|  | 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.

|  | G01F |
MEASURING VOLUME, VOLUME FLOW, MASS FLOW, OR LIQUID LEVEL; METERING BY VOLUME (milk flow sensing devices in milking machines or devices Fulltext... Hierarchy... Expanded...A01J 5/01; measuring or recording blood flow Fulltext... Hierarchy... Expanded...A61B 5/02, Fulltext... Hierarchy... Expanded...A61B 8/06; metering media to the human body Fulltext... Hierarchy... Expanded...A61M 5/168; burettes or pipettes Fulltext... Hierarchy... Expanded...B01L 3/02; arrangements of liquid volume meters or volume-flow meters in liquid-delivering apparatus, e.g. for retail sale purposes, Fulltext... Hierarchy... Expanded...B67D 5/16; pumps, fluid motors, details common to measuring or metering devices and pumps or fluid motors Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...F01-F04; locating, determining distance or velocity using reflection or reradiation of radio waves, analogous arrangements using other waves Fulltext... Hierarchy... Expanded...G01S; systems for ratio control Fulltext... Hierarchy... Expanded...G05D 11/00) [2,5]

|  | G01F |
Note(s) Attention is drawn to the Notes following the title of class Fulltext... Hierarchy... Expanded...G01.

|  | G01F |
Subclass index
MEASURING VOLUME | 17/00, 19/00, 22/00
MEASURING VOLUME FLOW |
In continuous flow; in discontinuous flow; by proportion of flow | 1/00; 3/00; 5/00
With multiple measuring ranges | 7/00
By comparison with another value | 9/00
LEVEL INDICATORS | 23/00
METERING BY VOLUME | 11/00, 13/00
DETAILS, ACCESSORIES | 15/00
TESTING, CALIBRATING | 25/00

|  | G01F 1/00 - G01F 9/00 |
Measuring volume flow

|  | G01F 1/00 |
Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through the meter in a continuous flow (measuring a proportion of the volume flow Fulltext... Hierarchy... Expanded...G01F 5/00; measuring speed of flow Fulltext... Hierarchy... Expanded...G01P 5/00; indicating presence or absence of flow Fulltext... Hierarchy... Expanded...G01P 13/00; regulating quantity or ratio Fulltext... Hierarchy... Expanded...G05D) [2]

|  | G01F 1/05 - G01F 1/68 |
Note(s) Groups Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...G01F 1/704-G01F 1/76 take precedence over groups Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...G01F 1/05-G01F 1/68. [2]

|  | G01F 1/05 |
· | by using mechanical effects [2]

|  | G01F 1/06 |
· · | using rotating vanes with tangential admission [2]

|  | G01F 1/07 |
· · · | with mechanical coupling to the indicating device [2]

|  | G01F 1/075 |
· · · | with magnetic or electromagnetic coupling to the indicating device [2]

|  | G01F 1/08 |
· · · | Adjusting, correcting, or compensating means therefor [2]

|  | G01F 1/10 |
· · | using rotating vanes with axial admission [2]

|  | G01F 1/11 |
· · · | with mechanical coupling to the indicating device [2]

|  | G01F 1/115 |
· · · | with magnetic or electromagnetic coupling to the indicating device [2]

|  | G01F 1/12 |
· · · | Adjusting, correcting, or compensating means therefor

|  | G01F 1/20 |
· · | by detection of dynamic effects of the fluid flow [2]

|  | G01F 1/22 |
· · · | by variable-area meters [2]

|  | G01F 1/24 |
· · · · | with magnetic or electric coupling to the indicating device [2]

|  | G01F 1/26 |
· · · · | of the valve type [2]

|  | G01F 1/28 |
· · · | by drag-force, e.g. vane type or impact flowmeter [2]

|  | G01F 1/30 |
· · · · | for fluent solid material [2]

|  | G01F 1/32 |
· · · | by swirl flowmeter, e.g. using Karman vortices [2]

|  | G01F 1/34 |
· · | by measuring pressure or differential pressure [2]

