are mixed and the determined condition or characteristic may be taken from any or all the fluent materials and used to control the quantitative flow in any or all the branches or in the mixed channel. SEE OR SEARCH THIS CLASS, SUBCLASS: 87.01+, for self proportioning or correlating systems, especially subclasses 88+ for those involving mixture condition maintaining or sensing.

4	Controlled by consistency of mixture:
	This subclass is indented under subclass 3.  Processes in which the determined condition is the consistency of the mixture. SEE OR SEARCH THIS CLASS, SUBCLASS: 92, for systems for mixture condition maintaining or sensing by viscosity or consistency. 467.5, for line consistency responsive flow controller.

5	Controlled by conductivity of mixture:
	This subclass is indented under subclass 3.  Processes in which the determined condition is the conductivity of the mixture. SEE OR SEARCH THIS CLASS, SUBCLASS: 93, for systems for maintaining or sensing a mixture condition by optical or chemical properties.

6	Controlled by heat of combustion of mixture:
	This subclass is indented under subclass 3.  Processes in which the determined condition or characteristic is the heat of combustion of the mixture. SEE OR SEARCH THIS CLASS, SUBCLASS: 90, for systems of mixture condition maintaining or sensing by temperature or heat content. SEE OR SEARCH CLASS: 431,  Combustion,   subclass 12 for a process of combustion involving the control or proportioning of burner feed.

7	Controlled by pressure:
	This subclass is indented under subclass 3.  Processes in which the determined condition or characteristic is a pressure. SEE OR SEARCH THIS CLASS, SUBCLASS: 87.01+, for self-correlating or proportioning flow systems controlled by the pressure in one or more flow lines or branches.

8	For producing uniform flow:
	This subclass is indented under subclass 2.  Processes in which one or more characteristics or conditions of a fluent material is determined and used to control the system in such a manner as to cause a uniform flow of a fluent material through a part of the system. SEE OR SEARCH THIS CLASS, SUBCLASS: 494+, particularly subclasses 505+ for pressure regulators having a separate connected reactor service. 517+, for direct response condition change controlled valves of the pressure regulating type, and see the search notes to subclass 517. SEE OR SEARCH CLASS: 222,  Dispensing,   subclass 55 for dispensers which maintain a constant weight, volume or pressure by means controlled by the output.

9	For producing proportionate flow:
	This subclass is indented under subclass 2.  Processes in which one or more conditions of a fluent material is determined and used to produce or control the flow of a fluent material at a part of the system, which flow is regulated by the condition or conditions sensed so as to vary proportionally therewith. (1) Note. The flow in which the condition is sensed may be the controlled flow or a different flow. SEE OR SEARCH THIS CLASS, SUBCLASS: 82+, for pressure modulating relays or followers, per se. 98+, for self-proportioning flow systems. 109+, for self-controlled branched flow systems.

10	By speed of fluid:
	This subclass is indented under subclass 2.  Processes in which the condition or characteristic determined is the speed of the fluent material of the system. SEE OR SEARCH THIS CLASS, SUBCLASS: 497+, for line condition responsive valves which are responsive to a change in the rate of fluid flow, and see the search notes to subclass 497.

11	For regulating boiler feed water level:
	This subclass is indented under subclass 2.  Processes in which one or more conditions or characteristics of a fluent material is determined and used to control the flow of boiler feed water. SEE OR SEARCH THIS CLASS, SUBCLASS: 94, for fuel control devices for boilers responsive to boiler or water system conditions. 156+, for gas pressure discharge of liquid feed traps to boilers. 386+, for liquid level responsive or maintaining systems. SEE OR SEARCH CLASS: 122,  Liquid Heaters and Vaporizers,   subclasses 451+ for boiler feeders combined with boilers, and subclasses 412+ for boiler feed heaters.

12	By fluid pressure:
	This subclass is indented under subclass 2.  Processes in which the condition or characteristic which is determined is a fluid pressure and the determination is used to cause delivery of controlled quantity of a fluent material at a part of the system. SEE OR SEARCH THIS CLASS, SUBCLASS: 7, for processes of mixture control depending on pressure sensing. 455+, for line condition change responsive valves, and see the search notes to subclass 455.

12.5	Carbonated beverage handling processes:
	This subclass is indented under subclass 1.  Processes for handling potable liquids which are impregnated with gas. SEE OR SEARCH THIS CLASS, SUBCLASS: 154+, for systems which contain, under pressure, a plurality of diverse type fluids, as gas and liquids, and especially 170.1+ for apparatus for controlling foam in handling such liquids, and 206+ for gas pressure storage over or displacement of liquids in such systems. SEE OR SEARCH CLASS: 222,  Dispensing,   subclass 1 for dispensing methods and subclasses 394 and 396 to 402 for apparatus for dispensing liquids under fluid (gas) pressure. 426,  Food or Edible Material: Processes, Compositions, and Products,   appropriate subclasses, especially 474+ for process involving gas-liquid contact including preparation of carbonated beverages.

13	Affecting flow by the addition of material or energy:
	This subclass is indented under subclass 1.  Processes in which the flow of fluent material is facilitated by the addition of material which affects the flow characteristics of the fluent material, or by the application of heat or other forms of energy. SEE OR SEARCH THIS CLASS, SUBCLASS: 3, for processes of mixing plural fluids with automatic control. 88+, for automatic mixture condition maintaining by the addition of materials, etc. 334+, for fluid handling means combined with heating means, and see the search notes thereto. 565.01+, for distribution systems comprising pumps, and see the search notes thereto. 803+, for a pure fluid device or system capable of performing the process of this subclass (13). SEE OR SEARCH CLASS: 208,  Mineral Oils: Processes and Products,   subclass 370 for miscellaneous treatments of mineral oils during transportation. 507,  Earth Boring, Well Treating, and Oil Field Chemistry,   subclass 90 for compositions for preventing contaminant deposits in petroleum oil conduits and methods of preventing such deposits involving no significant manipulative steps. 516,  Colloid Systems and Wetting Agents; Subcombinations Thereof; Processes of Making, Stabilizing, Breaking, or Inhibiting,   appropriate subclasses for subject matter relating to: colloid systems (such as sols*, emulsions, dispersions, foams, aerosols, smokes, gels, or pastes) or wetting agents (such as leveling, penetrating, or spreading); subcombination compositions of colloid systems containing at least an agent specialized and designed for or peculiar to use in making or stabilizing colloid systems; compositions and subcombination compositions specialized and designed for or peculiar to use in breaking (resolving) or inhibiting colloid systems; processes of making the compositions or systems of the class; processes of breaking (resolving) or inhibiting colloid systems; in each instance, when generically claimed or when there is no hierarchically superior provision in the USPC for the specifically claimed art. 520,  Synthetic Resins or Natural Rubbers,   appropriate subclasses, particularly Class 523, subclass 175 for a composition containing a synthetic resin or natural rubber having utility related to improving drag reduction formation or systems which are effective for reducing the dynamic drag of a turbulent fluid in contact with a surface or to processes of preparing said composition.

14	Involving pressure control:
	This subclass is indented under subclass 1.  Processes in which the pressure of the fluent material is reduced for the purpose of facilitating handling of the material or avoiding damage to the equipment, or equalized with the pressure in another part of the system or a container to facilitate transfer of the fluent material or of control thereof, or regulated to maintain the pressure of the fluent material at a desired value. SEE OR SEARCH THIS CLASS, SUBCLASS: 7, for processes of mixing fluids automatically controlled by pressure. 12, for processes for controlling the flow of material by sensing the pressure thereof.

15.01	Cleaning, repairing, or assembling:
	This subclass is indented under subclass 1.  Subject matter wherein the method comprises the removal of undesirable material from the system, restoration of the system or its component to a sound condition, or connecting together various components of the system. Figures 1, 2, and 3: A typical example of the subject mattershowing various steps of assembling and mounting a faucet structure. A - Sink deck; B - Valve stem; C - Nut; D - Protective shield; E - Groove; F - "C" clip; G - Spout tube; H - Spout bolt; J - Clamping screw; K - Wrench; L - Draw spout. SEE OR SEARCH THIS CLASS, SUBCLASS: 237 through 246.23, with cleaner, lubrication added to fluid or liquid sealing at a valve interface. 315.01 through 329.4, for a fluid handling system with repair, tapping or assembly means. SEE OR SEARCH CLASS: 29,  Metal Working,   subclasses 402.01 through 402.21for a method of mechanical repair. 166,  Wells,   subclass 277 for a process of repairing an object in a well, subclasses 311-312 for a process of cleaning or unloading a well or subclasses 378-380 for a process of assembling a well part.

15.02	Repairing or assembling hydrant (e.g., fireplug, etc.):
	This subclass is indented under subclass 15.01.  Subject matter wherein the process of repairing or assembling is directed to a system having a discharge pipe including a valve and a spout, at which water may be drawn from a water main or water system. Figure 1: A typical example of the subject matter. A - Firehydrant; B - Nozzle; C - Cap; D - Jet of water; E - Nozzle expander bolted to "B" by bolts "F"; F - Bolts; G - Shutoff valve; H - Flange; J - Bolts secure to "E" and "G". SEE OR SEARCH THIS CLASS, SUBCLASS: 236.1, for a fluid handling distribution system involving a geographic feature. 272 through 308, for a hydrant type.

15.03	Gas or water meter repairing or assembling:
	This subclass is indented under subclass 15.01.  Subject matter wherein the process of repairing or assembling is directed to an instrument for measuring and recording the quantity of combustible mixture used for commercial or industrial heating or for measuring and recording the quantity of water supplied for commercial or domestic use. A typical example of the subject matter. Figure 1: A - Gasmeter; B - Outlet gas supply; C - Control valve; D - Regulator; E - Riser nipple; F - Relief valve. Figure 2: A - Water meter; B - Backflow prevention valve;C - Meter pit; D - Coaxial fitting; E - Fluid conduit; F - Flow control valve; G - Fittings to facilitate meter mounting. SEE OR SEARCH THIS CLASS, SUBCLASS: 364 through 371, for a static ground supported valve or meter well. SEE OR SEARCH CLASS: 138,  Pipes and Tubular Conduits,   subclasses 97 through 99for repairing of a pipe or tubular conduit.

