Document x1m270Rr6J6nvv47Mqx4gEgyy

FILE NAME: Household Contact (HC) DATE: 1913 DOC#: HC003 DOCUMENT DESCRIPTION: Book Excerpt - Safety Methods for Preventing Occupational and Other Accidents and Disease rV i */ wva--.* utwmaatg^m M m ifitssm m m m A m m sias& m xeaaBxam I ntroduction CONTENTS Part I GENERAL CONDITIONS T he Philosophy of Sa f e t y .................................................... 3 Neglected F a c t o r s ................................................................... 24 T he Working-p l a c e ................................................................... 35 Part II DANGER ZONES Y ards*. Walks, Railings, and H oists . . 53 Cutting and G rinding To o ls.................................................... 65 iLLUMtNXnoN . . 79 Fi r e ................................................................................................ T ransportation............................................................................122 Safety Co m m it t e e s ..................................................................128 I ron and St e e l ............................................................................144 Mines and M in in g .......................................................................167 E l e c t r i c i t y .................................................................................178 General Aids to Sa f e t y ........................................................191 Organized E ffort by E m p l o y e r s ........................................210 Part III INDUSTRIAL HYGIENE XV. Committees on Sanitation........................................................235 XVI. I ndustriai. Po i s o n s ..................................................................245 XVII. Chemical I n d u st r ie s................................................................. 266 X\ III. Shop Sanitation........................................................................... 274 iv CONTENTS Part IV CHAP. XIX. XX. XXL XXII. XXIII. XXIV. SOCLA.L W ELFARE PACE I ndustrial E d u c a t io n ............................................................291 M eeting the P u b l ic .................................................................319 T raining F uture Wo r e e r s .................................................341 Something More t h a n Wa g e s ............................................ 362 After Ho u r s ........................................................................... 384 T he American M useum of Sa f e t y .................................. 395 I n d e x .......................................................................................... 409 i DEVICE i PROA* COMP MOVABLE FROM CITAE HOODED C INHAL GUARDS O COMP G E A RS ON TIO S/ INDIVIDUA MENS SPEC IM EN M A G N IFIED TRAVELING - SHOW SAFEGUARJ COMP/ THE NATIO' of m TYPES OF SAFETY O AND COMP / INCLOSED NO DIRECT MORE LIGH LOCAT IN TR O D U C TIO N TH IS book is the only comprehensive work on safety that has yet appeared in the English language. It is a handbook of practical information for every one in terested in industry. It shows how big business can be good business, in surrounding the workers with the ade quate safeguards to protect them at work and in promot-^ ing the ' essentials"of shop hygiene. T w o sentences froin^ President Wilson's "inaugural address might be applied here: _ " Society must see to it that it does not itself crush or weaken or damage its own constituent parts. The first duty of law is to keep sound the society it serves. The author has illustrated the underlying principles of the world movement for safety and industrial hygiene by means of typical examples, showing the methods through which simple and practical safeguards are being applied to further these ends. This application has resulted in lowered costs and increased production, with cumulative tendency toward greater knowledge, caution, and self-control on the part of the workers. While the subject of accident prevention and shop hygiene has been treated in a broad way, the treatment has necessarily been limited to include only those features common to the generality. This book proves the author's contention that 50 per cent, of industrial accidents are preventable, by examples taken from many sources, among others the prevention work in the shops and plants of the Pennsylvania Rail road Company, the Midvale Steel Works, and the United States Steel Corporation, where the reduction of serious shop accidents last year was 63 per cent., 61 per cent., and 45 per cent, respectively. From official connection with the great International Expositions of the last decade: as delegate from the United States Government to the International Congresses of Housing, Hygiene, and Demography, Workmen's Insurance and Accident Prevention at Paris, Berlin, Rome, London, Vienna, and Milan; as corresponding member of the Imperial Technological Museum of Vienna and the Illuminating Society of London; as secretary of the American Section of the International Committee for Improved Dwellings, and Chairman of the American Section of the International Committee of Workmen's Insurance, the author has had unusual opportunities for studying these problems at original sources here and abroad. " Ever}' life saved is a national asset" is the philosophy of the wise men in Europe. W hat they save America often destroys. The sanctity of life is a lesson industrial America must learn. All unnecessary social waste is one fundamental cause for; the increased