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AIR I-IYGIEKE FOUNDATION OF AMERICA, Inc. Preventive Engineering Series, Bulletin No. 2, Part 8 ( Routine Sampling for Control of Atmospheric Impurities ' i ' ^PITTSBURGH, PENNSYLVANIA JANUARY. USD Oi J26 ROUTINE SAMPLING FOR CONTROL OF ATMOSPHERIC IMPURITIES* The control and sampling of atmospheric contaminants in routine pro duction operations are matters with which plant and mine managers today re definitely concerned. A few years ago, such control was more or less limited to firms that were losing a valuable product through faulty operation, or to those that knew that neglect of dust, fly ash, or gas control meant a health, nuisance, or explosion risk, cither to themselves or to their neighbors. Today, however, twenty-eight states (Table 1) have industrial hygiene bureaus whose function it is to advise industry on the control of its indus trial hazards, while many insurance companies are well equipped to investi gate industrial hygiene- problems from both the engineering and medical aspect.f Baltimore, Maryland; Detroit, Michigan; Rockford, Illinois, and St. Louis, Missouri, are reported as having industrial hygiene bureaus. The formulation of codes of good practice is a trend of comparatively recent date. Underwriters' codes covering fire and explosion risks have been available for some years. To them is now being added information, such as the National Silicosis Conference's recommendations on dust counts in relation to silicosis prevention1, New York State's codes on silica dust control in rock drilling2, and the American Foundrymen's Association's codes on exhaust systems for general foundry work*. The American Standards Association has a committee which, it is understood, will suggest, from time to time, safe concentrations of various contaminants. Some states now furnish, on request, a list of maximum safe concentrations which they recommend for various dusts and gases. (The Massachusetts list is given in Tabic 2). In some instances, as in Wisconsin and New York, the codes have been made legally binding. Other states have issued the lists merely for the guidance of persons who ask how clean the air of a workplace should be. It Is not our intention to criticize these codes. The concentrations gen erally ure not fixed by accepted medical standards, but represent zones or ranges arrived at by practical trial. Obviously, the figures must be revised from time to time as medical knowledge on the subject progresses, and especially as industry improves its housekeeping. The purpose of this bulletin is to give in brief form descriptions of apparatus and methods which are actually being used by one or more labora tories in appraising the environment in which men work. In making such appraisals, two distinct steps are involved: first, measurement of air cur rents, and second, estimation of impurities. The resulting data can then be applied to the design of control equipment or to the appraisal of the results brought about by such equipment. Air Movement Ltw jiir Vilmtits Air velocities In workplaces generally are below 100 F. P. M. (feet per minute). Exceptions are warm places where fans or air blasts are used for their cooling effect, mine shafts and haulage ways used as ventilation ducts. * Thin is |tart $ in thv writ** JJifUitJn Sn, 2, ttmlvr the &u*iiccs of tin4 lTtvrtuive Kiiffinvri-itii: Commitirr. t DvtaMvct Information on urtlvlttvy can hail from Aincrivati Mutual AUiimvr, si! North Mit-Minm Avt'iim*. ChtuuKo. ami ifto Association ot Cas ualty it Sunty Kx^citilvr*. John Nrw* York City. 1 0iJ2 and atmosphere? within the immediate zone of exhaust hoods. Low veloci ties must be measured by special instruments as they are below the range measurable by pitot tube, venturi meter, or vane anemometer. Smoke Bombs: In schoolrooms or auditoriums, air conditioning: engineers usually study air distribution by the use of smoke. Smoke from tobacco is of too fine a tex ture to serve as well as the coarser smoke made from hygroscopic substances. Titanium tetrachloride smoke tubes for testing work are safer to use and give satisfactory results. They can be made as follows: glass serum ampoules, costing about S2.40 a gross, are filled with 0.10 cc. of titanium tetrachloride. The ampoule is then sealed and the neck out about 0.25 inch, dipped in water-glass as an adhesive, and about an inch of wicking pushed over the neck. The wicking used in a sulfur lamp is satisfactory. Since the compound reacts with air and becomes vitiated, the ampoules should be sealed promptly. When a smoke test is desired, the neck of the ampoule is broken by lay ing it on a hard surface and pressing down with the thumb; the wicking will protect the thumb against cutting with the glass. The TiCl4 runs out into the wtek and smoke immediately results. . A smoke gun can be made by soaking pumice with titanium chloride and packing in small glass tubes, such as calcium chloride drying tubes. Air is then blown through the pumice by means of a rubber aspirator bulb. When not in use, the ends of the tube should be closed with stoppers. Titanium tetrachloride is carried by most supply houses and costs about 75 cents per quarter pound, which is enough to fill a large number of ampoules. Smoke tubes and smoke guns in convenient form arc supplied by (g), (j).* Thermo-anemometer: C. P. Yaglou has recently developed4 a simple thermo-anemometer capa ble of measuring velocities between 10 and 6,000 F. P. M. The temperature of the wire is only 10* to 40* above air temperature and is indicated on an ordinary thermometer around the bulb of which the wire is wound. Small dry cells furnish the heating current and the voltage is regulated by means of a rheostat. These auxiliaries are assembled in a smalt box. Readings to be taken are temperature of heated and of unheated thermometer and voltage used. The velocity is read off a table or chart, or computed from an equation. By varying the voltage, any velocity can be measured with an accuracy of 98<i. ... A unit which is vest-pocket size and sensitive to very low velocities will be available shortly. This instrument compensates for variations of air density due to tem perature changes, and is negligibly affected by humidity, radiant heat, and convectional currents which it causes. It is particularly useful for measure- ing air movement in rooms and in exploring "point" velocities in front of exhaust hoods, because it offers negligible obstruction to airflow. Its disadvantages arc that it is not direct reading, it requires a short time for the heated thermometer to reach equilibrium, and its readings must be corrected for partial stem immersion when used inside small pipes. The instrument is too new to have had any widespread field use. It is supplied by <m). (a), n, nc.. refer to arms supplying eciulpment. For full list and nddrersc*. we Table t. Pact- IS. of till* bulletin. High Air l 'ttwinft In the effective tone of exhaust hoods, the minimum velocity is about 150-200 feet per minute extending on up to 1,000 K, P. 31. or more at the face of the hood. It is often desirable to increase the hood's effectiveness by changes in design. Velocity contours tan be sketched out as indicated in Figure 1 of Bulletin No, 2 of this series. For measurements in such velocity ranges, Yaglou's thermo-anemometer device is well suited. Vane Anemometer: In the cose of large houu&, such as those placed over electroplat'rg covats, either a velometer or a small vane anemometer is convenient. For exploring