15.04	Fluid cleaning or flushing:
	This subclass is indented under subclass 15.01.  Subject matter wherein the process of comprises injecting a pressurized gas, liquid, or a mixture of flowable solid and liquid through the system to eliminate or wash out the material from the system. (1) Note. The liquid may contain a solid particle. Figure 1: A typical example of the subject matter. A -Storage tank; B - Oil; C - Sludge (unwanted material); D - Tank roof; E - Loading valve; F - Riser; G - Pump hose (pressuirzed cleaning fluid); H - Bottom hose; J - Main valve. SEE OR SEARCH THIS CLASS, SUBCLASS: 238 through 245.5, for a fluid handling system with a cleaning or steam sterilizing means. SEE OR SEARCH CLASS: 15,  Brushing, Scrubbing, and General Cleaning,   subclass 246.5 for a brushing, scrubbing, or general cleaning implement, device, or machine attached to a tank.

15.05	Liquid cleaning or flushing:
	This subclass is indented under subclass 15.04.  Subject matter wherein the process of washing out or eliminating the undesirable material from the system is accomplished by use of a desirable material which is a fluid that is not in gaseous form. Figure 1: A typical example of the subject matter. Brake cylinder"A" is filled with brake liquid "B". Inlet valve "C" is provided for introduction of new brake liquid. The outlet valve "D" is for removal of spent brake liquid due to purging. SEE OR SEARCH CLASS: 134,  Cleaning and Liquid Contact with Solids,   subclass 22.12 for a process of cleaning the internal surface of a pipe, tubing, hose, or conduit with pressurized fluid or fluid manipulation, or subclass 40 for a process of removing oil, grease, tar, or wax by dissolving.

15.06	Valve or valve seat cleaning:
	This subclass is indented under subclass 15.05.  Subject matter wherein the flushing liquid is being passed through the body of a flow regulating device or around the circular ring or annular sealing surface used for resting or supporting the head of the device. Figure 1: A typical example of the subject matter. A - Seatassembly; B - Valve seat; C - Replaceable gasket; D - Represents washing fluid being flushed; E, F - Path of washing fluid through slots of gasket. SEE OR SEARCH THIS CLASS, SUBCLASS: 246 through 246.23, for a fluid handling system with liquid supplied at a valve interface for sealing.

15.07	Mechanical cleaning (e.g., pig, etc.):
	This subclass is indented under subclass 15.01.  Subject matter comprising an internally movable element consisting of a brush, scraper, inflatable ring, or similar means used for removing undesirable material from the system. (1) Note. The pig is an in-line scraper, brush, blade, cutter, or swab forced through a pipeline by fluid pressure to remove undesirable material. Figure 1: A typical example of the subject matter. A -Cleaning tool to clean "B" of "B1"; B - Axial bore; B1 - Manifold body; C - Manifold flange; D - Manifold opening for "E"; E - Mounting bolt; F, G, H, J, K, L - Cleaning tool assembly; M - Cleaning member with sharp edge. SEE OR SEARCH CLASS: 15,  Brushing, Scrubbing, or General Cleaning,   subclasses 3.5 through 3.52for a machine with means to pass a solid cleaning agent and a fluid carrier through tubular work or subclasses 104.03-104.33 for a pipe, tube, or conduit cleaning implement, especially subclasses 104.05-104.33 for an implement to clean inside a pipe, tube, or conduit. 138,  Pipes and Tubular Products,   subclass 93 for a pipe or conduit with an inflatable closure or plug.

15.08	Repairing, securing, replacing, or servicing pipe, joint, valve, or tank:
	This subclass is indented under subclass 15.01.  Subject matter wherein the process is directed to a tubular product, coupling, a flow regulating device, or a container or receptacle. Figures 1and 2: A typical example of the subject matter. A- Supply main; B - Pipe saddle; C - Pipe conduit; D - Coupling; E - Flange adaptor; F - Coupled assembly; G - Standard tool; H - Control valve. SEE OR SEARCH CLASS: 138,  Pipes and Tubular Conduits,   subclasses 97 through 99for repairing of a pipe or tubular conduit. 251,  Valves and Valve Actuation,   subclass 152 for a correlated flow line having a pipe coupling or union where a valve seat and coupling element is removable as a unit. 285,  Pipe Joints or Couplings,   subclasses 18 through 40for a pipe joint or coupling with assembly means or feature.

15.09	Including joint or coupling:
	This subclass is indented under subclass 15.08.  Subject matter wherein the significance is attributed to a union formed by two abutting pipes or ducts, an area at which two ends or edges of the pipe or duct are attached, or a device that serves to connect the ends of adjacent parts of a pipe or duct. A typical example of the subject matter. Figure 1: COUPLING:A, B - Flanges; C - Gasket; D - Band; E, F - Welds; G - Seat; H, J - Sealing nuts; K - Bolt. Figure 2: PIPE JOINT: A - Pipe Joint; B, C - Pipe; D - Internalshelf; E - Connector; F - Fitting. SEE OR SEARCH CLASS: 29,  Metal Working,   subclasses 509 through 513for a method of assembling by deforming a part over an edge of a seated part or subclasses 525.01-525.15 for assembling or joining by applying separate fastener. 285,  Pipe Joints or Couplings,   subclasses 15 through 17having repairing means, subclasses 18-40 with or having means to assemble or disassemble, or subclasses 363-368 for a flanged pipe joint having a packing. 403,  Joints and Connections,   subclasses 11 through 22for a protector or broken part retainer with repair, assembly, or disassembly feature. 405,  Hydraulics and Earth Engineering,   subclasses 169 through 170for assembling a line of pipe or cable in or from a marine environment.

15.1	HIGHSPEED FLUID INTAKE MEANS (E.G., JET ENGINE INTAKE):
	This subclass is indented under the class definition.  Apparatus comprising intake means described for use in an ambient gaseous medium to gather a portion of that medium, said incoming medium moving at a relatively high speed with respect to the intake means, said intake means comprising a flow passage for the incoming medium, said flow passage disclosed as having at least (1), a portion which converges in the direction of flow or (2), a portion which diverges in the direction of flow or (3), an enlarged portion downstream of the intake end. (1) Note. Many of the patents herein disclose the intake means as being used to convert a portion of the kinetic energy of the incoming gas into static pressure energy. (2) Note. A claim to merely recite the wall structure of a tubular member, or to a mere tubular member with a restricting or baffle means for facilitating or restricting flow of fluid is classifiable in Class 138, Pipes and Tubular Conduits. For classification in Class 137, some additional fluid handling features must be claimed. See the reference to Class 137 under "SEARCH CLASS" in the definition of subclass 37 in Class 138. (3) Note. A claim with a nominal recitation of the apparatus to which the incoming gaseous medium is being delivered, (e.g., jet engine, pump), in combination with the intake means, does not preclude classification in Class 137.

15.11	Detecting or repairing leak:
	This subclass is indented under subclass 15.08.  Subject matter wherein the significance is attributed to discovering or determining presence or existence of a crack, crevice, or hole that usually by wear and tear or mishap allows gas or liquid to escape, and restoring to a sound condition by patching, applying, or injecting a liquid, semi-liquid, or semi-solid material to prevent gas or liquid entry to or loss from a pipe, duct, container, or valving system. A typical example of the subject matter. Figure 1: INJECTINGSEALANT: A - Leak repair clamp; B - Pipe line; C - Cavity for receiving sealant; D - Passageway for sealant injection; E - Stopper plug. Figure 2: FLEXIBLE PATCH: A - Sealing leak; B - Pipe; C- Sealing patch. SEE OR SEARCH THIS CLASS, SUBCLASS: 312 through 314, for leakage or drip collecting. SEE OR SEARCH CLASS: 29,  Metal Working,   subclasses 402.09 through 402.17for a method of repairing by attaching a repair preform (e.g., remaking, restoring, patching, etc.). 73,  Measuring and Testing,   subclasses 40 through 49.3using fluid pressure to test or determine a leak. 228,  Metal Fusion Bonding,   subclass 119 for a process of repairing, restoring, or renewing a product for reuse. 285,  Pipe Joints and Couplings,   subclasses 13 through 14for leakage or drip disposal including weep holes.

15.12	Tapping pipe, keg, or tank:
	This subclass is indented under subclass 15.08.  Subject matter wherein the significance is attributed to piercing an aperture or removing a plug from a tubular product, a small cask or barrel, or a container or receptacle used for transporting, holding, or storing a gas or liquid. Figure 1: A typical example of the subject matter. A - Concretetube or pipe; B - Tensioned wires; C - Cement coating; D - Sealing gland; E - Shell cutter; F - Film (auxiliary coating); G - Saddle; H - Straps; J - Saddle neck; K - Gasket; L - Tightening bolts; M - Grout; N - Valve casing; P - Valve; Q - Adapter for tapping machine; R - Tapping machine; S - Conduit for fluid under pressure; T - Cutting machine shaft; V - Centering drill. SEE OR SEARCH THIS CLASS, SUBCLASS: 317 through 325, for an apparatus for tapping a pipe, keg or apertured tank under pressure. SEE OR SEARCH CLASS: 29,  Metal Working,   subclasses 522.1 through 524.1for a method of assembly or joining by deforming a radially expanding part in a cavity, aperture, or hollow body or subclasses 890.14-890.15 for a method of making a specific gas or water plumbing component. 138,  Pipes and Tubular Products,   subclasses 94 through 94.5for a laterally insertable closure or plug.

