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CLASS 95,	GAS SEPARATION: PROCESSES
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SECTION I - CLASS DEFINITION

This class provides for processes involving steps resulting in separation of a gas from a fluid mixture comprising (i) a gas and solid or liquid particles entrained therein, (ii) a liquid and gas entrained therein, or (iii) a plurality of gases. As a general rule for this class, there must be a relationship of process steps embracing: (a) inflow of the fluid mixture to be treated, (b) a step or steps effective to cause the separation into constituent parts, and (c) an outflow of at least one constituent which is separate and distinct from the outflow of another constituent, including outflow of a constituent by removing the separating medium itself. The gas separation for this class is effected by processes other than chemical reaction.

The basic subject matter of this class is of a subcombinational nature and may include only such ancillary process steps (e.g., fluid handling, etc.) as are necessary to perfect the gas separating function. Significant inclusion in a claim of features beyond merely perfecting the gas separating function indicates classification in a more comprehensive class. Thus, the combination of a gas separation process of this class and any cleaning or regenerating of the separation media is properly in this class, because the cleaning or regenerating is perfecting the gas separating function. Generally, however, the mere naming of an art process in a claim to gas separation does not affect classification. Thus, a claim to filtration of a gas from a named source with no details of that source is proper for this class.

SECTION II - LINES WITH OTHER CLASSES AND WITHIN THIS CLASS

The gas separation processes for this class generally involve the use of physical chemistry, chromatography, solid sorption, gas and liquid contact, gas contact, electrical fields, magnetic fields, wave energy, selective diffusion, filtration, deflection, or other mechanical means. See the class search note in section III for Class 423, Chemistry of Inorganic Compounds, for the line concerning the processes in which the gas separation is caused by a chemical reaction. Also, see the class search note in section III for Class 588, Hazardous or Toxic Waste Destruction or Containment, for the line concerning the processes in which the gas separation is caused by destruction or permanent containment of the hazardous or toxic waste.

Degassing or purging processes for the removal of a gas from a solid will be placed in the class where the solid is either manufactured or treated. The removal of a gas from a solid sorbent (i.e., regeneration), per se, will be found in Class 502, Catalyst, Solid Sorbent, or Support Therefor: Product or Process of Making. However, the use of a solid sorbent to separate a gas from a fluid mixture and the removal of the gas from the solid sorbent (i.e., regeneration) will be found in this class. For the removal of a gas from a solid, where the solid is not identified, see Class 134, Cleaning and Liquid Contact With Solids.

The Search Notes below also contain lines with other classes.

SECTION III - REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:

SECTION IV - GLOSSARY

DETECT

The term "detect," which is used in many of the control subclasses, is used in both a quantitative and a qualitative sense. This means that a definite measurement of a process variable is made (e.g., temperature, pressure, concentration, etc.) or that the presence of a particular event is determined (e.g., presence of sparking, change in liquid level determined by position of float, etc.).

FILTER

An article or mass of material made of closely spaced or intimately arranged intermeshed or unconnected fibers, elements, strands, or particles that collectively act as a barrier to physically retain at least one constituent of a fluid mixture on its surfaces or in the spaces between the fibers, elements, strands, or particles while permitting passage of the remaining constituents.

A filter has no "chemical" affinity for a constituent of a fluid mixture. The retention of the constituent by the filter depends upon a mechanical entrapment of solid or liquid particles because of their relatively large size compared with the interstices or spaces between individual fibers, elements, strands, or particles. The retained particles can be removed by brushing, wiping, shaking, or similar mechanical action.

FLUID MIXTURE

The phrase "fluid mixture" is used throughout the definitions to mean (a) a gas and solid or liquid particles entrained therein, (b) a liquid and gas entrained therein, or (c) a plurality of gases.

GAS

Matter of very low density and viscosity, relatively great expansion and contraction with changes in pressure and temperature, that is readily diffusive, with a tendency to expand indefinitely, with molecules in free movement. The term "gas" includes "vapor" (q.v.).

GASEOUS FLUID MIXTURE

The phrase "gaseous fluid mixture" is used throughout the definitions to mean (a) a gas and solid or liquid particles entrained therein or (b) a plurality of gases.

LIQUID SORBENT

A liquid capable of retaining part of a fluid mixture with which it is contacted. The action in most cases is that of selective retention (i.e., the sorbent removes only that part of the fluid mixture for which it has the greatest affinity).

REGENERATION

Restoration of the separatory material to the condition it was in before the separatory process.

SEPARATING APPARATUS

The entire gas separating means, which consists of all of the apparatus parts related to gas separation and includes apparatus parts that are in addition to the separator.

SEPARATING MEDIUM (MEDIA)

Liquid sorbent or means that effects the separation into constituent parts (e.g., deflector, filter, molecular sieve, sorber, etc.). (Media has been used in the singular and in the plural.)

SEPARATOR

The portion of the apparatus that consists of a separating medium and the structure supporting, retaining, or substantially confining the separating medium.

SOLID SORBENT

A solid sorbent is a solid material which separates a constituent (e.g., a gas, vapor, etc.) from a fluid mixture containing such constituents in a "quasi-chemical" manner. The action in most instances is that of selective retention (i.e., the sorbent removes only the part of the fluid mixture for which it has the greatest affinity). The retained constituent cannot be removed by shaking, brushing, or similar mechanical action, but generally can be removed by heating, pressure reduction, or use of a stripping or denuding fluid.

TREATMENT

(a) With respect to the class subject matter, the term is restricted to reversible and nonchemical changes in physical characteristics of the fluid mixture or a separated constituent (e.g., heating, cooling, humidity control, agitating, pressure regulation, etc.). (b) With respect to the media used to perform the gas separation or to a material used to condition the fluid mixture for separation, the term may include chemical preparation, reconditioning, or reaction.

VAPOR

The gaseous state of matter that is liquid or solid under a temperature of 0°C and 760 mm Hg pressure.

SUBCLASSES

1	WITH CONTROL RESPONSIVE TO SENSED CONDITION:
	This subclass is indented under the class definition.  Process in which the separation is regulated by detecting a characteristic or a change in a characteristic of the process and by implementing an action in the process based upon the detected characteristic or change therein. (1) Note. In this subclass and the subclasses indented hereunder, a single means may be used both to detect the characteristic or the change in the characteristic in the process and to implement an action in the process based upon the detected characteristic or change therein. There must be a positive action made by the means because of the detected characteristic or change therein. An example is the use of a pressure relief valve in which a certain pressure must be reached before the valve opens to relieve the high pressure in the process. Another example is the use of a bimetallic element in a thermostat in which a certain temperature must be reached before a switch is tripped in order to control the temperature in the process. A third example is the use of increased weight on a separating media because of accumulation of a separated constituent to cause the separating media to move to a position of nonuse or regeneration. Excluded from this subclass and the subclasses indented hereunder are processes in which there is no positive action made by the single means because of the detected characteristic or change therein. An example of a process which is excluded and placed below is the flow of liquid over a baffle once the liquid level reaches the top of the baffle. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclasses 23.2 through 31.07for gas analysis, and see the class definition of Class 95 for a statement of the line. 96,  Gas Separation: Apparatus,   subclasses 18 through 24for electrical separation apparatus with control means responsive to sensed condition; subclass 102 for chromatography apparatus with control means responsive to sensed condition; subclasses 109-114 for solid sorbent apparatus with control means responsive to sensed condition; subclasses 156-174 for degasifying means with control means responsive to sensed condition; subclasses 397-412 for gas separation apparatus with automatic control means for gas or nongaseous constituent discharge; and subclasses 417-423 for gas separation apparatus with signals, indicators, measuring, or testing means.

2	Electric or electrostatic field (e.g., electrostatic precipitation, etc.):
	This subclass is indented under subclass 1.  Process in which there is a step including discharge of an electric current into the fluid mixture or electrifying a fluid or solid that contacts the fluid mixture. SEE OR SEARCH THIS CLASS, SUBCLASS: 57 through 81, for processes using electric or electrostatic fields without control responsive to a sensed condition. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 18 through 24for electrical separation apparatus with control means responsive to sensed condition.

3	Concentration sensed:
	This subclass is indented under subclass 2.  Process in which concentration of a constituent present in the process or a change therein (e.g., dust, humidity, etc.) is detected and is used to control some aspect of the process.

4	Temperature sensed:
	This subclass is indented under subclass 2.  Process in which temperature or a change therein is detected and is used to control some aspect of the process.

5	Sparking sensed:
	This subclass is indented under subclass 2.  Process in which the presence or frequency of sparking in the gas phase, often accompanied by short bursts of increasing current flow or decreasing electrode voltage, is detected and is used to control some aspect of the process.

6	Current sensed:
	This subclass is indented under subclass 2.  Process in which current flowing between discharge and collector electrodes or a change therein is detected and is used to control some aspect of the process.

7	Voltage sensed:
	This subclass is indented under subclass 2.  Process in which voltage applied, either directly to an electrode or indirectly to the fluid mixture, or a change therein is detected and is used to control some aspect of the process.

8	Concentration sensed:
	This subclass is indented under subclass 1.  Process in which concentration of a constituent present in the process or a change therein (e.g., pH, humidity, dust content, etc.) is detected and is used to control some aspect of the process.

9	pH sensed:
	This subclass is indented under subclass 8.  Process in which pH or a change therein is detected and is used to control some aspect of the process.

10	Humidity sensed:
	This subclass is indented under subclass 8.  Process in which humidity or a change therein is detected and is used to control some aspect of the process.

11	Flow of fluid mixture to sorber stopped or diverted to other equipment, or sorbent regenerated:
	This subclass is indented under subclass 8.  Process in which the flow of the fluid mixture to a sorber is stopped or the flow of the fluid mixture is switched to another sorber based upon the detected concentration or change therein; or process in which a sorbent is regenerated based upon the detected concentration or change therein.

12	Gas flow rate modified:
	This subclass is indented under subclass 8.  Process in which flow rate of a gas is changed based upon the detected concentration or change therein.

13	Sorbent flow rate modified:
	This subclass is indented under subclass 8.  Process in which flow rate of a sorbent is changed based upon the detected concentration or change therein.

14	Temperature sensed:
	This subclass is indented under subclass 1.  Process in which temperature or a change therein is detected and is used to control some aspect of the process.

15	And pressure sensed:
	This subclass is indented under subclass 14.  Process in which pressure or a change therein is also detected and is used to control some aspect of the process.

