WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
90.23 - Instruments, apparatus and models, designed for demonstrational purposes (for example, in education or exhibitions), unsuitable for other uses. This heading covers a wide range of instruments, apparatus and models designed for demonstrational purposes (e.g., in schools, lecture rooms, exhibitions) and unsuitable for other uses. Subject to this proviso, the heading includes : (1) Special demonstrational machines or a pliances such as the Wimshurst experiments with electricity), the Atwoo$ machine (for demonstrating the law of Mapdeburg hemispheres (for demonstrating the effects of atmospheric the s Gravesande ring (for demonstrating thermal expansion), Newton's demonstrating the coIour composition of wh~telight). (2) Models of human or animal anatomies (whether or not articulated or fitted with electric lighting ; models of stereometric bodies, of crystals, etc. Models of this kind are usually made o plastics or of compositions based on plaster. I (3) Trainin dummies, constituting an inflatable life-size model of the human body with artificia respiratory arts r roducing those of a human being; used for training in the " kiss-of-life " revivarmetho (4) '% Cross-sectional models of shi s, locomotives, engines, etc., cut to show their internal an important part; panels showing, in relief, for example, operation or the functioning o! the assembly of a radio for radiotelegraphists schools), or the oil circulation in an engne, etc., whether or not fitte with an electric lighting system. (5) Show-cases and exhibit panels, etc., displaying samples of raw materials (textile fibres, woods, etc.), or showing the various stages of manufacture or processing of a product (for instruction m technical schools). (6) Models, etc., for artillery training, used in training courses held indoors. (7) Prepared slides for microscopic study. (8) Models of towns, public monuments, houses, etc. (of plaster, paperboard, wood, etc.). (9) Small scale demonstrational models (of aircraft, ships, machines, etc. generally of metal or wood (e.g., for advertising purposes, etc.). It should, however, e noted that models suitable solely for ornamental purposes are classified in their respective headings. (10) Relief maps (of provinces, towns, mountain ranges, etc.), relief plans of towns, and terrestrial or celestial globes in relief, whether or not printed. (1 1) Military tank simulators which are used for the training (including advanced training) of tank hvers. These consist essentially of the following components : - a driving cabin mounted on a movable platform, - a viewing system consisting of a scale model of terrain and a television camera mounted on a travelling gantry, - an instructor's console, - a computer unit, - a hydraulic power unit, and - an electrical supply cabinet. PARTS AND ACCESSORIES Subject to the provisions of Notes 1 and 2 to this Cha ter (see the General Ex lanatory Note), parts and accessories of apparatus or appliances of this Fieading remain classifie here. B The heading also excludes : (a) Printed plans, diagrams, illustrations, etc., even if designed for use in teaching, advertising, etc. (Chapter 49). (b) Ground flying trainers, of heading 88.05. (c) Articles designed for both recreational and demonstrational purposes (e.g., certain model sets of mechanical parts; mechanical or electrical toy locomotives, boilers, cranes, aircraft, etc.) (Chapter 95). (d) Automata, etc., of heading 96.18. (e) Collectors' pieces of heading 97.05. ( Antiques (e.g., relief plans and globes) of an age exceeding 100 years (heading 97.06). 90.24- Machines and appliances for testing the hardness, strength, compressibiii elasticity or other mechanical properbes of materials (for example, metals, woo textiles, paper, plastics). 9024.10 - Machines and appliances for testing metals - Other machines and appliances 9024.90 - Parts and accessories 9024.80 This heading covers a wide range of machines and appliances for testing the hardness, elastic1 , tensile strength, corn ressibility or mechanical properties of various materials (e. ., met s, wood, concrete, texh e yams and fabrics, paper or paperboard, rubber, plastics, Lather). It therefore excludes : S (a) Instruments or appIiances for examining the microscopic structure of materials (e.g., metalIographic or other microsco es - heading 90.11 or 90.12), or for analysing materials, or measuring properties such as porosity, & m a 1 expansion, etc. (heading 90.27). (b) Instruments or a paratus designed only for ordinary measurement or checking of width, thickness, etc. (e.g., of macIl ned parts, wire, metal goods) (heading 90.17 or 90.31). (c) Instruments