small hoods, however, both instruments take up too much space and interfere seriously with the normal air currents which the hood is in tended to form. Furthermore, the portable vane anemometer is a delicate instrument; it needs frequent calibration, and is easily damaged by corrosive chemicals, by dusts, and even by steam or water vapor. It is advisable to use the vane anemometer only when no corrosive substances are being generated. Velometer: ` This is a direct-reading device consisting of a double-pivoted vane which is deflected by impact against the air stream. A pointer attached to the vane indicates the velocity on a calibrated scale. All moving parts are housed in a small case. For low-range readings, the air enters the meter directly through a small port and the whole case must be placed into the air stream. For high-velocity readings, various size orifices are placed within the port to reduce vane deflections. For measurements of velocity inside pipes, a double-pitot tube is provided and connected to the meter ports by rubber tubing. . Velometer readings are instantaneous, but several must be taken to insure a good average. One can measure velocities of several thousand feet per minute, as in exhaust ducts, or a few hundred feet per minute in the vicinity of large exhaust hoods. Although a dust-filter attachment is now available for keeping the mechanism clean, it is questionable whether it is wise to use the instrument in any but clean air. The device is supplied by (h). A less accurate, but very practical instrument, known as the "Grillometer," has been developed for measuring air velocities through grills. It is a torsion device and is direct reading. It is supplied by (d). Pitot Tube, Venturi Meter and Orifice Meter: While these three instruments measure flow rather than velocity, they are too well known to need any description. The pitot tube has- long been the sole "self-standard" instrument and the most used for determining flow in pipes or ducts, for making traverses, and the like. Recording venturi meters and orifice meters for measuring the flow of fluids (liquids and gases) are sold today by several firms. In the construction of exhaust systems, it is well to consider the permanent installation of a venturi, or an orifice meter, or even a recording meter near the exhaust fan. The A. S. M. E. book7 gives full details of the basic principles, design, and use of these instruments. 3 / / 1 Atmospheric Impurities For the purposes of selecting sampling anti control methods, in relation to exhaust systems in plants or mines, several distinct types of atmospheric impurities must be considered: A. Relatively insoluble mineral dusts, such as silica, many silicates, and fly ash. B. Relatively soluble mineral dusts, like calcite (limestone). - C. Finely-divided fume substances that are difficult to catch in water. Examples arc lead, lead oxide, and zinc oxide, D. Busts that may be affected by water. Examples are flour, leather, <1 liu ouap. Many of these dusts are explosive iX in Ixed with air. E. Aqueous mists, such as chromic acid entrained from electroplat ing baths, or condensate from vats of various sorts. F. Water-soluble gases, such as hydrochloric acid. Such soluble gases usually contain mist as well as gas, the proportions depending upon local conditions, G. Gases or organic vapors, like benzene, soluble with difficulty. These react slowly with most liquids but may be adsorbed readily by solids, such -as activated carbon. Impinger: Instruments for Bust Sampling The impinger is commonly used in sampling dusts, like classes A, B, and occasionally mists, like class E, and some gases, like class F. It is definitely unsuited to class G gases, like chlorine or organic vapors. It is not efficient against finely-divided fume substances, Class C, such as lead or zinc oxide, and rarely is it suited to sampling organic dusts, like class D. The impinger9 consists in a flask in which a tube with tapered end is held at a fixed distance from an attached glass plate or from the bottom of the flask. Air is drawn through the tube and the impurities are trapped in the liquid in which the tip of the tube is immersed. Suitable fractions of the dusty suspension are then withdrawn and the dust particles counted under the microscope or the total dust concentration is estimated by the usual analytical procedures. . The impinger is now made in two sizes, one sampling at one cubic foot per minute, and the other at three to five liters per minute. Bsed originally with water as the dust-catching medium, it is now- common practice to use other liquids, such as isopropyl alcohol, limitation depending upon volatility of the liquid and its readiness to foam. The suction device for the impinger can be run by a compressed-air actuated ejector or by a pump driven by an electric motor. The midgetimpinger equipment is much smaller and can he run by hand. It is lighter than the large unit. Furthermore, it is hand operable, all of which makes It particularly suited to mine-air sampling. Both types of impinger were developed by the U. S. Bureau of Mines, which recommends both for general use in measuring dustiness. Impingers, cither large or midget size, are supplied by (e), (i), (j), (k), (m). For sampling finely-divided fume substances, like lead, which are well dispersed, a small electric precipitator gives accurate results. While the complete precipitator assembly is not expensive, it requires a transformer 0*030 weighing some 15-25 pounds to raise the voltage to 15,000 to 25,000. Con struction details with a list of equipment needed for making such precipi tators are given in Drinker & Hatch. This equipment is available from (m). Barnes & Penney, of the Westinghouso Electric & Manufacturing Com pany, have described5 a small precipitator which should be well adapted to field use and is now available from (j). The high-tension side of this newtype precipitator is grounded, making it more practicable for general field use. Sampling l)usl for Direct Microscopy and Counting The purpose of taking and counting dust samples is to determine how much the dustiness of the air in question departs from some arbitrary figure or accepted standard. The grao-sample instruments, vis., the kor.imttci (j}t the Bausch & Lomb dust counter (a), (m), and the Owens jet dust counter (e), give useful indications of changes in dustiness. All three instruments are light and arc operated entirely by hand. However, they do not imitate the impinger in any way, so that it is impossible to convert impinger to grab-sample counts. The reason why such conversions are faulty is because the grab samplers favor dust sizes below the size-particle range for which the impinger technic is best adapted. A skilled technician can count about twelve impinger samples in a day. It is easy, however, to compare some thirty to forty grab samples in a short time. In practical field work with the grab sampler, the effectiveness of dust-control equipment or methods can thus be demonstrated rapidly. Explosive Dusts Host explosive dusts are affected by water, while some of them, espe cially organic dusts, such as flour, ore difficult to wet. Explosive concentra tions of all such dusts are very high (10-15 gms./m3) as compared with dust concentrations of hygienic significance (0.5 gms./m3), so that explosive dusts are determined by weight rather than by count. Air is drawn through a weighed paper extraction thimble and the increase in weight caused by the dust from a known volume of air is noted. An