|  | G01F 1/36 |
· · · | the pressure or differential pressure being created by the use of flow constriction [2]

|  | G01F 1/37 |
· · · · | the pressure or differential pressure being measured by means of communicating tubes or reservoirs with movable fluid levels, e.g. by U-tubes [2]

|  | G01F 1/38 |
· · · · | the pressure or differential pressure being measured by means of a movable element, e.g. diaphragm, piston, Bourdon tube or flexible capsule [2]

|  | G01F 1/40 |
· · · · | Details of construction of the flow constriction devices [2]

|  | G01F 1/42 |
· · · · · | Orifices or nozzles [2]

|  | G01F 1/44 |
· · · · · | Venturi tubes [2]

|  | G01F 1/46 |
· · · · · | Pitot tubes (specially adapted for measuring speed of fluids Fulltext... Hierarchy... Expanded...G01P 5/165) [2]

|  | G01F 1/48 |
· · · | the pressure or differential pressure being created by a capillary element [2]

|  | G01F 1/50 |
· · · | Correcting or compensating means [2]

|  | G01F 1/52 |
· · | by measuring the height of the fluid level due to the lifting power of the fluid flow [2]

|  | G01F 1/54 |
· · | by means of chains, flexible bands, or wires introduced into, and moved by, the flow [2]

|  | G01F 1/56 |
· | by using electric or magnetic effects (Fulltext... Hierarchy... Expanded...G01F 1/66 takes precedence) [2]

|  | G01F 1/58 |
· · | by electromagnetic flowmeters [2]

|  | G01F 1/60 |
· · · | Circuits therefor [2]

|  | G01F 1/64 |
· · | by measuring electrical currents passing through the fluid flow; by measuring electrical potential generated by the fluid flow, e.g. by electrochemical, contact, or friction effects (Fulltext... Hierarchy... Expanded...G01F 1/58 takes precedence) [2]

|  | G01F 1/66 |
· | by measuring frequency, phase shift, or propagation time of electromagnetic or other waves, e.g. ultrasonic flowmeters [2]

|  | G01F 1/68 |
· | by using thermal effects [2]

|  | G01F 1/684 |
· · | Structural arrangements; Mounting of elements, e.g. in relation to fluid flow [6]

|  | G01F 1/688 |
· · · | using a particular type of heating, cooling or sensing element [6]

|  | G01F 1/69 |
· · · · | of resistive type [6]

|  | G01F 1/692 |
· · · · · | Thin-film arrangements [6]

|  | G01F 1/696 |
· · | Circuits therefor, e.g. constant-current flow meters [6]

|  | G01F 1/698 |
· · · | Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters [6]

|  | G01F 1/699 |
· · · · | by control of a separate heating or cooling element [6]

|  | G01F 1/704 |
· | using marked regions or existing inhomogeneities within the fluid stream, e.g. statistically occurring variations in a fluid parameter (Fulltext... Hierarchy... Expanded...G01F 1/76, Fulltext... Hierarchy... Expanded...G01F 25/00 take precedence) [4]

|  | G01F 1/708 |
· · | Measuring the time taken to traverse a fixed distance [4]

|  | G01F 1/712 |
· · · | using auto-correlation or cross-correlation detection means (measuring speed by using correlation detection means in general Fulltext... Hierarchy... Expanded...G01P 3/80, Fulltext... Hierarchy... Expanded...G01P 5/22) [4]

|  | G01F 1/716 |
· · · | using electron paramagnetic resonance (EPR) or nuclear magnetic resonance (NMR) [4]

|  | G01F 1/72 |
· | Devices for measuring pulsing fluid flows [2]

|  | G01F 1/74 |
· | Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid [2]

|  | G01F 1/76 |
· | Devices for measuring mass flow of a fluid or a fluent solid material (weighing a continuous stream of material during flow Fulltext... Hierarchy... Expanded...G01G 11/00) [2]

|  | G01F 1/78 |
· · | Direct mass flowmeters [2]

