|  | G |
SECTION G — PHYSICS

|  | G |
Note(s) In this section, the following term is used with the meaning indicated: "variable" (as a noun) means a feature or property (e.g., a dimension, a physical condition such as temperature, a quality such as density or colour) which, in respect of a particular entity (e.g., an object, a quantity of a substance, a beam of light) and at a particular instant, is capable of being measured; the variable may change, so that its numerical expression may assume different values at different times, in different conditions or in individual cases, but may be constant in respect of a particular entity in certain conditions or for practical purposes (e.g., the length of a bar may be regarded as constant for many purposes). Attention is drawn to the definitions of terms or expressions used, appearing in the notes of several of the classes in this section, in particular those of "measuring" in class Fulltext... Hierarchy... Expanded...G01 and "control" and "regulation" in class Fulltext... Hierarchy... Expanded...G05. Classification in this section may present more difficulty than in other sections, because the distinction between different fields of use rests to a considerable extent on differences in the intention of the user rather than on any constructional differences or differences in the manner of use, and because the subjects dealt with are often in effect systems or combinations, which have features or parts in common, rather than "things", which are readily distinguishable as a whole. For example, information (e.g., a set of figures) may be displayed for the purpose of education or advertising (Fulltext... Hierarchy... Expanded...G09), for enabling the result of a measurement to be known (Fulltext... Hierarchy... Expanded...G01), for signalling the information to a distant point or for giving information which has been signalled from a distant point (Fulltext... Hierarchy... Expanded...G08). The words used to describe the purpose depend on features that may be irrelevant to the form of the apparatus concerned, for example, such features as the desired effect on the person who sees the display, or whether the display is controlled from a remote point. Again, a device which responds to some change in a condition, e.g., in the pressure of a fluid, may be used, without modification of the device itself, to give information about the pressure (Fulltext... Hierarchy... Expanded...G01L) or about some other condition linked to the pressure (another subclass of class Fulltext... Hierarchy... Expanded...G01, e.g., Fulltext... Hierarchy... Expanded...G01K for temperature), to make a record of the pressure or of its occurrence (Fulltext... Hierarchy... Expanded...G07C), to give an alarm (Fulltext... Hierarchy... Expanded...G08B), or to control another apparatus (Fulltext... Hierarchy... Expanded...G05). The classification scheme is intended to enable things of a similar nature (as indicated above) to be classified together. It is therefore particularly necessary for the real nature of any technical subject to be decided before it can be properly classified.

INSTRUMENTS

|  | G01 |
MEASURING (counting Fulltext... Hierarchy... Expanded...G06M); TESTING

