Other

90.29 - Revolution counters, production counters, taximeters, mileometers, pedometers and the like; speed indicators and tachometers, other than those of heading 90.14 or 90.15; stroboscopes. 9029.10 -Revolution counters, production counters, taximeters, mileometers, pedometers and the like 9029.20 9029.90 - Speed indicators and tachometers; stroboscopes - Parts and accessories This heading includes : (A) Counters indicating a total number of units of an kind revolutions, items, length, etc.), or an amount to be paid. But the heading exclu es tot ling devices of a kind falling in heading 84.73, the gas, liquid or electricity supply or roduction meters of heading 90.28, and opisometers or planimeters of heading 90.17 or 9d131. J h (B) Apparatus indicating a speed of revolution or a linear speed in relation to a time factor (tachometers and speed indicators), other than those of heading 90.14 or 90.15. (C) Stroboscopes of all kinds. Such apparatus and instruments remain classified here whether or not they incorporate a clockwork recording device, and whether or not they are fitted with simple mechanical or electric devices for bringing a signalling apparatus, machine controls, brakes, etc., into action. (A) COUNTING DEVICES (1) Revolution counters. These instruments count the number of revolutions of a mechanical part (e.g., machine shaft . They consist mainly of a driving spindle geared to pointer or drum indicators. They usua ly have a device for re-setting the counter to zero. The counters may be coupled to the revolving part either directly (in some cases the part drives the gearing itself) or by remote control. The driving spindle may be operated by a rotary, alternating or pulsating movement of the turning part (e.g., encoders). ? It should, however, be noted that the heading excludes yam grading windin reels, torsiometers and similar testing or checking apparatus incorporating revolution counters (bea&ng 90.31). (2) Production counters. These are similar in construction to revolution counters. They are used, in particular, for measuring lengths (e.g., on twisting machines); for counting the movements of a machine (an the picks of a spinning machine, etc.); or for counting a number of delivered by a rotary ress, articles carried by a conveyor belt, bank notes, etc.). In practice, liances use for these purposes are generally revolution counters whch have been to indicate the length or number of units in terms of the revolutions of the driving !i' Electronic production counters. The articles to be counted interrupt a beam falling on a photoelectnc cell. A recording apparatus then computes the number of articles which have passed through the beam. This group also covers multiple counters (e.g., those used to check the output of several operators working on the same machine). This group also includes the electro-magnetic counters used in automatic telephone exchanges to count the number of telephone calls made by a subscriber; they usually incorporate an electro-magnet which moves the recording mechanism (cyclometer-type rollers, etc.) one position each time a pulse of electric current is passed through its windmg. (3) Counters for indicating the working hours of machines, motors, etc., (time or hour meters). In practice, these are revolution counters calibrated in working hours. (4) Entry counters. These counters are operated by turnstiles or other appliances laced at the entrances of museums, parks, sports grounds, etc., where they record t e number of visitors or spectators. R (5) Billiards meters. These are mechanical counters (roller-type and the like), usually hand-operated, for recording the score. The heading excludes meters which employ a clock movement to indicate the time in play or the amount payable based on that time (heading 91.06). Billiard markers, ball or slide type, fall in heading 95.04. (6) Instruments and apparatus for measurin short time intervals by counting, and which, not having a movement of the watch or cloc type (including spchronous movements), do not fall in Chapter 91. The heading also covers electronic lmpulse counters (scalers) (e.g., passenger counters on motor coaches, trains, etc.). % (7) Taximeters. These usually have a clock movement. They indicate the fare payable in relation to time and to the distance covered. (8) Mileometers. These are revolution counters for vehicles, and are usually aduated in linear units (miles, kilometres, etc.). ~ o smileometers t are combined with spee indicators. (9) Pedometers. These instruments have a watch type mechanism and are used for an approximate measurement of distances. They contan a pendulum which, at each step, advances the train of wheels by one unit. The distance covered is calculated from the number of steps