|  | G01F 1/80 |
· · · | operating by measuring pressure, force, momentum, or frequency of a fluid flow to which a rotational movement has been imparted [2]

|  | G01F 1/82 |
· · · · | using a driven wheel as impeller and one or more other wheels or moving elements which are angularly restrained by a resilient member, e.g. spring member, as the measuring device [2]

|  | G01F 1/84 |
· · · · | Gyroscopic mass flowmeters [2]

|  | G01F 1/86 |
· · | Indirect mass flowmeters, e.g. measuring volume flow and density, temperature, or pressure [2]

|  | G01F 1/88 |
· · · | with differential-pressure measurement to determine the volume flow [2]

|  | G01F 1/90 |
· · · | with positive-displacement meter or turbine meter to determine the volume flow [2]

|  | G01F 3/00 |
Measuring the volume flow of fluids or fluent solid material wherein the fluid passes through the meter in successive and more or less isolated quantities, the meter being driven by the flow (measuring a proportion of the volume flow Fulltext... Hierarchy... Expanded...G01F 5/00)

|  | G01F 3/02 |
· | with measuring chambers which expand or contract during measurement

|  | G01F 3/04 |
· · | having rigid movable walls

|  | G01F 3/06 |
· · · | comprising members rotating in a fluid-tight or substantially fluid-tight manner in a housing

|  | G01F 3/08 |
· · · · | Rotary-piston or ring-piston meters

|  | G01F 3/10 |
· · · · | Geared or lobed impeller meters

|  | G01F 3/12 |
· · · · | Meters with nutating members, e.g. discs

|  | G01F 3/14 |
· · · | comprising reciprocating pistons, e.g. reciprocating in a rotating body

|  | G01F 3/16 |
· · · · | in stationary cylinders

|  | G01F 3/18 |
· · · · · | involving two or more cylinders

|  | G01F 3/20 |
· · | having flexible movable walls, e.g. diaphragms, bellows (diaphragms or bellows therefor Fulltext... Hierarchy... Expanded...G01F 15/16)

|  | G01F 3/22 |
· · · | for gases

|  | G01F 3/24 |
· | with measuring chambers moved during operation (wet gas-meters Fulltext... Hierarchy... Expanded...G01F 3/30)

|  | G01F 3/26 |
· · | Tilting-trap meters

|  | G01F 3/28 |
· · | on carriers rotated by the weight of the liquid in the measuring chambers

|  | G01F 3/30 |
· | Wet gas-meters

|  | G01F 3/32 |
· · | comprising partitioned drums rotating or nutating in a liquid

|  | G01F 3/34 |
· · | comprising bells reciprocating in a liquid

|  | G01F 3/36 |
· | with stationary measuring chambers having constant volume during measurement (with measuring chambers which expand or contract during measurement Fulltext... Hierarchy... Expanded...G01F 3/02)

|  | G01F 3/38 |
· · | having only one measuring chamber

|  | G01F 5/00 |
Measuring a proportion of the volume flow

|  | G01F 7/00 |
Volume-flow measuring devices with two or more measuring ranges; Compound meters

|  | G01F 9/00 |
Measuring volume flow relative to another variable, e.g. of liquid fuel for an engine

|  | G01F 9/02 |
· | wherein the other variable is the speed of a vehicle

|  | G01F 11/00 - G01F 13/00 |
Metering by volume

|  | G01F 11/00 |
Apparatus requiring external operation adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container, without regard to weight, and to deliver it

|  | G01F 11/02 |
· | with measuring chambers which expand or contract during measurement

|  | G01F 11/04 |
· · | of the free-piston type

|  | G01F 11/06 |
· · · | with provision for varying the stroke of the piston

|  | G01F 11/08 |
· · | of the diaphragm or bellows type (diaphragms or bellows therefor Fulltext... Hierarchy... Expanded...G01F 15/16)