|  | G01 |
Note(s) This class covers, in addition to "true" measuring instruments, other indicating or recording devices of analogous construction, and also signalling or control devices insofar as they are concerned with measurement (as defined in Note 2 below) and are not specially adapted to the particular purpose of signalling or control. In this class, the following term is used with the meaning indicated: "measuring" is used to cover considerably more than its primary or basic meaning. In this primary sense, it means finding a numerical expression of the value of a variable in relation to a unit or datum or to another variable of the same nature, e.g. expressing a length in terms of another length as in measuring a length with a scale; the value may be obtained directly (as just suggested) or by measuring some other variable of which the value can be related to the value of the required variable, as in measuring a change in temperature by measuring a resultant change in the length of a column of mercury. However, since the same device or instrument may, instead of giving an immediate indication, be used to produce a record or to initiate a signal to produce an indication or control effect, or may be used in combination with other devices or instruments to give a conjoint result from measurement of two or more variables of the same or different kinds, it is necessary to interpret "measuring" as including also any operation that would make it possible to obtain such a numerical expression by the additional use of some way of converting a value into figures. Thus the expression in figures may be actually made by a digital presentation or by reading a scale, or an indication of it may be given without the use of figures, e.g. by some perceptible feature (variable) of the entity (e.g. object, substance, beam of light) of which the variable being measured is a property or condition or by an analogue of such a feature (e.g. the corresponding position of a member without any scale, a corresponding voltage generated in some way). In many cases there is no such value indication but only an indication of difference or equality in relation to a standard or datum (of which the value may or may not be known in figures); the standard or datum may be the value of another variable of the same nature but of a different entity (e.g. a standard measure) or of the same entity at a different time. In its simplest form, measurement may give merely an indication of presence or absence of a certain condition or quality, e.g. movement (in any direction or in a particular direction), or whether a variable exceeds a predetermined value. Attention is drawn to the Notes following the title of section G, especially as regards the definition of the term "variable". In many measuring arrangements, a first variable to be measured is transformed into a second, or further, variables. The second, or further, variables may be (a) a condition related to the first variable and produced in a member, or (b) a displacement of a member. Further transformation may be needed. [6] When classifying such an arrangement, (i) the transformation step, or each transformation step, that is of interest is classified, or (ii) if interest lies only in the system as a whole, the first variable is classified in the appropriate place. [6] This is particularly important where two or more conversions take place, for instance where a first variable, for example pressure, is transformed into a second variable, for example an optical property of a sensing body, and that second variable is expressed by means of a third variable, for example an electric effect. In such a case, the following classification places should be considered: the place for the transformation of the first variable, that for sensing the condition caused by that variable, subclass Fulltext... Hierarchy... Expanded...G01D for expression of the measurement, and finally the place for the overall system, if any. [6] The measurement of change in the value of a physical property is classified in the same subclass as the measurement of that physical property, e.g. measurement of expansion of length is classified in subclass Fulltext... Hierarchy... Expanded...G01B.

|  | G01L |
MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (methods or devices for measuring specially adapted for metal-rolling mills Fulltext... Hierarchy... Expanded...B21B 38/00; sensing pressure changes for compensating measurements of other variables or for compensating readings of instruments for variations in pressure, see Fulltext... Hierarchy... Expanded...G01D or other relevant subclasses for the variable measured; weighing Fulltext... Hierarchy... Expanded...G01G; converting a pattern of forces into electrical signals Fulltext... Hierarchy... Expanded...G06K 11/00) [4]

|  | G01L |
Note(s) Attention is drawn to the Notes following the title of class Fulltext... Hierarchy... Expanded...G01.

|  | G01L |
Subclass index
MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY |
General methods; apparatus adapted to special purposes | 1/00, 3/00; 5/00
MEASURING FLUID PRESSURE |
Methods of measuring | 7/00, 9/00, 11/00
Measurements of differential or multiple pressure values | 13/00, 15/00
Details of apparatus or accessories | 19/00
SPECIAL ADAPTATIONS OF MEASURING APPARATUS |
Measurements of pressure of inflated bodies | 17/00
Vacuum gauges | 21/00
INDICATORS OF FAST CHANGES, PARTICULARLY IN THE OPERATION OF FLUID-PRESSURE ENGINES | 23/00
TESTING OR CALIBRATING | 25/00, 27/00

|  | G01L 1/00 |
Measuring force or stress, in general (measuring force due to impact Fulltext... Hierarchy... Expanded...G01L 5/00; measuring fluid pressure Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...G01L 7/00-G01L 27/00; measuring deformation of bodies as a result of stress by using gauges Fulltext... Hierarchy... Expanded...G01B) [4]

|  | G01L 1/02 |
· | by hydraulic or pneumatic means

|  | G01L 1/04 |
· | by measuring elastic deformation of gauges, e.g. of springs

|  | G01L 1/06 |
· | by measuring the permanent deformation of gauges, e.g. of compressed bodies

|  | G01L 1/08 |
· | by the use of counterbalancing forces

|  | G01L 1/10 |
· | by measuring variations of frequency of stressed vibrating elements, e.g. of stressed strings (using resistance strain gauges Fulltext... Hierarchy... Expanded...G01L 1/22)

|  | G01L 1/12 |
· | by measuring variations in the magnetic properties of materials resulting from the application of stress

|  | G01L 1/14 |
· | by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators

|  | G01L 1/16 |
· | using properties of piezo-electric devices

|  | G01L 1/18 |
· | using properties of peizo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material (resistance strain gauges for measuring linear expansion or contraction Fulltext... Hierarchy... Expanded...G01B)