taken and their length. (10) Hand-held counters. These counters usually read no more than four numbers in fixed categories. The user depresses a button in the category being counted to activate the display. (B) SPEED INDICATORS AND TACHOMETERS These instruments differ from the revolution counters and production counters of Part (A) above in that they indicate the number of revolutions, speed, output, etc., per unit of time (e.g., revolutions per minute, miles per hour, kilometres per hour, metres per minute). The are usually mounted on vehicles (cars, motorcycles, b e cles, locomotives, etc.) or m a c L s (motors, turbines, paper-making machines, printing mac&nery, textile machinery, etc.). The speed indicators and tachometers classified here normally function on one of the following principles : (1) Chronometric system. The measuring mechanism is combined with a clock or watch movement. Sometimes the time is measured by means of a separate chronograph; in this case, the two instruments are classified in their appropriate headmgs. (2) Centrifugal system. A vertical governor arm, held by a spring, rotates with the driving spindle. A air of weights carried by the governor arm are thrown outwards by centrifu a1 force, so t at the distance the governor arm is displaced is proportional to the speed. flus displacement is transmitted to the instrument pointer. R (3) Vibration system. This type is used for high s eed machines such as steam turbines, pumps, compressors, electric motors, etc. The mec anical resonance of vibrations of the frame or bearings of the machine cause graduated reeds to oscillate at a rate corresponding to the number of revolutions of the machine. ! (4) Magnetic (induction) system. A system of permanent mapets rotatin with the driving s indle generates eddy-currents in a disc of copper or aluminium place in the ma etic fie d. This current is proportional to the rotating s eed of the magnets. The disc is &s '' dragged " or pulled round, but its rotation is retar ed by a restraimng spring. The disc is connected to a pointer indicating the speed. B d P (5) Electrical systems. These are either fitted with a photoelectric cell or operated by an impulse generator mounted on the machine. Speed indicators and tachometers of this heading may be fixed or portable, sim le or multi-function (e.g., maximum or minimum), differential (in which case they give the dif erence between two speeds as a percentage), combined with an adding counter or a time meter or graphical recordng device, etc. The heading also covers certain instruments which s~multaneouslyrecord speed, mileage, time in motlon and at a standstill, etc, !' (C) STROBOSCOPES Stroboscopes enable machines in o eration to be observed as though they were moving slowly or were stationary; they can also l e used to measure the speed of rotating or reciprocating movements. In the latter case, they are known more particularly as strobosco ic tachometers. Stroboscopes o erate on the rinciple of roducing apparent immobility or re uced speed in the mechanism to e observed, y means o successive glimpses (flashes) at fixed intervals. The mechanism under observation may be permanently illuminated for examination through an o tical instrument (a disc with one or more radial slots or " windows ") which interrupts the line o sight; or the mechanism may be placed in the dark and illuminated periodically for very short eriods (flashes). The speed of the rotating or reciprocating mechanism under observation can ge ascertained by adapting the speed of the disc or the frequency of the flashes until the impression of immobility is obtained. E B P g P Stroboscopes based on the principle of permanent illumination consist essentially of a clockwork driven with one or more windows, a speed regulator, an eyepiece and a graduated drum (usually graduated in revolutions per. minute). Stroboscopes functioning on the principle of periodic illumination differ a preciably according to the devlce producing the light flashes. The most simple types consist o an ordinary lam a motor with a s eed regulator coneolling the frequency of the flashes, and a graduated dial. ?he flashes may a so be produced by a as discharge lamp. These gas discharge stroboscopes are much more complex m structure an can be used for taking photographs or making films; they are sometimes mounted on castors or rollers. The flashes re uired for the observation of a rotating or reciprocating mechanism may be controllea by the mechanism itself. S chtonisation is achieved by means of a spring-type interrupter, a photoelectric cell, an e ectro-magnetic relay, etc. P ? d r" Except when permanently incorporated in stroboscopes, the photographic or cinematographic cameras fall in their appropriate