THE efficiency of cotton mills Is Intimately dependent upon the working conditions prevailing therein. Fresh, dustless atmosphere at a reasonable temperature is of paramount importance in promoting the welfare of the workers during their daily occupation. How to clear the air in certain parts of these mills has for some time occupied the serious attention of employers. Several schemes, more or less effective, have been launched forth; but few have gone beyond the experimental stage. They are either too expensive, or impracticable on a large scale. The common plan, until recently, was to install fans of 15 to 24-inch diameter in wall-boxes or window-frames, at - various parts of the room, and exhaust; the impure or dusty air 'so as to change the atmosphere of the room three or four times during each day. Dust is generated in most carding-rooms in such a degree as to be particularly injurious to the strippers. In card-rooms the raw cotton is combed, in machines known as “carding-engines,” hy a myriad of pointed wires attached to revolving cylinders. A roll or “lap” of cotton is fixed on the front of this machine, and it issues from the back as a thick woolly band of yarn, with the fibers combed in one direction. This machine makes the first semblance of a thread in the operations of a cotton mill. Between the lap and the thick yarn the cotton is passed over .the cylinders covered with wires. Here the short fibers are held between the wires; the dust and small particles of the cotton-plant are also retained here. These millions of wire-points act much like an ordinary clothes brush. The \vires thus cleanse the cotton, combing and preparing it for the “frames” which follow. As each carding-machine has two cylinders, one of which is 4 feet wide and makes 160 revolutions per minute, it follows that in a few hours the wires become surcharged with dust and short fibers. And if they were not stripped of these they would be so glutted with refuse that the machine would fail to do its work. Hence, when the carding-engine has been in operation for two or three hours, the process is stopped, and the two strippers bring up a cylindrical brush covered with wire bristles. This is placed in contact with ea.ch of the cylinders in turn, and revolved at a rapid rate. The brush strips the wires of nearly all the short fibers which clogged up the interstices. It also roots out the dust and sticks which have been retained in the cotton up to its treatment in the carding-machine. When the stripping-brush has done its work, it is an easy matter to clean it by means of a hand-card. It contains short fibers only; the dust has passed into the air of the room in dense volumes. Here, then, is the specific function of the new appliances—to prevent this dust pervading the air of the room. This is of greatest importance to the men who manipulate the brush. They must stand in close proximity while the brush is revolving. The volumes of dust pass into their nostrils, and much is unavoidably inhaled. This involves serious risk to the men, and in time, tells upon their physical strength. It is, indeed, seldom that strippers are able to follow their employment to a normal age of say 60 to 65 years. The work induces pulmonary troubles in some men at an early age. The danger is, to some extent, mitigated where the men adopt the precaution of holding a tuft of clean cotton fiber, pressing it between the lips while stripping. This forms an old-fashioned respirator i I'i:;. 1), which is used daily by men who have often proved its value. Other men have recourse to specially-designed respirators, which are adapted to facial outline (Fig. 3), and preserve the mouth and nose from contact with dust. The fact that strippers have suffered acutely from their occupation has been definitely proved by investigations in various cotton towns where between - 40 and 50 per cent have been found affected in varying degrees. Fans, exhaust or indraught, have doubtless done much to purify the air of carding-rooms ; but they do not touch dust-clouds for some time after the dust is generated. The result is that the dust becomes mixed with the air of the room and, after having affected the strippers close by, it 'is diffused in the room generally, and traverses the area where the women and girls are at work on the spinning-frames. There is a moderate amount of dusty material given off from the frames themselves in cotton mills. This in itself, however, does not occasion either inconvenience or injury. The new methods work on different lines from any before put into practice. Several of these are now in operation, but the general principle adopted is to collect the dust at the point of its generation and remove it by means of trunks to the external parts of the mill-premises or to inclosed dust-chambers. Several plans are at work in the cotton districts of Lancashire. By one of these (Fig. 2) a dust-receiver is fixed over each carding-machine. This- is as wide as the machine itself and has an opening about 2 inches wide; it bears a balanced lid by which the aperture can be opened and closed at the will of the stripper. The