cost of living, since, in addition' to loss " of services, it imposes an additional burden on the tax- payer in the increased expenditures of our great city departments of health, charity, education, and police. To-day, through our lack of foresight an army of producers are thrown into the ranks of another great army of consumers, and through their disablement and wageearning incapacity, are diverting money which ought to go to dividends, profit, increased wages and salaries, into river mear disea Well can 1 xi anc} stud: the " In t ion arch. kind ment In sugg were Dire' Gese Dr. ( ly g Cher th : prev. supe- vani. able Depr with T1 man INTRODUCTION xi rivers of expenditure for these social and industrial de pendents and defectives. Conservation of human life means a credit balance on the ledger of social efficiency. Dusty trades, industrial poisons, and occupational diseases run the cost of needless deaths and disablement well up into nine figures. This socio-economic waste can be cut in two. The author is thoroughly familiar with the best shops and plants in all sections of our own country, having studied actual conditions in every industrial state in the Union. In acknowledging indebtedness it is important to men tion that opportunities for utilizing the collections and archives of the American Museum of Safety and the kind co-operation of its president and heads of depart ments greatly facilitated the work. In covering the general subject of industrial hygiene the suggestions and notes of Professor Rambousek, of Prague, were of great assistance. Acknowledgment is made to Director Hirschberg of the Allgemeine Elektridtaets Gesellschaft, Berlin, for facts and illustrative material. Dr. Charles A . Doremus and Mr. L. B. Marks very kind ly gave the benefit of their revision of the chapters on Chemical Industries and Illumination respectively. In the section devoted to the theory and practice of fire prevention acknowledgment is made to R. H. Newbem, superintendent Insurance Department of the Pennsyl vania Railroad Company, for permission to use his valu able papers, " Private Fire Brigades" and " Private Fire Departments and Fire Drills," dealing so exhaustively with these subjects. The author is particularly indebted to C. L. Close, manager of the Safety, Relief, Sanitation, and Welfare xii INTRODUCTION Bureau of the United States Steel Corporation, for his most generous co-operation in placing the latest technical and photographic material, together with statistical in formation contained in the archives of his department, at my disposal. I wish also to thank Miss Adelaide Wood Guthrie for her valuable aid in the preparation of this book and in seeing it through the press. It is believed that men of affairs, business managers, officers, the upper employees, students who are entering upon industrial careers, and that portion of the public which is interested in the industrial issues of the da)', in social welfare, and in broad humanitarian considerations will find a distinctive value in the first general exposition which has been made in the English language of the vital subject of safety. at^-jt or the )thing limize f < dercd XVI INDUSTRIAL POISONS IN the fight against industrial disease and industrial poisoning systematic co-operation of all concerned is absolutely necessary. The services of the medical man are required as a toxicologist, as a hygienist, as a practical physician, but particularly as workmen's doctor; the technical man is called upon to co-operate as constructive engineer, a s,manager .or.official of the works, as factory or insurance inspector, or inspecting engineer. Of utmost importance for the success of protective measures is the energetic co-operation of employers and employees and of the organizations of both. An effective measure for protection against occupa tional danger is the selection of workers whose physical qualifications develop high resistance. Only those of the best physique should be employed in occupations en dangered by poisons. A selection of the physically strong is partially made automatically, inasmuch as the weaker ones are compelled by repeated illnesses to leave, or are eliminated in con sequence of chronic ill health and shortened life. This natural selection, causing not only social and physical misery, but also unemployment, disease, and early death, should be supplanted by a selection of the physically capable through an expert medical examination before they are accepted for employment. iS . 246 SAFETY Suitable instruction should be given in schools as to the dangers connected with the various occupations, and there should be medical examination of pupils, particu larly of scholars entering into industrial trade - schools, with a view to their physical suitability for the occupation selected. A s before mentioned, those persons naturally weak should be entirely excluded from work offering any pos sibility of poisoning. It is advisable, further, not to ex pose to this danger for too long a time workers who are accepted for such employment. They should be granted, apart from other protective measures, a shorter working period and frequent recesses. Change of work-- that is, change from injurious employ ment to work in the open air-- should occur at periodic intervals. These changes are particularly recommended where industrial poisoning may result from the gradual absorption of poison; during the period when the dan gerous substance is not handled the organism has