objection to this procedure is the trouble and time required to equilibrate the paper thimble against the moisture in the air. This objection, however, is not serious if the weight of the dust sample, as in the case of explosive dusts, approximates that of the thimble. It should be remembered that in sampling explosive dusts one must use a suction device that avoids the chance of electric sparks. Quantitative' Analysis In the case of all dusts, classes A, B, C, and D, the estimation of the sample taken from the air can be made by counting representative fractions under the microscope, or the sample can be analyzed by appropriate chemi cal methods, or the material can be weighed. The large impinger and the elcctrie precipitator are equally well adapted to either procedure: The mid get impinger collects, in reasonable sampling time, a relatively small amount of dust, but enough for counting. Dusts, like silica, that arc troublesome to determine chemically, are generally counted, while those like lead, manganese, and cadmium, are determined chemically. In places where composition of the dust and the particle size remain 5 01031 substantially the same day after day, it is possible to estimate roughly dusti ness in impinger samples from the turbidity of the dusty emulsions. Such estimates can be made in Kessler tubes, by tynd:iltmctcr':, or by an adapta tion of the turbidity methods commonly used in water analysis. Light-Field vs. Dark-Field Counting For routine control work-, the relative advantages of these two methods of counting dust samples (no matter what sampling instrument is used) are unimportant. It is immaterial which method is used. If the person doing the counting feeds that the light-field set-up is hard on his eyes, or the 'mag nification too low, Ky -.n means he should try the dark-fiehl On the other hand, if he is using the impinger and wishes to copy in exact detail the procedure recommended by the \J. S. Public Health Service, then light- field counts must be made. The Bureau of Mines recommends a micro-pro jection method for impinger counts3. The konimetcr, recommended by the Bureau of Mines for control sampling, is used in South Africa, where it originated, with dark-field, while the Bauscli & Lomb counter is.available with dark-field only. Owens samples can be counted by either light- or dark-field. Gas Sampling Gas concentrations commonly met in sanitary air analysis are very low. Concentrations that men may breathe usually are given in parts per million by volume (P. P. M.), or in milligrams per liter, or per cubic meter under specified temperatures and pressures. Some gases and vapors, notably carbon monoxide, hydrogen sulfide, and mercury, in minute amounts, give strong chemical reactions which makes possible rapid estimations and still better, continuous records of pollution. However, the great bulk of gases and vapors from organic solvents, such as benzene, carbon tetrachloride, and carbon disulfide, cannot be caught effi ciently unless sampled at slow rates, such a* Vi to 1 liter per minute. Some of them, such as benzene, can be absorbed directly in special solvents or adsorbants, like charcoal or silica gel, or con be converted into another compound which can then be estimated by an appropriate method. The greatest difficulty in estimating organic vapors in air occurs when mixtures of vapors are present. Unfortunately, this is all too often the case. Then, the devising of short cuts in itself offers a major problem, but local conditions sometimes permit the approximations of the proportions of the several ingredients in the collected sample and calculation of the total by estimating only the most easily-determined single constituent. Condensation The general availability of "dry ice" (temperature = --79* C.) makes convenient the routine collection and estimation of volatile compounds, like gasoline, for which liquid air (temperature s= --192* C.) formerly was used. A convenient cooling mixture is made by pouring ethyl alcohol or gasoline on cracked dry ice. The condensation apparatus is then immersed in the cooling mixture. Liquid air is available in most large cities and offers a convenient cooling medium, but it should be remembered that it forms explosive mixtures with Inflammable dusts or gases. 6 Vapor-Pressure Measurements If only one substance is present--and that in a big'll degree of purity-- measurements of concentration can be made conveniently and quickly by condcusing the vapor with the dry-ice mixture and then estimating the con centration by the Burrell-Joncs vapor-tension method1'. This procedure is not in common use in industrial hygiene problems and needs further study. Routine Sampling and Recording of Air Impurities If control equipment has been installed, samples should be taken period ically for check-ups. This is the best way to tell whether the equipment is functioning as it should. If concentrations obviously are high, it is usually a waste of time to take the sample and to estimate it. For instance, a leaky elevator in a crushing plant or a defective rattler or an unhooded swing grinder in a foundry may cause such high dust concentrations that an impinger sample will be turbid in a few minutes. Little is gained by going through the sampling routine in such cases, unless one wishes to have records before and after repairs have been made. Today, many plants operate crushing units and other dust producers at night to take advantage of reduced power rates and to stagger employment over twenty-four hours. During the night shift, dust inspections can be made rapidly, using nothing but the beam from an ordinary flash light to detect dust leaks. In the case of some gases and vapors, one's sense of smell often permits detection of gas concentrations which exceed desirable limits. Such a test Ii la quite unreliable unless one returns frequently to clean air or carries with him a respirator with an activated charcoal cartridge through which he takes several breaths before attempting to gauge the strength of the odor. One becomes used to even such dangerous or disagreeable odors as hydrogen sulfide in a few monments and it is, therefore, risky to estimate their I strength by smelt. ! i Such crude tests do not take the place of regular sampling technic. How often the routine samples should be taken depends entirely upon local conditions. In some places, they are taken daily, while in others, several times s year is enough. It is well to play safe and to take them too often l rather than too seldom. The men quickly become used to such sampling and pay no attention to the procedure. Obviously, the sooner'the sampler has the man's interest in his results, the better will be the outcome. It is com mon for the workmen to ask what the results are and to see to it that the samples in their particular departments are satisfactory. We know of one mining company whose concentrating plant is equipped for the taking of monthly dust samples. Various sampling stations have compressed air piped to convenient points and each station has an arrange ment for holding the impinger bottles. In this plant, it is usual for one operator to take, at the same time, samples on four floors of a single building. Samples should be taken wherever men work. It is a mistake to ignore 1 places where one believes that there is no dust or gas. The samples are i about the only proof that the employer can bring forth that he has taken proper precautions to prevent a disease, such as silicosis or a chronic poison ing from benzol. The mere statement that he or anyone else thought the atmosphere sufficiently clean is not enough. It is advisable to plot the results of periodic samples with the days or 7 01033 months as abscissae and the concentrations or dust counts as ordinates. Such plots can be made conveniently on a master sheet, comments noted on the plot which is blue printed with each new hatch of samples, and the prints given to the appropriate departments, ` Continuous Records It is obvious that continuous records of either dust or gaseous impuri ties arc more informative than occasional or intermittent records. It is possible to take continuous records of relatively heavy pollution, as in the stacks of pov.