heading. Stroboscopes are used, in particular, for observing or measuring the speed of motors, transmission gear, textile machine (parts such as spindles, winders, cards, shuttles), aper-making machines, printing or machine-tools. They are also used in medicine !or examination of the vibration PARTS AND ACCESSORIES Subject to the provisions of Notes 1 and 2 to this Chapter (see the General Explanatory Note), separate1 presented parts and accessories of apparatus or appliances of this heading remain classifie here. L? 90.30- Oscilloscopes, spectrum analrsers and other instruments and apparatus for measuring or checking electrical quantities, excluding meters of heading 90.28; instruments and apparatus for measuring or detecting alpha, beta, gamma, X-ray, cosmic or other ionising radiations. 9030.10 9030.20 - Instruments and apparatus for measuring or detecting ionising radiations - Oscilloscopes and oscillographs - Other instruments and apparatus, for measuring or checking voltage, current, resistance or power : 9030.31 9030.32 9030.33 9030.39 9030.40 - - Multimeters without a recording device - - Multimeters with a recording device - - Other, without a recording device - - Other, with a recording device - Other instruments and apparatus, specially designed for telecommunications (for e.xarnple, cross-talk meters, giun measuring mstruments, distortion factor meters, psophometers) - Other instruments and apparatus : 9030.82 9030.84 9030.89 9030.90 - - For measuring or checking semiconductor wafers or devices - - Other, with a recording device - - Other - Parts and accessories (A) INSTRUMENTS AND APPARATUS FOR MEASURING OR DETECTING ALPHA, BETA, GAMMA, X-RAY, COSMIC OR OTHER IONISING RADIATIONS These instruments and apparatus are used in scientific research, for industrial purposes (metallurgy, petroleum prospectin , etc.), or for biological or medical purposes (in conjunction with radioactive tracers). They inc ude : f (1) Detection instruments incorporating ionisation chambers. A potential difference is set up between two electrodes contained in the ionisation chamber. The ions formed when a radiation enters the chamber are attracted to the electrodes, and the resulting changes in the potential difference may be amplified and measured. (2) Geiger counters. A large otential difference is maintained between the electrodes of the counter; the ions produce by an incoming radiation are eatly accelerated, and in turn ionise the gas contained in the tube. This sets up impulses w ich may be counted. ~f' f The ionisation chamber and Geiger counter apparatus of this heading normally consist of several units such as a chamber or counter, an amplifier, a voltage supply unit for the chamber or counter, and a counting circuit or indicating instrument. All these units are often incorporated in the same case. Sometimes all the units except the chamber or counter are in the same case, and a aratus of this type (which requires a chamber or counter before it is complete) remains classi ed in this heading (as an essentially complete instrument). When the indimdual units are resented se arately the are classified in accordance with the provisions of the General ~xPlanatory ote to this hapter. ?l Certain ionisation chambers which are used to measure total quantities of radiation over an appreciable time (e.g., 24 hours) do not require any auxiliary amplifiers, etc., but inco orate a very light moving pointer which can be read under a microsco e and then shows t e total amount of radiahon which has assed through the chamber. 7%ese chambers (which offen resemble fountain pens) are comp ete measuring instruments in themselves and are classified in this heading. 'R P The heading also covers scintillation counters. These consist of a device hotomultiplier) which is made up essentially of a photoelectric cell and an electron multi lier. hey operate on the principle that radiation be detected or measured by its e fect in exclting the fluorescence of certain activated sodium iodide, anthracene, The crystals are placed between the F % This group also includes : (1) Dosimeters and similar apparatus used in radiology for measuring and checking the intensity and penetrating power of X-rays. (2) Apparatus for measuring cosmic or similar radiations. (3) '' Thermopile '' neutron detectors and measuring or detecting instruments incorporatin neutron detector tubes (boron, boron trifluonde or hydrogen types, or using radioactive issionable elements). f (4) Radiation measuring or detecting instruments incorporating liquid or solid scintillators. The heading excludes : (a) Apparatus incotporatin a scintillation counter whose data are converted into analogue signals for the purpose of making me lcal diagnoses (e.g., gamma camera, scintillation