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FILE NAME Corning OC DATE 1944 June DOC OC008 DOCUMENT DESCRIPTION Trade Journal Article - Dust as an Industrial Health Hazard ENGINEERS | MAGAZINE FOR AND CONTRACTORS CONCERNED WITH VENTILATING | COMMERCIAL INDUSTRIAL AND INSTITUTIONAL AIR CONDITIONING REFRIGERATION PIPING HEATING VENTILATION a Publisher : | THE INDUSTRIAL PRESS President ROBERT B. LUCHARS President and Treasurer EDGAR A. BECKER Secretary ERIK OBERG ; 3 Editorial Staff - a } i a Editor CLIFFORD CLIFFORD STROCK AsAssoscoicaitaete EditEodritor N. N. WOLPERT ) PubPlishingublishing InformatioIn nformation t HEATING AND VENTILATING is : published monthly by The Industrial Press at 148 Lafayette Street * New York 13. N. Yearly sub- Fy scription in the United States : Spain South America Mexico and } Canada 2.00 in all other coun- tries 3.00 Single copies 30 cents Entered as second class matter Office April 18 1925. at the Post ! New York N. Y. under the act of March 3 1879 i { Advertising Representatives } Eastern Representatives : DWIGHT COOK ; HARRY J. TWINE ae 148 Lafayette Street New York 13. Y. i 33 ~~ Western Representative GEORGE G. TURNER 228 North La Salle Street Chicago 1. III : eo . : aKe MEMBER Audit Bureau of Circulation Associated Bicctaence Di... at : ABI CONTENTS FOR JUNE 1944 VOLUME 41 NUMBER 6 , Dust Collecting System in Gunstock Plant .........00....0......... 51 : GrindiWnhegelQuality Wheel C. Controlled Baker Quality , Improved by Air Air oy Dust as an Industrial Health Hazard .:.................. ae F. W. Hutchinson ote e een 55 58 . Ventilation CEE Saggy for Welding M. E. Ringquist Booths on te. oe N 58 ! .Sw...-.c00060-......, Ventilation for Radium Dial Storage Off Again On Again ee 64 Jaku J. Woolfenden ...... Oe eeeeeeeees oe Se nn Sons peeeeee 64 Blueprint of Post Realities for Heating and Steam Generation ..... be hem eerceevccscecs Se eewcssas ~ 65 Train R. Hofman . Some Notes Heating on Radiant .................000055 sacteceeces 81 W. . Weather Observers Have Difficulties Cece eee cncccseeenes teeresseces 81 Central Plant Heats 46 F. N. Hollingsworth Buildings .......cccccaseee teeoecvens **** 8 Building Brazil Lote ................000. eeseecceectceecens er - Washington Loring News Overman .... tosecenes sevens see eeees ta eeesesncee eeecaes - 84 86 News of the MoMonnthth 0... eee to ereeece be eeeee teeeee Pe becees . Brief News Reviews ...........08, Whee e cee reneenencecoccscccenccsvccracs of Equipment and Materials ........ Boe cee re reccece eeeeees oe Degree for April 1944 ..,......... Ce With the Manufacturers . se eeeeees Ceo e eens ea eecesencecens Reference Data 271-272 ...... ee oo eec cea cennence teeccees de cecceee + Personals and Personnel ............... oeees Hee weer rnscecnseens Getting Personal ..... oe Poeteewres Peeeeeeee eet nececoes Army E Awards New Catalogs ..... ....... pe ceeseseeeees LelalTDNn ccccssceees ee eeceeeeneteeces Sede cceccccsvescccceccece Industrial Degree for April 1944 ..,,,9....... pd eccceeeecenes 88 90 92 100 104 104 107 110 110 111 113 Coming Events ...... oe Poeem rcovereatensssesecseces oeceeaee seceroe 113 Copyright 1944. by The Industrial Press NEXT MONTH'S Process piping is a subject that reaches Starting with our July issue 17 rr ISSU out into 1 PLAINTIFF'S PLAINTIF'S EXHIBIT OCFOCF anan Industrial Health Hazard .F W. HUTCHINSON re 3 Assistant Professor of Mechanical Engineering University of California Berkeley Calif health problem arising from dust in indus- toy is one of increasing seriousness Socially Basket and ingally it has traduzine svident that immediate steps must be taken to combat the hazard represented by wholesale industrial exposure to the pneumoconiosis dusts Pneumoconiosis in many of its forms is incurable Thus consideration of the problem which it represents is based largely on methods of dust reduction and removal and is therefore as much a responsibility of the engineer as It is of the physician Fortunately medical knowledge and engineering quipment have progressed to such a point that recognition of hazardous conditions and availability of methods for correcting them will now permit a complete practical and economical solution of the problem Unfortunately prejudice and fear have -urrounded the entire subject with such an aura of uspicion and distrust that neither workmen nor em- ployers have until recently been willing to acknowledge the hazard or recognize the need for preventive measures In addition the slow action of the disease with failure on the part of many physicians 02 int themselves with the proper diagnostic me ; has made it difficult for the worker to es- ablisn his claim for compensation in the event of ung injury and equally difficult for the employer to lefend himself against fraudulent claims it has been aid that silicosis claims constitute one of the most widespread of legal rackets Workmen have bitterly opposed adoption of the exacting