for (heading 90.31). detecting faults, fissures, cracks or other defects in materials The machines and appliances of this heading are generally used in industrial or research laboratories for testing manufactured articles (usually carefully selected or standard specimens). They may also be used durin manufacturing processes, in constructional work (in workshops, building sites, etc.) or to chec!i goods on delivery in warehouses, etc. They may range fkom large mechanically, electrically or hydraulically operated machines of considerable weight (several tons) to small portable or even pocket size instruments. Some "universal " types (e.g., for metal testing) can be used for hardness, tensile, bendine, etc., tests by means of separate attachments. Although they usually operate on the " start-stop ' principle, some are designed for automatic or semi-automatic operation, (e.g., for testing Iarge output off an assembly line). Test results may be ascertained either by direct reading (sometimes with the aid of a simple optical device such as a magnifying glass, or even a built-in microscope or profile projector), or by se arate microscopic examination of the test-piece (e.g., observation of ball-test marks on metalr. In addition, certain machines may have provision for recording the stresse~strains, etc., borne by the test-piece. (I) MACHINES AND APPLIANCES FOR TESTING METALS This group covers machines and appliances for : (A) Tensile testin on test- ieces, bars, wire, cables, springs, etc. Tensile tests are used to ascertain the e asticity, Leaking stress and many other important pro erties of a metal. Tensile testin machines are of various types (e.g., vertical or horizonta!, endless screw or hydraulic loa types); basically, however, they each comprise jaws or clamps for holding the sample under test. 'i f (B) Hardness tests on test-pieces, bars, machined parts, etc., the hardness of a metal being measured in terms of resistance of that metal to indentation. These tests include : (1) The steel ball indentation test (hardened steel or metallic carbide The indentation is.produced b applying a continuous pressure repeated blows) to the steel ba 1, by means of a lever, spring or the imprint is then measured with a microscope. r (2) The diamond by the Vickers method forms of these tests are instruments for method). The above (3) The rebound test carried out by the aid of scleroscopes or sclerographs. A small hammer (usually ti ped with a diamond pyramid) is released from a pre-determined height on to the s ace of the piece under test. The harder the metal, the higher will be the rebound of the hammer. d (4) The pendulum hardness test in which the oscillations of a pendulum resting on the s ec~menare observed. The pendulum consists of an inverted U-shaped cast iron body $ad in the middle with a steel ball. (C) Bending tests. (1) Impact tests carried out on bars (whether or not notched). The bar rests on two supports and is subjected to the repeated impacts of a ram until it breaks; its limiting resistance is thus determined. (2) Pressure tests (mainly for bars), bending tests (springs). (D) Ductili tests mainly used to test sheet metal. An indentin tool, usually tip ed with a steel ba 1, is gradually pressed into the sheet up to the point o perforation; the lrst contact is recorded, and the stress and deflection are then measured. 'r f ? (E) Folding tests (sheets, bars and wire), compression tests and shearing tests (mainly for cast iron). (P) Fati ue tests. Test-pieces are not only submitted to sim le stresses, as described above, but 1% are a so subjected to com ound and varying stresses. ese tests are carried out by means of rotating bending mac ines (the s ecimens rotate at hi speed), or reversal torsional machines (in which the torsional grection is alternate y reversed), electro-magnetic fatigue-teshng machines, etc. i k" (11) MACHINES AND APPLIANCES FOR TESTING TEXTILES The main tests carried out by machines of this group include : (1) Extensibility and resistance to rupture tests, elasticity or tensile strength under strain tests, and the like (and combinahons of such tests . The material under test may be raw fibres or yarns, ropes or cables, ordinary fabrics, web ing, belts, etc. b These tests are made with the aid of dynamometers of various types, usually named after their operating principle (e.g., pendulum or balance-lever, dynamometers) or according to the material for which they are most frequently used (e.g., single yarn, twisted am or rope, glass fibre, hank or skein, fabric, dynamometers); these tests may also be mac er by the use of extensometers. Some dynamometers are equipped with a ball device for perforation tests