time to eliminate the stored toxins, thereby avoiding any serious results. B y means of rational change of work in dangerous employments schooled and strong regular workers are obtained who are acquainted with the danger and know ,how to meet-it, 'On the other hand, an enforced change .of work, due to frequent illness among employees, causes a further increase in the frequency of the disease, as the new-comers, not being skilled, are more exposed to the danger. The prosperity of an industry often materially depends on the existence of a trained set of workers. A change of work rather than a change of workers is, therefore, particularly desirable in establishments where there is great danger of poisoning. Employees in these plac acce afte eliir. R ger per, dur. cou: by emt T star to r deri cau li oxy; resp rese pan pois 3f a and shen Y rega th and felle vice not be g m *i -"MV*** ' /A ^ '- '. ', V *. INDUSTRIAL POISONS 247 places should be medically examined not only when accepted for employment, but also at regular periods afterward. In this w ay the physically unfit may be eliminated and handed over for treatment. Records should be kept of the workers exposed to dan ger of poisoning, their state of health, the result of the periodic medical examinations, and of the diseases, their duration, symptoms, treatment, and cure. In many countries where the keeping of such records is required by law it has been found of great advantage to the employers. . The health of the workers should be a matter of con stant supervision by inspectors, foremen, or anybody able to recognize the first signs of poisoning, capable of ren dering first-aid treatment and of...supervising proper pre cautionary measures. ` In addition to the customary first-aid equipment oxygen apparatus is especially useful. Helmets and respirators should always be at hand for members of the rescue corps. These should never enter premises, ap paratus, gas-tanks, drains, and sim ilar' places in which poisoning has occurred, or in which there is the probability of a poisonous atmosphere, or into which poisonous gases and vapors may enter, without protection. Provision should also be made for giving trained medical aid promptly. Workers 'who handle poisons should be instructed with regard to the character and action of these substances, the initial symptoms, and, particularly, all the means and measures necessary for rendering first aid to their fellows. The best hygienic provisions, protective de vices and measures are valueless when the worker does not use and follow them. Not only should instruction be given with regard to the object and use of devices, but I H iI s- . f * If ! 248 SAFETY workers should be urged and, if necessary, compelled to use them. Instruction to workers, especially those just entering dangerous employment, may be given in various ways. Apart from lectures on the subject concise instruction should be available in the form of notices and illustrated placards displayed in the workrooms or handed out as leaflets. Official leaflets are drawn up and published by some governmental departments, the employers being obliged to make known and distribute the same. Of individual protective measures, those have the greatest importance which, as far as possible, prevent poison from contact with an}7portion of the body and from inhalation. If this is not completely possible, however, the poison should be quickly removed, so that it shall not penetrate more than is absolutely necessary. Such pro tection can be secured by means of suitable equipment for the worker, as, for instance, proper clothing, protectors for the mouth and nose, and scrupulous cleanliness when eating. It cannot be sufficiently emphasized that only these measures afford effective protection against in dustrial poisoning, particularly against those having a lingering chronic action. The importance of wearing suitable clothing on the premises should be strongly impressed upon workers in dangerous trades. The ordinary or street-clothes should be taken off and replaced by special suits to be worn dur ing working-hours. It is not sufficient for a working-suit, jacket, or apron to be put on over the ordinary clothing. The working-suit should be taken off before the midday meal and before leaving the factory and exchanged for the street - clothes. Working - garments should be cut perfectly plain, without folds or pockets, and should be INDUSTRIAL POISONS 249 made of strong, smooth, washable materials. B y remov ing the workirig-clothes before meals and before leaving the factory the poison is not carried into lunchrooms or into the homes of the workers. Direct contact with poisonous substances should be avoided as far as possible. If, however, it is necessary for the workman to handle poisonous materials, moisten or dust his hands with them, gloves should be worn. This is particularly necessary when the poison is of such character as to easily enter the skin, producing skindiseases, sores, and the like. When there is danger that poisonous substances might come in contact with the body it is wise to order that extra strong and impermeable working-garments be worn. When dealing with dusty, poisonous materials the wprkman should be provided with a suitable head-dress, as poisonous dust readily adheres to hair and scalp. Employers should see the advantages of providing and maintaining suitable working-clothes for employees, where there is danger of poisoning. But, as before mentioned, the mere provision is not enough; employees must be com pelled to wear them if the benefits are to be at all apparent. Of very great importance is the provision of rooms for changing clothing, with adequate washing facilities and lockers for holding both the street and working clothes. Each worker should have an appointed washing-place and a locker for his individual use. The best type of locker is one divided by a partition into two separate compartments closed by separate doors, one compart ment for the working-clothes and the other for streetgarments. This separation of the clothing worn inside and outside the premises is of importance in factories dealing with poisonous materials. 