employment qualifications and periodical hysical examinations of those exposed to dust which re essential to medical control Yet it is essential that persons having a predisposition to tuberculosis ar a low nasal filtering efficiency be excluded from The dusty trades Similarly protection of the worker Lemands that he be removed from exposure at the rst indication of lung damage Employers on the other hand have adopted the oint of view that most claims of silicosis are unfair and in unscrupulous attempt to take advantage of them The explanation behind an employer's unwillingness acknowledge the hazard is not unreasonable The ust diseases are almost invariably of long duration nd frequently are not discovered until many years fter exposure has ceased Thus many employers re now in the difficult and alarming position of fac- for disease which is a result of exposure tions that existed in their plants 10 or 15 CL ago at that time they were unaware of the health hazard associated associated with dustydusty atmospheres and consequently though they might have had every desire to furnish their employees with full protection from occupational injury they did not take the special care which is now known to be necessary Wilson states Most intentioned employers may be said to have used reasonable care in past years considering their lack of knowledge- this is now their best defense in damage suits However from now on with the spread ... available knowledge only special care will safeguard the interests of employer and workman alike Recent interest in dust diseases has built up an extensive literature theories have been confirmed with experimental evidence and innumerable case histories of individuals and of entire groups are available In contrast to the widespread ignorance of ten years ago it would probably be difficult at the present time to find a worker in the dusty industries who has not at least heard of silicosis or an employ- er who is unaware of the crippling damage suits which will face him if his employees through failure on his part to take the necessary preventive mea- sures contract the disease The cost of dust control is often far less than the cost of one damage suit Jury awards in silicosis cases of 10,000 17,000 22,500 25,000 and like sums are matters of record In the St. Louis area alone there were some time ago over 2000 suits pending A Missouri mining company as another example faced claims aggregating 5,000,000 and spent 500,000 in court settlements of a few of them The purpose of this article is to review the liter- ature on the physiological effects of some of the haz- ardous industrial dusts and to summarize present- day criteria acceptable as a basis for the design of . dust control systems Silicosis Silicosis is a disease of the lungs caused by the inhalation of dust containing free silica Some authorities believe but this fact has not been estab- lished that the inhalation of silicates is also a caus- ative factor ---- important Incurable and Progressive The important facts about this disease are that for practical purposes it is progressive and incurable The qualification for practical purposes is necessary because recent in- vestigations suggest that uncomplicated silicosis is not progressive however the continued existence of a case of silicosis without the onset of complications is so rare that from the standpoint of social conse- regarded quences the disease can in itself be medical literature as pro- progres ive gressive In the medical literature the progressive HEATING AND VENTILATING JUNE 1944 57 ; es = +e tf. e - ve, oweweum ' % o-e.e Tetrgetecmneee em og | i{ : \ a panes no as . ' Ly a: IG ; \ Doth . ta d I ru 4 tf a : j i . 1 Metanica ALIA, 1650 peewee weree -- . viewpoint is the one which has been most widely readers to beware because it penetrates into the * adopted but the possible future significance of the windpipe away the implants consump- recent findings is promising tion in the body He called attention to the fact With reference to the incurability of silicosis that the death rate among Carpathian miners was recent work has also indicated the possibility of a that a wife could often outlive six husbands solution but it is as vet too soon to hold out hope so great of time has done little to alleviate the for satisfactory medical treatment One promising The passage hazard The development of pneumatic tools has led method consists in the administration of thyroxene increase in the dust concentrations at- to a great the investigators report that tending the grinding polishing and cutting of stone - Thyroid therapy may possibly not only prevent The death rate among Barre granite cutters for ex- the development of silicosis but may also arrest increased from 1.5 per 1,000 in the year 1890 its further progress and possibly reduce to some ample 19.6 1,000 in 1924 an increase attributable to extent the degree of fibrosis already existing to