15.13	Particular aperture forming means:
	This subclass is indented under subclass 15.12.  Subject matter wherein the significance is attributed to creating a hole, gap, indentation, or a narrow, deep opening. Figure 1: A typical example of the subject matter. A - Nipple(outer end); B - Exterior threads; C - Enlarged outer end portion; D - Perforating tool; E - Exterior taper; F Main pipe; G - Allen wrench; H - Passageway; J - Valve. SEE OR SEARCH THIS CLASS, SUBCLASS: 318, for an apparatus for tapping a pipe, keg, or apertured tank under pressure with aperture forming means. SEE OR SEARCH CLASS: 83,  Cutting,   subclass 54 for a process of cutting the wall of a hollow work in general. 408,  Cutting by Use of Rotating Axially Moving Tool,   subclasses 22 through 30combined with diverse cutting means, subclass 704 for drilling small holes, or subclass 705 for drilling deep holes.

15.14	Cutter or cutting tool:
	This subclass is indented under subclass 15.13.  Subject matter comprising a shearing device to remove a portion of the pipe or keg to provide an aperture. Figure 1: A typical example of the subject matter. A - Cutterassembly; B - Piston; C - Recess; D - Bushing; E - Resilient ring; F - Cutter; G - Tubular insert; H - Annular ring; J - Pipe wall; K - Cut portion (coupon); L - Allen wrench; M - Piston movement. SEE OR SEARCH CLASS: 83,  Cutting,   subclass 30 for a process of puncturing or subclass 54 for a process of cutting a wall of hollow work. 222,  Dispensing,   subclasses 81 through 90for a cutter or punch to form a dispensing opening in a container. 228,  Metal Fusion Bonding,   subclass 171 for a process of producing opposed complementary matching bonding surfaces by cutting prior to bonding. 408,  Cutting by Use of Rotating Axially Moving Tool,   subclasses 87 through 102for a cutting tool in combination with a tool-opposing, work-engaging surface.

15.15	Having deformable or inflatable means:
	This subclass is indented under subclass 15.13.  Subject matter wherein the method of forming an aperture further includes sealing by use of an abnormally expandable bladder, compressible stopper, or similar resilient member. Figure 1: A typical example of the subject matter. A - Pipemain; B - Resilient plug (inflatable); C - Inner rod; D - Saddle; E - Opening in pipe; F - Pipe plug; G - Stopper rod; H - Intermediate rod; J - U-bolt; K - Service tree. SEE OR SEARCH CLASS: 138,  Pipes and Tubular Conduits,   subclasses 89.1 through 89.2for an inflation stem type air and dust cap, subclass 89.3 for an inflation stem type air cap, subclass 89.4 for an inflation stem type dust cap, subclass 93 for an inflatable closure or plug, subclasses 94-94.5 for a laterally insertable closure or plug, or subclasses 97-99 for repairing a pipe or tubular conduit.

15.16	With content loading or unloading (e.g., dispensing, discharge assistant, etc.):
	This subclass is indented under subclass 15.08.  Subject matter comprising a method of filling the pipeline or tank with a substance or material or removing a substance or material from a pipeline or tank. Figure 1: A typical example of the subject matter. A - Vessel;B - Viscous material; C - Gear pump; D - Drain opening; E - Boss; F - Valve body; G - Flange connection; H - Side outlet; J - Piston; K - Actuator; L - Hose; M - Container; N - Solenoid valve. SEE OR SEARCH THIS CLASS, SUBCLASS: 587 through 588, for a fluid handling system having a tank that includes a gas vent and a liquid inlet or outlet. SEE OR SEARCH CLASS: 141,  Fluent Material Handling, With Receiver or Receiver Coacting Means,   subclasses 2 through 3for a process of filling a dispenser or subclasses 5-7 for a process of manipulating gas within the receiver and filling with fluent nongaseous materials, especially subclass 7 for a process of evacuation of a container. 222,  Dispensing,   subclasses 321.1 through 321.9with discharge assistant (e.g., impeller, pump, conveyer, movable trap chamber, etc.), a movable nozzle interconnected with it and a material supply container and discharge assistant casing.

15.17	Specific valve or valve element mounting or repairing:
	This subclass is indented under subclass 15.08.  Subject matter wherein the significance is attributed to the process of installing, replacing, or servicing a flow regulating device or its component. Figure 1: A typical example of the subject matter. A - Valveassembly; B - Interior wall; C - Distribution pipe; D - Tank; E - Tank inlet; F - Main valve; G - Water inlet line; H - Flexible tube; J - Fittings. SEE OR SEARCH THIS CLASS, SUBCLASS: 15.18 through 15.26, for a process of assembling, disassembling, or repairing a valve or valve member. SEE OR SEARCH CLASS: 29,  Metal Working,   subclasses 213.1 through 221.6for assembly or disassembly means for applying or removing a valve, subclass 890.121 for a method of repairing, converting, servicing, or salvaging a valve or choke, or subclasses 890.124-890.131 for a method of assembly, disassembly, or composite valve or choke making.

15.18	Valve or valve element assembling, disassembling, or repairing:
	This subclass is indented under subclass 15.01.  Subject matter wherein the significance is attributed to the process of installing, replacing, or securing a flow regulating device or its component. Figure 1: A typical example of the subject matter. A - Valvebody; B - Inlet port; C - Outlet port; D - Flanges; E - Valve chamber; F - Seat sections; G - Valve body portion; H - Hanger surface; J - Hanger recess; K - Clapper; L - Annular ring; M- Spherical segment; N - Annular recess; P - Clapper pin; Q - Bushing. SEE OR SEARCH THIS CLASS, SUBCLASS: 15.17, for a process having a particular repairing or mounting feature for the valve or valve member. 329.01 through 329.06, for repair by means where a valve head or seat is replaceable or having an unworn surface movable into operative position. SEE OR SEARCH CLASS: 29,  Metal Working,   subclasses 213.1 through 221.6for assembly or disassembly means for applying or removing a valve, subclass 890.121 for a method of repairing, converting, servicing, or salvaging a valve or choke, or subclasses 890.124-890.131 for a method of assembly, disassembly, or composite valve or choke making.

15.19	Fluid actuated or retarded:
	This subclass is indented under subclass 15.18.  Subject matter wherein the significance is attributed to the opening or closing movement of the valve and is produced by the relative force of a gas, liquid, or a mixture of a solid and liquid. Figure 1: A typical example of the subject matter. A - Controlvalve; B - Valve stem; C, D, E, F - Lever and link mechanism; G - Piston; H - Servomechanism; J - Actuator; K - Manifold to control actuator. SEE OR SEARCH THIS CLASS, SUBCLASS: 601.13, for systems dividing into parallel flow lines then recombining having a fluid actuated or retarded valve. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 12 through 63.6for a fluid actuated or retarded valve actuating means or subclass 175 for means to increase head and seat contact by fluid pressure.

15.2	With condition responsive control means:
	This subclass is indented under subclass 15.1.  Apparatus having means sensing a condition of the ambient medium, or of the medium flowing through the intake means, said sensing means controlling operation of a control means for the medium flowing through the intake means, or for a separate fluid. SEE OR SEARCH THIS CLASS, SUBCLASS: 601.13, for systems dividing into parallel flow lines then recombining having a fluid actuated or retarded valve. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 12 through 63.6for a fluid actuated or retarded valve actuating means or subclass 175 for means to increase head and seat contact by fluid pressure.

15.21	Multi way valve:
	This subclass is indented under subclass 15.18.  Subject matter wherein the valve regulates or controls a plurality of flow lines. Figure 1: A typical example of the subject matter. A - Valvebody; B - Valve cage; C - Valve plug; D - Valve stem; E - Bonnet; F, G - Valve ports; H - Central boss; J - Valve body bridge; K, L - Side ports; M - Bottom port. SEE OR SEARCH THIS CLASS, SUBCLASS: 315.09, for a fluid handling system with means for assembling or disassembling a multi way valve device. 625 through 625.5, for a multi way valve unit.

15.22	Ball valve or rotary ball valve:
	This subclass is indented under subclass 15.18.  Subject matter wherein the significance is attributed to a valve comprising a recriprocating spherical element, a pivoting spherical element, or a housing having a flow passage therethrough with a valve seat, and a spherical head that contacts the seat and can be rotated about an axis passing generally through its geometrical center by actuating means. Figure 1: A typical example of the subject matter. A - Valveseat; B - Upper valve seat; C - Lower valve seat; D - Packings; E, F - Retainers; G, H -Bearing packings; J - Valve box; K - Valve rod; L - Packing gland; M - Gland screw; N - Ball handle; P - Cap nut; Q - Lock nut; R, S, T - Fluid passages. SEE OR SEARCH THIS CLASS, SUBCLASS: 315.18 through 315.21, for a rotary ball valve with assembling or disassembling. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 315.1 through 315.15for housing construction for a ball valve.

15.23	Gate valve:
	This subclass is indented under subclass 15.18.  Subject matter wherein the significance is attributed to a valve comprising essentially a wedge-shaped or flat sliding plate that can be lowered into a seat or raised to regulate fluid flow. Figure 1: A typical example of the subject matter. A - Gatevalve; B - Valve body; C - Passageway; D -Valve gate; E - Valve seats; F - Valve stem; G - Valve yoke; H - Valve handle. SEE OR SEARCH THIS CLASS, SUBCLASS: 315.29 through 315.32, for a reciprocating gate valve with assembling or disassembling means. 625.45, for system shaving a multi way valve unit that uses a pivoted gate valve unit. 625.49, for systems having a multi way valve unit that uses a reciprocating combined disk or plug for closing one port and a gate or piston valve for closing another port. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclass 300 for a pivoted terminal gate valve, subclasses 301-302 for a pivoted gate valve, or subclasses 326-329 for a reciprocating gate valve.