on fabrics. (2) Tests to detect changes in the dimensions of textile sam Ies. The expansion or shrinkage of a sample of fabric is measured after it has been stretche in the dry and in the wet states. f (3) Wear and tear tests. These are carried out on textile goods liable to be exposed to fiiction (sheets, cloths, table linen, etc.) and sometimes also on the yarn itself. These tests are carried out by means of abrasion-testers, wear-testers, etc. A strip of cloth stretched at a suitable tension is progressively worn away by a fiiction instrument (an abrasive disc, a rotating cylinder fitted with metal flanges, a steel millin wheel, etc.). Wear and tear resistance is measured by the number of revolutions required or the friction instrument to cause the fabric to break. The heading does not include instruments used to inspect textile materials (e.g., yarn uniformit testers; etc.; strain-testers to determine the tension to which yarn a subjected on warping-frames, on sPoo~rss, yam torsion counters and torsiographs to measure the torsion of yarns (heading 90.31). (119 MACHINES AND APPLIANCES FOR TESTING PAPER, PAPERBOARD, LINOLEUM, FLEXIBLE PLASTICS OR FLEXIBLE RUBBER These tests are mainly concerned with tensile strength (measuring of extensibility, break-load, etc.) or resistance to erforation. They are effected by means of dynamometers similar in basic design to those used or textiles. ! This group includes bursting strength testers, fold testers, etc. (e.g., for paper), elasticity meters, reboundimeters, tensile testers, abrasion machines, plastimeters (e.g., for rubber or plastics). (IV) MACHINES AND APPLIANCES FOR TESTING OTHER MATERIALS Most of these materials (e.g., wood, concrete, hard plastics) are sub'ected to tensile, bending, hardness, compression, shearin , abrasion, etc., tests, by means o machines and apparatus similar in principle to those use for metal testing (by ball-imprint, impact, etc.). d t The headin also includes a large number of instruments, usually small in size, designed to determine t e tensile strength, resistance to bending, compression, etc., of test-pieces moulded moulding sand. It also covers instruments designed for rneasutlng the surface hardness "Om of inished foundry moulds or mould cores. f """r PARTS AND ACCESSORIES a Subject to the provisions of Notes 1 and 2 to this Cha ter (see the General Ex lanatory Note), parts and accessories of apparatus or appliances of this eading remain classifie here. E 90.25- Hydrometers and similar floating instruments, thermometers, pyrometers, barometers, hygrometers and psychrometers, recording or not, and any combination of these instruments. - Thermometers and pyrometers, not combined with other instruments : 9025.1 1 - - Liquid-filled, for direct reading - - Other 9025.80 - Other instruments 9025.90 - Parts and accessories 9025.19 (A) HYDROMETERS AND SIMILAR FLOATING INSTRUMENTS These instruments are used for determining, generally by direct readin on a graduated stem, the specific gravity of solids or li uids, or some arbitrary value relatefto s ecific gravity (e.g., strength of spirituous liquors). ?he reading is sometimes converted by a tab e into other units. f A The instruments are usual1 made of glass though some may be of metal, e.g., nickel-silver, , and weighte at one end wi mercury or fine lead shot. These weights are etc.)ixed, but instruments for ascertainin the density of liquids of different specific generally gravities are sometimes designed so that the weiats can be varied or additional weights added. Some hydrometers (e.g., those used to determine the strength of the acid in accumulators) are enclosed in a glass synnge. Other types are combined with a thermometer. 2' Most of these instruments are known according to the use for which they are designed, for example, alcoholometers; saccharometers (used in brewin or in su ar manufacture); salinometers; lactodensimeters or lactometers; acidimeters (for etermining fie specific gravity of accumulator or other acid); urinometers; etc. Others are named after the inventor (e.g., B a u k , Brix, Balling, Bates, Gay-Lussac, Richter, Tralle, Sikes, Stoppani, etc.). Nicholson's hydrometer is used for solids. The heading does not cover (a) Instruments which determine s ecific avity by other methods, for example, pyknometers (specific gravity bottles) (beading 7 0 . 