|  | G01F 11/10 |
· | with measuring chambers moved during operation

|  | G01F 11/12 |
· · | of the valve type, i.e. the separating being effected by fluid-tight or powder-tight movements (involving the tilting or inverting of the supply vessel Fulltext... Hierarchy... Expanded...G01F 11/26)

|  | G01F 11/14 |
· · · | wherein the measuring chamber reciprocates

|  | G01F 11/16 |
· · · · | for liquid or semiliquid

|  | G01F 11/18 |
· · · · | for fluent solid material

|  | G01F 11/20 |
· · · | wherein the measuring chamber rotates or oscillates

|  | G01F 11/22 |
· · · · | for liquid or semiliquid

|  | G01F 11/24 |
· · · · | for fluent solid material

|  | G01F 11/26 |
· · | wherein the measuring chamber is filled and emptied by tilting or inverting the supply vessel, e.g. bottle-emptying apparatus

|  | G01F 11/28 |
· | with stationary measuring chambers having constant volume during measurement (with measuring chambers which expand or contract during measurement Fulltext... Hierarchy... Expanded...G01F 11/02)

|  | G01F 11/30 |
· · | with supply and discharge valves of the lift or plug-lift type

|  | G01F 11/32 |
· · · | for liquid or semiliquid

|  | G01F 11/34 |
· · · | for fluent solid material

|  | G01F 11/36 |
· · | with supply or discharge valves of the rectilinearly-moved slide type

|  | G01F 11/38 |
· · · | for liquid or semiliquid

|  | G01F 11/40 |
· · · | for fluent or solid material

|  | G01F 11/42 |
· · | with supply or discharge valves of the rotary or oscillatory type

|  | G01F 11/44 |
· · · | for liquid or semiliquid

|  | G01F 11/46 |
· · · | for fluent solid material

|  | G01F 13/00 |
Apparatus for measuring by volume and delivering fluids or fluent solid materials, not provided for in the preceding groups

|  | G01F 15/00 |
Details of, or accessories for, apparatus of the preceding groups insofar as such details or appliances are not adapted to particular types of such apparatus

|  | G01F 15/02 |
· | Compensating or correcting for variations in pressure, density, or temperature

|  | G01F 15/04 |
· · | of gases to be measured

|  | G01F 15/06 |
· | Indicating or recording devices, e.g. for remote indication

|  | G01F 15/07 |
· | Integration to give total flow, e.g. using mechanically-operated integrating mechanism [2]

|  | G01F 15/075 |
· · | using electrically-operated integrating means [2]

|  | G01F 15/08 |
· | Air or gas separators in combination with liquid meters; Liquid separators in combination with gas-meters

|  | G01F 15/10 |
· | Preventing damage by freezing or excess pressure or insufficient pressure

|  | G01F 15/12 |
· | Cleaning arrangements; Filters (filters in general Fulltext... Hierarchy... Expanded...B01D)

|  | G01F 15/14 |
· | Casings, e.g. of special material

|  | G01F 15/16 |
· | Diaphragms; Bellows; Mountings therefor

|  | G01F 15/18 |
· | Supports or connecting means for meters

|  | G01F 17/00 - G01F 22/00 |
Measuring volume

|  | G01F 17/00 |
Methods or apparatus for determining the capacity of containers or cavities, or the volume of solid bodies (measuring linear dimensions to determine volume Fulltext... Hierarchy... Expanded...G01B)

|  | G01F 19/00 |
Calibrated capacity measures for fluids or fluent solid material, e.g. measuring cups

|  | G01F 22/00 |
Methods or apparatus for measuring volume of fluids or fluent solid material, not otherwise provided for [5]

|  | G01F 22/02 |
· | involving measurement of pressure [5]

|  | G01F 23/00 |
Level indicators

|  | G01F 23/00 |
Indicating or measuring liquid level, or level of fluent solid material, e.g. indicating in terms of volume, indicating by means of an alarm (in wells Fulltext... Hierarchy... Expanded...E21B 47/04; adaptation to, or mounting on, steam boilers Fulltext... Hierarchy... Expanded...F22B 37/78; level regulation Fulltext... Hierarchy... Expanded...G05D; alarm devices Fulltext... Hierarchy... Expanded...G08B)