receiver is attached above to a carrier-tube running to the main air-trunk. In this an inclosed blower runs at 1,200 to 1,500 revolutions per minute. The blower will take care of forty to sixty carding-machines, and the additional mechanical power used is nominal. The modus operandi is as follows: When the strippers place the revolving brush on a carding-machine, the receiver-lids of the whole series are closed except the one over this particular machine. Thus the total exhausting force of the blower is concentrated on one machine; and when the stripping begins, the air-currents about the aperture are strong enough to gather the dust as it is generated. The attendants require no cotton tufts or respirators; the dust is completely prevented from reaching their breathing organs. Then the receiver-lid is closed, the brush removed to the next machine, another lid opened, and the process is repeated throughout the series of fifty or sixty machines. Another method (Fig. 4) has been devised, in which a single traveling receiver is available for each row of carding-machines. In cotton mills generally these machines are laid in parallel lines of ten to forty, with intervening spaces of 10 to 18 inches. It is therefore possible to build up carrier-tubes in line with the machines, and about four feet above them. On either side of the tube-line a rail is fixed to hold the grooved wheels of the traveling receiver. The exhaust in this arrangement is maintained by a blower running at about 1,300 revolutions per minute. Over each carding-engine is an aperture in the air trunk; this aperture is closed when stripping is not in operation at that machine.- The draught is thus concentrated on one machine only. The aperture is automatically opened by the receiver itself as it reaches the machine to be stripped. The appliance is propelled by hand to any part desired by the workman. On arriving at a given machine, the funnel-receiver is brought immediately over the card-cylinder, close by the line where the dust is generated by the strip-ping-brush, and the indraught collects the dust before it can diffuse. By a third method (Fig. 5) of dust extraction a vertical tube is provided over each carding-engine this tube being connected with a casing or “hood, “ which Is lowered to cover the stripping-brush when operating. A sliding shutter is fitted in the vertical tube. This is opened when ready for stripping, all other shutters being then closed. Thus the exhaust from the fan is concentrated on one “card” only. When stripping is completed the hood is raised in the vertical tube. A fourth method (Fig. 6) has pipes depending from horizontal trunks following the lines of cards ; but in each pipe is a patent valve, formed where the pipe can be flexed. When the pipe is vertical the interior is fully open; when flexed as far' as possible, the aperture Is closed. Hence in all tubes bent, so as to be out of the way of the workers, the valves are automatically closed. To operate this dust-extractor an aluminium cover is pro-vid ed for each stripping-brush. The outlet pipe of the cover fits into the down-pipe just mentioned, so that when the fan is started the dust is drawn off as stripping proceeds. The power required for an average mill is estimated at about one horse-power. The method now described (Fig. 7) works on a por table principle. The stripping-brush is inclosed in a hood which has a flexible-tube connection with the dust-extractor. This comprises a portable chamber built on an angle-iron frame, braced with tie-rods and bolts, and having a wooden top and base. The whole is moved on wheels after the style of a bogie, and contains the exhaust fan and dust-bag. When stripping, the fan is operated by bands running from the carding-machine to grooved pulleys on the ends of the fan-shaft, these pulleys availing for right- or left-hand cards. The stripping of a card having been completed, the brush and casing are placed in brackets on the top of the chamber, and the next card is treated. Most of these dust-extractors perform another important function. They may be used as ventilators of rooms generally, apart from the removal of dust from carding-engines. The stripping process is performed four times each day, and occupies 40 to GO minutes. In the intervals between these operations any of the apertures of. the dust-extractors, may be opened in any part of the room. Impure air may thus be dra wn from twenty or more localities at the same moment by moderate exhaust currents, and without draughts playingrdquo; on the workers. The improved condition of the air from the use of these widely-distributed exits will be readily appreciated. With the installation of dust-extractors in the card-rooms of cotton mills, the health and working of the operatives concerned will be bly improved. Likewise the material produced, in the shape of finished yarn, being free from specks of dust, will be very materially enhanced in its market value.
This article was originally published with the title "The Methods of Dust Extraction on Cotton-carding Engines" in Scientific American 105, 27, 592-593 (December 1911)