16	Modification of flow rate of liquid which is added to gas:
	This subclass is indented under subclass 14.  Process in which flow rate of liquid which is added to a gas is modified based upon the detected temperature or change therein.

17	Cooling:
	This subclass is indented under subclass 14.  Process in which the fluid mixture, a separated constituent, or an apparatus involved in the process is cooled based upon the detected temperature or change therein.

18	Heating:
	This subclass is indented under subclass 14.  Process in which the fluid mixture, a separated constituent, or an apparatus involved in the process is heated based upon the detected temperature or change therein.

19	Pressure sensed:
	This subclass is indented under subclass 1.  Process in which pressure or a change therein is detected and is used to control some aspect of the process.

20	Apparatus cleaned:
	This subclass is indented under subclass 19.  Process in which apparatus is cleaned based upon the detected pressure or change therein.

21	Sorbent regenerated:
	This subclass is indented under subclass 19.  Process in which a sorbent is regenerated based upon the detected pressure or change therein.

22	Gas flow rate modified:
	This subclass is indented under subclass 19.  Process in which flow rate of a gas is changed based upon the detected pressure or change therein.

23	Gas flow rate sensed:
	This subclass is indented under subclass 1.  Process in which gas flow rate or a change therein is detected and is used to control some aspect of the process.

24	Liquid level sensed:
	This subclass is indented under subclass 1.  Process in which liquid level or a change therein is detected and is used to control some aspect of the process.

25	WITH RECORDING OR SIGNALING CONDITION:
	This subclass is indented under the class definition.  Process in which a characteristic or a change in a characteristic of the fluid mixture, of a separated constituent, or of apparatus used in the process is set down for preservation in permanent form or is indicated by means giving information of an audible or a visual nature (e.g., alarm, etc.). SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclasses 23.2 through 31.07for gas analysis and see the class definition of Class 95 for a statement of the line.

26	WITH TIMING OF OPERATION:
	This subclass is indented under the class definition.  Process in which the time at which an operation occurs is controlled or the length of time in which an operation is performed is controlled.

27	MAGNETIZED PARTICLE BED:
	This subclass is indented under the class definition.  Process in which magnetic lines of force are applied to a bed of loose particles that contain a magnetizable component. (1) Note. The application of magnetic lines of force to a magnetizable particle bed may be to stabilize the bed, to prevent back-mixing, or to control porosity of the bed.

28	MAGNETIC SEPARATION:
	This subclass is indented under the class definition.  Process in which the separation is caused or aided by magnetic lines of force. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 1 through 3for apparatus which separates a gas by magnetic lines of force. 209,  Classifying, Separating, and Assorting Solids,   subclasses 38 , 39, 40, 212, and 213-232 for classifying, separating, and assorting solids using apparatus of the magnetic type. 210,  Liquid Purification or Separation,   subclasses 222 through 223for magnetic apparatus for purification or separation of a liquid and subclass 695 for processes of purifying or separating a liquid using magnetic force.

29	SOUND WAVES USED:
	This subclass is indented under the class definition.  Process in which the separation is effected or enhanced by the energy of compressional vibratory waves in a fluid medium, the waves being below, within, or above the audible spectrum. (1) Note. Pressure pulses in a fluid generated merely by intermittent discharge of a gas are not considered to be compressional vibratory waves under this definition. However, compressional vibratory waves under this definition may be produced by intermittent discharge of a gas, as in a siren. SEE OR SEARCH CLASS: 55,  Gas Separation,   subclass 292 for cleaning means for separating media of the sonic type. 96,  Gas Separation: Apparatus,   subclass 389 for gas separation apparatus using wound waves.

30	Degasification of liquid:
	This subclass is indented under subclass 29.  Process in which the wave energy is used to separate gas from a liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 46, for processes of degasification of a liquid by selective diffusion of gases through a substantially solid barrier. 156 through 186, for processes of contacting a gas with a liquid and degasification of the contact liquid. 241 through 266, for other processes of degasification of a liquid.

31	DIFFERENCE IN MOLECULAR VELOCITY, DENSITY, OR MOMENTUM OF GASES USED:
	This subclass is indented under the class definition.  Process in which the plurality of gases is separated into constituent gaseous parts by making use of physical differences in molecular speed, weight, or inertia of the constituent gaseous parts. SEE OR SEARCH THIS CLASS, SUBCLASS: 267 through 272, for processes of separating solid or liquid particles from a gas by deflection.

32	Passing gases through nozzle:
	This subclass is indented under subclass 31.  Process in which gaseous constituents having different molecular weights or different gas kinetic cross sections are separated, with the plurality of gases flowing out of a short tube, usually tapering, that forms the vent of a hose or pipe in order to effect the separation.

33	Directing gas streams toward one another:
	This subclass is indented under subclass 32.  Process in which gas streams or jets are directed toward one another and are deflected.

34	Centrifugal force:
	This subclass is indented under subclass 31.  Process in which the plurality of gases is separated by the effect of centrifugal action which causes the gases to assume a rapid arcuate or circular movement, with this movement causing the constituents of the mixture to separate into more or less distinct layers, depending upon the density of the constituents. SEE OR SEARCH THIS CLASS, SUBCLASS: 269 through 271, for processes of separating solid or liquid particles from a gas by using centrifugal force.

35	Created by rotating equipment:
	This subclass is indented under subclass 34.  Process in which the centrifugal force is caused by a rotating element moving around an axis. SEE OR SEARCH THIS CLASS, SUBCLASS: 270, for processes of separating solid or liquid particles from a gas by using centrifugal force created by rotating equipment.

36	LIQUID-SOLID SLURRY USED:
	This subclass is indented under the class definition.  Process in which the separation is accomplished by contacting the fluid mixture with a pumpable mixture of a solid and a liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 92, for a two-step process of solid sorption and liquid sorption.

37	Organic compound removed from gas
	This subclass is indented under subclass 36.  Process in which an organic compound is removed from gas by contact with a liquid-solid slurry.

38	Halogen containing compound removed from gas:
	This subclass is indented under subclass 36.  Process in which a halogen (i.e., fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At)) containing compound is removed from gas by contact with a liquid-solid slurry.

39	COMPRESSING AND INDIRECT COOLING OF GASEOUS FLUID MIXTURE TO SEPARATE:
	This subclass is indented under the class definition.  Process in which the separation of a constituent from a gaseous fluid mixture is accomplished by extracting heat in an indirect heat exchanger before, after, or while increasing the pressure on the gaseous fluid mixture. (1) Note. The cooling must not involve details of a refrigeration process or apparatus. See the class definition for the line between Class 95 and Class 62.

40	And use of heat absorbing agent:
	This subclass is indented under subclass 39.  Process in which a substance is added to the gaseous fluid mixture to prevent a material rise in temperature of the gaseous fluid mixture by absorbing the heat of compression.

41	And solid sorption:
	This subclass is indented under subclass 39.  Process in which a solid sorbent is used to remove a constituent from the gaseous fluid mixture. SEE OR SEARCH THIS CLASS, SUBCLASS: 90 through 148, for processes of solid sorption without compressing and cooling of the gaseous fluid mixture in order to separate.

42	And liquid contact (e.g., scrubbing, sorption, etc.):
	This subclass is indented under subclass 39.  Process in which a liquid is used to remove a constituent from the gaseous fluid mixture (e.g., scrubbing, sorption, etc.). SEE OR SEARCH THIS CLASS, SUBCLASS: 149 through 240, for processes of liquid contact without compressing and cooling of the gaseous fluid mixture in order to separate.

43	SELECTIVE DIFFUSION OF GASES:
	This subclass is indented under the class definition.  Process in which a fluid mixture containing a gas to be separated contacts a solid, liquid, or gaseous barrier, with the gas separating because of the differential permeability of the barrier with respect to the gas. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 4 through 14for apparatus for selective diffusion of gases.

44	Selective diffusion of gases through immobilized liquid:
	This subclass is indented under subclass 43.  Process in which a plurality of gases containing a gas to be separated contacts a liquid barrier that is supported or immobilized in or on a porous medium, with the plurality of gases being separated because of the differential permeability of the liquid with respect to the gases. SEE OR SEARCH THIS CLASS, SUBCLASS: 149 through 240, for processes of contacting a fluid mixture with a liquid. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 5 for corresponding apparatus. Patents are not cross-referenced from Class 96, subclass 5 to this subclass based only on disclosure. Therefore, relevant disclosures of gas separation processes may be found in the apparatus area.

45	Selective diffusion of gases through substantially solid barrier (e.g., semipermeable membrane, etc.):
	This subclass is indented under subclass 43.  Process in which a plurality of gases or a mixture of gas entrained in a liquid contacts a substantially solid surface (e.g., semipermeable membrane, etc.) and a gas is separated from another gas or a gas is separated from the liquid because of the differential permeability of the surface of the solid with respect to the gases. (1) Note. Class 95 will take dissociation of a gas molecule at the barrier boundary when such dissociation facilitates passage of the gas through the barrier; the atoms reconvert to the gas molecule on the downstream side of the barrier. If the dissociation of the gas occurs away from the barrier and a resulting product diffuses through the barrier, then the patent will be in Class 423 for an inorganic gas and in the appropriate organic class for an organic gas. SEE OR SEARCH CLASS: 205,  Electrolysis: Processes, Compositions Used Therein, and Methods of Preparing the Compositions,   subclasses 334 through 639 for processes using a solid electrolyte membrane (SEM) situated between two electrodes positioned to apply external voltage across the membrane. These membranes are used where the partial pressure of the gas to be diffused through the membrane on the feed side of the membrane is lower than that on the permeate side. Molecules on the feed side of a cell containing a solid electrolyte membrane are electrochemically dissociated into ions on the cathode. The ions are then transported across the matrix of the membrane by the applied voltage and recombined to form molecules on the anode. Class 95 takes the use of a solid electrolyte membrane which functions without electrodes and without externally applied voltage. These membranes are used where the partial pressure of the gas to be diffused through the membrane on the permeate side is lower than that on the feed side. Electrodeless solid electrolyte membrane cells are operated by maintaining a pressure on the feed side such that a positive driving force for ion transport can be achieved in the absence of an externally applied voltage and power source. 210,  Liquid Purification or Separation,   subclasses 96.2 , 257.2, and 321.6-321.9 for apparatus having membranes or dialyzers for separating liquids, subclasses 500.21-500.43 for semipermeable membranes used in the separation of liquids, and subclasses 634-655 for processes of separating a liquid by selective diffusion of a component of a liquid through a membrane or septum. 427,  Coating Processes,   subclasses 245 through 246for methods of coating a base so that the resulting product is foraminous or porous, wherein the coating includes openings or holes which are very small, generally microscopic in size. 520,  Synthetic Resins or Natural Rubbers,   appropriate subclasses for synthetic resins or natural rubbers that may be used for selective diffusion of gases. 585,  Chemistry of Hydrocarbon Compounds,   subclasses 818 through 819 for processes in which a liquid hydrocarbon is recovered from a liquid mixture containing the hydrocarbon by the use of selective diffusion through a semipermeable membrane.