15.24	Plug valve:
	This subclass is indented under subclass 15.18.  Subject matter wherein the significance is attributed to a valve comprising a cock with a conical or cylindrical piece which is being turned to regulate the flow. Figure 1: A typical example of the subject matter. A - Valveassembly; B, C - Inlet and outlet in axial alignment with each other; D - Cylindrical plug assembly with valve assembly "A"; E - Upper actuating portion of plug "D"; F - Lower actuating portion of plug "D"; G, H - Sealing grooves for plug "D"; J - Plug valve handle; K - Valve support surface. SEE OR SEARCH THIS CLASS, SUBCLASS: 315.25 through 315.26, for a plug valve with means to assemble or disassemble. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 309 through 312for a rotary plug valve or subclass 904 for a snap-fit plug valve.

15.25	Butterfly valve:
	This subclass is indented under subclass 15.18.  Subject matter wherein significance is attributed to a valve comprising a substantially flat and coplaner wings depending from a central axis of rotation. Figure 1: A typical example of the subject matter. A - Throttlevalve shaft; B - Cylindrical bosses; C - Throttle valve disk; D - Spring retainer and lever; E - Holes to receive bosses "B". SEE OR SEARCH THIS CLASS, SUBCLASS: 315.22 through 315.24, for a butterfly valve with assembly or disassembly means. 601.17, for systems dividing into parallel flow lines then recombining including a butterfly valve. SEE OR SEARCH CLASS: 29,  Metal Working,   subclasses 890.124 through 890.131for valve making in general with assembly, disassembly, or composite article making. 454,  Ventilation,   subclasses 333 through 336for an adjustable damper type valve; subclass 369 for a fire damper in general.

15.26	Float valve:
	This subclass is indented under subclass 15.18.  Subject matter wherein the significance is attributed to a valve comprising a hollow, buoyant element, usually attached at the end of a lever, providing positive buoyancy while resting on the fluid surface. Figure 1: A typical example of the subject matter. A - Tank;B - Water level; C - Standpipe; D - Ballcock valve; E - Lever arm; F - Float; G - Port; H - Fill tube. Note: Valve "D" operates such that downward articulation of lever arm "E" causes valve "D" to open so that water can communicate between port "G" and the fill tube "H". SEE OR SEARCH THIS CLASS, SUBCLASS: 165 through 168, for a float responsive to liquid in a trap (e.g., boiler, etc.) to control gas pressure within the trap. 315.08, for a fluid handling system combined with means to assemble or disassemble a float or float valve. 409 through 451, for a liquid level responsive or maintaining system by a float controlled valve. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 322.5 for a float structure. 119,  Animal Husbandry,   subclasses 78 through 80for a watering or liquid feed device with a float-controlled supply. 340,  Communications: Electrical,   subclasses 623 through 625for a liquid level responsive indicating system using a float sensor.

38	CONTROL BY CHANGE OF POSITION OR INERTIA OF SYSTEM:
	This subclass is indented under the class definition.  Apparatus wherein a flow of fluid is controlled in response to (1) the shifting of the position of the system as a whole relative to gravitational field or to a body of liquid in which the system exists or (2) the inertia or dislocation of the system as a whole. (1) Note. Systems which are controlled by overflow pipes or arrangements are excluded from this and indented subclasses and are classified on a basis appropriate to the system claimed. SEE OR SEARCH THIS CLASS, SUBCLASS: 53+, for systems wherein the control is in response to the inertia or position of a speed responsive element (e.g., fly ball governors). 581, for distribution systems comprising a movable tank. SEE OR SEARCH CLASS: 184,  Lubrication,   subclass 26 for lubricating pumps operated by the vibration of a machine. 220,  Receptacles,   subclasses 203.19+ for a receptacle closure comprising a pressure responsive vent or valve which is also responsive to tilting of the receptacle. 222,  Dispensing,   subclasses 160+ for movably mounted supply containers for dispensers; subclasses 454+ for dispensers which have a trap which is filled and emptied solely by the tilting motion of the assembly, and subclasses 500+ for dispensers having gravity or inertia operated outlet elements. 399,  Electrophotography,   subclasses 237+ for liquid developer applied to a latent image within an electrophotos:graphic device. 417,  Pumps,   subclasses 231+ for pumps operated by a vehicle. 700,  Data Processing: Generic Control Systems or Specific Applications,   subclass 281 for control of fluid level or volume, and subclasses 282-285 for flow control.

39	With second control:
	This subclass is indented under subclass 38.  Apparatus which includes, in addition to the control responsive to the position or inertia of the system as a whole, a second means for operating the control means. (1) Note. The second control may be manual or operated in response to some other condition, such as pressure, temperature, etc. (2) Note. This subclass also provides for systems including means to neutralize or overcome the effect of a change of position on a second flow control. (3) Note. See the class definition, section 3, for search notes on combined automatic and manual control of fluid handling systems.

40	Position relative body of water (e.g., marine governors):
	This subclass is indented under subclass 38.  Apparatus wherein the flow is controlled in response to the position of the system as a whole relative to a body of water in which the system is located. (1) Note. To be classifiable in this or indented subclass the apparatus must include some means for sensing the position of the system relative to the body of water. (2) Note. Marine governors operated in response to the shifting of the position of the system relative to gravity (due to ocean wave motion for example) but which do not include means for sensing the position of the system relative the water are found in other subclasses of this group. SEE OR SEARCH THIS CLASS, SUBCLASS: 146, for the plunge or immersion starting of siphons. SEE OR SEARCH CLASS: 440,  Marine Propulsion,   subclass 74 for marine propulsion screw type propellers combined with propeller brakes to prevent racing of the propeller.

41	Float controlled:
	This subclass is indented under subclass 40.  Apparatus which includes a float means for sensing the position of the system relative the body of water in which the system exists. SEE OR SEARCH THIS CLASS, SUBCLASS: 386+, and Notes thereto for other float controlled apparatus.

42	Pressure or head controlled:
	This subclass is indented under subclass 40.  Apparatus which includes means to sense the pressure or head of the body of water in which the system exists. SEE OR SEARCH THIS CLASS, SUBCLASS: 403+, for liquid level responsive or maintaining systems in which the level is determined by head or pressure.

43	Vent opening or closing on tipping container:
	This subclass is indented under subclass 38.  Apparatus including means to close or open a vent opening on a container when the position of the container is varied, e.g., when the container is tipped. SEE OR SEARCH THIS CLASS, SUBCLASS: 583+, for distribution systems having plural flow passages, one of which is a gas vent, and see the search notes to subclass 583. SEE OR SEARCH CLASS: 222,  Dispensing,   subclass 500 for gravity or inertia actuated outlet elements for dispensers. 429,  Chemistry: Electrical Current Producing Apparatus, Product, and Process,   subclasses 84+ for vents combined with battery structure and battery vents, per se, of the nonspill type.

44	By shifting of liquid level:
	This subclass is indented under subclass 38.  Apparatus wherein the control is effected by a change in a level of a liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 40+, where the control is in response to a change or shift in the level of a body of water in which the system is located relative to the system. 45, for similar devices in which a liquid is employed as a shifting weight in combination with a pendulum or swinging member. 386+, for liquid level responsive systems which are not inertia controlled.

45	By pendulum or swinging member:
	This subclass is indented under subclass 38.  Apparatus wherein the flow is controlled by means of a pendulum or other pivoted member swinging about its pivot in response to a change of position of the system or to the inertia of the system. SEE OR SEARCH CLASS: 33,  Geometrical Instruments,   subclasses 391+ for pendulum type levels or plumbs.

46	With servo connection to valve:
	This subclass is indented under subclass 45.  Apparatus in which the pendulum or pivoted member controls the application of another source of power for operating the control instead of by acting directly through a mechanical connection. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 25+ for fluid servo or pilot operated valves, and see the search notes to subclass 25.

47	SPEED RESPONSIVE VALVE CONTROL:
	This subclass is indented under the class definition.  Systems including the combination of a valve or valves and an actuator therefor, the actuator including a driven means which changes its position or produces a regulating pressure which varies in accordance with the speed at which it is driven. (1) Note. The driven means may comprise one or more governors. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclasses 488+ for a speed responsive device, per se. 116,  Signals and Indicators,   subclasses 37+ and 57 for vehicle speed responsive indicators and subclasses 200+ for speed limit indicators. 399,  Electrophotography,   subclasses 237+ for liquid developer applied to a latent image within an electrophotos:graphic device. 700,  Data Processing: Generic Control Systems or Specific Applications,   subclasses 282 through 285for flow control including valve or pump control, and subclasses 301 and 304 for pressure and speed control, respectively.

48	Acceleration responsive valve control:
	This subclass is indented under subclass 47.  Control systems wherein the driven means changes its position in accordance with the rate of change of speed at which it is driven.

49	With manual valve control:
	This subclass is indented under subclass 47.  Control systems including additional means whereby the valve or valves may be manually operated. (1) Note. Manually operated means to modify the response setting of the speed responsive means or to reset the trip latch, are not deemed to constitute a manual control within the definition of this subclass. However, if the manual reset means also actuates the valve or valves, the device would be considered as being manually operated for classification herein. See the class definition, section 3, for search notes on combined automatic and manual control means for fluid handling systems, and Section 5, for a listing of manual control, resetting and adjusting devices in this class. (2) Note. The term "manual" as used herein includes both hand and foot actuated means. (3) Note. This subclass includes manual valve actuating means in which a speed responsive device become effective at a predetermined speed of the engine or vehicle, either (1) to disconnect the mechanical movement of the manual actuator, and in some instances also to operate a trip mechanism to permit a biasing means to close the valve, or (2) to act as a limit stop to prevent further valve opening by the manual actuator. SEE OR SEARCH THIS CLASS, SUBCLASS: 57, for excess speed responsive control, and see the search notes thereto. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 513 for a speed responsive device combined with manual control.