|  | G01L 1/20 |
· | by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids (of piezo-resistive materials Fulltext... Hierarchy... Expanded...G01L 1/18); by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress

|  | G01L 1/22 |
· · | using resistance strain gauges (resistance strain gauges for measuring linear expansion or contraction Fulltext... Hierarchy... Expanded...G01B)

|  | G01L 1/24 |
· | by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis

|  | G01L 1/25 |
· | using wave or particle radiation, e.g. X-rays, neutrons (Fulltext... Hierarchy... Expanded...G01L 1/24 takes precedence) [4]

|  | G01L 1/26 |
· | Auxiliary measures taken, or devices used, in connection with the measurement of force, e.g. for preventing influence of transverse components of force, for preventing overload

|  | G01L 3/00 |
Measuring torque, work, mechanical power, or mechanical efficiency, in general

|  | G01L 3/02 |
· | Rotary-transmission dynamometers

|  | G01L 3/04 |
· · | wherein the torque-transmitting element comprises a torsionally-flexible shaft

|  | G01L 3/06 |
· · · | involving mechanical means for indicating

|  | G01L 3/08 |
· · · | involving optical means for indicating

|  | G01L 3/10 |
· · · | involving electric or magnetic means for indicating

|  | G01L 3/12 |
· · · · | involving photoelectric means

|  | G01L 3/14 |
· · | wherein the torque-transmitting element is other than a torsionally-flexible shaft

|  | G01L 3/16 |
· | Rotary-absorption dynamometers, e.g. of brake type

|  | G01L 3/18 |
· · | mechanically actuated

|  | G01L 3/20 |
· · | fluid actuated

|  | G01L 3/22 |
· · | electrically or magnetically actuated

|  | G01L 3/24 |
· | Devices for determining the value of power, e.g. by measuring and simultaneously multiplying the values of torque and revolutions per unit of time, by multiplying the values of tractive or propulsive force and velocity (measuring velocity per se Fulltext... Hierarchy... Expanded...G01P)

|  | G01L 3/26 |
· | Devices for measuring efficiency, i.e. the ratio of power output to power input

|  | G01L 5/00 |
Apparatus for, or methods of, measuring force, e.g. due to impact, work, mechanical power, or torque, adapted for special purposes (measuring pressure of a fluent medium Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...G01L 7/00-G01L 21/00; measuring rapid changes of pressure in steam, gas, or liquid Fulltext... Hierarchy... Expanded...G01L 23/00)

|  | G01L 5/03 |
· | for measuring release force of ski safety bindings

|  | G01L 5/04 |
· | for measuring tension in ropes, cables, wires, threads, belts, bands, or like flexible members

|  | G01L 5/06 |
· · | using mechanical means

|  | G01L 5/08 |
· · | using fluid means

|  | G01L 5/10 |
· · | using electric means

|  | G01L 5/12 |
· | for measuring axial thrust in a rotary shaft, e.g. of propulsion plants

|  | G01L 5/13 |
· | for measuring the tractive or propulsive power of vehicles

|  | G01L 5/14 |
· | for measuring the force of explosions; for measuring the energy of projectiles

|  | G01L 5/16 |
· | for measuring several components of force

|  | G01L 5/18 |
· | for measuring ratios of force

|  | G01L 5/20 |
· | for measuring wheel side-thrust (in balancing Fulltext... Hierarchy... Expanded...G01M)

|  | G01L 5/22 |
· | for measuring the force applied to control members, e.g. control members of vehicles, triggers

|  | G01L 5/24 |
· | for determining value of torque or twisting moment for tightening a nut or other member which is similarly stressed (arrangements in wrenches or screwdrivers Fulltext... Hierarchy... Expanded...B25B 23/14)

|  | G01L 5/26 |
· | for determining the characteristic of torque in relation to revolutions per unit of time