-cr plants, and also of ordinary atmospheric pollution which is of relatively low concentration. It is understood that Mine Safety Appli ances Company, Pittsburgh, will offer shortly a dust recorder that may prove nseful in common sanitary air analyses. As noted previously, gases that give strong chemical reactions, particu larly those involving pronounced heat or color changes, are suited to estima tion by continuous recorders. A carbon monoxide recorder (j), which meas ures the heat liberated by a catalytic combustion reaction, is in wide use today. A recorder for mercury vapor (f) has also found considerable appli cation. The applicability of recorders in sanitary air analyses has hardly been touched upon and it is reasonably certain that others Will be developed as need arises. Photographs It is common practice in power-plant operation automatically to take photographs at regular intervals of the smoke escaping from the stack. Such records provide useful evidence if the plant is accused of faulty operation. Occasional photographs of various plant and mine operations are often of greater practical usefulness than are records of dust counts or of gas or vapor concentrations. As an exhibit on the company's bulletin boards, photo graphs are effective warnings to the men to clean up. In routine sampling, they should certainly be taken occasionally and incorporated as part of the inspector's report. . s'W: ST: 8 TABLES I.Summary of Industrial'Hygiene Activities in States and Cities in the United States from Jane, 1033. List fur nished by the Division of Industrial Hygiene, U. S. Public Health Service, "Washington, D. C. IL Concentrations of Inflammable Vapors, Suggested by the U. S. Bureau of Mines, and Limits for Practical Control, Suggested by the Massachusetts Division of Occupational Diseases. III. Analytical Proce*dures in Current Use in Industrial Hygiene.IV. IV. Firms Supplying Equipment Mentioned in this Bulletin. O- * Q I I i \ 1I 1 l K. (=3 * t- < ws- o B fc a B B Si a *es-sVc cs <0 ft, o c ul ;sj iIr<i :1ii il - J , I it IL* xL* iS-S-S 5 *XxLix wJEO E 9 *-< * e t> i3s o a <; CO *3 H P ej: c o P *S 5* a * 5j -? r* s jj-C a CQ a SS ca >*-t M ecb** e & >1,; r\ j"\ ;!r-v 5rL5* JS H O < aa a * o >< K < w K f-t CO Qa *-l &5 'S-i = 2 > 1ijS'-js = f|l*| JT* II p| l -P *3 * * * -s * * *s Si *UuU! A X i.SilESu Jus < T Vlb H w3 -IS t Vy i wj -i o --- -! *1 14 ts *n^o 3 a if o S-8 !* jSfl -ficj| flfl 5> i 5K < !w SN 8- 11 = i.|-rjreg>ij2a**.'s---Sf-s:-?-: SN- iSs; -h ,r **}>._, rt IN >C *jvsp!*.'X^S`Pi - 9 4 ao !s3xC c, S3 B - w 5 SSto *K JC iji -*=> >5v.sS 1" 5 MEKjrs 1s5 i l c ;3 &snf|i- e Xcc i'E '*1 w c= J2S S iH ^ir.'iN'ttiv -mIa f SS.OiO 11 01037 TABLE II CONCENTRATION'S OF INFLAMMABLE VAPORS, SUGGESTED BY THE U. S. BUREAU OF MINES, AND LIMITS FOR PRACTICAL CONTROL, SUGGESTED BY THE MASSACHUSETTS DIVISION OF OCCUPATIONAL DISEASES CAS OR VAPOR Lower Limit, by Volume % Ammonia______________ ---------------16 Acetaldehyde ------------------ 4 Acetone ---------------------------------------- 3 Acetone (turbulent mixture)-- 2.5 Acetylene ------------------------------------ 3.0 Acetylene (turbulent mixture)-- 2.3 Benzene _______ ___ ______________ 1.4 BensInV............. -- 1.1 Blast furnace gras --_.---------------- 35 Butane................. .............--______ -- 1.9 Butyl acetate (V>` C.)--------------- .1.7 Carbon disulfide______________ -- 1.0 Carbon monoxide _____ -- 12.5 Cylclohexane --------------------- ---------- l.S Dirhlorethylene ________ -- 10 Ethane -------- ------.------------------- -- 3.2 Ethyl acetate ---------------- ---- 2.S Ethyl alcohol ------------------- ---- 4 Ethyl bromide..... ......--_________ 7 Ethyl chloride 4 Ethyl ether --------------------------------- 1.7 Ethyl formate ----------- 3.6 Ethyl nitrite ----------------------_-- 3 Ethylene --...... .............3.0 Ethylene dlehloride __--_____ -- t Ethylene oxide ------------------ -- 3.0 Furfural (125* c\>_______________ 2 Gasoline ----------------- -------------- 1.4 Hydrogen ------------------- ----------- 4.1 Illuminating Gas --------- -------- ---- S.3 Methane ----------- ---- -------- _--,-- 8.3 Methane (turbulent mixture)-- 6.0 Methyl acetate______________ __ 4.1 Methyl alcohol ___________ --____ 7 Methyl bromide ------------------- ------ 13.8 Methyl chloride-------------------- _TM 3 Methyl cyclohexane ____ --__-- l.S Methyl ethyl ketone --..--_____ 2 Methyl formate______ _______ 6 Natural gas ------------------------ 4.1 Pentane ------------------------------------ 1.45 Propane ______________ __ 2.4 Pronyl acetate ----------- ______ 2,0 Pyridine (TO* C.)------------------------- 1.3 Toluene ... ........................_______ 1.4 Vinyl chloride __________ _ 4 Water gas ___________________ 6 to 2 Mltllgrams/cu. meter Maximum Concentration Suggested by CAS OR VAPOR P. P. M. Ammonia ________________________ 100 Amyl acetate ._____________ 400 Aniline --___ Arsine ,--------------- .-------.-- ---------- 5 1 Benzol ________________________ 75 Cadmium 0.1* Butyl acetate __________ ___ -- 400 Carbon bisulfide ......... 15 Carbon monoxide____ 100 Carbon tetrachloride ..... 100 Chlorine --______ t Chlorodfphenyls ____________ _ l* Chloronaplithalenes____ 1 to 5* Chromic acid _________________ 0.1* Dlchlorbenzene ______ ____ __ 75 DIcliJorethyl ether__________ 15 Ether--------------------------------------------- 400 Ethylene dlehloride ___ 1______ 100 Formaldehyde________ ,______ Gasoline_________________1000 Hydrochloric acid__________ Hydrogen cyanide________ Hydrogen fluoride ____________ Hydrogen sulfide ____________ Lead ------------------------ --------- 0.15* 20 Jo 20 3 20 Mercury____________ ____ --____ 0.1* Methanol ____________ 200 Monochlorbenxene ,___ .____ 75 Nitrobenzene Nitrogen oxides ___________ S 10 Phosgene"------------ Phosphine _______________ Sulfur dioxide___ _______ Tetrachlorethane _______ Tetrachlorethylene ____ Toluol ____ Trtchlorethylene ____ Turpentine____ __ ____________ Xylol, coal tar naphtha--____ SSfne oxide fume ____________ __ l 2 10 10 200 200 200 200 200 15T 12 Oi J38 / TABLE III. ANALYTICAL PROCEDURES IX CURRENT USE IN INDUSTRIAL HYGIENE The substances listed in the following table are more or less commonly found in industrial atmospheres. Methods of deter mination which are suggested have all been used by laboratories in this country and found to be satisfactory. Not all of the methods listed, hp'vav^v are specific. It is assumed that the user of this table is familiar with common analytical procedures and with the general methods of sampling or collecting atmospheric impurities. For example, lead as a dust, such as lead arsenate, would be caught by impinger; lead fume from lead burning by electric precipitator; while lead tetraethyl would be collected by means of a bubbler. Differ ent rates of flow would be used in each case. MATERIAL Method of Collection Method of Determination Acetone Draw air through bubbler containing H,0. Modified iodometric**. Ammonia Draw air through H.