1 6 spec& gravity or hydrostatic balances (besdmg 90.16). (b) Certain analysis apparatus which are not floating instruments, for example, butyrometers (for determining the fatty content of butter), ureometers (for testing urea content); these are classified in heading 70.17. (B) THERMOMETERS, THERMOGRAPHS AND PYROMETERS This group includes : (1) Glass thermometers, with a liquid-filled glass tube. These include household thermometers (room, window thermometers, etc.), floating thermometers (bath thermometers, etc.), clinical thermometers, industrial thermometers (for boilers, furnaces, autoclaves, etc.), laboratory thermometers (used in calorimetry, etc.), special meteorological thennometers (e.g., for measuring solar or terrestrial radiabons), thermometers used in hydrography (e.g., reversible thermometers used in taking deep-sea soundings). The heading also includes glass thermometers called minimum and maximum thermometers since they are designed to indicate the highest and lowest temperature they have recorded. (2) Metallic thermometers (in particular bi-metallic thermometers which make use of the different coefficients of expansion of two metal strips welded together). They are mainly used in meteorology, for air conditioning and for other scientific or industrial purposes; thermometers for use with motor vehicles, to indicate the temperature of the radiator water, are usually of this type. (3) Expansion or ressure thermometers with metallic systems. In these thermometers the ex ansible me lum (liquids, vapours, gases) develops a pressure and actuates a Bourdon tu e or similar pressure measurrng device, which then operates a pointer over an indicator dial. Most of these thermometers are used for industrial purposes. t t (4) Liquid crystal thermometers. These contain liquid crystals which change their physical properties (e-g., colour) according to variations in temperature. (5) Electrical thermometers and pyrometers, such as : (i) Resistance thermometers and pyrometers operating by changes in the electrical resistance of a metal (e.g., platinum) or of a semconductor. (ii) Thermocouple thermometers and pyrometers based on the princi le that the heating of the junchon of two different electric conductors generates an e ectro-motive force proportional to the tern erature. The combinations of metals used are generally : plat~numwith rhodium-p atinum; copper with copper-nickel; iron with copper-nickel; nickel-chromium with nickel-aluminium. I' s (iii) Radiation (including optical) pyrometers. These are of various types, e.g. : (a) Pyrometers in which a concave mirror concentrates the radiations from an incandescent body, e.g., onto the hot junction of a thermocouple placed at the focal point of the mirror. (6) Disappearin filament yrometers. In these the temperature is measured by varying the !I rightness o a filament of an incandescent lam , by means of a rheostat device, until it coincides with that of the image o the source to be controlled. f! P Electrical thermometers and pyrometers are sometimes combined with automatic regulating devices which control the operation of the furnace, oven, fermentation vats, etc. Such combinations are classified in heading 90.32. (6) Optical, photometric cube e pyrometers. A prism provides a field of view in which the centre section is illuminate by a standard incandescent lamp and the surrounding field is illuminated by light from the hot body. A circular glass disc, coated with an emulsion of varying density, is rotated so as to vary the intens~tyof li t from the hot body. The number of degrees of rotation of the disc necessary to match e brightness in the inner and outer parts of the field is a measure of the temperature. ?!' (7) Optical, disappearing filament e pyrometers. The intensity of the image reflected from the furnace is equalised wi that of the standard lam b int osing a series of smoked glasses, or by the rotation of a graduated wedge of al?soriing3ss corresponding to given temperatures. p (8) Pyrometric telescopes based on rotatory polarisation. These consist of two Nicol prisms between which is placed a calibrated quartz crystal; the temperature may be calculated from the angle through which one of the Nicol prisms must be turned to obtain a particular colouring. (9) p~rometers based on contraction of a solid substance clay, for instance). These consist o an oscillating lever, one arm of which moves before a 'al, the other connecting with the rod which serves to estimate the temperature. 