|  | G01L 5/28 |
· | for testing brakes

|  | G01L 7/00 - G01L 23/00 |
Measuring fluid pressure

|  | G01L 7/00 |
Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements (transmitting or indicating the displacement of mechanical pressure-sensitive elements by electric or magnetic means Fulltext... Hierarchy... Expanded...G01L 9/00; measuring differences of two or more pressure values Fulltext... Hierarchy... Expanded...G01L 13/00; measuring two or more pressure values simultaneously Fulltext... Hierarchy... Expanded...G01L 15/00; measuring tyre pressure or the pressure of other inflated bodies Fulltext... Hierarchy... Expanded...G01L 17/00; vacuum gauges Fulltext... Hierarchy... Expanded...G01L 21/00; hollow bodies deformable or displaceable under internal pressure per se Fulltext... Hierarchy... Expanded...G12B 1/04)

|  | G01L 7/02 |
· | in the form of elastically-deformable gauges

|  | G01L 7/04 |
· · | in the form of flexible, deformable tubes, e.g. Bourdon gauges

|  | G01L 7/06 |
· · | of the bellows type

|  | G01L 7/08 |
· · | of the flexible-diaphragm type

|  | G01L 7/10 |
· · | of the capsule type

|  | G01L 7/12 |
· · · | with exhausted chamber; Aneroid barometers

|  | G01L 7/14 |
· · · · | with zero-setting means

|  | G01L 7/16 |
· | in the form of pistons

|  | G01L 7/18 |
· | using liquid as the pressure-sensitive medium, e.g. liquid-column gauges

|  | G01L 7/20 |
· · | involving a closed chamber above the liquid level, the chamber being exhausted or housing low-pressure gas; Liquid barometers

|  | G01L 7/22 |
· · | involving floats, e.g. floating bells

|  | G01L 7/24 |
· · | involving balances in the form of rings partly filled with liquid

|  | G01L 9/00 |
Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means (measuring differences of two or more pressure values Fulltext... Hierarchy... Expanded...G01L 13/00; measuring two or more pressure values simultaneously Fulltext... Hierarchy... Expanded...G01L 15/00; vacuum gauges Fulltext... Hierarchy... Expanded...G01L 21/00)

|  | G01L 9/02 |
· | by making use of variations in ohmic resistance, e.g. of potentiometers

|  | G01L 9/04 |
· · | of resistance strain gauges

|  | G01L 9/06 |
· · | of piezo-resistive devices

|  | G01L 9/08 |
· | by making use of piezo-electric devices

|  | G01L 9/10 |
· | by making use of variations in inductance

|  | G01L 9/12 |
· | by making use of variations in capacitance

|  | G01L 9/14 |
· | involving the displacement of magnets, e.g. electromagnets

|  | G01L 9/16 |
· | by making use of variations in the magnetic properties of material resulting from the application of stress

|  | G01L 9/18 |
· | by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electric potential is procuced or varied upon the application of stress

|  | G01L 11/00 |
Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group Fulltext... Hierarchy... Expanded...G01L 7/00 or Fulltext... Hierarchy... Expanded...G01L 9/00

|  | G01L 11/02 |
· | by optical means [6]

|  | G01L 11/04 |
· | by acoustic means [6]

|  | G01L 11/06 |
· · | Ultrasonic means [6]

|  | G01L 13/00 |
Devices or apparatus for measuring differences of two or more pressure values

|  | G01L 13/02 |
· | using elastically-deformable members or pistons as sensing elements

|  | G01L 13/04 |
· | using floats or liquids as sensing elements

|  | G01L 13/06 |
· | using electric or magnetic pressure-sensitive elements

|  | G01L 15/00 |
Devices or apparatus for measuring two or more pressure values simultaneously

|  | G01L 17/00 |
Devices or apparatus for measuring tyre pressure or the pressure in other inflated bodies (specially adapted for mounting on vehicles or tyres Fulltext... Hierarchy... Expanded...B60C 23/00; connection of valves to inflatable elastic bodies Fulltext... Hierarchy... Expanded...B60C 29/00)

|  | G01L 19/00 |
Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges

|  | G01L 19/02 |
· | Arrangements for preventing, or for compensating for, effects of inclination or acceleration of the measuring device; Zero-setting means (for aneroid barometers Fulltext... Hierarchy... Expanded...G01L 7/14)