per the introduction of pneumatic equipment When one The above remarks on the progressiveness and realizes that a threshold concentration of 5 million incurability of silicosis have been included because cubic foot is required to constitute a they show how very far the medical profession has psailritciocsliess hpaezrard for dust made up of 100 free yet to go to achieve a solution of the silicosis prob- silica it is then evident that there are many indus- lem In terms of concrete present gain the sum trial operations today which represent health haz- total of the best that medicine can now offer is not ards that did not exist prior to the introduction of of much value When dealing with contagious disand Spanish influenza it mechanical equipment estimates have been made of the number cases such as smallpox to achieve a satisfactory treatment Many hazardous concentrations of haassabefiernst psotsespibtloeward the elimination of the disease contagious dis- of persons exposed to silica dust but such estimates are usually based only When account is taken of itself in the case of silicosis a the only advance of real significance which is case be brought about on industrial exposure the fact that 60 of the earth's crust consists of that such estimates possible is an advance which must silica the likelihood seems great by the application of basic engineering principles- are conservative Lanza and Vane estimated that the reduction of dust concentrations at the breathing the number of industrial workers exposed to the zone to a point such that a health hazard no longer silica dust hazard is in excess of half a million in exists only in this way can silicosis be eradicated those industries in which the processing or handling If permitted to run its course without complica- of siliceous material is of basic importance this esti- tion silicosis will lead to death by suffocation * mate does not take account of the many workers lungs becoming incapable of maintaining a gas transsustain life Usually however ter- exposed as a result of the industrial use of silica as silicosis fer sufficient to mination occurs as a result of complications such as correlation a filtering agent In one other respect the silicosis hazard has not mentioned there is tuberculosis or heart disease a definite been evaluated As already has been established between silicosis and tubercu- yaedtefinite relationship between silicosis and tubercu- losis but an explanation is as yet lacking losis This fact leads to the probability that in any With reference to tuberculosis a study of axe showed a death rate of 1,900 community in which there is a large number of silicotics there will be a decided familial tuberculosis grind1e0r0s,0a0n0dfrpoolmisthuebresrculosis as contrasted with 150 - hazard Fortunately however this danger is some- per 100,000 for the general population of the same lessened as a result of the long incubation per In this study the death rate of all workers in what which is found with silicosis the time : state the dusty trades investigated was used More strik- pweorrikomdan's lungs have reached the stage at which ing figures and more significant ones were obtained tuberculosis is most likely to set in it is more tha from a Massachusetts investigation in which the that his children will have grown past th tuberculosis death rate of 961 silicotic quarry work- the general popula- probable of their contracting the dis age at which the danger , ers was compared with that for ease is greatest tion and found to be forty times as great That silicosis is definitely related to a particula Background and Extent The name silicosis is of kind of occupational risk is demonstrated by th relatively recent origin but the existence of the from examinations ray of 2500 workme health hazard associated with dusty work has been data from all departments of a typical heavy industry recognized by medical men for many centuries had silicosis but 90.0 of those affected we From the literature of the period we find that the 5.8 workers The great importance of the sili Ptolemies knew of it Pliny the Elder referred to fhoauznadrrdyis clearly indicated from the following cor - the stone cutters disease and devised a crude mortality figures from a 1933 publicatio parative respirator for the protection of miners Aristotle of Hollis and Yule _____ warned Greek workmen against the inhalation of 1000 for standard population all causes for before Christ population Hippocrates three centuries dnuotsitced that his surgical knives were dulled by dust in the lungs of stone workers In the 16th century Georges Agricola a mining engineer wrote De Re ages 20-65 1984 for silica group 967 for silica group JUNE 1944 HEATING AND VENTILATI 58 a . ee ed2 ed 8s. COae4 -- ers me ry Mee te Have ar wt ae che gm o> tam Seren eam ome o ee . me o8 CO te - ae ae ae o or ' Lior os. ah so peatOSot. Ee : mee = hts ce te pean at et OD + meme Ve mS - ae than 1.0 micron