50	Speed change and excess speed valve control:
	This subclass is indented under subclass 47.  Control systems wherein the driven means is operable to vary the extent of opening of the valve or valves in response to changes in speed and to effect closing of the valve or valves in response to a speed above a predetermined speed. (1) Note. The driven means may comprise one or more governors which may control a single valve or a plurality of valves. SEE OR SEARCH THIS CLASS, SUBCLASS: 57, for excess speed responsive valve control of the centrifugal mass type, and see the search notes thereto.

51	With other condition responsive valve control:
	This subclass is indented under subclass 47.  Control systems including additional means responsive to another operating condition which may actuate the same valve which is actuated by the speed responsive means, or another valve. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 509 for a speed responsive device that is also responsive to a nonspeed condition.

52	Governor drive failure responsive:
	This subclass is indented under subclass 51.  Control systems wherein the additional condition responsive means comprises a control device responsive to the breaking or failure of the driving means for the speed responsive governor to effect closing or substantial closing of a valve. (1) Note. The valve which is closed or substantially closed on failure of the driving means may be the valve controlled by the speed responsive governor or another valve. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 508 for a governor having drive failure responsive means. 251,  Valves and Valve Actuation,   subclass 27 for fluid pressure servo operated valves having means to close the valve on failure of the servo means, and subclass 69 for biased trip valves having the trip actuated on failure of the electric power.

53	Centrifugal mass type (exclusive of liquid):
	This subclass is indented under subclass 47.  Control systems wherein the speed responsive means comprises a rotating or revolving weight or weights, the position assumed by such weight or weights due to centrifugal force varying as a function of the speed at which they are rotated or revolved. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclasses 535+ for a centrifugal type speed responsive device, per se.

54	With multiple valves:
	This subclass is indented under subclass 53.  Control systems wherein two or more valves are provided, at least one of said valves being actuated by the speed responsive means. (1) Note. See the class definition, section 3, for search notes on plural automatic valves in this and related classes.

55	Periodically actuated valve:
	This subclass is indented under subclass 53.  Control systems wherein the valves or valve are periodically and continually opened and closed, the governor being effective to vary the period and/or the extent of opening. (1) Note. The valves are usually disclosed for use in a reciprocating type of expansible chamber motor, the valves being periodically actuated for admitting motive fluid to the power cylinder and the governor varies the quantity of motive fluid in accordance with the motor speed. SEE OR SEARCH THIS CLASS, SUBCLASS: 631+, for nonautomatic cyclically operated valves, and see the search notes to subclass 631.

56	Rotating valve and rotating governor:
	This subclass is indented under subclass 53.  Control systems wherein the speed responsive means and the valve or valves are combined to comprise a continuously rotating construction. SEE OR SEARCH THIS CLASS, SUBCLASS: 55, for valves connected with a speed responsive governor to rotate therewith in order to periodically open and close the valve, the governor producing an axial motion of the valve to control the period and/or extent of valve openings.

57	Excess speed responsive:
	This subclass is indented under subclass 53.  Control systems wherein the speed responsive means is effective to actuate the valve or valves only at speeds above a predetermined speed. SEE OR SEARCH THIS CLASS, SUBCLASS: 50, for speed change and excess speed valve control. 456+, for safety cut-offs of general utility which respond to line condition and require resetting. SEE OR SEARCH CLASS: 116,  Signals and Indicators,   subclass 57 and 62.1+ for vehicle speed limit indicators and alarms.

58	With fluid servo-motor:
	This subclass is indented under subclass 53.  Control systems wherein the speed responsive means transmits its regulating motion to the valve or valves by means of a fluid type servo-motor mechanism. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   subclasses 366 and 458 for speed governor operated expansible chamber motors. 251,  Valves and Valve Actuation,   subclasses 25+ for fluid pressure actuated valves of the pilot or servo-motor type, and see the search notes to subclass 25. 418,  Rotary Expansible Chamber Devices,   subclasses 40+ for speed controlled rotary expansible chamber devices.

59	FREEZE CONDITION RESPONSIVE SAFETY SYSTEMS:
	This subclass is indented under the class definition.  Apparatus which includes means which senses the existence of conditions which would cause the freezing of liquid within the system and in response thereto exercises a control to protect the liquid from freezing or to safeguard the system as a whole from the effects of freezing of a part thereof. SEE OR SEARCH THIS CLASS, SUBCLASS: 72+, for valves controlled by heat destructible or fusible means. 79+, for devices responsive to atmospheric temperature not amounting to a freeze condition. 107, for apparatus wherein a waste valve opens in response to the stopping of flow through the line, disclosed as preventing freezing. 118.01+, for branched flow systems responsive to temperature of the system. 301+, for hydrants with means to prevent freezing. 457, for safety cut-offs requiring reset and responsive to thermal conditions in a fluid line. 468, for other valves controlled in response to thermal conditions in a fluid line. SEE OR SEARCH CLASS: 62,  Refrigeration,   subclasses 132+ for condition sensing controls for a refrigeration system, particularly subclasses 139+ for control by accumulation on a freezing surface. 123,  Internal-Combustion Engines,   subclasses 41.14 , 41.15, 41.42, 41.5, and 142.5 for devices for protecting the cooling systems of internal combustion engines against cold. 138,  Pipes and Tubular Conduits,   subclasses 27+ for freeze protecting pressure compensators, and subclasses 32+ for freeze protection for pipes and tubular conduits. 236,  Automatic Temperature and Humidity Regulation,   appropriate subclasses. 237,  Heating Systems,   subclass 80 for heating radiators having means for preventing freezing.

60	With freeze waste:
	This subclass is indented under subclass 59.  Apparatus which includes means to protect the liquid from freezing by responding to the freezing of the liquid in a chamber. (1) Note. The freeze chamber may be in the main flow line or may be an auxiliary control chamber which is more exposed to the low temperature. SEE OR SEARCH THIS CLASS, SUBCLASS: 67+, for frangible control elements not responsive to a freeze condition.

61	Stop and waste:
	This subclass is indented under subclass 59.  Apparatus which closes the system to liquid flow and opens a waste outlet so that at least part of the liquid in the system is drained or wasted in response to the sensing of low temperature or freezing conditions. SEE OR SEARCH THIS CLASS, SUBCLASS: 107, for opening fluid waste passage in response to stopping of the main flow. 596+, for stop and waste devices not responsive to change in condition, and see the search notes thereto.

62	Low temperature responsive drains:
	This subclass is indented under subclass 59.  Apparatus which operates to open an outlet so that at least part of the system is drained or emptied of liquid in response to the sensing of low temperature or freezing conditions. SEE OR SEARCH THIS CLASS, SUBCLASS: 570, for drain valve actuator combined with a pump. 596+, for distribution systems comprising a drain which is not automatic, and see the search notes thereto.

65	COMBUSTION FAILURE RESPONSIVE FUEL SAFETY CUT-OFF FOR BURNERS:
	This subclass is indented under the class definition.  Subject matter comprising a flow control device or safety valve in the fuel supply to a burner which is automatically actuated to discontinue the fuel flow in response to the extinguishment of the main or pilot burner. (1) Note. These devices are not self-opening, but must be manually reset, usually requiring that the pilot burner be lighted first. SEE OR SEARCH THIS CLASS, SUBCLASS: 405, for cut-offs responsive to an accumulation of unburned fuel oil delivered to a burner. 456+, for safety cut-offs responsive to a change in line condition, which also require resetting. SEE OR SEARCH CLASS: 431,  Combustion,   subclasses 42+ for a burner system in which the sensor of a first burner controls a second burner and subclasses 77+ for a burner shutdown by a means sensing a failure of the burner flame.

66	Thermo-electric:
	This subclass is indented under subclass 65.  Control systems wherein the safety valve is retained in its set or open position under the action of a solenoid, which solenoid is energized by the electric current generated by a thermoelectric element, e.g., a thermocouple, subject to the heat of the pilot burner or main burner. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclass 11 for heat motor actuated valves of general utility, and subclasses 68+ for electrical trip actuation of biased valves, including electrical resetting. 431,  Combustion,   subclass 80 for a burner assembly including a shutdown control responsive to combustion failure or overheat having a thermoelectric combustion sensor.

67	DESTRUCTIBLE OR DEFORMABLE ELEMENT CONTROLLED:
	This subclass is indented under the class definition.  Subject matter in which the flow of fluid is controlled in response to the destruction, fusion or permanent deformation of an element or body. (1) Note. The destruction, fusion or deformation may result automatically in response to the existence of some condition causing destruction, fusion or deformation (e.g., heat), or may be deliberately brought about by external means. SEE OR SEARCH THIS CLASS, SUBCLASS: 318, for tapping a system under pressure by making an aperture therein. SEE OR SEARCH CLASS: 166,  Wells,   subclasses 316+ for closures used in wells and destructible by drilling. 222,  Dispensing,   subclass 54 for automatic control of dispensers by fusible or soluble means; subclasses 80+ for dispensers having a cutter or punch associated therewith; subclasses 541.1+ for dispensers having a frangible outlet element. 251,  Valves and Valve Actuation,   subclass 1.2 for a blowout preventer having a deformable annulus.

68.11	Destructible element:
	This subclass is indented under subclass 67.  Subject matter in which the fluid flow control element is physically broken by having a force acting directly upon it. SEE OR SEARCH THIS CLASS, SUBCLASS: 797, for frangible elements, the breaking of which do not control any flow of fluid. SEE OR SEARCH CLASS: 222,  Dispensing,   subclasses 80+ for dispensers having a cutter or punch associated therewith.