250 SAFETY % Direct protection for the nasal passages is also neces sary. Fo r this purpose specially designed respiratory apparatus should be worn. Sometimes simply sponges or rags tied in front of the mouth or nose are sufficient. Generally, however, conditions require more complicated devices. Some of these surround only the mouth and nose; others, the entire face, like a mask; and there are stul other types, as a helmet, which take in the entire head. These devices are all fitted closely by means of Indiarubber mounts, and possess a breathing-aperture closed, generally, b y two parallel grids of wire gauze, between which is a layer of cotton wool, through which respiration takes place. The cotton w'ool acts as a filter and retains all the dust. The outer grid either is removable or can be turned on a hinge so that the wool can be taken out and replaced b y a fresh supply. Whether the mask sur rounds only the mouth and nose of the wearer or the entire face and head, it should be constructed of material impermeable to air and provided with protected openings for the eyes when the type of protection renders it neces sary. There could be mentioned many different types of respirators; but in selecting the model best suited to ..any particular need, it must be remembered that, to be effective, respiration must not be obstructed, and the apparatus should be fitted with a valve to close auto matically -when inhaling and allow' the air to escape un impeded when exhaling wnthout passing through the filter. M any, respiratory devices do not fulfil these re quirements, or do so only imperfectly. In course of time the pressure of the respirator is generally found to be troublesome, and often causes the face to become un bearably hot. Undoubtedly, breathing is rendered more INDUSTRIAL POISONS 251 difficult through a respirator, but this can be largely minimized by choosing a proper type. Discomfort is particularly felt when, for protection'against poisonous gases, sponges or rags soaked in liquids are employed as respirators. In general, respirators should be used merely as auxil iar}' means of protection. When a worker must tempo rarily be in an atmosphere filled with poisonous dust, the wearing of respiratory apparatus, preferably covering the entire head, is recommended. Respirators offer no, or very imperfect, protection against noxious gases and vapors, and respirators saturated with neutralizing liquids can be borne only for a short time. When rooms filled with poisonous gases must be en tered, the workman should carry with him the requisite stock of oxygen in a suitable apparatus, the oxygen in such apparatus being supplied to the helmet worn by the workman freely enough, so that his respiration is com pletely independent of the surrounding atmosphere. - Workers should be instructed about the importance of cleanliness. When dusty or vaporous materials are em ployed, the hands and mouth should be thoroughly cleansed before meals and when leaving the factory. Factory regulations should make compulsory frequent washing, as well as the removal of working-clothes before meals and before leaving the factory in the evening. Washing and bathing should take place during workinghours, and without any loss of time and wages to the em ployees. Certain hours should be definitely fixed by the management during which the workmen may bathe in turn. Eating, drinking, smoking, and chewing tobacco in premises endangered by impure air should be prohibited. 252 SAFETY If possible, clean dining-rooms should be so constructed that the workers may enter them only through the changing-rooms and washrooms. In these rooms work ers should eat the food brought with them or prepared in the factory kitchen. When no provision is made for dining-rooms, the workmen usually eat their meals in the. workrooms, sometimes in the midst of unhealthful dusts and poisons. By providing separate lunchrooms it is possible to enforce the rule that working-clothes shall be changed before eating. The old saving, " Cleanliness is next to godliness," holds especially good with regard to the welfare of work men in factories endangered by poisonous materials. In numerous large industries the demands of cleanliness are now being met by the provision of bathing establishments for the employees. For cleansing the hands, face, and other parts of the body exposed to dust and dirt, simple individual washingbasins are recommended; washing-arrangements used by several persons, such as troughs and channels, are entirely unsuitable. The basins, to be easily cleaned, must be made of porcelain or glazed enamel. The dirty water must readily flow from them; for this reason experience has proved tilting-basins to be best. C- In all washing-arrangements, including Ijaths. for the workmen, an adequate supply of hot and cold