in contrast only % of 6.000 industrial dust particles were less than 1.0 micron the majority being between 1 and 3 microns and the mean 1.5 microns Hatch and Moke investigated foundry dusts and found that composition is a function of particle size the proportion of combustible matter and acid soluble iron carbonates etc. increase with decreasing size the proportion of clay and other silicates varies without a definite trend with size the quartz becomes less as the size decreases and for particles under 2 microns which comprises 90 of the total number it is from 1/5 to 1/25 of that found in the particles greater than 10 microns These findings emphasize the necessity of taking dust samples di- rectly from the contaminated air and not utilizing rafter or any other kind of settlement sample which does not contain a representative size distri- bution Hazardous Concentration Permissible concentra- tions of dust vary with size composition and the dust retention characteristics of the individual The latter factor is one which offers some hope from the standpoint of preventive medicine Practically all that is known of the dust retaining characteristics of the human nose is attributable to the work of one man Lehmann This experimenter has shown that the dust fixation in the nose varies from % to % and is almost completely independent of such factors as the condition of the nasal secretion the rate of air currents the degree of concentration or chemical composition of the dust the width or narrowness of the nasal passages seemingly fixa- tion is a function of the vortex formation and re- bound after passage through a restriction Aion Aion Aion Aion and siffionals would seem to follow from the following tests Of 46 stone cutters with fixations above 40 only up were found to have silicosis of 31 stone cutters with fixa- tions less than 29 only 2 were healthy After ex- amining the above data Lehmann concludes that applicants for work with poor dust fixation capacity should not be allowed to work where a menace of silicosis exists As a result of 418 experiments with magnesium magnesium oxide retained during normal breathing while at rest varied little from about 60 at a com centration of 10 mg Above 10 mg the retention changed but little but as the concentration dropped below 10 mg the retention rapidly appr achet 100 The relation between dust concentration and the incidence of silicosis has been studied by many in vestigators but no general empirical relationship has as yet been established One commonly used rule proposed by Drinker recommends the accep tance of 5 million particles per cubic foot as the minimal permissible dust concentration for pore silica and 50 million particles per cubic foot for dan that are very low in silica Some evidence suggest that this rule is unduly conservative for dusts which contain little silica and an alternative which is widdy used is to limit the total dust count to a value su that the product of the dust concentration by the percentage of silica be less than 5,000,000 :1. -<'r gives 100,000,000 particles per cubic foot as the minimal concentration for siliceous dusts Physiological Effect The lung condition as as silicosis results only from the inhalation of kille bearing dusts Why silica possesses the atyr atyr atyr bring about this condition has been the subject much investigation and theories of silicos de at present responsible for considerable contre sz. Physiologically the effect of omplin omplin omplin silicosis affects the normal functioning at the body in the same way that the formation of stathe affects the efficiency of a heat transfer device iz the heat exchanger the hot and cold fluids are se a- rated by an exchange surface and the deposit si scale on this surface reduces its effectiveness as an ci exchange medium If the scale bezames sufficient heavy it will be impossible to secure the transfer encugh heat to accomplish the purpose for which the exchanger was installed similarly the lung is a surface through which oxygen is transferred from the air to the blood The formation of scar tissue re- duces the effective transfer area and eventually the lung is unable to accomplish its purpose from suffocation is the result oxide and calcium carbonate Carlton E. Brown gives the following relationships between dust re- tention and other factors Asbestosis Asbestos dust is second only to free silica in the Per Cent Retention is inversely proportional to 1. Respiration rate for rates below 20 per - minute An increase above 20 per minute is apparently followed by no changes in per cent retention 2. volume of air breathed This prob- ably results from increase in respiration rate with volume Per Cent Retention is unaffected by 1. Volume per respiration 2. Vital capacity 3. Relative humidity The same investigator found that the percentage of magnitude of health hazard which it represents Asbestos is a fibrous material of varying composition but is