46	Degasification of liquid:
	This subclass is indented under subclass 45.  Process in which gas is separated from a liquid by selective diffusion of the gas through a substantially solid barrier. SEE OR SEARCH THIS CLASS, SUBCLASS: 30, for processes of degasification of a liquid by use of sound waves. 156 through 186, for processes of contacting a gas with a liquid and degasification of the contact liquid. 241 through 266, for other processes of degasification of a liquid. SEE OR SEARCH CLASS: 75,  Specialized Metallurgical Processes, Compositions for Use Therein, Consolidated Metal Powder Compositions, and Loose Metal Particulate Mixtures,   subclass 405 for processes of removing gas from liquid metal by use of a gas permeable membrane. 96,  Gas Separation: Apparatus,   subclass 6 for corresponding apparatus. Patents are not cross-referenced from Class 96, subclass 6 to this subclass based only on disclosure. Therefore, relevant disclosures of gas separation processes may be found in the apparatus area. 210,  Liquid Purification or Separation,   subclass 640 for processes of separating a constituent from a liquid by selective diffusion of the constituent through a membrane or septum wherein the constituent is not initially present as a gas in the liquid and passes through the membrane or septum in vapor phase.

47	Nitrogen or nitrogen containing compound permeates barrier:
	This subclass is indented under subclass 45.  Process in which nitrogen (N2) or a nitrogen containing compound selectively diffuses through a substantially solid barrier.

48	Halogen containing compound permeates barrier:
	This subclass is indented under subclass 45.  Process in which a halogen (i.e., fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At)) containing compound selectively diffuses through a substantially solid barrier.

49	Sulfur containing compound permeates barrier:
	This subclass is indented under subclass 45.  Process in which a sulfur (S) containing compound selectively diffuses through a substantially solid barrier.

50	Organic compound permeates barrier:
	This subclass is indented under subclass 45.  Process in which an organic compound selectively diffuses through a substantially solid barrier.

51	Carbon dioxide or carbon monoxide permeates barrier:
	This subclass is indented under subclass 45.  Process in which carbon dioxide (CO2) or carbon monoxide (CO) selectively diffuses through a substantially solid barrier.

52	Water vapor permeates barrier:
	This subclass is indented under subclass 45.  Process in which water (H2O) vapor selectively diffuses through a substantially solid barrier.

53	Helium permeates barrier:
	This subclass is indented under subclass 45.  Process in which helium (He) selectively diffuses through a substantially solid barrier.

54	Oxygen permeates barrier:
	This subclass is indented under subclass 45.  Process in which oxygen (O2) selectively diffuses through a substantially solid barrier.

55	Hydrogen permeates barrier:
	This subclass is indented under subclass 45.  Process in which hydrogen (H2) selectively diffuses through a substantially solid barrier.

56	Elemental metal or alloy barrier:
	This subclass is indented under subclass 55.  Process in which hydrogen (H2) selectively diffuses through a substantially solid barrier that is made of elemental metal or alloy or contains a layer of elemental metal or alloy. (1) Note. The hydrogen (H2) molecule may dissociate into hydrogen (H) atoms at the surface of the barrier. The atoms will then diffuse through the barrier and recombine into a hydrogen (H2) molecule on the downstream side of the barrier. SEE OR SEARCH CLASS: 210,  Liquid Purification or Separation,   subclass 500.25 for a metal-containing semipermeable membrane used in liquid separation. 423,  Chemistry of Inorganic Compounds,   subclass 658.2 for processes of producing elemental hydrogen (H) by direct decomposition of a binary compound (e.g., chemical storage, etc.).

57	ELECTRIC OR ELECTROSTATIC FIELD (E.G., ELECTROSTATIC PRECIPITATION, ETC.):
	This subclass is indented under the class definition.  Process in which an electric current is discharged into the fluid mixture or the fluid mixture is contacted with a fluid or solid which has been electrified. (1) Note. The separation of the fluid mixture need not be accomplished directly by the electrical treatment, provided that the overall process results in separation of the fluid mixture. The electrical treatment may be for the purpose of causing entrained particles to become agglomerated for easier removal by other means, such as filtration or deflection. (2) Note. Gas separation processes including the mere application of electricity to a material contacting the fluid mixture for the purpose of resistance heating is classified below. (3) Note. Processes for separating isotopes are classified based upon the specific methods used (e.g., the separation of liquid isotopes by distillation is classified in Class 203, subclass 5; isotope separation involving chemical reaction brought about by wave energy is found in Class 204, subclasses 157.2-157.22, etc.). SEE OR SEARCH THIS CLASS, SUBCLASS: 2 through 13, for processes involving an electric field with control responsive to sensed condition. 25, for processes involving an electric field with recording or signaling of a condition. 26, for processes involving an electric field with timing of an operation. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 15 through 100for apparatus using an electric field to separate gas constituents. Also, see other collected search class notes regarding related subject matter. 204,  Chemistry: Electrical and Wave Energy,   subclasses 164 through 179for processes involving gas treatment by chemical reaction and electrical discharge or chemical change by electrical discharge, and subclasses 554-573 and 660-674 for similar processes and apparatus for electrical separation or purification of liquids and for degasification of liquid aided by electrical discharge involving the conversion of constituents to other compounds. When such chemical conversion is in doubt, placement of electrical processes and apparatus for degasifying liquid is proper for Class 95 or Class 96, respectively. 209,  Classifying, Separating, and Assorting Solids,   subclass 12.2 for a combination process or apparatus of classifying, separating, and assorting solids including an electrostatic field; and subclasses 127.1-131 for process and apparatus for classifying, separating, or assorting solids by an electrostatic field. 210,  Liquid Purification or Separation,   subclass 748 for processes of treating a liquid by directly subjecting the liquid to an electric field or a current or to a regular pulsating source of energy. Also, see the search class note to Class 204. 250,  Radiant Energy,   subclasses 282 through 284for methods of separating certain accelerated ionized material from similar accelerated ionized material having different mass-to-electric-charge ratios by use of electrostatic or magnetic fields.

58	With addition of solid, gas, or vapor:
	This subclass is indented under subclass 57.  Process which includes adding a solid, gas, or vapor to the fluid mixture undergoing treatment or separation. (1) Note. To come under this definition, the added solid, gas, or vapor must not be merely a different amount of the same fluid mixture that is to be separated, but may be a constituent of this mixture, which may be derived from a previous separation process. (2) Note. The addition of solid includes the use of a fluidized solid particle bed, regardless of whether the solid remains entrained in the gas after passage through the bed. The use of a stationary particle bed is not considered to be addition of a solid, and patents in which a stationary particle bed is used will be found elsewhere under subclass 57. Also, for the purposes of this subclass, the added solid, gas, or vapor may include any combination thereof (except for a different amount of the fluid mixture to be separated, as in (1) Note), including aerosols. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 27 for means to add charged solid or liquid particles to the gas stream, subclass 52 for vapor or liquid contact apparatus involving electrical separation, and subclass 74 for gas separation apparatus including an electrical precipitator and means to treat or condition the gas before, during, or after precipitation.

59	Electrode treating (e.g., coating, cleaning, etc.):
	This subclass is indented under subclass 58.  Process which includes the physical treatment of an electrode (e.g., by addition of a protective or reactive layer to the electrode or the removal of collected material from the electrode, etc.). SEE OR SEARCH THIS CLASS, SUBCLASS: 74 through 76, for processes with cleaning of a collecting electrode but without the addition of a solid, gas, or vapor. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 28 through 51for electrical separation apparatus with electrode cleaner, apparatus part flusher or discharger, or wet collector.

60	Heating or cooling:
	This subclass is indented under subclass 58.  Process in which the fluid mixture to be separated is heated or cooled either by or along with the addition of solid, gas, or vapor.

61	Solid is electrically conducting:
	This subclass is indented under subclass 58.  Process in which a solid of low electrical resistance is added to the fluid mixture. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 28 through 51for electrical separation apparatus containing electrodes coated with a wet conductive film.

62	Agglomerating gas-borne particles:
	This subclass is indented under subclass 58.  Process in which solid or liquid particles to be separated from a gas are agglomerated into larger conglomerates either in the gas phase or on a collecting surface, with the agglomeration being facilitated by addition of a solid, gas, or vapor to the incoming fluid mixture. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 77 for electrical separation apparatus containing electrical means for agglomerating particles.

63	And nonelectrical separation of fluid mixture:
	This subclass is indented under subclass 57.  Process which includes methods of separation of the fluid mixture other than those explicitly connected with an electrical separation technique. SEE OR SEARCH THIS CLASS, SUBCLASS: 74 through 76, for processes involving the removal of material from a collecting electrode. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 27 for electrical separation apparatus with means to add charged liquid or solid particles to the gaseous fluid mixture, subclass 52 for electrical separation apparatus with means to add a liquid or vapor to the gaseous fluid mixture, and subclass 55 for electrical separation apparatus with serially arranged nonelectrical separators.

64	Liquid addition to gaseous fluid mixture:
	This subclass is indented under subclass 63.  Process in which a liquid is added to a gaseous fluid mixture before, during, or after electrical treatment either (a) to cause separation or (b) to condition the gaseous fluid mixture in any way. SEE OR SEARCH THIS CLASS, SUBCLASS: 75, for processes involving the removal of material from a collecting electrode by flushing with a liquid. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 52 through 53for electrical separation apparatus with vapor or liquid contact.

65	Liquid addition precedes electrical precipitation:
	This subclass is indented under subclass 64.  Process in which liquid addition is made before the gaseous fluid mixture is subjected to electrical separation.

66	With heating or cooling:
	This subclass is indented under subclass 65.  Process including heating or cooling either as a result of the liquid addition or as a separate, additional gas treatment.

67	By heating or cooling:
	This subclass is indented under subclass 63.  Process in which nonelectrical gas separation is caused by heating or cooling a gaseous fluid mixture.