water must be available. " Mixing-cocks" should be provided, in order that the desired temperature may be quickly obtained. Workmen's baths can be arranged as shower-baths, full baths, or swimming-baths. Some establishments are furnished with all these types. The shower-bath has many advantages, and, therefore, INDUSTRIAL POISONS 253 is -most frequently used for workmen's baths. The cost of providing this type if relatively small, as the apparatus is exceedingly simple. For this reason it is possible for the employer to place the baths at the disposal of the workmen fie. charge. The bather is quickly and thoroughly cleansed. Shower-baths are also more easily maintained in good condition. When this type is in stalled it is a good plan to provide double compartments as bathing and dressing rooms. The walls as well as the floor of the compartments should be constructed of smooth, impervious materials. In the bathing-compart ment the floor should slope down toward a trough from which the water may flow away. It is better to control the flow of water by means of a chain or other device than to have the water start automatically on entering \ .the bath_ ' " -- Suitable food for the workers is well-nigh essential for protection against industrial poisoning. Well-fed, strong workers are better able to resist the action of poisons; while badly fed workers, who generally suffer from di gestive disturbances, are ve iy sensitive to toxic influ ences. It has been found that the excessive use of alcoholic liquors can be checked by provision of suitable beverages. In most cases of industrial poisoning the combination with chronic alcoholism has most serious consequences. Owing to the pernicious effects of alcohol on the'kidneys, liver, digestive organs, nervous system, and assimilation of food, a number of points of low resistance are created for attack by the poison. Not only good drinking-water, but in certain cases coffee, tea, fruit syrups, and the like should be furnished the workers; milk is especially to be recommended. In many industries where the danger 254 SAFETY of poisoning is great-- notably of lead-poisoning-- milk is supplied to the workers free of charge. Every measure for strengthening workmen physically and increasing their general resistance to disease must be included in protective measures. Above all should be mentioned all movements whose purpose is to keep the workers as much as possible in the fresh air when not at work, to cultivate sport, and to strengthen the body. Much has already been accomplished in this respect by certain employers and by the workmen themselves in their various athletic organizations. Experience has shown that the industrialist is more than recouped for the comparatively small initial expense of making the working-place as healthy as possible in ad vance, and using every' precaution to maintain the health of the workers at the highest point of efficiency. The greatest danger for the workman is occasioned by those poisonous substances which, by virtue of their dusty nature, their volatility, or gaseous form, render it impossible to keep the atmosphere of the workroom pure. Among the measures of protection the avoidance and removal of poisonous air plays the greatest part. Whep the spread.of impurities into the atmosphere of the factory cannot be entirely avoided, these must be overcome b y introducing a sufficient quantity of fresh air. In addition, an attempt must be made to prevent the poisonous materials in the air from collecting and settling. As far as possible those processes should be avoided in which poisonous materials are employed and by which the air is rendered impure. A substitution of less danger ous methods is sometimes possible without added expense. International prohibition of certain modes of production Ik is 'ally .mr' :>ul lee^ not Ay. by j in han t o( ad dth by eir i* on ice of be esh ;nt nd .ed ch ?r;e. on IN D U ST R IAL POISONS 255 has been under consideration, and in part carried out. To paralyze branches of industry by prohibitory measures works, of course, economic damage, not only to employers, but also to the employed and the community in general. Economic considerations must be weighed before carry ing into effect prohibitory measures. If effective sub stitutes for injurious methods can be found, ways and means can also be developed to effect the change in pro duction. For instance, the dangerous development of dust can be avoided b y employing " w et" methods when the product or material admits of it, such as the moist clean ing of white-lead chambers and wet dressing in smelting- works. Injurious gases and vapors can be avoided in glass-silvering b y substituting the safer process for mercury amalgamation; also in fire-gilding, where the articles to be gilded are coated with mercury amalgam and the mercury is vaporized; in the manufacture of incandescent lamps, b y replacing the mercury air-pumps and switches b y apparatus without mercury; in the manu facture of matches, b y using the red instead of the poison ous white phosphorus; in the manufacture of hats, by J soaking rabbit-slrins in a solution free from mercury salts, j As in the case of the individual, the most important : factory protective measure against industrial poisoning is : cleanliness-- that is, in keeping the rooms and air of the factory free from impurities. Workrooms should be so constructed and arranged that they and the air con I tained in them can be easily kept clean. Of course, light, high