|  | G01L 19/04 |
· | Means for compensating for effects of changes of temperature

|  | G01L 19/06 |
· | Means for preventing overload or deleterious influence of the measured medium on the measuring device or vice versa

|  | G01L 19/08 |
· | Means for indicating or recording, e.g. for remote indication

|  | G01L 19/10 |
· · | mechanical

|  | G01L 19/12 |
· · | Alarms or signals

|  | G01L 19/14 |
· | Housings

|  | G01L 19/16 |
· | Dials; Mounting of dials

|  | G01L 21/00 |
Vacuum gauges

|  | G01L 21/02 |
· | having a compression chamber in which gas, whose pressure is to be measured, is compressed

|  | G01L 21/04 |
· · | wherein the chamber is closed by liquid; Vacuum gauges of the McLeod type

|  | G01L 21/06 |
· · · | actuated by rotating or inverting the measuring device

|  | G01L 21/08 |
· | by measuring variations in the transmission of acoustic waves through the medium, the pressure of which is to be measured

|  | G01L 21/10 |
· | by measuring variations in the heat conductivity of the medium, the pressure of which is to be measured

|  | G01L 21/12 |
· · | measuring changes in electric resistance of measuring members, e.g. of filaments; Vacuum gauges of the Pirani type

|  | G01L 21/14 |
· · | using thermocouples

|  | G01L 21/16 |
· | by measuring variation of frictional resistance of gases

|  | G01L 21/18 |
· · | using a pendulum

|  | G01L 21/20 |
· · | using members oscillating about a vertical axis

|  | G01L 21/22 |
· · | using resonance effects of a vibrating body; Vacuum gauges of the Klumb type

|  | G01L 21/24 |
· · | using rotating members; Vacuum gauges of the Langmuir type

|  | G01L 21/26 |
· | by making use of radiometer action, i.e. of the pressure caused by the momentum of molecules passing from a hotter to a cooler member; Vacuum gauges of the Knudsen type

|  | G01L 21/28 |
· · | using torsional rotary measuring members

|  | G01L 21/30 |
· | by making use of ionisation effects (tubes therefor Fulltext... Hierarchy... Expanded...H01J 41/02)

|  | G01L 21/32 |
· · | using electric discharge tubes with thermionic cathodes

|  | G01L 21/34 |
· · | using electric discharge tubes with cold cathodes

|  | G01L 21/36 |
· · | using radioactive substances

|  | G01L 23/00 |
Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid

|  | G01L 23/02 |
· | mechanically indicating or recording and involving loaded or return springs

|  | G01L 23/04 |
· | involving means subjected to known counteracting pressure

|  | G01L 23/06 |
· | Indicating or recording by optical means

|  | G01L 23/08 |
· | operated electrically

|  | G01L 23/10 |
· · | by pressure-sensitive members of the piezo-electric type

|  | G01L 23/12 |
· · | by changing capacitance or inductance

|  | G01L 23/14 |
· · | by electromagnetic elements

|  | G01L 23/16 |
· · | by photoelectric means

|  | G01L 23/18 |
· · | by resistance strain gauges

|  | G01L 23/20 |
· | combined with planimeters or integrators

|  | G01L 23/22 |
· | for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines

|  | G01L 23/24 |
· | for measuring pressure in inlet or exhaust ducts of internal-combustion engines

|  | G01L 23/26 |
· | Details or accessories

|  | G01L 23/28 |
· · | Cooling means

|  | G01L 23/30 |
· · | Means for indicating consecutively positions of pistons or cranks of internal-combustion engines in combination with pressure indicators

|  | G01L 23/32 |
· · | Apparatus specially adapted for recording pressure changes measured by indicators (apparatus for recording steady or quasi-steady pressure Fulltext... Hierarchy... Expanded...G01L 19/08)

|  | G01L 25/00 |
Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency [2]

|  | G01L 27/00 |
Testing or calibrating of apparatus for measuring fluid pressure [2]

|  | G01L 27/02 |
· | of indicators