68	Including cleaning or regeneration of separating means (e.g., particulate bed filter, deflector, etc.):
	This subclass is indented under subclass 63.  Process which includes removal of collected material from or regeneration of a nonelectrical gas separating means, such as a particulate bed filter or deflector. SEE OR SEARCH THIS CLASS, SUBCLASS: 90 through 148, for processes of solid sorption which may include regeneration of the solid sorbent. 276, for processes of cleaning a particulate filter bed. 278, for processes of cleaning a cohesive filter. SEE OR SEARCH CLASS: 55,  Gas Separation,   subclasses 282 through 305for gas separating apparatus with nonliquid cleaning means for separating media, and subclass 431 for means contacting an apparatus part with a fluid for discharge of material residue. 96,  Gas Separation: Apparatus,   subclass 228 for gas separation apparatus with means using liquid to clean the gas separation apparatus.

69	Distinct separation step precedes electric or electrostatic treatment:
	This subclass is indented under subclass 63.  Process in which at least one nonelectrical separating step is performed on the fluid mixture before electric or electrostatic treatment. SEE OR SEARCH CLASS: 55,  Gas Separation,   subclasses 315 through 337for serial diverse separating media not including an electrical separation apparatus. 96,  Gas Separation: Apparatus,   subclasses 55 through 59for electrical separation apparatus with serially arranged diverse separators; in particular, subclass 57 for such apparatus preceded by a nonelectrical separator.

70	Distinct separation step follows electric or electrostatic treatment:
	This subclass is indented under subclass 63.  Process in which at least one nonelectrical separating step is performed on the fluid mixture after electric or electrostatic treatment. SEE OR SEARCH CLASS: 55,  Gas Separation,   subclasses 315 through 337for serial diverse separating media not including electrical separation apparatus. 96,  Gas Separation: Apparatus,   subclasses 55 through 59for electrical separation apparatus with serially arranged diverse separators.

71	With addition of liquid to gaseous fluid mixture:
	This subclass is indented under subclass 57.  Process in which a liquid is added to a gaseous fluid mixture undergoing treatment, but does not directly result in the separation of gas constituents. SEE OR SEARCH THIS CLASS, SUBCLASS: 64 through 66, for processes involving contacting a gaseous fluid mixture with a liquid in a diverse type operation (in which gas constituents are also separated by nonelectrical methods, such as directly results from liquid addition). SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 52 for corresponding electrical field separation apparatus with means to add liquid or vapor to the gas and subclasses 243-371 for gas separation apparatus with gas and liquid contact means.

72	Vaporization of liquid:
	This subclass is indented under subclass 71.  Process in which the added liquid is vaporized to join the gas phase.

73	With heating or cooling:
	This subclass is indented under subclass 57.  Process which includes heating or cooling of the fluid mixture being treated. SEE OR SEARCH THIS CLASS, SUBCLASS: 67, for related processes in which a nonelectrical gas separation is caused by heat exchange with the gas.

74	With cleaning of collector electrode:
	This subclass is indented under subclass 57.  Process which includes cleaning or removing of a deposited constituent from an electrical element provided to attract and retain the constituent. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 28 through 51for corresponding electrode cleaning means. 134,  Cleaning and Liquid Contact With Solids,   appropriate subclasses for cleaning matter from solid materials or objects.

75	By liquid flushing:
	This subclass is indented under subclass 74.  Process in which the cleaning of the element is performed by the application of a liquid stream. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 43 through 50for corresponding apparatus with fluid contacting means.

76	By scraping or vibrating:
	This subclass is indented under subclass 74.  Process in which the cleaning of the element is performed by the application of mechanical contacting or jarring means to remove retained material. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 32 through 38for corresponding apparatus with vibrating means, and subclass 51 for corresponding apparatus with scraping means.

77	Continuously moving electrode:
	This subclass is indented under subclass 57.  Process in which an element discharging electricity into the fluid mixture or collecting deposits therefrom continually moves during operation. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 39 through 42for electrical separation apparatus with movably mounted electrode assembly for cleaning purposes and subclass 94 for electrode supporting means permitting movement thereof during use or for orientation.

78	Including baffling, deflection, or restriction of gas flow:
	This subclass is indented under subclass 57.  Process in which a restriction or redirection of gas flow is caused by inclusion of a baffle, deflector, or specially shaped electrode for the purpose of such restriction. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 60 through 73for corresponding apparatus with gas flow distribution means, subclasses 95-97 for apparatus with specific type or shape of discharge electrode, and subclasses 98-100 for specific collector means.

79	Plural separate stages or zones (e.g., separate ionization and collection regions, etc.):
	This subclass is indented under subclass 57.  Process in which a gaseous fluid mixture passes through two or more distinct regions or units, such regions providing either multiple identical gas treatments or plural diverse treatments for removal of entrained particles. (1) Note. The stages or zones may be arranged in series or in parallel. (2) Note. A single stage with two or more regions or zones of differing applied voltage is included under this definition. SEE OR SEARCH THIS CLASS, SUBCLASS: 63 through 70, for processes with nonelectrical gas separating steps. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 55 through 59for electrical separation apparatus with serial diverse separators and subclasses 75-79 for electrical separation apparatus with diverse or serially distinct electrical fields.

80	Pulsing or time-varying electric field (e.g., AC, pulsed DC, etc.):
	This subclass is indented under subclass 79.  Process involving the application of a voltage which fluctuates with time during treatment of the gaseous fluid mixture. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 54 for electrical separation apparatus having an alternating current field.

81	Pulsing or time-varying electric field (e.g., AC, pulsed DC, etc.):
	This subclass is indented under subclass 57.  Process involving the application of a voltage which fluctuates with time during treatment of the gaseous fluid mixture. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 54 for electrical separation apparatus having an alternating current field.

82	CHROMATOGRAPHY:
	This subclass is indented under the class definition.  Process in which (a) the plurality of gases to be separated enters a column to contact a liquid, known as the "stationary liquid phase," supported by a base of solid material to successively sorb therein the different gases of the mixture or (b) the plurality of gases to be separated enters a column to contact a solid sorbent to successively sorb thereon the different gases of the mixture with or without subsequently successively eluting or displacing the sorbed gases in (a) or (b) with a gas which is inert with respect to the sorbed gases and sorbent; and subcombinations of the processes in (a) and (b) that do not result in separation when the subcombinations are not provided for elsewhere. (1) Note. The plurality of gases is usually allowed to flow slowly through a column of particulate sorbent. Different gases will pass at different speeds through the column and will eventually be separated into zones. The zones can be eluted by passing an inert gas through the column and collecting the various fractions. (2) Note. When a liquid is supported by a base of solid material for the separation of the mixture of gases, the process is known as "gas-liquid chromatography" or "GLC." If liquid is not present, the process is known as "gas-solid chromatography." Other phrases used when referring to chromatography are "gas-chromatography" or "GC," "vapor-phase chromatography" or "VPC," "gas-liquid partition chromatography," "vapor fractometry," "capillary column gas chromatography" or "CC-GC," and "partition chromatography." (3) Note. Sometimes a "carrier" gas is mixed with or used to propel the plurality of gases to be separated through the chromatography column. (4) Note. The plurality of gases to be separated may be obtained by vaporizing a liquid. The liquid that is injected into the chromatography column is vaporized, and then the resulting vapors are separated in the chromatography column. SEE OR SEARCH THIS CLASS, SUBCLASS: 245 through 246, and 263-265, for processes of separating gases from liquids by contacting the liquid with a gas. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclasses 19.02 , 23.22-23.27, and 23.35-23.42 for chromatography including analysis of eluted or displaced gas. 96,  Gas Separation: Apparatus,   subclasses 101 through 107for gas chromatography apparatus. 210,  Liquid Purification or Separation,   subclasses 656 through 694and 198.2-198.3 for processes and apparatus of liquid purification or separation involving chromatography. 436,  Chemistry: Analytical and Immunological Testing,   subclasses 161 through 162for processes which involve a chemical reaction for analytical testing including chromatography and for processes of analysis of the chemical properties of a sample including chromatography.

83	Liquid supported on surface of capillary column:
	This subclass is indented under subclass 82.  Process in which the base of solid material supporting the stationary liquid phase as a thin film is the inner surface of a capillary tube or column.

84	Liquid supported on particulate packing:
	This subclass is indented under subclass 82.  Process in which the base of solid material supporting the stationary liquid phase is a granular solid.

85	Including use of gas flow distributor in column:
	This subclass is indented under subclass 82.  Process in which gas is directed or channelled by use of a deflector inside the column. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 107 for corresponding apparatus. Patents are not cross-referenced from Class 96, subclass 107 to this subclass based only on disclosure. Therefore, relevant disclosures to gas separation processes may be found in the apparatus area.

86	Plural separate columns:
	This subclass is indented under subclass 82.  Process in which the plurality of gases passes through two or more parallel or serial columns. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 104 for chromatographic apparatus having two or more separate and distinct stages or zones.

87	With heating or cooling:
	This subclass is indented under subclass 82.  Process in which the plurality of gases, a liquid, a separated constituent, or an apparatus involved in the process is heated or cooled (e.g., the column may be heated in order to degas the solid sorbent or a gas may be heated or cooled, etc.).

88	Specific column packing or sorbent material (e.g., particle size, composition, etc.):
	This subclass is indented under subclass 82.  Process in which a specified packing or sorbent material (e.g., sorbent compositions, particle size, etc.) is used.

89	Injection, per se, without separation:
	This subclass is indented under subclass 82.  Process in which a method of injecting the plurality of gases or a liquid into the chromatography column is claimed, per se, without gas separation. SEE OR SEARCH CLASS: 141,  Fluent Material Handling, With Receiver or Receiver Coacting Means,   appropriate subclasses for processes and apparatus for the transfer of fluent material through a flow confining system, the source and receiver parts of which are normally separable.