usually made up of approximately 43 magnesia 40 silica and % water Oxide of iroa is frequently present and appears as dark particles among the translucent fibers fibers are of such length and fineness that cloth weighing less than oz per square yard has been made from them The lung condition resulting from the inhalation of this dust is known as asbestosis and resembles silicosis in its main clinical aspects but differs due to the enhanced rate of development Under average industrial conditions the length of employment in fatal cases is only about half that which is usual : Sof ._ . e e silica group above showed only three causes ation of human valuesin the solution of engineering death diabetes appendicitis digestive diseases problems ry which did not differ significantly from the general The above case is only one of a number of similar . The significance of these figuresis at once ent el when it is considered that an estimated but less sensational cases which have shown that there is a real of contracting an acute possibility atmosphere 500 workers in the United States have silicosis form of silicosis if workis in an having . me tu some degree an extremely high concentration of siliceous dust cmen fomres Development of the Disease The time required Experimentally the possibility of acute silicosis has _ for incapacitation due to silicosis has been the sub- been demonstrated by laboratory tests on animals ject of a great deal of attention but as yet no gen- for exposures of eight hours a day to concentrations 1eee ee erally accepted conclusions have been reached Ap- of 200 million particles per cubic foot or more it has parently the period of exposure preceding contrac- been shown that the last stage of silicosis may be we tion of the disease is a function of the dust concen- expected in a relatively short time _ tration nature of the dust nature of the work and Size of Ilazardous Dust Theimportance of par- em individual physical idiosyncrasies From a study of associated 9.500 cutters in the Ruhr it is concluded that FET 15 years exposure are required to show slight sili- ticle size in determining the hazard with dusts has received a great deal of attention Par- ticles 25 to 30 microns in size will usually settle out cosis and 20 years to cause incapacitation This rapidly and are therefore not likely to be breathed vem same study reveals that % of the deaths among in quantities sufficient to constitute a hazard How- silicotics occur from tuberculosis complications In ever particles of this magnitude such as pollen of porcelain workers silicosis develops slowly but pro- gressively the second stage is usually not reached the Giant Ragweed or wood dust in carpenter shops may be responsible for hay fever or for various types until after 10 years Among sandstone workers the of asthma In general particles greater than 10 mi- minimal exposure has been found to be 11 years crons are caught in the trachea large bronchi and while for iron miners an exposure of 4 to 5 years mucous membrane Particles around 5 microns go may be responsible for the appearance of lung chances 4 to 8 years after the exposure has ceased In contrast to the above relatively long incubation to the respiratory tract but few of them reach the alveoli where the 1 micron particles are most numer- ous Policard made a detailed examination of the periods are those found among workers engaged in sand blasting and in the manufacture of abrasive t: in these occupations only 3 or 4 years may .ede the onset of the disease Likewise an exam- ation of 175 men engaged in rock drilling showed lungs of two silicotic miners and found that 50 of the particles were less than .4 micron and 75 less than 1 micron his findings should be used with care however because it is very probable that the dust distribution in the lungs is a function of the distribu- that 50 were affected in less than one year tion of particle size in the inhaled thus Poli- believing There is a good reason for that under ' particularly heavy dust concentrations silicosis takes card's findings may be applicable only for the conditions under which the men whose lungs he | smaller an acute form and may appear after an exposure of | examined had worked The particles are only a few months Not soon forgotten will be the obviously the most dangerous since on a weight ie case of the Hawk's Nest Hydro Plant on the New basis they offer a much larger surface than do the gem River Some 4000 workers mostly negroes were larger ones For this reason dust counts are of more te employed for wages of 3.00 for a hour day in value in evaluating the hazard associated with a ews: a relatively short time after completion of the tunnel work 475 of them were dead and an estimated 1500 dusty environment than are gravimetric dust de- terminations sm others incurably ill This case was investigated by The dust particles that are most effective in the a committee in the House of Representatives