68.12	Combined destructible and fusible element:
	This subclass is indented under subclass 68.11.  Subject matter in which the element breaks and melts at a specific temperature to control the fluid flow or has, in addition to the destructible element, a separate element which melts at a specific temperature to control the fluid flow.

68.13	Explosive actuation:
	This subclass is indented under subclass 68.11.  Subject matter which includes means capable of detonation for creating a force for breaking or deforming the destructible element (e.g., an explosive element moves a plunger or creates a pressure surge to break the element).

68.14	Separable valve coupling or conduit:
	This subclass is indented under subclass 68.11.  Subject matter where the destructible element is a fluid-conveying assembly such as a nipple, valve assembly, or hose that disconnects at a specific joint when an excessive force is applied to it.

68.15	Tensile or sheer pin or bolt:
	This subclass is indented under subclass 68.14.  Subject matter where the destructible element is a pin or bolt that holds the coupling together and destructs when a perpendicular or axial excessive force is applied to the coupling.

68.16	Tensile or sheer pin or bolt:
	This subclass is indented under subclass 68.11.  Subject matter where the destructible element is a pin or bolt that destructs when an excessive force is applied.

68.17	Pressure causes pin or bolt to destruct:
	This subclass is indented under subclass 68.16.  Subject matter that destructs when the applied excessive force that fractures the pin or bolt is applied over the surface of the pin or bolt.

68.18	With alarm or indicator:
	This subclass is indented under subclass 68.11.  Subject matter that includes a sensing means that sends a signal when the element breaks.

68.19	Rupture disc:
	This subclass is indented under subclass 68.11.  Subject matter where the destructible element is a diaphragm or seal that holds fluid. SEE OR SEARCH THIS CLASS, SUBCLASS: 72, for a fluid-controlled fusible diaphragm. SEE OR SEARCH CLASS: 220,  Receptacles,   subclasses 89.2+ for a receptacle that is a frangible diaphragm within a container or vessel.

68.21	Means for holding entire disc after rupture:
	This subclass is indented under subclass 68.19.  Subject matter that has a specific means for preventing the rupture disc from tearing away (e.g., hinge-reinforcing member).

68.22	Disc burst after destruction of additional element:
	This subclass is indented under subclass 68.19.  Subject matter that includes a second frangible element in a system which destructs before the rupture disc. (1) Note. This subject matter would include a system with two or more rupture discs in a flow passage.

68.23	Direct pressure causes disc to burst:
	This subclass is indented under subclass 68.19.  Subject matter wherein the destructible element is destroyed by excessive pressure exerted by the fluid flow.

68.24	Two-way rupture disc:
	This subclass is indented under subclass 68.23.  Subject matter that is designed to break either in the direction of or opposite the direction of the fluid flow when an excessive pressure differential exists.

68.25	Dome shape:
	This subclass is indented under subclass 68.23.  Subject matter that is specifically designed to be hemispherical to enable the disc to more easily rupture as pressure builds.

68.26	Reverse buckling:
	This subclass is indented under subclass 68.25.  Subject matter which has excessive pressure at the convex side of the disc to cause the disc to reverse its concavity and burst.

68.27	Specific weakening point:
	This subclass is indented under subclass 68.19.  Subject matter specially modified to have an area of varied thickness creating a vulnerable section to enable the pressure disc to more easily break.

68.28	Integral disc assembly:
	This subclass is indented under subclass 68.19.  Subject matter including a support member welded or bonded with adhesive to the rupture disc or the rupture disc is directly bonded or welded to the assembly.

68.29	Knife or cutter causes disc to break:
	This subclass is indented under subclass 68.19.  Subject matter penetrated by a piercing device to enable the disc to more easily break when the internal pressure in the system becomes excessive.

68.3	Movable knife or cutter:
	This subclass is indented under subclass 68.29.  Subject matter wherein the piercing device is positionable.

69	With counterbalancing element:
	This subclass is indented under subclass 68.12.  Apparatus which includes means for applying a force or bias to the frangible means in a direction opposing the force (usually fluid pressure) which tends to break the frangible element.

70	Frangible element returns pressure responsive valve:
	This subclass is indented under subclass 68.12.  Apparatus in which a valve which opens in response to increased pressure is retained in closed position by means of a frangible element, opening of the valve resulting from the breaking of the frangible element. SEE OR SEARCH THIS CLASS, SUBCLASS: 455+, for line condition responsive valves not opposed by frangible means.

71	Having pressure responsive valve:
	This subclass is indented under subclass 68.12.  Apparatus including a pressure responsive valve controlling the fluid flow in response to the pressure thereof in addition to the control in response to the breaking of the frangible element. SEE OR SEARCH THIS CLASS, SUBCLASS: 511+, for direct pressure responsive valves. SEE OR SEARCH CLASS: 220,  Receptacles,   subclass 203.08 for a vent or valve in a removeable closure, said vent or valve designed to rupture when exposed to excessive pressure.

72	Heat destructible or fusible:
	This subclass is indented under subclass 67.  Apparatus in which the flow is controlled in response to an element which is fusible or destructible by heat (e.g., combustible). SEE OR SEARCH THIS CLASS, SUBCLASS: 79+, for atmospheric temperature responsive flow control. 457, for safety cut-off valves controlled by a thermal condition of the line. 468, for other valves controlled by a thermal condition of a fluid line. SEE OR SEARCH CLASS: 116,  Signals and Indicators,   subclasses 217+ for indicators of the fusible type. 122,  Liquid Heaters and Vaporizers,   subclass 504.1 for safety device for a boiler with fusible control and subclass 504.3 for a fusible type safety device extinguishing a fire under a boiler. 222,  Dispensing,   subclass 54 for dispensers having a fusible controller. 431,  Combustion,   subclass 21 for a burner assembly controlled by a combustion destructible element.

73	With second sensing means:
	This subclass is indented under subclass 72.  Apparatus which includes a means for controlling the fluid flow in response to a change in condition in addition to the control in response to the fusion or destruction of the heat destructible element. (1) Note. See the class definition, section 3 for search notes on plural automatic controls in fluid handling devices. SEE OR SEARCH THIS CLASS, SUBCLASS: 75+, for safety cut-offs operated by fusible means but without responding to a second sensing means.

74	In fluid flow path:
	This subclass is indented under subclass 72.  Apparatus in which the fusible or heat destructible element is in the passage carrying the flow controlled and functions as a barrier or stop member for such flow. (1) Note. The fusion of the fusible element may result in either the opening or closing of the passage carrying the fluid flow. SEE OR SEARCH THIS CLASS, SUBCLASS: 251+, for liquid valves or barriers.

75	Safety cut-off:
	This subclass is indented under subclass 72.  Apparatus in which the valve controlling the fluid flow is biased toward a closed position but is held open by a restraining means, the fusion or destruction of the heat destructible or fusible means causing a release of the restraining means. SEE OR SEARCH THIS CLASS, SUBCLASS: 457, for other cut-offs which are operated in response to a change in thermal condition in the fluid within the controlled line. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 66+ for biased trip valve actuators not responsive to a condition change.

76	With heater for destructible or fusible element:
	This subclass is indented under subclass 75.  Apparatus which includes a heating means for the fusible or heat destructible element. (1) Note. The heating element is usually for the purpose of fusing or otherwise destroying the destructible element to control the operation of the valve. SEE OR SEARCH THIS CLASS, SUBCLASS: 468, for line condition responsive valves controlled by thermal conditions, and see the search notes thereto. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclass 11 for heat motor actuators for valves.

77	With external closing means:
	This subclass is indented under subclass 75.  Apparatus including a means for closing the valve by manual or external means in addition to the operation in response to the fusible or heat destructible element. (1) Note. See the class definition, Automatic Control, and Subclass References to the Current Class for search notes on combined automatic and nonautomatic control of a fluid handling device. SEE OR SEARCH THIS CLASS, SUBCLASS: 76, for manual or external closing by heating the fusible or heat destructible element. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 66+ for biased trip valve actuators not responsive to a condition change.

78.1	AMBIENT CONDITION CHANGE RESPONSIVE:
	This subclass is indented under the class definition.  Apparatus which controls a flow of a fluid in response to a variation in a condition of, or in the surrounding environment. (1) Note. To be classifiable in this or indented subclasses the apparatus must include a sensing means responsive to changes in environmental conditions and there must be a disclosure that the control is in response to such changes. Devices which employ a sensing means using environmental pressure merely as a standard against which some internal pressure or condition is measured are not classified in this or indented subclass but are classified elsewhere on a basis appropriate to the system. (2) Note. This and indented subclasses include devices which include means for sensing changes in an environmental condition and exercising a compensating effect so as to neutralize any effect the change in environmental condition would otherwise have on the operation of the device. (3) Note. See the class definition, section 3, for search notes on the automatic control of fluid handling systems. SEE OR SEARCH THIS CLASS, SUBCLASS: 59+, for device which sense the existence of freeze condition in the atmosphere and in response thereto operate to prevent freezing of liquid in the system.

78.2	For controlling soil irrigation:
	This subclass is indented under subclass 78.1.  Apparatus in which flow of water to the ground is controlled by means responsive to an environmental condition.

78.3	Coil moisture sensing:
	This subclass is indented under subclass 78.2.  Apparatus in which flow of water to the ground is controlled in response to a change in moisture content of the ground.

78.4	Burner gas cutoff:
	This subclass is indented under subclass 78.1.  Apparatus in which flow of flammable gas to a burner is stopped in response to a sensed environmental extinguishing action to the flame of the burner.

78.5	Atmospheric:
	This subclass is indented under subclass 78.1.  Apparatus in which control of a flow of fluid is responsive to a variation in a condition of, or in surrounding atmosphere.