90	SOLID SORPTION:
	This subclass is indented under the class definition.  Process in which a solid sorbent is used to retain on its internal or external surfaces a constituent of the fluid mixture passing in contact therewith. (1) Note. A solid sorbent is a solid material which separates a constituent (e.g., a gas, vapor, etc.) from a fluid mixture containing such constituents in a "quasi-chemical" manner. The action in most instances is that of selective retention (i.e., the sorbent removes only the part of the fluid mixture for which it has the greatest affinity). The retained constituent cannot be removed by shaking, brushing, or similar mechanical action, but generally can be removed by heating, pressure reduction, or use of a stripping or denuding fluid. A filter (particulate solids or other) has no particular "chemical" affinity for a constituent of a fluid mixture. The separation in the case of a filter depends on a mechanical entrapment of solid or liquid particles because of their relatively large size compared with the interstices or spaces between individual elements of the filter. The retained particles can be removed by brushing, wiping, shaking, or similar mechanical action. (2) Note. "Absorption" is the holding of a constituent by cohesion or capillary action in the pores of a solid. "Adsorption" is the ability of a sorbent to hold or concentrate gases, liquids, or dissolved substances upon its surface. (3) Note. The desorption of a solid sorbent, which may appear in one of the subclasses below, must be before or after its use as a sorbent, as claimed. The mere treatment of a solid sorbent to drive off the fluid sorbed thereon or therein is proper subject matter for Class 502. See search class note below. (4) Note. This subclass and the subclasses indented hereunder will take the degasification of a liquid by use of a solid sorbent. SEE OR SEARCH THIS CLASS, SUBCLASS: 41, for processes using compressing and cooling of a fluid mixture to separate a constituent from the mixture in addition to using a solid sorbent to separate a constituent from the gas. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 108 through 154for apparatus containing solid sorbents. 203,  Distillation: Processes, Separatory,   subclass 41 for a separatory distillation process including the step of passing the produced vapor through a solid sorbent. 210,  Liquid Purification or Separation,   subclasses 660 through 694for processes of using a solid sorbent to purify or separate a liquid. 420,  Alloys or Metallic Compositions,   subclass 900 for hydrogen (H2) storage alloys or metallic compositions. 423,  Chemistry of Inorganic Compounds,   subclass 658.2 for processes of producing elemental hydrogen (H) by direct decomposition of a binary compound (e.g., chemical storage, etc.). 436,  Chemistry: Analytical and Immunological Testing,   subclass 167 for processes wherein the basis for analysis is an optical result of a chemical reaction that is measured mechanically or visually, including solid sorption of a gas. 502,  Catalyst, Solid Sorbent, or Support Therefor: Product or Process of Making,   subclasses 20 through 56for regenerating or rehabilitating solid sorbent compositions, per se, subclasses 60-87 for zeolite compositions and for processes of making zeolite compositions, and subclasses 400-438 for other solid sorbent compositions and for processes of making solid sorbent compositions. Class 95 will take the combination of gas separation using a solid sorbent composition and regenerating or rehabilitating the solid sorbent composition. 585,  Chemistry of Hydrocarbon Compounds,   subclasses 820 through 831for processes in which a mixture of a hydrocarbon compound with another substance is treated to recover that same compound in a more usable condition, that is, a purer or more desirable condition, by a treatment which comprises separating the hydrocarbon from the other substance by contact with a solid sorbent.

91	Soluble or deliquescent material used:
	This subclass is indented under subclass 90.  Process in which the solid sorbent dissolves in the constituent retained or sorbed therein or thereon. (1) Note. The resultant solution may be used in a liquid contacting zone to aid in the separation. (2) Note. A deliquescent material is a water-soluble chemical salt used to sorb atmospheric water vapor. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 118 through 120for apparatus containing a soluble or deliquescent sorbent material.

92	And liquid contact (e.g., scrubbing, sorption, etc.):
	This subclass is indented under subclass 90.  Process in which a gaseous fluid mixture is contacted by a liquid in addition to a solid sorbent in order to remove a gas, solid, or liquid therefrom. SEE OR SEARCH THIS CLASS, SUBCLASS: 36 through 38, for processes in which a liquid-solid slurry is used to cause gas separation.

93	Sweep gas used on solid sorbent:
	This subclass is indented under subclass 92.  Process in which a gas is used to purge the constituent separated from the solid sorbent or a gas is used to regenerate the solid sorbent. SEE OR SEARCH THIS CLASS, SUBCLASS: 97 through 102, and 104-105, for processes of using a sweep gas on a solid sorbent including reduction of pressure.

94	And recycle or reuse of contact liquid for further contact:
	This subclass is indented under subclass 92.  Process in which (a) the contact liquid is recirculated for further contact with the fluid mixture or a portion thereof or (b) the contact liquid is used in another step of the process for further contact with the fluid mixture or a portion thereof.

95	Including reduction of pressure:
	This subclass is indented under subclass 90.  Process in which pressure over a mass of solid sorbent is decreased in order to separate from the solid sorbent the constituent sorbed in the gas separation process.

96	Plural pressure varying steps (e.g., pressure swing adsorption, etc.):
	This subclass is indented under subclass 95.  Process in which there is more than one step of increasing or decreasing the pressure on the solid sorbent.

97	Sweep gas used:
	This subclass is indented under subclass 96.  Process in which a gas is used to purge the constituent separated from the solid sorbent or a gas is used to regenerate the solid sorbent. SEE OR SEARCH THIS CLASS, SUBCLASS: 93, for processes of solid sorption and liquid contact including use of a sweep gas on a solid sorbent. 104 through 105, for processes in which a sweep gas is used to carry desorbed gas without the use of plural pressure varying.

98	Feed gas or constituent thereof is sweep gas:
	This subclass is indented under subclass 97.  Process in which the sweep gas is the gaseous fluid mixture or a portion thereof, before or after being treated or separated.

99	With heating or cooling:
	This subclass is indented under subclass 98.  Process in which the solid sorbent or a gas is heated or cooled.

100	Stepped pressure reduction:
	This subclass is indented under subclass 98.  Process in which the pressure over the solid sorbent is decreased in more than one step. SEE OR SEARCH THIS CLASS, SUBCLASS: 103, for processes in which there is use of pressure reduction in more than one step without the use of a sweep gas to carry desorbed gas.

101	Vacuum applied:
	This subclass is indented under subclass 100.  Process in which a step of pressure reduction is accomplished by using a pressure below that of the atmosphere.

102	Vacuum applied:
	This subclass is indented under subclass 98.  Process in which a step of pressure reduction is accomplished by using a pressure below that of the atmosphere.

103	Stepped pressure reduction:
	This subclass is indented under subclass 96.  Process in which the pressure over the solid sorbent is decreased in more than one step. SEE OR SEARCH THIS CLASS, SUBCLASS: 100, for processes in which there is use of pressure reduction in more than one step with the use of a sweep gas to carry desorbed gas.

104	Sweep gas used:
	This subclass is indented under subclass 95.  Process in which a gas is used to purge the constituent separated from the sorbent or a gas is used to regenerate the solid sorbent. SEE OR SEARCH THIS CLASS, SUBCLASS: 93, for processes of solid sorption and liquid contact including use of a sweep gas on a solid sorbent. 97 through 102, for processes in which a sweep gas is used to carry desorbed gas with the use of plural pressure varying.

105	Feed gas or constituent thereof is sweep gas:
	This subclass is indented under subclass 104.  Process in which the sweep gas is the gaseous fluid mixture or a portion thereof, before or after being treated or separated.

106	With heating or cooling:
	This subclass is indented under subclass 95.  Process in which the solid sorbent or a gas is heated or cooled.

107	Moving sorbent:
	This subclass is indented under subclass 90.  Process in which the solid sorbent is moved from one zone to another by moving a housing, is moved from one zone to another in a stationary housing, or is blown about or fluidized by a gas in a housing. (1) Note. The zones need not all be for sorbing the gas or for desorbing the solid sorbent; it is sufficient that the solid sorbent be moved from one zone to another, in each of which zones the solid sorbent either is treated or is used to treat. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 150 for apparatus having a moving solid sorbent.

108	Fluidized bed:
	This subclass is indented under subclass 107.  Process in which the solid sorbent is blown about or fluidized by a gas in a housing.

109	Having gravity flow of sorbent from zone to zone:
	This subclass is indented under subclass 108.  Process in which the solid sorbent is moved from one zone to another in a stationary housing by the forces of gravity.

110	Gravity flow of sorbent from zone to zone:
	This subclass is indented under subclass 107.  Process in which the solid sorbent is moved from one zone to another in a stationary housing by the forces of gravity.

111	Sweep gas used:
	This subclass is indented under subclass 110.  Process in which a gas is used to purge a constituent separated from the solid sorbent or a gas is used to regenerate the solid sorbent.

112	Steam is sweep gas:
	This subclass is indented under subclass 111.  Process in which the sweep gas is steam.

113	Rotating housing containing fixed sorbent or rotating plurality of housings:
	This subclass is indented under subclass 107.  Process in which the housing containing a fixed solid sorbent turns on its axis in order to move the solid sorbent from one treatment zone to another or a plurality of housings is turned about a central axis to the housings to place a housing in a position of use or nonuse or regeneration.

114	With plural indirect heat transfer steps on solid sorbent or gaseous fluid mixture or constituent thereof:
	This subclass is indented under subclass 90.  Process in which there is more than one step of heating or cooling the solid sorbent or the gaseous fluid mixture or constituent thereof through a wall before or after separation. (1) Note. The heat transfer steps must be part of a larger process containing subject matter for Class 95, such as will be found in this and the indented subclass where the heat transfer steps are combined with sorption of a constituent from a gas on a solid sorbent. If the only separation involved is conducted by the heat transfer steps, then classification in Class 165 is proper. SEE OR SEARCH CLASS: 165,  Heat Exchange,   appropriate subclasses for processes where only indirect heat exchange causes the separation of a constituent from a gas.

115	Heating and cooling:
	This subclass is indented under subclass 114.  Process in which there is heating and cooling of the solid sorbent or of a gas. SEE OR SEARCH CLASS: 165,  Heat Exchange,   subclasses 58 through 66and 201-265 for processes of heating and cooling where only the indirect heat exchange causes the separation of a constituent from a gas.

116	Inorganic gas or liquid particle sorbed (e.g., vapor, mist, etc.):
	This subclass is indented under subclass 90.  Process in which an inorganic gas or liquid particle (e.g., vapor, mist, etc.) is sorbed from the plurality of gases or the gas with entrained liquid particles. (1) Note. For purposes of classification in this area, "inorganic" compounds or elements are those that would fall within the definition of Class 423. For example, the cyanides (CN joined only to a metal or to hydrogen) and the carbon oxides are found in the indented subclasses.

117	Water sorbed:
	This subclass is indented under subclass 116.  Process in which water is sorbed from the plurality of gases or the gas with entrained liquid particles. SEE OR SEARCH THIS CLASS, SUBCLASS: 91, for processes in which water-soluble chemical salts are used to sorb atmospheric water vapor.