before causation of silicosis are of a magnitude so small whom witnesses testified that In the tunnel 10 drills were in operation at once and you could not _ that they are not perceptible to the human eye A micron is 1/1000 of a millimeter or about 25,000 see ten feet ahead of you even with the headlight of the donkey engine Workmen were so thoroughly covered with a silica dust that you could not tell a important di- of an inch As has been shown the particles most in silicosis are in the neighborhood of .5 awemicron or 50,000 of an inch represents a white man from a colored man 15 feet away It mension of the same order of magnitude as the wave recognize length was this case that a senator from West Virginia de- of that form of radiant energy which we @ scribed as the most horrible industrial disasterin as light If one cubic inch of quartz were ete the history the world It was of this case that broken into cubes 5 micron on a side enough par- Representative Marcantonio of New York charged ticles would be formed to create a silicosis hazard that 169 workers had been buried unidentified be- in a 250,000 cubic foot space e the undertaker had lost his records On the The determination of mean dust sizes was the is of all evidence which has yet been brought for- purpose of a series of comprehensive studies con- ward it would seem to the impartial investigator that the Hawk's Nest Tunnel should remain a tragic reminder to the engineer of the need for consider- ducted by the U. Public Health Service examination of 18.000 outdoor dust particles showed the median size to be 5 micron all were less HEATING AND ventilATING JUNE 1944 59 . stlicos's It is estimated that there are in the Coed States approximately 10,000 men exposed to this hazard as a result of work the insulating asbestos cloth and similar industries As is true of sis of such dusts brought to light the interesting fact that their composition is similar to that of the soil in which the cotton was grown estimates the silicosis exposure this figure does not t take into account the number of persons exposed as result of employment in the process industries where asbestos finds use under various trade names as filter aid In one respect asbestosis is less dead- ly than silicosis is there is seemingly a lower susceptibility to the supervention of pulmonary tuberculosis The danger of contracting the disease is apparently not influenced by either age or sex Like silicosis it is incurable and progressive a case is re- ported of a patient who was exposed to asbestos dust for one year and whose sputum showed the presence of asbestosis bodies fourteen years later Very few data are available on the relation of dust Siliceaus Dusts Apparently there is a great difference of opinion as to whether or not siliceous dusts are harmful either to normal or tubercular persons The data are so scant that a review of the literature must con- sist essentially of a catalogue of the few and scat- tered investigations that have been made of particu- lar dusts General conclusions can not be drawn and an extension of available data to dusts of even the same mineral family is hazardous German investigators have studied a number of different carbon dusts and rate them in the order of hazard which they represent lignite coal graphite charcoal soot concentration to the incidence of the disease No minimal safe concentrations have yet been set up and information is scant as to the conditions in those plants where a hazard is known to exist It has been determined however that the asbestos dust encountered in fabricating plants is free of silica when air is floated at the breathing level and that the danger of the dust increases as the quality or length of the Fibers increases Miscellaneous Siliceous Dusts A statistical study of the health hazard in a large American company which manufactures artificial abrasives led to the conclusion that persons who have had pulmonary tuberculosis should not be allowed to work where they will be exposed to dust from abrasives The dust in this particular plant was aluminum oxide combined with silicon carbide and the incidence to tuberculosis was 1 1/2 times as great in the dusty departments as in the dusty In this connection it is interesting to note that other investigators had previously reported aluminum ox- Many siliceous dusts other than quartz and asbestos have been carefully investigated Tale sili- te containing 62 silica been shown to be .sponsible for a form of pneumoconiosis when in- maled in large quantities One group of investigators report that 50 of the tale workers whom they examined were affected and about % had tubercu- containing losis The same report shows that tale % tremolite is much more dangerous than tale containing 40 tremolite but an explanation is lacking The action of cement on the lungs is not definitely known German investigators say that it produces only an inert deposit in the lungs but