-SO, ro tation in gas wash bottle. * Low Cone. Draw air through bnbbtar containing acidified fHrSO/i dist. water and methyl red Indicator. Continue to end point. Cone. Greater Than 1*4 Draw air through bubbler containing SO cc. of a satur ated solution of boric acid. Determine XH, by A. P. H. A. Standard Method u. Calculate XHs concentration as in ordinary acidlmetrv. Titrate with 0.023 X, HiSO, using methyl red indicator. Aniline Draw air through bubblers containing 10U H-SO. Depends- upon reaction of aniline with Br- using sodium Indigo disulfonate as an indi cator . Arsenic (dust) Draw air through Impinger containing water. Iodometric. Arsine (gas) Draw air through bubbler containing alcoholic KOH. Modified Gutzeit Benzene Draw air through nitrating add. outeriineinc or volumetric determination as dinltroben*<ne. Ref.: Air Hyg. Bull. No. 2, Part 1 (Jan., 1938), Draw afr through Indicating Equipment from (1). Instrument. \ Bromine Draw air through bubbler containing I- solution In K1 with starch. Iodometric. 13 .* 01vt?9 MATERIAL Carbon dioxide Carbon disulfide Carbon disulfide and hydrogen cutfide in pretence of each other Carbon monoxide Chlorine Chlorinated hydrocarbon*, general Carbon tetra chloride Chromic acid (mist) Method of Collection Method of Determination Draw iiir throiiyli "ahcnrltv" ifu-r removing w.iHr vii|ir on *'drlerite" and weigh. Draw nlr through bubbler coritnmlng.t buffered .X.t ii< `t > solution nml uhonolsulplinnophtlinlcln indicator. Gas-collcctlng bottles. Draw nlr through alcoholic KOH to form potassium ethyl xanthnte. Draw air through 10ft CdClj solution, then through 2,5 ft H;SO, and through 5ft acoholic KOH. Low concentrations, 10 t*> 1,500 PPM. by heat liberated from combustion with caltte n* catalyst. Concen tration on dial of a militantmeter. High concentrations. 0.05 to 1.0ft (500-10.000 PPM) use detector dc|>endinc upon liberation of Is front I-O- or color reaction with rdClnmpoulcs. Details from makers of the above equipment (b) fe) (j). Draw air through O-lolidinc reagent in special absorption tube. Draw air through 10ft KI solution. . Physical method such as ab sorption on activated char coal or by use of interfer ometer. Thermal decomposition meth od. . (As above). Compare resulting color against gtandards. Ite/.: Hig gins & Marriott. J. Am. Chem. Sor., vol. 3?. p. 3S 0917). Volumetric gas anal, method, lief.: II. S. Bureau of Mines Bulletin Xn. j;,, and 1. C. 7(H7 (IMS). Determine xanthnte lodomeirlcally. Hcf.: Matuszak, M. P.: ind. Kmc. Chem., Anal. Ed., vol. (, pp. 9S-100 (1932). Iodometric. Determine CSa ns above. Ref.: Barthclcmy, H. L.: Tubiie Chatillon Corp., Rome, Ga.. or Dlv. of Ind. Hyg., K. Y. State Dept, of Labor, SO Centre SL, New York. Ref.: U. S. Bureau of Mines, Tech. Paper SSI. Also: Drinker, C. K.: Carbon Monoxide Asphyxia, Chain. S by Sendroy. Oxford Univer sity Press, New York, 193S. Transfer sample to Kessler tube and compare n-Jih stan dards after standing. Ref.: Porter: J. Ind. Eng, Chem., vol. IS, p 730 (1926). Iodometric. Ref.: Air Hyg. Dnlletln Xo. 2, Part 3 (March, 193S). Equipment from (t)'(m). Tmplnger with approximately normal KaOH, or with elec tric precipitator. . 14 Iodometric. Ref: Bloomfield and Blum: U. S. Pub. Health Rep., No. (3. p. 2330 (192S). Determine chromate with xdtphenylcarbailde as indi cator. Ref.: Yoe, J. H.: Photochem ical analysis. 2 vols. lVitcy & Sons. S>w York. 392S-192S. 010 40 L MATERIAL Esters Ethyl bromide Ethyl chloride Formaldehyde Hydrocarbon*. general Hydrochloric acid Hydrofluoric acid Hydrogen cyanide Hydrogen ulfide Method of Collection Method of Determination Gas-coilecting bottle*. Hydrolyie with XaRJI, back titrate excess XaOH. Ref.: Patty, Yant an.l FchrenV: U. S, Pnb. Health Rep. No. 51. p. 511 (1M5). See MeBr. Draw air through bubbler containing water. (1) Zeiss portable Interfer ometer. (2) Absorption on solid ma terials, sucli as activated charcoal or silica pe lI-. Gas-collect ing bottle. Self-contained instrument* operate on the heat of com bustion principle and pive readings of the percentage of the lower explosive limits di rectly on dials. Special cali brations of the dials can he obtained depending on the application. Draw .air through glyceroljtotnsslum carbonate-water soln. of the ratio 1:1:1. Draw air through bubbler containing K01I. Draw air through bubbler* containing 0.51 KOH. Colorimetric Indicator. See also carbon disulfide. Draw air through activated alumina coated with AgCX or TbAc. Instrument nslne this method sensitive to 25-100 TPM. In strument for colorimetric method using test paper sen sitive to 0,0221 supplied by Colorimetric method using Schlfl'* soln. Also, Dcnipe method. Chapin, r.. 11.: J. tod. Knr. Chem., voi, 12, p. ats 0521). Full Information from (n). Volumetric gas analysis method K. Also. U, S. Bureau Mines I. C. 7017 (I92S). Equipment from (b) fc) fit fl>. Determine chloride ion by Volliard method. Ref.: Hel ler: Gesund- Ingenieur. vol. 55. p. 261 (19221. Chem. Abst.. vol. 27. p. 155 (1923). Distill fluoride* a* hydroftuo- slltclc acid. Titrate fluoride* .In distillate with thorium nitrate sadn. using sodium alisarine sulfonate as indi cator. . Ref.: Willard- and Winter: Ind. Eng. Chem.. Anal. Ed., vol. E. p. 7 (1922). , 1toruff nnd Abbott, (ibid), vol. S. p. 226 0325). Titrate with AgXO*. Range of SO-l.WO PPM. Equipment from CJ). Concentration 1* indicated by length of color change. Ref.: Littlefield. Yant and JVrger: U. S. Bureau M Sties. R. I. Xo. 3276 (June, 1525). . See also: Reed. 1. R.: J. Foe. Chem. Ind.. vol. 57. pp. 13-H <1S3S). Draw air through bubbler containing ]: soln. in KI with starch. IS lodometrlc. i' r* * ' Pit-. MATERIAL Lett), as duat or fume Mercury Methane Methanol Methyl bromide Methyl chloride Ethyl bromide Ethyl chloride Nitric acid Nitrogen tetroxide Oxygen Method of Collection Method of Determination Implngcr or electric precipl tator. Draw nir a gain*t ScS coated taper Lampshade detector (using SeS) available from (f) (j). Freeze vapor with dry ice. Gas-collecting bottle. Combustible ga* Indicator from (bj <c) (j) (1). Flame Safety Lamps from (b> (c) 0). See Air Ilyg. Bulletin Xo. 2, Part 6 (153S). Compare color change against standards. Ref.: Xordlandcr. B. W.: Ind. Eng. Chem., vol. 15, p. 522 0322). Ref.: 1'rastr: J, Ind. Hyg. A Ton.. Vol. 1C, p. 67 (1934). Vol. gas anal, method H. Ref.: Pone, Currie. U. S. Bureau Mines Buii. Xo. 331 (1530). See also: IT. S. Bureau Mines 1. C. Xo. 33 (1337). Draw air through bubbler containing water. Collect sample In partly evacuated bottle. Absorb McOH in distilled water by thorough agitation of water In the bottle. Discussion. Ref.: Wright. L. O.: Ind. Eng. Chem., vol. 19, p. 750 (1927), Oxidize to formaldehyde and determine colorimetricaliy (Denlgc method) **. See also: Formaldehyde, Chapin's method. Determine by modified Den lgc method. Ref.: Schrenk and Yant: U. S. Bureau Mines, Personal communication (1933). Collect samples by Hg dis placement. Analyse volumetrlcally by slow combustion with a white-hot platinum coil and large excess of O*. Ref.:Sayors, Yant, Thomas, and Berger. U. S, Public Health Bull. Xo. 155 (1929). For MeBr see also: Busbey and Drake: Ind. Kng. Chem.. Anal. Kd., vol. 10, p. 590 (1935). Draw air through an acidi fied S'* 11*0; bubbler followed by * or 3 KOH H;0- bub blers. Draw air through liquid air trap. Determine X,Os with phenolsulfonic acid by A. P. If. A. Standard method*1. Ref.: Drinker and Snell: J. Ind. Hyg- & Tox., vol. 20, p. 321, (1935). Oxidize as above and deter mine by nitron acetate method. Ref.: Coltman: J. Ind. Hyg. & Tox.. VOl. 20. p. 25$ (193S). Gas-collecting bottle. 