scanner) (heading 90.18). f (b) Measuring or checkin ap aratus designed to incorporate a radioactive source (in particular, artificial isotopes), for enampye, For measuring thickness of materials (sheets, linings or the like), for monltonng the contents of packages, for measuring low speed air currents (ionisation anemometers), etc. (headmg 90.22). (l3) OSCILLOSCOPES, SPECTRUM ANALYSERS AND OTHER INSTRUMENTS AND APPARATUS FOR MEASURING OR CHECKING ELECTRICAL QUANTITIES Oscilloscopes and oscillographs are used respectively for observing or recordin rapid variations of an electrical quanhty (voltage, current, etc.). The instruments may be divi ed into three main categories : % (a) DuddeIl oscillographs, in which a coil, usually consistin of a loop of taut wire with mirrors attached, moves in the field of an electro-magnet. T e periodic phenomenon under study can be observed directly on a sheet of fi-osted glass, or recorded on a photographic tape. i? (b) Soft iron and raver type oscillo raphs, with a coil acting on a stri of soft iron placed in a constant fielf, A lightweight ro , pointed at one end, is fured to t e strip and traces the phenomenon (e.g., by cutting a coated cellulose acetate tape). d E (c) Cathode-ray oscillosco es and oscillographs; these operate by recording how a cathode-ray beam is L e c t e d by electrostatic or electro-ma etic forces. These instruments, which may be in one or more arts, consist essentially o the cathode-ra tube, feeding devices and transformers, a sweeping or scanning system an other auxiliary devices and, sometimes, switch. Oscilloscopes with a memory, used to examine isolated rapid transient phenomena, are e uipped with either a cathode-ray memory tube or a numeric memo associated with a ca ode-ray tube. In the first type, the image of the signal is captured an maintained on the cathode-ray tube. In the second type, the signal is recorded in the memory and can be retrieved at will to be viewed on the screen. y K ~r ll S ectrum analysers are instruments which identify the different frequency components of an e ectrical input signal. They are mainly used to analyse electrical quanbties. They can also analyse ionisin radiations, sound waves or other non-electrical quantities when used in con unction wi radiation detectors or other devices which can detect non-electrical quantities an convert them into electrical signals. P B f The heading covers transient phenomena recorders which are apparatus designed to capture a signal and to record it with a view to transmitting it later, in an appro riate form, onto a display apparatus (television monitor, for exam le). Logic analysers ", wfich are a paratus used to examine electrical circuits consisting or the most part of semiconductor evices, are also classified here. P B Instruments and apparatus for measuring or checking electrical quantities may be indicating or recording types. They may be subdivided, according to their mode of operation, into a number of groups, such as : (I) Moving-coil instruments, in which the current to be measured passes through a coil free to move in the magnetic field provided by a permanent magnet. The pointer is secured to the moving coil. (2) Movin iron instruments, in which the pointer is deflected by a solenoid acting upon. a piece o soft iron fixed to the pointer shaft. b (3) Electrodynamic instruments, in which the current to be measured asses through fixed and moving coils, the moving coils operating in the magnetic field o the fixed coils. The pointer is secured to the moving coils. F (4) Induction instruments,, consisting of a pointer shaft on which is mounted a flat disc or cylinder which operates in the air gap of an electro-magnet having one or more coils. Pa (5) Thermocouple instruments, in which the current to be measured is passed throu heater applied to the hot junction of a bi-metallic thermocouple whose electromotive orce is then measured. (6) Electronically operated instruments based on semiconductor technology with a pointer or an opto-electronicdisplay for analogue or digital readout. which the The following are, however, excluded (Chapter 85) when presented separately : transformers, standard resistors, standard capacitors, standard inductors, standard cells, etc.; also earphones (headsets) (used instead of the visual null indicator in some types of measuring bridge). The main types of electrical measurements are : (I) Measurement of electric currents. This is carried out, in particular, by means of galvanometers or amperemeters (ammeters). (11) Voltage measurement, by voltmeters, potentiometers, electrometers, etc. The electrometers used for measuring very high voltages are electrostatic; they diffe~fiom the usual type of voltmeter in that they are fitted urlth spheres or