American reports show that the frequency of disability from respiratory diseases in cement plants is about double that found among employees in dusty manu- ide as not being a factor in the production of silicosis thus a distinction must be drawn between the forming ability of a particular dust and its danger through increased susceptibility to pulmonary tuberculosis This leads to the conclusion that the claim is unwarranted that a dust is not harmful merely because its reaction on lung tissue is inert The U. Public Health Service has grouped dusts - siliceous as well as siliceous in three classifi- cations 1. Those causing an inert reaction the amount of dust in the peritoneal cavity remaining approximately constant soapstone carborundum jewel- er's rouge anthracite coal bituminous coal and precipitator ash 2. Those causing a proliferative reaction nodules continuing to increase in size quartz chat and flint facturing plants absence from work was also twice as frequent Yet animal experiments show that cement like limestone and gypsum produces an adsorptive reaction the dust disappears from the peritoneal cavity without the production of scar tissue 3. Those causing an absorptive reaction dust disappears from the peritoneal cavity but scar tissue is not formed calcite limestone precipitat- ed calcium carbonate gypsum and cement -A similar list of dusts has been prepared by Slate % quartz in concentrations of 700 million particles per cubic foot produces a fibrosis and pneumoconiosis but few cases have been known to progress seriously On the other hand there is reason for believing that clay and slate dusts are onsible for a high incidence of tuberculosis italian investigators have studied the dust hazard in cotton spinning mills and report that the silicosis hazard is apparently negligible Mineralogic analy- Haynes who carried on a long series of animal ex- periments He arranges them in order of toxicity as follows precipitated silica flint slate hydroxide carborun- precipitated chalk magnesium carbonate dum calspar emery colloidal coal in massive amounts All of the respiratory disorders discussed above together with many others which are caused by the inhalation of forming dusts are grouped un- der the one broad term Pneumoconiosis HEATING AND VENTILATING JUNE 1944 a 61 ow rE -_ ry t- aS Se Lk ae ie ee RS CT | em +d meee: were oO i Every 49 seconds another bomb casing with tail end heated ic 2100 F. leaves Tacco unit for spinning Tocco treating m's made by The Ohio Crankshaft Company Cleveland ee a & ~ e ee e oe ae) en elie eh enka 8 e . meme cal equipment air is circulated that can be easily removed when throughout the cabinet This air clogged with dirt accumulations and units make better bomb cases must obviously be clean as a whistle replaced with a new clean Stop etre . Beat airplane propeller ends to Stop Air Filters inside the in a few minutes OA FF 115 seconds Increase out- Pret, wk intake louvres see inset make it Tocco is but one interesting ex- Fall chucks 600 per cent In that way . ample of how Stops can be te to hundreds of manufac designed and engineered into ma- SERED ~7 faster productio lower Saves Possible Expense chines where dust must be control- | improved products Pakgurye-an insides consist of expensive oe machinery A gener- machinery e ator is its heart Stops are one of the coistributing factors to Tocco's remarkably low maintenance costs made possible by careful design and engineering of the led For further information on this type of application write OwensCorning Fiberglas Corporation 1912 Nicholas Build ~ er = Cort . To assure proper operating tem- . complete unit . All users of machinery equipped ing Toledo 1 Ohio Fiberglas Tee te mo Py *e Wey dp: perature for the enclosed electri- with Stops have the advantages of a change standard size filter Canada Ltd. Oshawa Ontario ba Tdd are WY he oF egile. bee ri bee) Oe Ned DUSTOP DUSTOP FILTERS Bhity MRNTHE MRNTHE MRNTHE AMILLA M. Reg U.S. Pat Of Sthaehkinfi 4064 AIR . re ths: . a4 re eye Be a . wCiSta or = ee va eeare ctl catibendth cumntoen, Sem 78 ps @ Burkhart Mfg Co. St. Louis CR r ee Satay one, = we IN radio studios hospitals churches theaters hotels offices wherever quiet working and living conditions are required all asbestos prefabricated duct will eliminate noise from the air conveying system Careyduct is a development of the Carey Research Laboratory and scientific field testing It is a natural sound absorber conductor of sound and resonating It quieta fan noises and cuts down speaking tube effects and eliminates cracking due to changes in air pressure By effectively absorbing noises it permits the use of smaller duct sizes with higher air velocities This also solves difficult installation problems where space is limited Besides its absorption of noise Careyduct has many other advantages over older and less efficient methods It is fireproof is quickly installed absence of noise in erection