workrooms having jointless-- preferably water-proof floors-- are the best. The walls should be coated with a light-colored washable paint, i Angles and comers should be avoided, just as in hospital 256 SAFETY construction. The rooms should be frequently and care fully cleaned by washing or, better yet, by the more recent vacuum method. Impregnating the floor with oil is recommended in some cases. But this method of binding dust is not its removal, and where the action of the oil is relied upon regular cleaning is more likely to be neglected. For keeping the air of a factory pure there must be sufficient air space and suitable change of the air in this space. These measures are of far more importance than may seem at first glance, as almost all the throat and lung disorders to which workmen are subject are in many cases directly related to the amount of oxygen contained in the air in which they work. With regard to the cubic volume of fresh air allowed to each workman, the minimum amount has been legally fixed in many states and countries, but it has been found that when three or four times this quantity is provided the efficiency of each individual worker is raised to a point that far offsets any charge on the rental account. Only rarely will the natural change of air in workshops-- that is, through the pores of the building-material, cracks, joints of floors, through windows and doors-- provide the necessary renewal. .Under ordinary, circumstances air is renewed only once b y natural ventilation in about one to two hours, so that in keeping employees up to " concert pitch" the need of artificial ventilation is apparent. The simplest method of airing rooms is by opening doors and window's-- so-called draught ventilation. Dur ing work-hours, however, such ventilation causes annoy ance, distraction, or indisposition, due to the impossi bility of controlling the temperature accurately during winter and summer. B y providing ventilator windows these ck pirmanf This r bring is can be adjuster proves s Artiffc special ( room tc is introd method ventilat: The c air whic creased the air bi ewers, the oper for sum current < should b pressure For ir warmed action a ir.troduc Ir. some building, are exte For fa or dust mecharri. nd ^n e 'e recent 1 '"'U is L. ring ` the oil be nust be in this ce than rat and n many atained aw to legally i found rm ` 'ed a p^mt hi -- cr s, de the ; air is at one ,-oncert :t. pening * Dur- i nnoy- ,i lpossi- i luring ndows . these defects m ay be obviated and the windows used for permanent ventilation. This method calls for the upper section of the window being made to rotate about a horizontal axle, so that it can be opened to the desired extent by means of an adjustable lever. Such arrangement, however, only proves satisfactory in summer. Artificial ventilation is best provided by means of special openings and flues, arranged at the part of the room to be ventilated, and b y means of which fresh air is introduced or the impure air drawn away. The former method is defined as pulsion, and the latter as aspiratoiy ventilation. _The difference in temperature between outer and innpr air which causes an upward force can be artificially in creased b y utilizing the action of the wind,- by'.heating the a ir 'in the ventilation flues, by mechanical. ..force, blowers, and so on. When the force of the wind is used the openings of the ventilation flues should be changed for summer and winter ventilation. To increase the current of air in the ventilation flues the outside sections should be provided with top pieces-- that is, suction and pressure head-pieces. For increasing the draught the air may be artificially warmed b y providing flames or stoves in the flues. The action of ventilating-flues is materially aided if they are introduced into existing chimneys and smokestacks. In some cases vertical ventilating-shafts are built into the building, or ventilating-chimneys, usually with top pieces, are extended above the roof. For factories endangered by poisons, either in gaseous or dust form, ventilation is best secured by means of mechanical force or blowers. Where other driving-forces  -sst 2 S8 SAFETY are employed and the draught is dependent on such factors as the wind or outside air, it is hardly possible to secure proper regulation. This, however, is fully secured when ventilating with mechanical power, as the quantity of air supplied or drawn away by the ventilator may be mathematically calculated and adjusted to the power employed. The ventilating-plant, its form, mechanical equipment, consumption of power, and dimensions, de pend, of course, on the requirements. But sufficient at tention should be given the subject to obviate all waste of capital and energy. As correct design and arrange ment determine the action, result, and fate of the plant, the services of an expert are required. This is particu larly so when problems of ventilation in factories endan gered by poisons must be solved. When steam jet blowers are employed a jet of steam or compressed air is introduced into the flues through a nozzle, whereby a powerful suction action is produced. This action can be regulated by the action of the jet. Injectors are recommended for removing acid vapors which corrode machinery, for exhausting explosive mix tures of dust, or in any case where the employment of other ventilators is not advisable and where there is sufficient excess steam, compressed air,..or water .for the motive power. ' ` ' 