16 Vol. gas anal, method M. IT. S. Bureau Mines I. C., 7017) (1935). 01042 1<e. MATERIAL Oaone Phenol Phosgene Phosphorite trichloride Radioactive substances Sulfur chloride Sulfur dioxide Sulfuric acid (mitt) Toluol Trtehlor* ethylene Method of Collection Method of Determination Partially evae. bottles con taining starch-Kl solution. In presence of XjO,, collect by liquid air. Draw air through bubbler containing XaOH solution. Draw air through bubbler containing aniline water sat urated with diphenyl-urea. Draw air' through bubbler containing Br water. Physical methods using elec troscope. Draw air slowly through HXOj solution of AgXO>. Draw air through I--K3 starch solution. Partially evacuated bottle containing J-KI starch soln. Draw air automatically through acid H-Ot- Draw air through XaOH In impingcr. Draw air through fuming HXCV Draw air through specially designed absorption tube containing absolute EtOH. Combustion method for chlorinated hydrocarbons. Indomctrlo Ref.: Coltman and McPher son. J. Jnd. Hyg. & Tox.. vol. 20, p. $ (193S). Determine colorimetrically . Kilter off precipitate of di phenyl* urea in tared Gooch crucible, dry and weigh, dis solve dlphenyl-urea with alcohol dry, and . rwiigh. Ref.: Yarn, et al.: Ind. Eng. Chem.. Anal. Ed., vol. $, p. 10 (1930). Boll and determine P by colorimetric molybdate meth od **. Ref.: Schwarts, et al.: J. Ind. Hyg. ti Tox., vol. IS. p. 302, tt, 431 (1333), Dissolve the precipitated AgCl in NH,OII again precipitat ing with H.VOs". Iodometrlc. Ref.: Griffin and Skinner, Ind. Eng. Chem., vol. U. p. tOt (1933). Solution from sampling bottle brought to same intensity as a blank by addition of stan dard iodine solution. Ref.: U. S. Bureau Mines, R. I. Xo. 300$ (1930). Conductivity method with recorder. Ref.: Thomas: Ind. Eng. Chem., Anal. Ed., vol. f, p. 153 (1932). Acidify with HCI and deter mine sulfate as !3aSQ. Similar to TJ. S. Bureau Mines method for C<H< using KOH Instead of XaOH. Determine colorimetrically *n reaction with pyridine and SOfi sodium hydroxide. Ref.: Barrett: J. Ind. Hyg. & Tox., vol. IK. p. 511 (1930). Air llyg. Bulletin Xo. 2, Part 3 (March, 1933). 17 0 TABLE IV. FIRMS SUPPLYING EQUIPMENT MENTIONED IN THIS BULLETIN (a) Bauseh & Lomb Company Rochester, New York. (b) E. D. Bullard Company 275 Eighth Street, San Francisco, California. (c) Davis Emergency Equipment Co. 55 Van Dam Street, New York. New York. (d) Detroit Air Meter Company Detroit, Michigan. (e) Fisher Scientific Co. 709-717 Forbes Street, Pittsburgh, Pennsylvania. (f) General Electric Company 1 River Rd., Schenectady, New York. (g) E. V. Hill Co. 179 West Washington Street, Chicago, Illinois. (h) Illinois Testing Laboratories, Inc. 420 N. LaSalle Street, Chicago. Illinois. (i) Maealaster Bicknell Co. 171 Washington Street, Cambridge, Massachusetts. (j) Mine Safety Appliances Company Pittsburgh, Pennsylvania. ' (k) Pulmosan Safety Equipment Corp. 176 Johnson Street, Brooklyn, New York. (l) Union Carbide Company--Linde Air Products, Inc. 80 East 42nd Street, New York, New York. (m) Willson Products, Inc. Reading, Pennsylvania. (n) Zeiss Company 485 Fifth Avenue, New York, New York. 18 0i0 4 4 References 1. Report of National Silicosis Conference. U. S. Dept. Labor, Div. Labor Standards, Washington, D. C. 2. Industrial Code. Bulletin No. 33, New York State Dept. Labor. Rules Relating to the Control of Silica Dust in Rock Drilling (May, 1937). 3. Tentative Recommended Good Practice Code and Handbook on the Fundamentals of Design, Construction, Operation, and Maintenance of Exhaust Systems. American Foundrvmen's Association, 222 W. Adams Street, Chicago, Illinois. Price S4.00. 4. Yaglou, C. P.: The li<.tvd Thermometer Anemometer, J. Ir.d. II;,*g. & Tox., 20: 497, 193S. 6. Brown, C. E.; and Schrcnk, H. H.: A Technique for Use of the Impinger Method.. U. S. Bureau Mines, I. C. 7026, June, 1938. 6. Drinker, P.; and Hatch, T.: Industrial Dust. McGraw-Hill Book Com pany, New York, New'York. Price $4.00. 7. American Society of Mechanical Engineers: Fluid Meters. 4th Edition, 1937. 29 West 39th Street, New York, New York. Price $3.00. 8. Barnes, E. C.; and Penney, G. W.: An Electrostatic Dust Weight Samp ler, J. Ind. Hyg. & Tox., 20: 259-265, 1938. 9. The Vapor Pressure Method for Estimating the Concentration of Organic Vapors, such as Gasoline, in Air. U. S. Bureau Mines, Tech. Paper No. 87 (1916). This Bulletin is out of print. . 10. Scott, W. W.: Standard Methods of Chemical Analysis. 4th Edition. Van Nostrand Company, New York, New York. 1927. 11. Standard Methods for the Examination of Water and Sewage. 9th Edition, 193G. American Public Health Association, New York, New York. 12. Zhitkova, A. S,; Kaplan, S. D.; and Flcklen, J. B.: Some Methods for the Detection and Estimation of Poisonous Gases and Vapors in the Air. A Practical Manual for the Industrial Hygienist. Service to Industry, Box 133, West Hartford, Connecticut, pp. 198. 13. Cook, W. A.; and Coleman, A. L.: Determination of Solvent Vapors in Air by Means of Activated Charcoal. J. Ind. Hyg, & Tox., 18: 194-210, 1936. 14. Cook, W. A.: The Industrial Hygiene Laboratory. J. Ind. Hyg. & Tox., 18: G23-G36, 1936. 15. Flury, F.; and Zemik, F-: Schfidliche Gase. Julius Springer, Berlin (1931). 16. Gas Chemist's Handbook. American Gas Association, New York, New York. Revised from time to time. 19 0ivJ45 AIR HYGIENE FOUNDATION OF AMERICA, Inc. Preventive Engineering Series, Bulletin No. 2, Part 8 Routine Sampling for Control of Atmospheric Impurities JS' mr PITTSBURGH, PENNSYLVANIA i JANUARY. IDS') 0i026 ROUTINE SAMPLING FOR CONTROL OF ATMOSPHERIC IMPURITIES* The control anti sampling of atmospheric contaminants in routine pro duction operations ace matters with which plant and mine managers today are definitely concerned. A few years ago, such control was more or less limited to firms that were losing a valuable product through faulty operation, or to those that knew that neglect of dust, fly ash, or gas control meant a health, nuisance, or explosion risk, either to themselves or to their neighbors. Today, however, twenty-eight states (Table 1) have industrial hygiene bureaus whose function it is to advise industry on the control of its indus trial hazards, while many insurance companies are well equipped to investi gate industrial hygiene problems from both the engineering and medical aspect.f Baltimore, .Maryland; Detroit, Michigan; Kocfci'ord, Illinois, and St. Louis, Missouri, are reported as having industrial hygiene bureaus. The formulation of codes of good practice is a trend of comparatively recent date. Underwriters' codes covering fire and explosion risks have been available for some years. To them is now being added information, such as the National Silicosis Conference's recommendations on dust counts in relation to silicosis prevention1, New York State's codes on silica dust control in rock drilling-', and the American Foundrymen's Association's codes on exhaust systems for general foundry work*. The American Standards Association has a committee which, it is understood, will suggest, from time to time, safe concentrations of various contaminants. Some states now furnish, on request, a list of maximum safe concentrations which they recommend for various dusts and