plates held on insulating pillars. (111) Measurement of resistance and conductivity, by means of ohmmeters or measuring bridges, in particular. (IV) Measurement of power by means of wattmeters. (V) Measurement of capacitance and inductance, effected by means of measuring bridges, and expressed in farads or henrys. (VI) Measurement of frequencies, by means of frequency meters graduated in hertz (cycles per second). (VH) Measurement of wavelengths or radio frequencies by wavemeters, or slotted line or slotted waveguide instruments. (VIII) Measurement of hase angles or power factors, carried out with phase meters, calibrated in power actors (cos phi). ? (IX) Measurement of the ratios of two electrical quantities by ratiorneters. asurement of magnetic fields or magnetic fluxes, effected with galvanometers or no Y!!eters. (XI) Measurement of the electrical or magnetic properties of materials, carried out with hysteresis testers, permeameters or similar instruments. (XI0 Testing of synchronism, by means of synchroscopes, instruments for indicating the phase relation and difference in fiequency between two periodic phenomena. Such instruments can be recognised by the fact that their dials bear the indications " Fast " and " Slow " (with corresponding arrows). (XUT) Measurement and recording of rapid variations of electrical quantities by means of the oscilloscopes or oscillographs described above. Some electrical measurin instruments can be used for many p oses, for example, electrical or electronic instruments fnown as " universal testers " (e.g., mu tirneters) which serve for the rapid measurement of voltages (direct or alternating), currents (direct or alternating), resistances and capacitances. "P The heading also includes a wide range of electrical or electronic instruments used in radio-communications or telecommunications. In addition to the voltmeters, potentiometers, measuring bridges, ammeters, wattmeters, phase meters and fiequency meters already mentioned, this range includes : (i) Impedance testers and brid es, for determining the impedance in a circuit, and also for measuring capacitances or in uctances. (ii) Inductance bridges and similar instruments, for measuring ring inductances on the Wheatstone bridge principle. f (iii) Nepermeters and decibel meters. These are used for measuring the attenuation over long distance telephone circuits. Instruments and apparatus for measuring quantities of sound fall in heading 90.27. (iv) Fading indicators. Unlike nepermeters (which 've measurements based on a compensatory system), these give a direct indication o the fading. (v) Cross-talk meters, used on telephone circuits for measuring various quantities. ? (vi) Transmission level indicators. (vii) Noise level meters, for use on high frequency lines. (viii) Gain measuring instruments, for measuring the gain through repeaters relaying long distance telephone circuits. (ix) Instruments for measurin interference, e.g., noise voltage in long distance telephone installations or interference om neighbouring high tension circuits. (x) Psophometers, instruments for calculating line-noise, i.e., the electromotive force of a source of current which would produce the same interference if substituted for the voltages induced in the telephone circuit. !& (xi) Peak indicators, for recording short voltage peaks such as occur in transmission systems (e.g., long distance telephone cables, radio transmission circuits, shortwave links). (xii) Echo meters, used in establishing line balance by direct readings of echo expressed in nepers or decibels. (xiii) Distortion factor meters, for measuring the harmonic distortion introduced into complex transmissions. Some of the above instruments, in particular those used for electro-acoustic measurements, are calibrated in nepers or decibels. This heading also covers other instruments and apparatus which perform operations of a kind described in the heading, includin valve testing or measuring instruments, in particular those for testing radio valves. T ese valve testing or measuring instruments are sometimes designed so as to produce the characteristic curve of the valve on the screen of an oscilloscope. f PARTS AND ACCESSORIES Subject to the provisions of Notes 1 and 2 to this Chapter (see the General Explanatory Note), resented parts and accessories of instruments or appliances of this heading remaxn classifie sepTate! ere. Examples of these are : coincidence units, elecixonic, for use with Geiger-Miiller counters or proportional counters, solid scintillators in the form of crystals or of elements of plastics, mounted or metal-sheathed, designed solely for fitting to detection instruments, neutron detector tubes using boron, boron trifluoride, hydrogen or fissionable elements.