Fibre glass filter/strainers for deep tubewell

70.19 Glass fibres (including glass wool) and articles thereof (for example, yarn, woven fabrics) (+). - Slivers, rovings, yarn and chopped strands : 7019.11 - - Chopped strands, of a length of not more than 50 mm 7019.19 - - Other - Thin sheets (voiles), webs, mats, mattresses, boards and similar nonwoven products : 7019.32 - - Mats - - Thin sheets (voiles) 7019.39 - - Other 7019.31 7019.40 70 19.51 7019.52 7019.59 7019.90 - Woven fabrics of rovings - Other woven fabrics : - - Of a width not exceeding 30 cm - - Of a width exceeding 30 cm, plain weave, weighing less than 250 g/m2, of filaments measuring per single yarn not more than 136 tex - - Other - Other This heading includes glass fibres themselves and glass fibres (including glass wool as defined in Note 4 to this Chapter) made up in various forms, including those glass fibre articles excluded from other headings by reason of their nature. Glass fibres have the following properties :the are less flexible than vegetable or animal textile fibres (glass yarns cannot be J e y do not stretch; they are strong (stronger than any of the textile fibres of Section do not burn; they do not rot and are reststant to of electricity and, in some cases, of heat or water and most acids; they are a sound; they are non-hygroscopic. Glass fibres can be obtained by various processes which, apart from a few exceptions, can be grouped in three broad categories : (I) Mechanical drawing. It flows into a forehearth, the underside of of alloys of recious metal (normally of rhodium or of T e bushings are pierced by a large number threads flow: After a sizin treatment (for example, with silicone), these threads are carried on to a high speed man il which draws them out into very fine arallel filaments. Thus a continuous strand similar to a man-made textile filament yarn is o tained. E f % Thicker fibres may be obtained by a more or less identical rocess; these are wound in the form of a web whch is used directly as such (heat- or sounfinsulation mats). (11) Centrifugal drawing. In this system, glass melted in pots falls on a refractory clay disc revolving at great speed and fitted alon the periphery with a very large number of teeth. The glass adheres to this disc, which is eated by the flame from a furnace, but, at the same tlme it is drawn into filaments by means of centrifugal force. These filaments are blown on to a stationary table and coiled on to a cooling drum. % This process thus yields short fibres known as glass wool, which is used in bulk without spimg. (III) Drawing by means of fluids. In this process, drawing is achieved by means of jets of high- ressure steam or com ressed air blown fiom either side on to the filaments of molten g ass coming fmm the L a c e through a drawing-plate. Under the action of these jets, the filaments are broken into short lengths which are coated with lubricants in the course of manufacture. P The fibres thus obtained are coiled on a drum to form either webs which are used as such (insulation blankets), or continuous slivers or rovings of fibres (similar to slivers or rovings of waste silk) which can subsequently be spun into yarn. Glass fibres and articles of glass fibres of this heading may be, in particular, in the following forms : (A) Glass wool in bulk. (B) Slivers, rovings, yarn and chopped strands. (C) Thin sheets (voiles), webs, mats, mattresses, boards and similar nonwoven products. (D) Woven fabrics, including narrow fabrics. This heading also covers curtains, draperies and other articles of woven glass fabrics. It is ointed out that although " chemical embroideries " or embroideries without visible ground, in w ich the embroiderin thread consists of glass fibres, are classified here, embroidery in any of the textiles classifie in Section XI, in which some of the effects are obtaned by embroidering threads made of glass fibres, is excluded (heading 58.10). R % f * * The uses of glass fibres are increasing steadily, for example : (1) In furnishing and interior decoration (e.g., for upholstery, wall hangings, curtains, mosquito-nets), in the form of fabrics, which can be dyed or printed. (2) For heat-insulation p oses (e.g., for insulating roofs, chimneys, boilers, furnaces, steam piping, steam turbine odies, tubes or pipes, ice-cupboards, and heat-insulated vans or wagons) in the form of fibres in bulk, nodules, felts, pads, casings (for pipes) or braids, (whether or not im regnated with glue, pitch or other substances, or with paper, textile or wire mesh supports$ (3) For sound-insulation (e.g., for flats, offices, ships' cabins, theatres) in the form of fibres in bulk, felts, mattresses or rigid boards. (4) For electrical insulation (e.g.,for electric wires, cables or other current carrying a paratus) in the form of filaments, yam, tape, braid, fabric (whether or not impregnated w& natural resins, plastics, asphalt, etc.). (5) For the reinforcement of thermoplastic and thermoset resins for making faqade coverings and panellings, domes and flat or cormgated plates for the building indus , tanks,vats and pipes for storin and trans orting li uids, machine hoods and other mou ded parts for industrial or agricu tural use, gum ers or motor vehjcles, equipment for track vehicles, railway coaches or aircraft, boat hu Is, skis, tennis rackets and other articles for sport, etc. H "Y I' 9 (6) For the manufacture of miscellaneous other products such as : filtration products for airconditioning or for the chemical industry, brushes, wicks for lamps and lighters, cinema screens. The heading excludes : (a) Semi-finished products and articles obtained by corn ressing glass fibres, or superim osed layers of glass fibres, impregnated with plastics, if havlng a ard, rigid character and hence aving lost the character of articles of glass fibres (Chapter 39). l? R (b) Mineral wools (see Note 4 to Chapter 70) and articles thereof of heading 68.06. (c) Roofin boards with a substrate consisting of glass-fibre web or fabric corn letely enveloped in, or coveref on both sides by, a layer of asphalt or smilar material (heading 68-05, (d) Multiple-walled insulating glass with an interlayer of glass fibres (heading 70.08). (e) Optical fibre cables of heading 85.44, electrical insulators (heading 85.46) and fittings of insulating material (heading 85.47). ( f ) Optical fibres, bundles and cables of heading 90.01. (g) Dolls' wigs of lass fibres (heading 95.03) and fishing rods made of glass fibres agglomerated with synthetic resin beading 95.07). (h) Brushes of glass fibres (heading 96.03).