gases. (The Massachusetts list is given in Table 2). In some instances, as in Wisconsin and New York, the codes have been made legally binding. Other states have issued the lists merely for the guidance of persons who ask how clean the air of a workplace should be. It is not our intention to criticize these codes. The concentrations gen erally are not fixed by accepted medical standards, but represent zones or ranges arrived at by practical trial. Obviously, the figures must be revised from time to time as medical knowledge on the subject progresses, and especially as industry improves its housekeeping. The purpose of this bulletin is to give in brief form descriptions of apparatus and methods which are actually being used by one or more labora tories in appraising the environment in which men work. In making such appraisals, two distinct steps are involved: first, measurement of air cur rents, and second, estimation of impurities. The resulting data can then be applied to the design of control equipment or to the appraisal of the results brought about by such equipment. Air Movement Low Air Velocities Air velocities in workplaces generally are below 100 F. P. M. (feet per minute). Exceptions are warm places where fans or air blasts are used for their cooling effect, mine shafts and haulage ways used as ventilation ducts, * This Is nnrt S In tin- series Issued us lltdlelin Xr>, C, timl.-i the ausnlccs of ttie Preventive Kntiineeiim; Committee. t Detailed Information on iii'inum-fr-mmi'any activities can te Pad from .\incriean .Mutual Si!- N-.i tli Mieldinin .Wetme. Cliivuuo. ami the association of (..'as* mtlty & Surely Kxeciitiv- s. i.'i Jolm street, New York City. 1 0i 02 and atmospheres within the immediate zone of exhaust hoods. Low veloci ties must be measured by special instruments as they are below the range measurable by pitot tube, venturi meter, or vane anemometer. Smoke Combs: In schoolrooms or auditoriums, air conditioning' engineers usually study air distribution by the use of smoke. Smoke from tobacco is of too fine a tex ture to serve as well as the coarser smoke made from hygroscopic substances. Titanium tetrachloride smoke tubes for testing work are safer to use and give satisfactory results. They can be made as follows: glass serum ampoules, costing about S2.40 a gross, are filled with 0.10 cc. of titanium tetrachloride. The ampoule is then sealed and the neck pniw out about 0.25 inch, dipped in water-glass as an adhesive, and about an incli of wicking pushed over the neck. The vicking used in a sulfur lamp is satisfactory. Since the compound reacts with air and becomes vitiated, the ampoules should be sealed promptly. When a smoke test is desired, the neck of the ampoule is broken by lay ing it on a hard surface and pressing down with the thumb; the wicking will protect the thumb against cutting with the glass. The TiG!4 runs out 'into the wick and smoke immediately results. . A smoke gun can be made by soaking pumice with titanium chloride and packing in small glass tubes, such as calcium chloride drying tubes. Air is then blown through the pumice by means of a rubber aspirator bulb. When not in use, the ends of the tube should be closed with stoppers. Titanium tetrachloride is carried by most supply houses and costs about 75 cents per quarter pound, which is enough to fill a large number of ampoules. Smoke tubes and smoke guns in convenient form arc supplied by (g), (i).* Thermo-anemometer: C. P. Yaglou lias recently developed4 a simple thermo-anemometer capa ble of measuring velocities between 10 and 6,000 F. P. M. The temperature of the wire is only 10" to 40' above air temperature and is indicated on an ordinary thermometer around the bulb of which the wire is wound. Small dry cells furnish the heating current and the voltage is regulated by moans of a rheostat. These auxiliaries are assembled in a small box. Readings to be taken are temperature of heated and of unheated thermometer and voltage used. The velocity is read off a table or chart, or computed from an equation. By varying the voltage, any velocity can be measured with an accuracy of 98f'<. A unit which is vest-pocket size and sensitive to very low velocities will be available shortly. This instrument compensates for variations of air density due to tem perature changes, and is negligibly affected by humidity, radiant heat, and convectional currents which it causes. It is particularly useful for measur ing air movement in rooms and in exploring "point" velocities in front of exhaust hoods, because it offers negligible obstruction to airflow. Its disadvantages are that it is not direct reading, it requires a short time for the heated thermometer to reach equilibrium, and its readings must be corrected for partial stem immersion when used inside small pipes. The instrument is too new to have had any widespread field use. It is supplied by (m). (*), (b). etc.. refer to firm* *uf>ftlylu equipment. For full list nnd niUlrexsox, *ec Tabic 4. IS. of this bulletin. o / High Air l'thelites In the effective '/one of exhaust hoods, the* nmi/ntmti velocity is about 150-200 feet per minute extending on up to 1,000 V. P. M. or more at the face of the hood. It is often desirable to increase the hood's effectiveness by changes in design. Velocity contours can be sketched out as indicated in Figure 1 of Bulletin No. 2 of this series. For measurements in such velocity ranges, Yaglou's thermo-anemometer device is well suited. Vane Anemometer: In the ease of large hoous, such as those placed over electroplarirg or vats, either a velometor or a small vane anemometer is convenient. For exploring small hoods, however, both instruments take up too much space and interfere seriously with the normal air currents which the hood is in tended to form. Furthermore, the portable vane anemometer is a delicate instrument; it needs frequent calibration, and is easily damaged by corrosive chemicals, by dusts, and even by steam or water vapor. It is advisable to use the vane anemometer only when no corrosive substances are being generated. Velorooter: ' This is a direct-reading device consisting of a double-pivoted vane which is deflected by impact against the air stream. A pointer attached to the vane indicates the velocity on a calibrated scale. All moving parts are housed in a small case. For low-range readings, the air enters the meter directly through a small port and the whole case must be placed into the air stream. For high-velocity readings, various size orifices are placed within the port to reduce vane deflections. For measurements of velocity inside pipes, a double-pitot tube is provided and connected to the meter ports by 1 rubber tubing. Velometcr readings are instantaneous, but several must be taken to insure a good average. One can measure velocities of several thousand feet per minute, as in exhaust ducts, or a few hundred feet per minute in the vicinity of largo exhaust hoods. Although a dust-filter attachment is now available for keeping the mechanism dean, it is questionable whether it is i! wise to use the instrument in any but clean air. The device is supplied by (h). A less accurate, but very practical instrument, known as the "Grillometer," has been developed for measuring air velocities through grills. It is a torsion device and is direct reading. It is supplied by (d). Pitot Tube, Venturi Meter and Orifice Meter: While these three instruments measure flow rather than velocity, they are too well known to need any description. The pitot tube has-long