118	Plural separating treatments of gas by solid sorbent to remove water:
	This subclass is indented under subclass 117.  Process in which the gas is passed through a plurality of discrete or diverse separating stages or steps, with the solid sorbent being the same or a different solid sorbent in each step of the process.

119	And regeneration of any solid sorbent:
	This subclass is indented under subclass 118.  Process in which at least one of the solid sorbents is revivified or regenerated.

120	Heating or cooling:
	This subclass is indented under subclass 119.  Process in which the solid sorbent or a gas is heated or cooled.

121	And regeneration of solid sorbent:
	This subclass is indented under subclass 117.  Process in which the solid sorbent is revivified or regenerated.

122	Sweep gas used:
	This subclass is indented under subclass 121.  Process in which a gas is used to purge the water separated from the solid sorbent or a gas is used to regenerate the solid sorbent.

123	Hot sweep gas:
	This subclass is indented under subclass 122.  Process in which there is a positive step of raising the temperature of the sweep gas above the ambient temperature or the sweep gas is already at a temperature above the ambient temperature.

124	And cooling of sweep gas:
	This subclass is indented under subclass 123.  Process in which the sweep gas is cooled.

125	And cooling of solid sorbent:
	This subclass is indented under subclass 123.  Process in which the solid sorbent is cooled.

126	By heating:
	This subclass is indented under subclass 121.  Process in which the solid sorbent is revivified or regenerated by heating.

127	Noble gas sorbed:
	This subclass is indented under subclass 116.  Process in which a noble gas (i.e., helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), or radon (Rn)) is sorbed.

128	Nitrogen containing compound sorbed:
	This subclass is indented under subclass 116.  Process in which a nitrogen containing compound is sorbed.

129	Nitrogen oxide sorbed:
	This subclass is indented under subclass 128.  Process in which a nitrogen oxide (e.g., nitric oxide (NO), nitrogen dioxide (NO2), etc.) is sorbed.

130	Nitrogen sorbed:
	This subclass is indented under subclass 116.  Process in which nitrogen (N2) is sorbed.

131	Halogen or halogen containing compound sorbed:
	This subclass is indented under subclass 116.  Process in which a halogen (i.e., fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At)) or a halogen containing compound is sorbed.

132	Chlorine or chlorine containing compound sorbed:
	This subclass is indented under subclass 131.  Process in which chlorine (Cl) or a chlorine containing compound is sorbed.

133	Metal or metal containing compound sorbed:
	This subclass is indented under subclass 116.  Process in which a metal or metal containing compound is sorbed. (1) Note. Arsenic (As) is considered to be a metal.

134	Mercury sorbed:
	This subclass is indented under subclass 133.  Process in which mercury (Hg) is sorbed.

135	Sulfur containing compound sorbed:
	This subclass is indented under subclass 116.  Process in which a sulfur (S) containing compound is sorbed.

136	Hydrogen sulfide sorbed:
	This subclass is indented under subclass 135.  Process in which hydrogen sulfide (H2S) is sorbed.

137	Sulfur dioxide or sulfur trioxide sorbed:
	This subclass is indented under subclass 135.  Process in which sulfur dioxide (SO2) or sulfur trioxide (SO3) is sorbed.

138	Oxygen or ozone sorbed:
	This subclass is indented under subclass 116.  Process in which oxygen (O2) or ozone (O3) is sorbed.

139	Carbon dioxide sorbed:
	This subclass is indented under subclass 116.  Process in which carbon dioxide (CO2) is sorbed.

140	Carbon monoxide sorbed:
	This subclass is indented under subclass 116.  Process in which carbon monoxide (CO) is sorbed.

141	Organic gas or liquid particle sorbed (e.g., vapor, mist, etc.):
	This subclass is indented under subclass 90.  Process in which an organic gas or liquid particle (e.g., vapor, mist, etc.) is sorbed from the plurality of gases or the gas with entrained liquid particles. (1) Note. For purposes of classification in this area, "organic" compounds are those that would fall within the definitions of Class 260.

142	Halogen containing compound sorbed (e.g., phosgene, etc.):
	This subclass is indented under subclass 141.  Process in which a halogen containing (i.e., fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At)) compound (e.g., phosgene, etc.) is sorbed.

143	Hydrocarbon sorbed:
	This subclass is indented under subclass 141.  Process in which a hydrocarbon is sorbed.

144	Alkene sorbed:
	This subclass is indented under subclass 143.  Process in which an alkene (i.e., olefin) is sorbed.

145	Alkyne sorbed (e.g., acetylene, etc.):
	This subclass is indented under subclass 143.  Process in which an alkyne (i.e., alkine) is sorbed (e.g., acetylene, etc.).

146	Gasoline sorbed:
	This subclass is indented under subclass 143.  Process in which gasoline is sorbed.

147	Benzene ring containing compound sorbed:
	This subclass is indented under subclass 143.  Process in which a benzene ring containing compound is sorbed.

148	And regeneration:
	This subclass is indented under subclass 90.  Process in which the solid sorbent is revivified or regenerated. SEE OR SEARCH THIS CLASS, SUBCLASS: 95 through 106, for processes of regeneration of the solid sorbent including the reduction of pressure. 107 through 113, for processes of regeneration of the solid sorbent including the use of a moving sorbent. 114 through 115, for processes of regeneration of the solid sorbent including plural indirect heat transfer steps. 116 through 140, and 141-147, for processes of regeneration of the solid sorbent including the sorption of a specifically named compound.

149	LIQUID CONTACTING (E.G., SORPTION, SCRUBBING, ETC.):
	This subclass is indented under the class definition.  Process in which the fluid mixture is contacted with a liquid. (1) Note. The contact of the fluid mixture with a liquid generally results in separation of a gas, solid particles, or liquid particles from a gaseous fluid mixture (e.g., sorption, scrubbing, etc.). The contact of the fluid mixture with a liquid does not have to cause separation of the mixture, however, but may be used for other reasons (e.g., to humidify a gas, etc.). As long as there is separation of the fluid mixture by some process of this class along with the contacting of the mixture with a liquid for reasons other than separation, the patent will be placed here (e.g., filtration plus humidification, etc.). SEE OR SEARCH THIS CLASS, SUBCLASS: 44, for selective diffusion of gases through an immobilized liquid. 64 through 66, and 71-72, for electric or electrostatic field processes combined with liquid addition to the gas. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 243 through 371for gas separation apparatus using gas and liquid contact means combined with means to further handle the process constituents before, during, or after separation. See the class line to Class 261 in Section III, References to Other Classes, of this class for further details about gas and liquid contact apparatus and processes. 261,  Gas and Liquid Contact Apparatus,   appropriate subclassesfor gas and liquid contact apparatus, per se, with or without separation, and for gas and liquid contact processes, per se, without separation (e.g., humidification, etc.). See the class line to Class 261 in Section III, References to Other Classes of this class for further details about gas and liquid contact apparatus and processes. 436,  Chemistry: Analytical and Immunological Testing,   subclass 168 for processes wherein the basis for analysis is an optical result of a chemical reaction that is measured mechanically or visually, including liquid sorption of a gas. 585,  Chemistry of Hydrocarbon Compounds,   subclasses 833 through 868 for processes in which a mixture of a hydrocarbon compound with another substance is treated to recover that same compound in a more usable condition, that is, a purer or more desirable condition, by a treatment which comprises separating the hydrocarbon from the other substance by addition of an extraneous agent (e.g., solvent, etc.).

150	Including foaming of liquid to aid in the separation:
	This subclass is indented under subclass 149.  Process in which a frothy or sudslike dispersion of gas in the contact liquid is formed to aid in the separation. (1) Note. When foam is intentionally formed, it will be assumed to aid in the separation unless otherwise stated. SEE OR SEARCH CLASS: 516,  Colloid Systems and Wetting Agents; Subcombinations Thereof; Processes of Making, Stabilizing, Breaking, or Inhibiting,   appropriate subclasses for colloid systems or agents for such systems or making or stabilizing such systems or agents ( subclasses 10-19 for foaming), appropriate subclasses for processes of or compositions for or subcombination compositions for the breaking of or inhibiting of colloid systems (subclasses 115-134 for defoaming); in each instance, when generically claimed or when there is no hierarchically superior provision in the USPC for the specifically claimed art.

151	Mechanical agitation of liquid body to contact gaseous fluid mixture:
	This subclass is indented under subclass 149.  Process in which the gaseous fluid mixture is contacted with the liquid by mechanically stirring a liquid body or mass or by mechanically disturbing the surface of a liquid body or mass in such a way that the liquid is flung into the mixture. SEE OR SEARCH THIS CLASS, SUBCLASS: 150, for processes in which agitation of the liquid body causes foaming of the liquid. 185, for processes of contacting a fluid mixture with a liquid combined with mechanical agitating in order to degasify the liquid. 260, for processes of degasification of a liquid by agitating.

152	Coagulating or flocculating agent:
	This subclass is indented under subclass 149.  Process in which solid particles are removed from a gas by a contact liquid that contains an agent that causes the solid particles to agglomerate. (1) Note. These agents are known as "coagulating" agents, "flocculating" agents, or "flocculent" materials. SEE OR SEARCH CLASS: 516,  Colloid Systems and Wetting Agents; Subcombinations Thereof; Processes of Making, Stabilizing, Breaking, or Inhibiting,   subclasses 98 through 112for colloid systems of continuous or semicontinuous solid phase with discontinuous liquid phase (gels, pastes, flocs, coagulates) or agents for such systems or making or stabilizing such systems or agents, when generically claimed or when there is no hierarchically superior provision in the USPC for the specifically claimed art.

153	Hydrate inhibitor:
	This subclass is indented under subclass 149.  Process in which the contact liquid contains an agent that prevents formation of a substance containing water combined in the molecular form (e.g., agent prevents formation of methane hydrate: CH4-7H2O, ethane hydrate: C2H6-8H2O, chlorine hydrate: Cl2-8H2O, etc.).

154	Surfactant or wetting agent:
	This subclass is indented under subclass 149.  Process in which the contact liquid contains an agent that reduces the surface tension of the contact liquid. (1) Note. These agents are known as "surfactants," "wetting" agents, or "surface-active" substances.