'v' ' ' '' Rotary blowers are substantially wheels having blade like flat spokes. They are inserted at various places in the ventilation flues according to the movement of air intended, and depend for their action on the fan principle. According to the mode of construction, ventilators are differentiated into screw and centrifugal ventilators; and according to their action, into low, medium, and high pressure ventilators. They can be driven by belts, water, steam, c which c Screw construe sometirr frames, column action, the ven; the ven Such fai low-pres by them designed air, and general c Centri in the v< on one numerou the air ; located As the ; and higl 'When th called m called hi;, suffices, required Mediu for local its point for exam IS on ch .sibic to secured ua~+ity . be power du al ms '2ient at1 waste rrange: plant, oarticuendan- s n ough a >duced. et. vapors e r*'ixieL jf le: s or the bladeplaces of air nciple. >rs are ;; and high water, steam, or, as is now very common, by electric power, in which case they may be coupled directly to the motor. Screw-blowers, like ships' propellers, are almost always constructed of iron, and generally have spiral blades-- sometimes only four light ones-- inserted b y means of frames, transversely, in the ventilation flue, on whose column of air they are to exercise a suction or pressure action. The air is driven in the direction of the axle of the ventilator, and generally it is possible b y reversing the ventilator to exhaust or drive the air as desired. Such fans produce a low pressure, and are therefore called low-pressure ventilators. The current of air produced by them has a relatively low velocity, but when suitably designed such ventilators can move large quantities of air, and are particularly suitable for bringing about a general change of air within the workroom. . Centrifugal'blowers are provided with cases inserted in the ventilating-flue in such manner that the air'enters' on one or both sides of the axle and passes between numerous straight radial spokes, b y whose rapid rotation the air is thrown to the periphery, where the outlet is located and from which the ventilating-flue continues. As the speed of rotation is great, considerable velocity and high pressure are imparted to the current of air. When the pressure is at 120 mm. centrifugal blowers are called medium-pressure blowers; when higher they are called high-pressure. 'In the former a casing of sheet iron suffices, but in the latter cast-iron cases are usually required. Medium-pressure centrifugal ventilators are employed for local ventilation-- that is, removing impure air from its point of original high pressure for technical purposes; for example, conveying a current of gas at high pressure. W' SAFETY Shutting off the rooms affected by impure air or danger of gases from the remaining sections of a factory facil itates measures for limiting and combating the danger. This plan, however, which protects only the workers not directly occupied with the poison cannot be considered sufficient. The workman endangered must also be pro tected and enabled to work at his fullest efficiency. Com pletely inclosing apparatus and processes producing poisonous dusts and gases is possible only when it is not necessary to reach the apparatus or when the work may be carried on by mechanical means. When, however, such arrangement is not possible the impurities must be removed at their source. As far as the work permits, the source of origin of the impure air should be shut off by means of boarding or sheet-metal partitions, so that only the working-place remains ac cessible. If this is impossible a funnel must be arranged in immediate proximity to the source of the impurities; this boarding, casing, or funnel, of course, to be con nected with the ventilating-pipe in which the necessary draught is produced to carry aw ay the dust or vapors. In the case of only slight development of dust, gases, or vapors, flues above the boiler, or chimney draughts, may suffice for successful local ventilation; but generally force must act on the ventilation tube to obtain the desired result. Medium-pressure blowers are most', frequently used as exhausters. In large factories, or in cases where exhaust is found to be necessary^ at many points, it is profitable to provide a centralized exhaust-plant. Such a plant consists in the opening of all the pipes leading away impure air into one common flue in which the necessary draught is main tained by the work of one or more powerful exhausters co; loc the ing 1 mu mo du: the ] nes wei poi flo\ the pip' pas sha ope / eve a v, V pro of the Bal con ball ous anc ors. fav nger. s r it pru3omjcing s not may e the ar e air netal s r nge>j ties' cc 3S pors. 