6, The heading also includes '' contact" thermometers which indicate temperature but also incorporate an auxiliary device which can operate an electric signal light, alarm, relay or switch. It further includes metallic or vapour pressure thermometers, sometimes called " pyrometers ", which enable maximum temperatures of up to 500 to 600 OC to be measured. Thermographs also fall in this heading. They consist of a thermometer combined with an indicator re stering the variations in temperature on a W,they are operated by a mechanical or electric c ock movement, or a synchronous motor. P The heading excludes " pyroscopes ",calliper-type instruments used for measuring the contraction of a clay, etc., test- iece taken from a ceramic furnace during firing to determine the course of the firing (heading 90.1for 9031). (C) BAROMETERS AND BAROGRAPHS These are instruments for deterrninin the atmospheric pressure; similar instruments (pressure gauges) for measuring the pressure ofKiquids or gases are excluded (heading 90.26). There are two types of barometer in general use, the mercury barometer and the aneroid barometer. The ordinary mercury-barometer consists of a end. In one type the lower end stands in a cistern of end of the tube is bent into a siphon, the atmospheric ressure of the tube. In both cases, the mercury column in t e tube atmosphere, and its rise or fall (indicated on a scale or on a the atmos heric pressure. Mercury barometers include the ,e!t siphon barometer (with adjustable scale), the R In the aneroid barometer the atmos heric pressure acts on one or more exhausted, corrugated metal capsules, or on a thin-walled, ent metal tube. The deformation of the capsules or of the tube is amplified and transmitted to a pointer indicating the atmospheric pressure on a scale or is converted Into an electrical signal. !i This heading also includes : (1) Barometric altimeters which indicate not only atmos heric pressure but also altitude; it should, however, be noted that the heading exclu es altimeters (especially for air navigation) which indicate altitude only (heading 90.14). (2) Sympiesometers. In these the mercury is replaced by a liquid such as oil which compresses a gas contained in the tube. Barographs are instruments for recording atmospheric pressure in a manner similar to that in which the thermographs record temperature (see Part (B) above). (D) HYGROMETERS AND HYGROGRAPHS These are used to determine the moisture content of the air ox other gases. The main types are : (1) Chemical hy rometers, based on absorption of moisture by chemical substances which are then weigfed. (2) Condensation or dewpoint hygrometers, using the " dewpoint " method (i.e., the temperature at which water vapour begins to condense). (3) Hair hygrometers, based on the change in length of one or more hairs or strips of plastics, accordmg to whether they are dry or humid. The hairs or stri s of lastics are strung over a frame, weighted with a countenvei t, and mounted on a pu ley e axle of which IS fitted with a needle moving across a di In some devices the movement is converted into an electrical signal. P 1R (4) Hygrometers consisting of a torus-shaped glass tube partly filled with mercury, and closed at one end by a diaphragm semi-pervious to the water va our in the atmosphere. The pressure of the water vapour acts on the mercury and thus disp aces the tube round a shaft connected to a needle on the dial. In some devices the displacement of the tube is converted into an electrical signal. (5) Hygrometers with metallic strips wound helicoidal1 and coated with a substance which reacts to humidity. The hygrosco ic reaction varies &e length of the metallic stri s. This movement is transmitted to an ax e fixed to the end of the metallic strips and fitte with a needle moving across a dial. In some devices the movement is converted into an electrical signal. g f' gmg., (6) Electrical hygrometers. The operation of electrical hy ometers is normally based on the variation of conductivity of s ecial absorbent salts lithium chloride) or on the variation of the capacity of an e ectrical element in relation to humidity. (These instruments are sometimes graduated to show the dewpoint of the element to be measured.) P Fancy h groscopes consisting essentially of more or less decorative objects (chalets, towers, etc.) fi ines coming in or going out, according to whether the weather is likely to be good or also classified here. On the other hand, papers impregnated with chemical substances, the colour of which varies according to the moisture content of the atmosphere are excluded (heading 38.22). wdbate Hygrographs, which also fall in this heading, are similar to hair hygrometers but record vanations of relative humidity in a manner similar to that in which thermographs record temperature (see Part: (B) above). This heading does not cover instruments which determine the moisture content of solid matter (heading 90.27). (E)PSYCHROMETERS These are a special type of hygrometer. They determine the humidity content by reference to the difference in the temperatures indicated by (a) a dry thermometer which registers air temperature, and (b) a wet thermometer whose bulb is kept continually moist by