79	Temperature:
	This subclass is indented under subclass 78.5.  Apparatus which controls a fluid flow in response to variations of temperature in the surrounding atmosphere. (1) Note. This subclass includes apparatus which sense the presence of a fire in the atmosphere and exercise a control in response thereto. SEE OR SEARCH THIS CLASS, SUBCLASS: 59+, for freeze condition responsive safety devices. 67+, for systems controlled by a heat destructible or fusible means. 468, for thermally responsive valves responding to line condition change, and see the search notes thereto. SEE OR SEARCH CLASS: 169,  Fire Extinguishers,   subclasses 56+ for fire extinguishers including valves responsive to the occurrence of fire conditions.

80	With additional diverse control:
	This subclass is indented under subclass 79.  Apparatus which also includes, in addition to the atmosphere temperature responsive element, an additional means for operating the control means. (1) Note. See the class definition, Section 3 for search notes on automatic and combined automatic and nonautomatic control of fluid handling systems.

81.1	Pressure:
	This subclass is indented under subclass 78.5.  Apparatus in which a fluid flow is controlled in response to variations of atmospheric pressure. (1) Note. See (1) Note and (2) Note to the definition of subclass 78.1. SEE OR SEARCH THIS CLASS, SUBCLASS: 455+, for valves controlled by changes in line pressure, especially subclass 482 for suction compensators for combustion engine induction type line conduction change responsive valves. SEE OR SEARCH CLASS: 454,  Ventilation,   subclasses 70+ , 238, 255, and 340 for apparatus for maintaining a pressure in enclosure including means responsive to air conditions either in the atmosphere or in the enclosure.

81.2	Underwater:
	This subclass is indented under subclass 78.1.  Apparatus in which control of a flow of fluid is responsive to a variation in a condition of, or in an environment beneath the surface of a body of water.

82	PRESSURE MODULATING RELAYS OR FOLLOWERS:
	This subclass is indented under the class definition.  Apparatus which continuously varies or modulates a fluid in response to a varying control condition. The modulation is usually accompanied by varying a pressure bleed. (1) Note. Only the subcombination, without a pressure responsive device, and a main valve controlled thereby is classified in this subclass; for the combination search appropriate succeeding subclasses, as indicated below. SEE OR SEARCH THIS CLASS, SUBCLASS: 102, for pressure regulators which regulate by supply and exhaust valves to maintain a pre-set pressure. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   appropriate subclasses for apparatus under this definition combined with the expansible chamber motor which is operated by the fluid pressure. 236,  Automatic Temperature and Humidity Regulation,   subclasses 79+ for temperature control systems utilizing pressure modulators to operate fluid pressure motors. 251,  Valves and Valve Actuation,   subclasses 25+ for apparatus which by means of a pilot valve controls the application of fluid pressure to an expansible chamber motor which in turn controls a main line valve. 399,  Electrophotography,   subclasses 237+ for liquid developer applied to a latent image within an electrophotos:graphic device.

83	Jet control type:
	This subclass is indented under subclass 82.  Apparatus which utilize a fluid jet and one or more jet receiving orifices with the control condition varying the pressure in the orifices by varying the amount of jet fluid entering the orifices. SEE OR SEARCH THIS CLASS, SUBCLASS: 625.6, for a jet control type pressure modulator combined with a pilot valve and a supply and exhaust valve. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   subclass 3 for expansible chamber motors combined with a jet type control therefor. 239,  Fluid Sprinkling, Spraying, and Diffusing,   appropriate subclasses, especially subclasses 505+ , 518+ and 587.1+ for jet producing discharge members, per se.

84	Plural series units:
	This subclass is indented under subclass 82.  Apparatus wherein a plurality of modulating relays on followers are connected in series; the output pressure of one controlling the modulation in the next.

85	With counter-balancing pressure feedback to the modulating device:
	This subclass is indented under subclass 82.  Apparatus in which the modulated pressure is utilized in a feedback arrangement to counterbalance the modulating control element.

86	With counter-counter balancing pressure feedback:
	This subclass is indented under subclass 85.  Apparatus in which the modulated pressure is utilized in a second feedback arrangement to counterbalance the counterbalance of the modulating control element.

87.01	SELF-PROPORTIONING OR CORRELATING SYSTEMS:
	This subclass is indented under the class definition.  Subject matter wherein a fluid flow in a first flow line is proportioned or correlated with the fluid flow in a second fluid flow line by a movable means, which is positioned in one of the fluid flow lines and controlling the fluid flow in the other fluid flow line in response to a sensor detecting a variable condition or characteristic of the fluid in the other fluid flow line. (1) Note. The flow proportioning or correlating may constitute plural separate flow lines, branches of the same flow and a branch thereof. (2) Note. The proportioning and correlating of the fluid flows may be continuous or discontinuous and may vary directly or inversely and according to any ratio or in any manner. (3) Note. Systems that rely on static means (e.g., a jet pump) to produce a correlated flow are excluded. SEE OR SEARCH THIS CLASS, SUBCLASS: 155, for gas lift devices for wells including a valve between a gas line and a liquid column responsive to the pressure differential between the gas and the liquid. SEE OR SEARCH CLASS: 210,  Liquid Purification or Separation,   subclasses 198.1+ for a system including a chemical feeder and a separating means. 222,  Dispensing,   subclass 57 for dispensing of one material controlled by the weight, volume, or pressure of a second dispensed material. 251,  Valves and Valve Actuation,   subclasses 12+ for mere fluid pressure actuated valves, even though the flow through the valve may be disclosed as being related or proportioned to the pressure in the fluid pressure actuator line. 399,  Electrophotography,   subclasses 237+ for liquid developer applied to a latent image within an electrophotos:graphic device.

87.02	Liquid level responsive:
	This subclass is indented under subclass 87.01.  Subject matter wherein the sensor is detecting the variation in an uppermost horizontal surface of the liquid in one of the flow lines and in response thereto the sensor controls the flow in the other flow line. SEE OR SEARCH THIS CLASS, SUBCLASS: 101.25, for a self-proportioning flow system with liquid level sensing. 386+, for a liquid level responsive means without proportionate or correlated flow.

87.03	Flow rate responsive:
	This subclass is indented under subclass 87.01.  Subject matter wherein the sensor is detecting the variation in the amount of fluid flowing in one of the flow lines in a set period of time or is detecting the variation in fluid pressure (i.e., pressure differential) along the flow line and in response thereto the sensor controls the flow in the other flow line.

87.04	Pressure differential:
	This subclass is indented under subclass 87.03.  Subject matter wherein the sensor is detecting the variation of the fluid pressures at two distinct points along one of the flow lines and in response thereto the sensor controls the flow in the other flow line. SEE OR SEARCH THIS CLASS, SUBCLASS: 101, for the self-proportioning flow system responsive to flow comparison or pressure differential.

87.05	Plural sensors:
	This subclass is indented under subclass 87.01.  Subject matter including two or more sensors for detecting two distinct or similar conditions or characteristics of the fluid in one of the flow lines and in response thereto the sensors control the flow in the other flow line.

87.06	For single valve:
	This subclass is indented under subclass 87.05.  Subject matter comprising one valve element and wherein the sensors operate only one valve element to control the flow.

88	Mixture condition maintaining or sensing:
	This subclass is indented under subclass 87.01.  Systems in which a condition of a fluid mixture is maintained by controlling the flow of at least one of the fluids mixed in response to a means which sense the condition of the mixture. SEE OR SEARCH THIS CLASS, SUBCLASS: 3+, for the corresponding processes.

89	Dividing and recombining flow:
	This subclass is indented under subclass 88.  Systems in which a fluid flow is divided into a plurality of flow paths which are subsequently recombined, the ratio of the flows thus divided and recombined being controlled in response to a means sensing a condition to be maintained. (1) Note. This subclass includes, for example, systems in which one of the plurality of flow paths pass through a means to treat the fluid to restore the property to be maintained, the amount of fluid passing through the treating means being controlled by the condition sensing means. SEE OR SEARCH THIS CLASS, SUBCLASS: 599.01 through 601.21, for systems dividing into parallel flow lines then recombining.

91	By specific gravity:
	This subclass is indented under subclass 88.  Systems in which the condition maintained or sensed is specific gravity. SEE OR SEARCH THIS CLASS, SUBCLASS: 403+, for systems in which a single flow is controlled by weight of an accumulated fluid, and see the search notes to subclass 403.

92	By viscosity or consistency:
	This subclass is indented under subclass 88.  Systems in which the condition maintained or sensed is viscosity or consistency. (1) Note. Due to their similarity with systems classified in this subclass, systems are also included in which the viscosity or consistency of a stream is sensed and in response thereto the subsequent addition of water is controlled in order to produce a predetermined or desired viscosity or consistency. SEE OR SEARCH THIS CLASS, SUBCLASS: 4, for the corresponding process. SEE OR SEARCH CLASS: 162,  Paper Making and Fiber Liberation,   subclasses 258 and 380 for systems for maintaining the consistency or viscosity of paper making pulp combined with paper making apparatus.

93	By optical or chemical property:
	This subclass is indented under subclass 88.  Systems in which the condition maintained or sensed is an optical or chemical property. SEE OR SEARCH THIS CLASS, SUBCLASS: 5, for processes of controlling flow according to the conductivity of the mixture. 392, for control of a single fluid flow by sensing electrical characteristics. SEE OR SEARCH CLASS: 250,  Radiant Energy,   subclasses 200+ for photocell circuits. 356,  Optics: Measuring and Testing,   for examination of material by light for optical properties particularly subclasses 128+ for refraction tests, subclasses 410+ for shade or color tests involving flowing liquids, and subclasses 432+ for light transmission tests involving gases or liquids. 422,  Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing,   subclasses 50+ for chemical analyzers; and subclasses 105+ for apparatus operating in response to a sensed condition.