unavoidable in handling metals permits in- stallation in occupied buildings such as hospitals stores banks etc conserves metals neat and compact can be painted to match walls and ceilings costs no more fra- -- quently less than insulated metal duct cosy For technical details and further informatiseonnd for Careyduct Manual Address Dept. 19 THE PHILIP CAREY MFG COMPANY Dependable Products Since LOCKLAND CINCINNATI 15 OHIO In Canada The Philip Caray Company Ud Office and Factory Lennoxville Q. QD Children's Hospital Cincinnati Vocational and Industrial Training Schools include the art of handling Careyduct in their courses on sheet metal work @ Residence Glendale Ohio @ Krager Grocery & Baking Co. . Laboratories Cincinnati JUNE 1944 HEATING AND VENTILATING : ALPHABETICAL ALPHABETICAL ALPHABETICAL INDEX OF ADVER ADVER DIDEN G Tena ctric Switch Co. ee Industries vicsescceeeeeeee 43 / ~ *s ud Conditioning Engineering Co. 116 Electric Mase Corporation ......00.-. 10 General Controls Co. General Co. wccc serene cevcesscacee 307 & Porter H. W. & Co. l^"c ....... ! Powers Regulator Co. wcccceeeeee Propellair Inc. sseevesvevseceees , 4 stemp Div Chrysler Corp. *** Airtberm Mfg Co. ccccccessecees $ 105 a H R 4 rh tt & | itl sf 1 inal LaF Alco Valve Co. .13.2 .13.4 24 .13.24 Allen Corporation ...c.eceesceess 13 American Air Filter Co. Inc. .... 27 American Blower Corp. sesnsssne American District Steam Co. American Pumps loc .... . 119 American Rolling Mill Co. ..-... 11 Armstrong Machine Works ...... 10 Automatic Products Co. ....+.-.. 108 B Badger Mfg & Sales Co. .....--, Baldor Electric Co. ......eeecee. % 105 Colman Co. ..cssreceees -- 38 ^' Ball & GossetOtp ...cc.cceeeeee 36 Bethlehem Steel Co. ....cceeneee 97 Henry Valve Co. ...ccscccvscees Holcomb & Hoke Mfg Co. .0.-0+ fi 39 Howell Electric Motors Co Inside Back Cover Rezoor Manufacturing Co. ....... Ric Co. secccscovcccseccccvas S I Ilg Electric Ventilating Co. ...... Illinois Engineering Co. Inc. * Illinois Testing Laboratories Inc. 114 Iron Fireman Mfg Co. .......00. 101 J Sall Mountain Co. e .-.+..- ecesete Sarco Company Inc. ..... tooctes Barcotherm Controls Inc. oases. Smith H. B. Co. loc eewesereces Somers H. J. Inc. .....-- eaerseone Star Electric Motor Co. ......006 Superior Sheet Steel Co. ....-04. Johnson Fan & Blower Corp. .... 36 T Johnson Service Co. ..Back Cover we ; te ole Cf no, a Breldert G. C. Co. cssssesseeees 9 Brooks Equipment Co. ..... ooeee 114 ~_ Bryant Heater Co. ...cccccsesone 32 7 Buffalo Bolt Co. .....ccseecaceee , Buffalo Forge Co. ccc ce vec c eee 45 enamelren vera M. Co. cccsecsseccecae fi t C 7 xa ce Carey Philip Mfg Co. ....00.... 34 Carrier Corporation ........scc008 3 Cash A W. Valva Mfg Corp. ... 13 Chrysler Corporation .... 4 -- Kewanee Boiler Corp. ...... Korfund Co. Inc. ....cccsecnevee 119 L + Ladish Drop Forge Co. vssseveeee 29 Leland Electric Co. ccscscsoeeees 33 Link Co. eee ereseenesssoe 16 N Classified Advertising ..,..+....0 116 Continental Steel Corp. Crane Co. Cease eroneesaevessnes 31 Crown Iron Works Co. ...ssee00. 116 Curtis Refrigerating Mch Div of Curtis Mfg Co. ... 41 . Marley Co. Inc. ..ccccecevessens Marlo Coll Co. cccsccevccscecsees 41 Marsh Jas P. Corp. ...cccseeees 49 Nercold Corp. eoeeoseseseeosregre 37 McCord Radiator & Mfg Co. 117 McDonnell & Miller ..ccecvecsene 5 . D Minneapolis Regulator Co. .. loside Front Cover Detroit Lubricator Co. ....-e0c05 = 6 Modine Manufacturing Co. ...... 4 Mueller Brass Co. ..cccceceesees 26 Dravo Corporation ..secosccasees 93 Dunham C. A. Co. coccveccsseee 103 oe . ~--N~ we e E E Economy Pumps loc weseessse.e ' Electric Auto Co. ,ocsseccses 112 Ligo Sbuller & Manufacturing Co. * Sisworth Pipe & Supply Co. .... 17 Nash Engineering Co. ...ccessee -- -- Nelson Herman Corp. 13-19 o Corning Fiberglas Corp. 09 are Oren Taylor Forge & Pipe Works Thrush H. A & Co. .......... .......... .......... >a a 2e! n =a Todd Shipyards Corp. Comber 50> Lion Equipment Div ......+6. it "| Trane Co. ..... 11 t it Trerice H. O Co. crseeeereecBeOSee af . Turns Inc. cece seeeeeeeMeeye Uo Tuttle & Ealley Inc. wcrseeeeenee ev oo i oe, ft ae Ae ba. 2 hae 3? U. S. Machine Corp. cssssccceses United States Air Conditioning ---- --DEC SHHREHE HEH EE Oe HHO DESH United States Radiator Corp. w+. BD a ; = s : in, yt aefa , q Be os Ww Wagner Electric Co. " ..cesceveees * . L"Y pi Want Advertisements sooreveres os W'ebsler W'arren & Co. .--sore- re ; Westinghouse hAist Electric & Manu facturing Co. saecasecscrescolhT, ee White Rodgers Electric Co. ..... a $i Whitlock Manufacturing Co. .... Wing L. J. Mfg Co. ...cveenee . Worthington Pump & Machinery 4 Ea 0 Amerson Electric Manufacturing Co. ceseceeneeoncsscaneneeses t ' . Freeman Bloker Div Illinois Iron p Pacific Steel Boilers ..cccccsseee Patterson Co. Inc. ....... = * Peerless Pump Div Food Machin- a ae atin Yarnall Co. .109-11413 aa Gg 2, e a York Heat Div Shipley Inc. 1 : be Young Radiator Co. ....----ser% ae sp...