a material impregnated with water which absorbs heat on evaporation. Electrical psychrometers usually employ resistance thermometers or semiconductors in place of the non-electric thermometers of the normal psychrometer. Hygrometers and psychrometers are employed for a wide variety of purposes, e.g., in meteorology (in observatories, in the home, etc.), in laboratories, in refrigerating plants, in artificial incubation, in air conditioning (especially in textile mills). COMBINATIONS OF INSTRUMENTS This heading also includes combinations of the instruments referred to above (e.g., combinations of hydrometers, thermometers, barometers, hy ometers, psychrometers), except combination the character of when the addition of one or more other devices equipment or appliances covered by more speci ic headinf:s heading 90.15 as meteorological instruments). In particular, the following remain c ass1 ~e '!m this heading : ? & F.i (1) Thermo-hygro ra hs and baro-thermo-hygrogra hs; actinometers (instruments consisting simp y o two special thermometers combine ). f ! (2) Pagoscopes, i.e., instruments giving warning of frost, and therefore used especially in horticulture. These also consist essentially of a combination of two thermometers. On the other hand, the heading excludes radio-sondes for atmospheric soundings (see Explanatory Note to heading 90.15). PARTS AND ACCESSORIES Subject to the provisions of Notes 1 and 2 to this Chapter (see the General Explanatory Note), separate1 presented arts and accessories of apparatus or appliances of this heading rernaln classifk here (eg., Jals, pointers, cases, graduated scales). B
1.- This Chapter does not cover : (a) Articles of a kind used in machines, appliances or for other technical uses, of vulcanised rubber other than hard rubber (heading 40.16), of leather or of composition leather (heading 42.05) or of textile material (heading 59.11); (b) Supporting belts or other support articles of textile material, whose intended effect on the organ to be supported or held derives solely from their elasticity (for example, maternity belts, thoracic support bandages, abdominal support bandages, supports for joints or muscles) (Section XI); (c) Refractory goods of heading 69.03; ceramic wares for laboratory, chemical or other technical uses, of heading 69.09; (d) Glass mirrors, not optically worked, of heading 70.09, or mirrors of base metal or of precious metal, not being optical elements (heading 83.06 or Chapter 71); (e) Goods of heading 70.07, 70.08, 70.11, 70.14, 70.15 or 70.17; (f) Parts of general use, as defined in Note 2 to Section XV, of base metal (Section XV) or similar goods of plastics (Chapter 39); however, articles specially designed for use exclusively in implants in medical, surgical, dental or veterinary sciences are to be classified in heading 90.21; (g) Pumps incorporating measuring devices, of heading 84.13; weight-operated counting or checking machinery, or separately presented weights for balances (heading 84.23); lifting or handling machinery (headings 84.25 to 84.28); paper or paperboard cutting machines of all kinds (heading 84.41); fittings for adjusting work or tools on machine-tools or water-jet cutting machines, of heading 84.66, including fittings with optical devices for reading the scale (for example, “optical” dividing heads) but not those which are in themselves essentially optical instruments (for example, alignment telescopes); calculating machines (heading 84.70); valves or other appliances of heading 84.81; machines and apparatus (including apparatus for the projection or drawing of circuit patterns on sensitised semiconductor materials) of heading 84.86; (h) Searchlights or spotlights of a kind used for cycles or motor vehicles (heading 85.12); portable electric lamps of heading 85.13; cinematographic sound recording, reproducing or re-recording apparatus (heading 85.19); sound-heads (heading 85.22); television cameras, digital cameras and video camera recorders (heading 85.25); radar apparatus, radio navigational aid apparatus or radio remote control apparatus (heading 85.26); connectors for optical fibres, optical fibre bundles or cables (heading 85.36); numerical control apparatus of heading 85.37; sealed beam lamp units of heading 85.39; optical fibre cables of heading 85.44; (ij) Searchlights or spotlights of heading 94.05; (k) Articles of Chapter 95; (l) Monopods, bipods, tripods and similar articles, of heading 96.20; (m) Capacity measures, which are to be classified according to their constituent material; or (n) Spools, reels or similar supports (which are to be classified according to their constituent material, for example, in heading 39.23 or Section XV).