94	Fuel controlled by boiler or water system condition:
	This subclass is indented under subclass 87.01.  Subject matter in which a condition of the fluid in a boiler or water heating system controls the flow of fuel used for heating the boiler or water. SEE OR SEARCH THIS CLASS, SUBCLASS: 386+, for liquid level responsive or maintaining systems. 468, for thermally responsive controllers, and see the search notes thereto. SEE OR SEARCH CLASS: 122,  Liquid Heaters and Vaporizers,   subclasses 448.1 through 448.4for automatic control of fluid fuel and feed water to a boiler.

98	Self-proportioning flow systems:
	This subclass is indented under subclass 87.01.  Systems in which the control means maintains a predetermined ratio between flows in a plurality of flow lines. (1) Note. The flows may be separate or may subsequently be combined or may be branches from a single source of a fluid. SEE OR SEARCH THIS CLASS, SUBCLASS: 577 through 579, for systems having a tank with movable or adjustable outlet or overflow pipe. 599.01 through 601.21, for systems dividing into parallel flow lines then recombining. 861 through 887, for systems having flow control means for branched passages. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclasses 195+ for rate of flow meter systems employing two or more meters usually for measuring and comparing a plurality of flows. 210,  Liquid Purification or Separation,   subclass 101 for proportionate feed means combined with separating means. 261,  Gas and Liquid Contact Apparatus,   appropriate subclass for gas and liquid contact devices including means for maintaining a proportional flow between a gas and liquid; see particularly subclasses 69.1+ for systems in which the flow of liquid is controlled in response to the rate of flow in the gas line as measured by means of a venturi in the gas line.

99	Interconnected flow displacement elements:
	This subclass is indented under subclass 98.  Systems in which the proportioning or correlating means includes mechanically interconnected flow displacement elements. (1) Note. Flow displacement elements include primarily pump and meter arrangements and vanes or other elements exposed to the flow and shifted in response to variations therein, such shifting elements usually acting both as controlling and detecting means. SEE OR SEARCH THIS CLASS, SUBCLASS: 565+, for nonautomatic distribution systems including pumps.

99.5	Movable trap chamber:
	This subclass is indented under subclass 99.  Subject matter wherein the flow displacement element comprises a bodily movable measuring chamber which provides continuous flow with increment feeding. SEE OR SEARCH THIS CLASS, SUBCLASS: 101.31, for a stationary measuring chamber. SEE OR SEARCH CLASS: 222,  Dispensing,   subclasses 344+ for systems wherein the movable discharge assistant is not related to a continuous flow, and see the search notes thereunder.

100	Flow comparison or differential response:
	This subclass is indented under subclass 98.  Systems in which the sensing means is sensitive to the differences between the rates of flow or pressure difference along the line in a plurality of flow lines or at spaced points along one line. (1) Note. Means sensing changes in the difference between the flows may control the flow in a third flow line or may exercise a control on the flows compared. SEE OR SEARCH THIS CLASS, SUBCLASS: 497+, for line change condition responsive valves controlled by change in the rate of flow, and see the search notes to subclass 497.

101	Flow dividers (e.g., reversely acting controls):
	This subclass is indented under subclass 100.  Systems in which a flow is divided into a plurality of flow paths and the ratio between the flow in each branch maintained in response to means sensing differences in flow or pressure in each branch by throttling one branch an amount equal to the amount the other branch is opened. (1) Note. Many of the patents in this subclass are for systems in which a single pressure fluid is employed to supply a plurality of fluid pressure motors with means to automatically maintain the amounts of fluid fed to each motor proportional. SEE OR SEARCH CLASS: 60,  Power Plants,   subclasses 420+ for automatic control of a plurality of fluid motors. 91,  Motors: Expansible Chamber Type,   appropriate subclasses and especially subclasses 165+ and 508+ for automatic control of a plurality of expansible chamber motors.

101.11	Main line flow displaces or entrains material from reservoir:
	This subclass is indented under subclass 100.  Subject matter wherein a shunt line having a reservoir therein relies on the pressure difference between its connection to the main line to cause flow therethrough to entrain material in the reservoir, or to displace the reservoir material or an intermediate distinct fluid layer or expansible chamber device whereby the reservoir material is forced into the main line without mixing with the flow while in the shunt.

101.19	With electrical controller:
	This subclass is indented under subclass 100.  Subject matter comprising an electrical controller responsive to the sensing means. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 129+ for an electrical valve actuator.

101.21	Flow displacement element actuates electrical controller:
	This subclass is indented under subclass 98.  Subject matter comprising an electrical controller responsive to a flow displacement element.

101.25	Liquid level response:
	This subclass is indented under subclass 98.  Subject matter comprising at least one means which senses the level of a liquid in means to receive an accumulation thereof and in response thereto exercises a control of the flow in one or more of the flow lines. SEE OR SEARCH THIS CLASS, SUBCLASS: 386+, for liquid level responsive means without proportionate or correlated flow. See the search notes thereunder.

101.27	Float controlled weir or valve:
	This subclass is indented under subclass 101.25.  Subject matter wherein a weir or valve is responsive to the level sensing means.

101.29	Swinging outlet pipe controller:
	This subclass is indented under subclass 101.25.  Subject matter wherein a swinging outlet pipe controls the flow from an accumulator or tank responsive to the level sensing means. SEE OR SEARCH THIS CLASS, SUBCLASS: 577+, for a tank with a movable or adjustable outlet or overflow pipe.

101.31	With measuring type discharge assistant:
	This subclass is indented under subclass 98.  Subject matter comprising a measuring type discharge assistant in one flow line responsive to a flow displacement element in another flow line or by the weight of accumulated fluid of a proportionate part of the flow in another line to provide continuous flow through the system with increment feeding. SEE OR SEARCH CLASS: 222,  Dispensing,   subclasses 261+ for dispensing apparatus with discharge assistants.

102	Supply and exhaust type:
	This subclass is indented under subclass 87.01.  Systems in which an outlet or receiver alternatively receives a fluid from a source of supply and drains the fluid to an exhaust, the flow of fluid from the supply or to the exhaust, being controlled in response to a means sensing a change in condition. (1) Note. Many of the patents classified in this subclass are drawn to distributor valves for fluid motors. SEE OR SEARCH THIS CLASS, SUBCLASS: 224+, for tire inflation apparatus which may have condition responsive filling and relief valves 596+, for distribution systems involving stop and waste arrangements, and see the search notes thereto. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   appropriate subclasses for apparatus under this definition combined with an expansible chamber motor which is controlled thereby.

103	Vacuum or suction pulsator type (e.g., milking machine):
	This subclass is indented under subclass 102.  Systems in which an outlet or receiver is alternately connected to a source of suction or vacuum and a source of fluid under pressure or vent (usually the atmosphere). (1) Note. Many of the patents classified in this subclass are for milking machine pulsators. SEE OR SEARCH THIS CLASS, SUBCLASS: 526, for vacuum relief valves of the type responding to fluid pressure exerted directly on the valve face. SEE OR SEARCH CLASS: 119,  Animal Husbandry,   subclasses 14.01+ for milking machines.

104	With trip linkage or snap action:
	This subclass is indented under subclass 103.  Apparatus which include a snap acting or trip linkage in the control system. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 66+ for valves with biased trips, and see the search notes to subclass 66, and subclass 76 for snap action valves, per se, and see the search notes thereto.

105	With pulsation responsive pilot valve:
	This subclass is indented under subclass 103.  Apparatus wherein the flow controlling valve is moved by a fluid servo under control of a second valve which is itself fluid operated under control of the first valve, there being no mechanical linkage between the two valves. SEE OR SEARCH THIS CLASS, SUBCLASS: 488+, for line condition change responsive fluid pressure type servo or pilot controlled valves. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 28+ for fluid servo or pilot actuated valves having fluid actuated pilot valve.

106	Reversing or 4-way valve systems:
	This subclass is indented under subclass 102.  Systems which include two outlets or receivers, one outlet or receiver being connected to the supply while the other is connected to the exhaust, the connections being reversed or changed in response to a means sensing a change in condition. (1) Note. Many of the patents classified in this subclass are drawn to distributor valves for plural expansible chamber motors. SEE OR SEARCH THIS CLASS, SUBCLASS: 625+, for multiway valve units and their actuators, and see the search notes to subclass 625.

107	Waste responsive to flow stoppage:
	This subclass is indented under subclass 102.  Systems wherein a waste or drain is opened in response to the stopping of the fluid flow from the supply to the outlet or receiver. SEE OR SEARCH THIS CLASS, SUBCLASS: 61, for stop and waste systems which are responsive to means sensing freeze conditions. 596+, for stop and waste systems not responsive to any change in a condition, and see the search notes thereto.

109	Self-controlled branched flow systems:
	This subclass is indented under subclass 87.01.  Systems in which a single flow is divided into a plurality of flow paths or a plurality of flow paths are combined into a single flow path or in which a single flow path is divided and then recombined, and in which the flow in one branch or line is controlled in response to a change in a condition in another branch or line. (1) Note. This and indented subclasses takes only those systems which include some significant branched structure such as having a valve and/or sensing means in a plurality of the branches or which require branched flow in order to be operative. For example, a pressure flow line having a mere relief valve or pressure relief passage mounted in the side is not classifiable as a branched system, because the outflow end of the line is not necessary for the operation of the pressure relief valve; such valves operate in the same manner when applied to a tank. (2) Note. Plural relief valves opening into the atmosphere or the same tank or source are not branched flow systems, nor is a valve in which the flow is divided and recombined within the same valve body a branched flow system. SEE OR SEARCH THIS CLASS, SUBCLASS: 455+, for relief and other condition responsive valves whether mounted in a flow line or in a container. (See (1) Note.) 561+, for branched flow distribution systems in which there is no control of a flow in response to a change in a sensed condition.