's, or may force sired mtly -d to )\'ide i the into lainsters connected with the flue. When the ventilating-flues are located near tne floor, it is wise to provide outlets for the purpose of removing sweepings. Then, when clean ing, if the dust is swept near these outlets it is drawn off. In removing impurities at their source the apparatus must act so that the current of air at the place of work moves away from the worker. It is preferable to draw dusts or gases vertically downward and, laterally, from the workman into the pipe or flue along the floor. In calculating the amount lost every year through sick ness and reduced speed on the part of the operator, it is well to consider this seemingly minor point: whether the poispn-Iacten air .is drawn away from the employee ' dr flows past'Kis nose and mouth. .. . The dimensions of the pipes and flues must accord with the force and nature of the exhausts. The system of pipes should offer as little resistance as possible to the passage of air; this m ay be accomplished by eliminating sharp bends in the piping, and by having them always open into the main flue at as obtuse an angle as possible. Apparatus generating poisonous dusts and gases, wher ever possible, should be inclosed and constructed in such a way that its action and ventilation are automatic. With regai'd to the development of dust, the following processes must be considered: disintegrating apparatus of every kind, stone-breaking, and mills. In general, these can be provided with closed and ventilated cases. Ball-mills can always be completely inclosed, as they consist only of a rotating iron cylinder in which the steel balls are thrown to and fro, crushing the material. Poison ous, dusty materials-- i. e., white lead, gypsum, cement, and others of like nature-- can be transported by convey ors, or pneumatically, in dosed piping. i 262 SAFETY ihe dust created in packing certain materials can be almost completely avoided by using ventilated packingmachines. More difficult is the confinement of dust when strewing, sifting, and mixing materials, because hand-work general ly must be employed. It is sometimes possible to inclose even this source of dust, however, by using boxes with armholes and having the top wall of glass. Ventilated tables can also be used for this purpose, having wire tops and connected by a funnel underneath with the exhaust-pipe. Such tables may be installed to advantage where the poisonous dust is a waste product, as, for example, glazing with lead or inspecting porcelain products. When grinding, polishing, or similarly treating materials from which poisonous dusts are given off, wheels should be hooded as far as possible and connected with the exhaust system. For preventing the spread of noxious gases and vapors, distillation and furnace-plants should be as tight as pos sible. It is better to have fans act directly on the fur nace or distilling-apparatus, so that their walls are re lieved from the pressure of the gases generated. In 1 this way a small .fall of .pressure is produced, within*- ' which provides for their non-escape. Mixing-apparatus should be provided with mechanical stirrers, inclosed and well ventilated. dryers. The same principle applies to Of great importance is the question of the ultimate disposal of the poisonous dusts, gases, and vapors removed from workshops and factories. When these are of non ! rising character and large in volume, consideration of public opinion in the neighborhood of the works demands I that r ciency injurio usable covere Pois jected or gas< suitabl destruc Dust remain: circulat point, i plished fied pas the dep in the { frames, the coll resistan removec of the fi way ma arrange: importa worked ployed < Wortl by burn kinds, dusty cu by spra; 264 SAFETY When gases and vapors can be utilized they are con densed and absorbed, or supplied to other industries. But, in any case, the proper condensation and absorption of poisonous gases and vapors is of the utmost impor tance among protective measures. The more completely and carefully this is done, the more are the workmen protected against the possibility of illness, incapacity, and lowered vitality. Condensation converts gas into solid or liquid form bv means of cooling. In condensing-apparatus the path of the vapor to be condensed is lengthened as much as possible by passing through coiled channels and pipes, artificially chilled, and by enlarging the surface for condensation by means of perforated partitions, curved walls, chambers, boxes, and cylinders. The longer the path the more perfect is the condensation. The chilling is generally accomplished by means of water-sprays. Poisonous gases and vapors can be absorbed by water or suitable solvents, the impure air rising in bubbles in vessels filled with the liquid. Absorption chambers and vessels are of various construction, and when necessary can be arranged in series. Absorption towers are also sometimes employed to great advantage, the air to be purified or the gas to be absorbed being- admitted be low, while water trickles down from above on the counter current principle. The construction and filling of these towers van.- with the character of the gas or vapor to be absorbed. There are coke, lime, earthenware, slab, and other kinds of towers. Materials recovered by condensation and absorption can be employed in various ways. Frequently they sup ply an intermediate product of the industry or a valuable by-product Sometimes the gas which is led away can INDUSTRIAL POISONS 265 be supplied to another industry, as, for example, when the production of sulphuric acid is connected with the roast ing process. Worthless noxious gases should be burned if possible. This may be accomplished in the case of combustible or semi-combustible gases and when rela tively harmless waste gases are produced b y the com bustion. It would, of course, be a mistake to bum poisonous sulphureted hydrogen and allow the product of combustion-- injurious sulphurous add-- to escape. Gases are most suitable for combustion which yield car bonic add and water vapor as the products of combus tion. Frequently a very valuable heating-agent, or fuel, can be obtained, as when burning blast-furnace gases and others containing carbon monoxide.