155	Defoaming or antifoaming agent:
	This subclass is indented under subclass 149.  Process in which the contact liquid contains an agent that either (a) resolves or breaks a frothy or sudslike dispersion that was formed during the liquid-gas contact into separate fluid phases or (b) prevents formation of a frothy or sudslike dispersion during the liquid-gas contact. SEE OR SEARCH THIS CLASS, SUBCLASS: 157, and 242, for other processes of defoaming a liquid. SEE OR SEARCH CLASS: 516,  Colloid Systems and Wetting Agents; Subcombinations Thereof; Processes of Making, Stabilizing, Breaking, or Inhibiting,   subclasses 115 through 134for processes of or compositions for or subcombination compositions for the breaking of or inhibiting of foam colloid systems, when generically claimed or when there is no hierarchically superior provision in the USPC for the specifically claimed art.

156	And degasification of a liquid:
	This subclass is indented under subclass 149.  Process in which a gas is removed from a liquid. (1) Note. Generally, the patents in this subclass and the subclasses indented hereunder involve contacting a plurality of gases, with or without solid or liquid particles entrained therein, with a liquid in order to sorb or remove a gas or gases from the plurality of gases, allowing the remaining gas or gases to pass out of contact with the liquid. The liquid with gas entrained therein then is treated to remove the sorbed gas. The removal may be for regenerating the liquid for further use or may be for obtaining the sorbed gas. In addition, this area takes processes in which the degasification of a liquid occurs first and the removed gas is subjected to a liquid contacting step (see subclass 158). (2) Note. In order for a patent to be placed here, the gas sorbed by a liquid from a plurality of gases and removed from the liquid must be normally gaseous at a temperature of 0°C and a pressure of 760 mm Hg (e.g., hydrogen sulfide (H2S), carbon monoxide (CO), carbon dioxide (CO2), ethane (C2H6), ammonia (NH3), etc.). If, however, a constituent is at a temperature above its boiling temperature for a particular pressure, then the constituent is presumed to be a gas and the patent is placed here when the constituent is sorbed as a gas by a liquid, remains in gaseous phase in the liquid, and is removed from the liquid as a gas. The C4 hydrocarbons, which have boiling points above and below a temperature of 0°C, are classified according to their individual boiling points in subclasses 149-240 (e.g., butane with a boiling point of -0.5°C at 760 mm Hg pressure is a gas at a temperature of 0°C and 760 mm Hg pressure; whereas 1,2-butadiene with a boiling point of 10.8°C at 760 mm Hg pressure is a liquid at a temperature of 0°C and 760 mm Hg pressure). This handling of the C4 hydrocarbons is in contrast to that of Class 203, in which all of the C4 hydrocarbons are arbitrarily classified as liquids at a temperature of 0°C and 760 mm Hg pressure. SEE OR SEARCH THIS CLASS, SUBCLASS: 30, for processes of degasification of a liquid by use of sound waves. 46, for processes of degasification of a liquid by selective diffusion of gases through a substantially solid barrier. 188 through 194, and 206-209, for removal of a liquid from the contact liquid. 241 through 266, for processes of degasification of a liquid without liquid contacting. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 155 through 220for degasifying means for liquid.

157	Defoaming:
	This subclass is indented under subclass 156.  Process in which a frothy or sudslike dispersion that was formed during the liquid-gas contact or was present before the liquid-gas contact is resolved or broken into separate fluid phases. SEE OR SEARCH THIS CLASS, SUBCLASS: 155, and 242, for other processes of defoaming a liquid. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 176 through 180for defoaming apparatus. 516,  Colloid Systems and Wetting Agents; Subcombinations Thereof; Processes of Making, Stabilizing, Breaking, or Inhibiting,   subclasses 115 through 134for processes of or compositions for or subcombination compositions for the breaking of or inhibiting of foam colloid systems, when generically claimed or when there is no hierarchically superior provision in the USPC for the specifically claimed art.

158	Degasification step occurs first, with removed gas subsequently contacted by liquid:
	This subclass is indented under subclass 156.  Process in which a liquid with gas entrained therein is degassed and the removed gas is then contacted with a liquid.

159	By stripping with gas:
	This subclass is indented under subclass 156.  Process in which the gas is removed from the contact liquid by passing a gas through or in contact with the contact liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 83, and 84, for processes of eluting or displacing separated constituents from a chromatographic column comprising a liquid solvent on a solid base. 191, and 207, for separation of liquid from contact liquid by stripping with gas. 245 through 246, for plural successive liquid degassing treatments which include stripping with gas. 263 through 265, for degasification of liquid by stripping with gas. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 202 through 203for degasifying means for liquid with gas contacting means.

160	And reduction of pressure (e.g., flashing, etc.):
	This subclass is indented under subclass 159.  Process in which the pressure acting on the contact liquid is decreased. (1) Note. The pressure reduction may be used in a separate step in order to remove gas from the contact liquid in addition to the step of removing gas from the contact liquid by stripping with gas, or the pressure reduction may be used in order to aid the removal by stripping with gas. SEE OR SEARCH THIS CLASS, SUBCLASS: 172 through 177, for liquid contacting and degasification of liquid by reduction of pressure. 247 through 250, for plural successive liquid degassing treatments which include reduction of pressure. 266, for degasification of liquid by reduction of pressure. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 193 through 201for degasifying means for liquid of the pressure reducing type.

161	And heating:
	This subclass is indented under subclass 160.  Process in which the contact liquid or a gas is heated. (1) Note. The heating may be used in a separate step in order to remove gas from the contact liquid in addition to another step of removing gas from the contact liquid, or the heating may be used in order to aid the removal by stripping with gas or by reduction of pressure. SEE OR SEARCH THIS CLASS, SUBCLASS: 165 through 169, for liquid contacting and degasification of liquid by stripping with gas combined with heating. 173 through 174, for liquid contacting and degasification of liquid by reduction of pressure combined with heating. 178 through 184, for liquid contacting and degasification of liquid by heating. 251 through 252, for plural successive liquid degassing treatments which include heating. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 218 for heat exchange apparatus to degasify liquid.

162	Steam is stripping gas:
	This subclass is indented under subclass 161.  Process in which the stripping gas is steam.

163	Liquid recycled or reused:
	This subclass is indented under subclass 160.  Process in which (a) the contact liquid is recirculated for further contact with the fluid mixture or a portion thereof or (b) the contact liquid is used in another step of the process.

164	Feed gas or constituent thereof is stripping gas:
	This subclass is indented under subclass 160.  Process in which the stripping gas is the gaseous fluid mixture or a portion thereof, before or after being treated or separated.

165	And heating:
	This subclass is indented under subclass 159.  Process in which the contact liquid or a gas is heated. (1) Note. The heating may be used in a separate step in order to remove gas from the liquid in addition to the step of removing gas from the liquid by stripping with gas, or the heating may be used in order to aid the removal by stripping with gas. SEE OR SEARCH THIS CLASS, SUBCLASS: 161 through 162, for liquid contacting and degasification of liquid by stripping with gas combined with reduction of pressure and heating. 173 through 174, for liquid contacting and degasification of liquid by reduction of pressure combined with heating. 178 through 184, for liquid contacting and degasification of liquid by heating. 251 through 252, for plural successive liquid degassing treatments which include heating. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 218 for heat exchange apparatus to degasify liquid.

166	Liquid recycled or reused:
	This subclass is indented under subclass 165.  Process in which (a) the contact liquid is recirculated for further contact with the fluid mixture or a portion thereof or (b) the contact liquid is used in another step of the process.

167	Vaporized component of contact liquid is stripping gas:
	This subclass is indented under subclass 165.  Process in which a constituent of the contact liquid is gasified and this constituent removes another gas from the contact liquid.

168	Steam is stripping gas:
	This subclass is indented under subclass 165.  Process in which the stripping gas is steam.

169	Liquid recycled or reused:
	This subclass is indented under subclass 159.  Process in which (a) the contact liquid is recirculated for further contact with the fluid mixture or a portion thereof or (b) the contact liquid is used in another step of the process.

170	Air is stripping gas:
	This subclass is indented under subclass 159.  Process in which the stripping gas is air.

171	Inert stripping gas:
	This subclass is indented under subclass 159.  Process in which the stripping gas is specified as being inert or is one of the following gases: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), nitrogen (N2), or carbon dioxide (CO2).

172	By reduction of pressure (e.g., flashing, etc.):
	This subclass is indented under subclass 156.  Process in which the gas is removed from the contact liquid by decreasing the pressure acting on the contact liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 160 through 164, for processes of liquid contacting and degasification of liquid by stripping with gas in which there is reduction of pressure. 192, and 208, for separation of liquid from contact liquid by reduction of pressure. 247 through 250, for plural successive liquid degassing treatments which include reduction of pressure. 266, for degasification of liquid by reduction of pressure. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 193 through 201for degasifying means for liquid of the pressure reducing type.

173	And heating:
	This subclass is indented under subclass 172.  Process in which the contact liquid or a gas is heated. (1) Note. The heating may be used in a separate step in order to remove gas from the liquid in addition to the step of removing gas from the liquid by reduction of pressure, or the heating may be used in order to aid the removal by reduction of pressure. SEE OR SEARCH THIS CLASS, SUBCLASS: 161 through 162, for liquid contacting and degasification of liquid by stripping with gas combined with reduction of pressure and heating. 165 through 168, for liquid contacting and degasification of liquid by stripping with gas combined with heating. 178 through 184, for liquid contacting and degasification of liquid by heating. 251 through 252, for plural successive liquid degassing treatments which include heating. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 218 for heat exchange apparatus to degasify liquid.

174	Liquid recycled or reused:
	This subclass is indented under subclass 173.  Process in which (a) the contact liquid is recirculated for further contact with the fluid mixture or a portion thereof or (b) the contact liquid is used in another step of the process.

175	Vacuum applied:
	This subclass is indented under subclass 172.  Process in which the step of pressure reduction is accomplished by using a pressure below that of the atmosphere.

176	Removed gas recycled:
	This subclass is indented under subclass 172.  Process in which the gas removed from the contact liquid is recirculated to the fluid mixture for further contact with liquid.

177	Liquid recycled or reused:
	This subclass is indented under subclass 172.  Process in which (a) the contact liquid is recirculated for further contact with the fluid mixture or a portion thereof or (b) the contact liquid is used in another step of the process.

178	By heating:
	This subclass is indented under subclass 156.  Process in which the gas is removed from the contact liquid by heating. SEE OR SEARCH THIS CLASS, SUBCLASS: 161 through 162, for liquid contacting and degasification of liquid by stripping with gas combined with reduction of pressure and heating. 165 through 168, for liquid contacting and degasification of liquid by stripping with gas combined with heating. 173 through 174, for liquid contacting and degasification of liquid by reduction of pressure combined with heating. 193, and 209, for separation of liquid from contact liquid by heating. 251 through 252, for plural successive liquid degassing treatments which include heating. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclass 218 for heat exchange apparatus to degasify liquid.