|  | G01F 23/02 |
· | by gauge glasses or other apparatus involving a window or transparent tube for directly observing the level to be measured or the level of a liquid column in free communication with the main body of the liquid

|  | G01F 23/04 |
· | by dip members, e.g. dip-sticks

|  | G01F 23/14 |
· | by measurement of pressure (measuring pressure in general Fulltext... Hierarchy... Expanded...G01L)

|  | G01F 23/16 |
· · | Indicating, recording, or alarm devices being actuated by mechanical or fluid means, e.g. using gas, mercury, or a diaphragm as transmitting element, or by a column of liquid

|  | G01F 23/18 |
· · | Indicating, recording, or alarm devices actuated electrically

|  | G01F 23/20 |
· | by measurement of weight, e.g. to determine the level of stored liquefied gas (weighing in general Fulltext... Hierarchy... Expanded...G01G)

|  | G01F 23/22 |
· | by measurement of physical variables, other than linear dimensions, pressure, or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water (involving the use of floats Fulltext... Hierarchy... Expanded...G01F 23/30)

|  | G01F 23/24 |
· · | by measuring variations of resistance of resistors due to contact with conductor fluid

|  | G01F 23/26 |
· · | by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields

|  | G01F 23/28 |
· · | by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material [6]

|  | G01F 23/284 |
· · · | Electromagnetic waves [6]

|  | G01F 23/288 |
· · · · | X-rays; Gamma rays [6]

|  | G01F 23/292 |
· · · · | Light [6]

|  | G01F 23/296 |
· · · | Acoustic waves [6]

|  | G01F 23/30 |
· | by floats (switches operated by floats Fulltext... Hierarchy... Expanded...H01H 35/18) [4]

|  | G01F 23/32 |
· · | using rotatable arms or other pivotable transmission elements [4]

|  | G01F 23/34 |
· · · | using mechanically actuated indicating means [4]

|  | G01F 23/36 |
· · · | using electrically actuated indicating means [4]

|  | G01F 23/38 |
· · · | using magnetically actuated indicating means [4]

|  | G01F 23/40 |
· · | using bands or wires as transmission elements [4]

|  | G01F 23/42 |
· · · | using mechanically actuated indicating means [4]

|  | G01F 23/44 |
· · · | using electrically actuated indicating means [4]

|  | G01F 23/46 |
· · · | using magnetically actuated indicating means [4]

|  | G01F 23/48 |
· · | using twisted spindles as transmission elements [4]

|  | G01F 23/50 |
· · · | using mechanically actuated indicating means [4]

|  | G01F 23/52 |
· · · | using electrically actuated indicating means [4]

|  | G01F 23/54 |
· · · | using magnetically actuated indicating means [4]

|  | G01F 23/56 |
· · | using elements rigidly fixed to, and rectilinearly moving with, the floats as transmission elements [4]

|  | G01F 23/58 |
· · · | using mechanically actuated indicating means [4]

|  | G01F 23/60 |
· · · | using electrically actuated indicating means [4]

|  | G01F 23/62 |
· · · | using magnetically actuated indicating means [4]

|  | G01F 23/64 |
· · | of the free float type [4]

|  | G01F 23/66 |
· · · | using mechanically actuated indicating means [4]

|  | G01F 23/68 |
· · · | using electrically actuated indicating means [4]

|  | G01F 23/70 |
· · · · | for sensing changes in level only at discrete points [4]

|  | G01F 23/72 |
· · · | using magnetically actuated indicating means [4]

|  | G01F 23/74 |
· · · · | for sensing changes in level only at discrete points [4]

|  | G01F 23/76 |
· · | characterised by the construction of the float [4]

|  | G01F 25/00 |
Testing or calibrating of apparatus for measuring volume, volume flow, or liquid level, or for metering by volume