179	Liquid recycled or reused:
	This subclass is indented under subclass 178.  Process in which (a) the contact liquid is recirculated for further contact with the fluid mixture or a portion thereof or (b) the contact liquid is used in another step of the process.

180	Liquid cooling step before being recycled:
	This subclass is indented under subclass 179.  Process in which there is a step of lowering the temperature of the liquid before it is recycled.

181	Sulfur compound removed:
	This subclass is indented under subclass 178.  Process in which a gaseous sulfur (S) compound is sorbed by the contact liquid and then is removed from the contact liquid by heating.

182	Halogen compound removed:
	This subclass is indented under subclass 178.  Process in which a gaseous halogen compound (i.e., a compound with fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At)) is sorbed by the contact liquid and then is removed from the contact liquid by heating.

183	Carbon dioxide removed:
	This subclass is indented under subclass 178.  Process in which carbon dioxide (CO2) is sorbed by the contact liquid and then is removed from the contact liquid by heating.

184	Organic compound removed:
	This subclass is indented under subclass 178.  Process in which a gaseous organic compound is sorbed by the contact liquid and then is removed from the contact liquid by heating.

185	By liquid flow modifying or mechanical agitating:
	This subclass is indented under subclass 156.  Process in which the gas is removed from the contact liquid by mixing, stirring, or turbulating by contact with a solid member or the flow path of the contact liquid is altered. SEE OR SEARCH THIS CLASS, SUBCLASS: 260 through 262, for degasifying liquid by liquid flow modifying or mechanical agitating.

186	Liquid recycled or reused:
	This subclass is indented under subclass 156.  Process in which (a) the contact liquid is recirculated for further contact with the fluid mixture or a portion thereof or (b) the contact liquid is used in another step of the process.

187	And recycle or reuse of contact liquid for further contact:
	This subclass is indented under subclass 149.  Process in which (a) the contact liquid is recirculated for further contact with the fluid mixture or a portion thereof or (b) the contact liquid is used in another step of the process for further contact with the fluid mixture or a portion thereof. (1) Note. The recycled or reused contact liquid may have been regenerated or it may be a mixture with the removed constituent.

188	After separation of liquid from contact liquid:
	This subclass is indented under subclass 187.  Process in which the contact liquid is recycled or reused after another liquid constituent is removed from the contact liquid. (1) Note. The liquid removed from the contact liquid may have been originally present as liquid particles entrained in a gas, or the liquid removed may have been originally present as vapors as part of a plurality of gases, in which case the vapors would have condensed to liquid because of the liquid contact. (2) Note. In order for a patent to be placed here, the vapors sorbed by a liquid from a plurality of gases and removed from the liquid must be normally liquid at a temperature of 0°C and a pressure of 760 mm Hg and the vapors must have condensed to liquid (e.g., methanol (CH3OH), ethanol (C2H5OH), etc.). SEE OR SEARCH THIS CLASS, SUBCLASS: 156 through 186, for liquid contact and removal of a gas from a liquid. 206 through 209, for separation of a liquid constituent from the contact liquid without recycling or reusing the contact liquid.

189	And separation of solid from contact liquid:
	This subclass is indented under subclass 188.  Process in which a solid is removed from the contact liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 195, and 205, for other processes of separating a solid from the contact liquid.

190	By liquid-liquid extraction or formation of azeotrope:
	This subclass is indented under subclass 188.  Process in which (a) a liquid extractant is mixed with the contact liquid in order to cause separation of a solute from the contact liquid and then the liquid extractant with the removed solute is separated from the contact liquid or (b) a compound that forms a mixture of constant boiling point with a solute in the contact liquid is added to the contact liquid and then the azeotropic mixture is separated from the contact liquid. SEE OR SEARCH CLASS: 210,  Liquid Purification or Separation,   subclass 634 for processes, per se, in which a dissolved or suspended constituent of a liquid is preferentially dissolved or dispersed into a second liquid.

191	By stripping with gas:
	This subclass is indented under subclass 188.  Process in which the liquid constituent is removed from the contact liquid by passing a gas through or in contact with the contact liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 159 through 171, for liquid contacting and degasification of liquid by stripping with gas. 207, for liquid contacting and separation of a liquid constituent from the contact liquid by stripping with gas without recycle or reuse of the contact liquid.

192	By reduction of pressure (e.g., flashing, etc.):
	This subclass is indented under subclass 188.  Process in which the liquid constituent is removed from the contact liquid by decreasing the pressure acting on the contact liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 172 through 177, for liquid contacting and degasification of liquid by reduction of pressure. 208, for liquid contacting and separation of a liquid constituent from the contact liquid by reduction of pressure without recycle or reuse of the contact liquid.

193	By heating (e.g., fractional distillation, etc.):
	This subclass is indented under subclass 188.  Process in which the liquid constituent is removed from the contact liquid by heating the contact liquid (e.g., fractional distillation, etc.). SEE OR SEARCH THIS CLASS, SUBCLASS: 178 through 184, for liquid contacting and degasification of liquid by heating. 209, for liquid contacting and separation of a liquid constituent from the contact liquid by heating without recycle or reuse of the contact liquid.

194	Indirect heat exchange:
	This subclass is indented under subclass 193.  Process in which heat is transferred through a wall.

195	After separation of solid from contact liquid:
	This subclass is indented under subclass 187.  Process in which the contact liquid is recycled or reused after a solid is removed from the contact liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 189, and 205, for other processes of separating a solid from the contact liquid.

196	By filtration:
	This subclass is indented under subclass 195.  Process in which the contact liquid containing the solid to be removed is passed through a foraminous or porous mass which separates the solid from the liquid by entrapment and retention while permitting the liquid to pass through.

197	By gravity separation:
	This subclass is indented under subclass 195.  Process in which the solid settles to the bottom of a mass of the contact liquid in a settling tank or the solid rises to the top of a mass of the contact liquid in a flotation tank due to the difference in density of the solid and the contact liquid, with the layer of the contact liquid containing the solid being separated from the remainder of the mass of contact liquid.

198	And deflection to remove liquid particles from gas:
	This subclass is indented under subclass 187.  Process in which the gas and liquid after contact impinge on a surface to effect an abrupt change in direction of the gas-liquid mixture or to guide the gas-liquid mixture to cause the liquid to drop out and remain behind while the gas flows on. SEE OR SEARCH THIS CLASS, SUBCLASS: 216 through 222, for other processes of liquid contacting and deflection. 267 through 272, for deflection without liquid contacting.

199	Liquid contact in plural serial stages:
	This subclass is indented under subclass 187.  Process in which liquid and gaseous fluid mixture contact is effected in more than one step or zone in series. SEE OR SEARCH THIS CLASS, SUBCLASS: 223 through 225, for liquid contact in plural serial stages without recycle or reuse of the contact liquid. SEE OR SEARCH CLASS: 96,  Gas Separation: Apparatus,   subclasses 267 through 280 for gas separation apparatus with gas and liquid contact means having diverse means for adding the liquid.

200	Removal of solid or liquid particles from gas:
	This subclass is indented under subclass 199.  Process in which solid or liquid particles are removed from a gas. SEE OR SEARCH THIS CLASS, SUBCLASS: 202, for removal of solid or liquid particles from gas in a single stage.

201	Reduction of pressure during liquid contact:
	This subclass is indented under subclass 199.  Process in which pressure is decreased during the liquid contact.

202	Removal of solid or liquid particles from gas:
	This subclass is indented under subclass 187.  Process in which solid or liquid particles are removed from a gas. SEE OR SEARCH THIS CLASS, SUBCLASS: 200, for removal of solid or liquid particles from gas in plural serial stages.

203	Reduction of pressure:
	This subclass is indented under subclass 187.  Process in which pressure is decreased.

204	And recycle of gas for further contact:
	This subclass is indented under subclass 149.  Process in which the gaseous fluid mixture or a separated gaseous constituent is recirculated for further contact with the liquid.

205	And separation of solid from contact liquid:
	This subclass is indented under subclass 149.  Process in which a solid is removed from the contact liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 189, and 195, for other processes of separating a solid from the contact liquid.

206	And separation of liquid from contact liquid:
	This subclass is indented under subclass 149.  Process in which a liquid constituent is removed from the contact liquid. (1) Note. The liquid removed from the contact liquid may have been originally present as liquid particles entrained in a gas, or the liquid removed may have been originally present as vapors as part of a plurality of gases, in which case the vapors would have condensed to liquid because of the liquid contact. (2) Note. In order for a patent to be placed here, the vapors sorbed by a liquid from a plurality of gases and removed from the liquid must be normally liquid at a temperature of 0°C and a pressure of 760 mm Hg and the vapors must have condensed to liquid (e.g., methanol (CH3OH), ethanol (C2H5OH), etc.). SEE OR SEARCH THIS CLASS, SUBCLASS: 156 through 186, for liquid contact and removal of a gas from a liquid. 188 through 194, for separation of a liquid constituent from the contact liquid with recycling or reusing the contact liquid.

207	By stripping with gas:
	This subclass is indented under subclass 206.  Process in which the liquid constituent is removed from the contact liquid by passing a gas through or in contact with the contact liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 159 through 171, for liquid contacting and degasification of liquid by stripping with gas. 191, for liquid contacting and separation of a liquid constituent from the contact liquid by stripping with gas with recycle or reuse of the contact liquid.

208	By reduction of pressure (e.g., flashing, etc.):
	This subclass is indented under subclass 206.  Process in which the liquid constituent is removed from the contact liquid by decreasing the pressure acting on the contact liquid. SEE OR SEARCH THIS CLASS, SUBCLASS: 172 through 177, for liquid contacting and degasification of liquid by reduction of pressure. 192, for liquid contacting and separation of a liquid constituent from the contact liquid by reduction of pressure with recycle or reuse of the contact liquid.

209	By heating (e.g., fractional distillation, etc.):
	This subclass is indented under subclass 206.  Process in which the liquid constituent is removed from the contact liquid by heating the contact liquid (e.g., fractional distillation, etc.). SEE OR SEARCH THIS CLASS, SUBCLASS: 178 through 184, for liquid contacting and degasification of liquid by heating. 193 through 194, for liquid contacting and separation of a liquid constituent from the contact liquid by heating with recycle or reuse of the contact liquid.