been the sole "self-standard" instrument and the most used for determining flow in pipes or ducts, for making traverses, and the like. Recording venturi meters and orifice meters for measuring the flow of fluids (liquids and gases) are sold today by several firms. In the construction of exhaust systems, it is well to consider the permanent installation of a venturi, or an orifice meter, or even a recording meter near the exhaust fan. The A. S. M. E. book" gives full dotaits of the basic principles, design, and use of these instruments. I3 I 01029  Atmospheric Impurities For the purposes of selecting sampling and control methods, in relation to exhaust systems in plants or mines, several distinct types of atmospheric impurities must be considered: A. Relatively insoluble mineral dusts, such as silica, many silicates, and fly ash. B. Relatively soluble mineral dusts, like calcite (limestone). C. Finely-divided fume substances that are difficult to catch in water. Examples are lead, lead oxide, and zinc oxide. D. Dusts that may be affected by water. Examples are flour, leather, a.,J ovap. Many of these dusts are explosive if mixed with air. E. Aqueous mists, such as chromic acid entrained from electroplat ing baths, or condensate from vats of various sorts. F. Water-soluble gases, such as hydrochloric acid. Such soluble gases usually contain mist as well as gas, the proportions depending upon local conditions. G. Gases or organic vapors, like benzene, soluble with difiiculty. These react slowly with most liquids but may be adsorbed readily by solids, such as activated carbon. Impinger: Instruments for Dust Sampling The impinger is commonly used in sampling dusts, like classes A, B, and occasionally mists, like class E, and some gases, like class F. It is definitely unsuited to class Cl gases, like chlorine or organic vapors. It is not efficient against fincly-dividt-d fume substances. Class C, such as iead or zinc oxide, and rarely is it suited to sampling organic dusts, like class D. The impinger3 consists in a flask in which a tube with tapered end is held at a fixed distance from an attached glass plate or from the bottom of the flask. Air is drawn through the tube and the impurities are trapped in the liquid in which the tip of the tube is immersed. Suitable fractions of the dusty suspension are then withdrawn and the dust particles counted under the microscope or the total dust concentration is estimated by the usual analytical procedures. . The impinger is now made in two sizes, one sampling at one cubic foot per minute, and the other at three to five liters per minute. Used originally with water as the dust-catching medium, it is now common practice to use other liquids, such as isopropyl alcohol, limitation depending upon volatility of the liquid and its readiness to foam. The suction device for the impinger can be run by a compressed-air actuated ejector or by a pump driven by an electric motor. The midgetimpinger equipment is much smaller and can be run by hand. It is lighter than the large unit. Furthermore, it is hand operable, all of which makes it particularly suited to mine-air sampling. Both types of impinger were developed by the U. S. Bureau of Mines, which recommends both for general use in measuring dustiness. Inipingers, either large or midget size, are supplied bv <e), (i), (j), (k), (m). For sampling finely-divided fume substances, like lead, which are well dispersed, a small electric precipitator gives accurate results. While the complete precipitator assembly is not expensive, it requires a transformer 4 010 3 0 weighing some 15-25 pounds to raise the voltage to 15,000 to 25,000. Con struction details with a list of equipment needed for making such precipi tators are given in Drinker & Hatch. This equipment is available from (m). Barnes &, Penney, of the Wcstinghouse Electric & Manufacturing Com pany, have described3 a small precipitator which should be well adapted to field use and is now available from (j). The high-tension side of this newtype precipitator is grounded, making it more practicable for general field use. Sampling Dust for Direct Microscopy and Counting The purpose of taking and counting dust samples is to determine how much the dustiness of the air in question departs from some arbitrary figure or accepted standard. The grao-sample instruments, vis., the konimetei (j), the Bausch & Lomb dust counter (a), (m), and the Owens jet dust counter (e), give useful indications of changes in dustiness. All three instruments are light and are operated entirely by hand. However, they do not imitate the impinger in any way, so that it is impossible to convert impinger to grab-sample counts. The reason why such conversions are faulty is because the grab samplers favor dust sizes below the size-particie range for which the impinger technic is best adapted. A skilled technician can count about twelve impinger samples in a day. It is easy, however, to compare some thirty to forty grab samples in a short time. In practical field work with the grab sampler, the effectiveness of dust-control equipment or methods can thus be demonstrated rapidly. Explosive Dusts Most explosive dusts are affected by water, while some of them, espe cially organic dusts, such as Hour, are difficult to wet. Explosive concentra tions of ail such dusts are very high (10-15 gms./m3) as compared with dust concentrations of hygienic significance (0.5 gms,/m3), so that explosive dusts are determined by weight rather than by count. Air is drawn through a weighed paper extraction thimble and the increase in weight caused by the dust from a known volume of air is noted. An objection to this procedure is the trouble and time required to equilibrate the paper thimble against the moisture in the air. This objection, however, is not serious if the weight of the dust sample, as in the case of explosive dusts, approximates that of the thimble. It should be remembered that in sampling explosive dusts one must use a suction device that avoids the chance of electric sparks. Quantitative' Analysis In the case of all dusts, classes A, B, C, and D, the estimation of the sample taken from the air can be made by counting representative fractions under the microscope, or the sample can be analyzed by appropriate chemi cal methods, or the material can be weighed. The large impinger and the electric precipitator are equally well adapted to either procedure; The mid get impinger collects, in reasonable sampling time, a relatively small amount of dust, but enough for counting. Dusts, like silica, that are troublesome to determine chemically, are generally counted, while those like lead, manganese, and cadmium, are determined chemically. In places where composition of the dust and the particle size remain 5 0 i 0 31 substantially the same day after day, it is possible to estimate roughly dusti ness in impingor samples from the turbidity of the dusty emulsions. Such estimates can be made in Xessler tubes, by tyndallmcter'h or by an adapta tion of the turbidity methods commonly used in water analysis. Light-Field vs. Dark-Field Countins For routine control work, the relative advantages of these two methods of counting dust samples (no matter what sampling instrument is used) are unimportant. It is immaterial which method is used. If tire person doing the counting feels that the iight-field set-up is hard on his eyes, or the mag nification too low, t>y 'll means he should try the dark-fie'd method. On the other hand, if he is using the impinger and wishes to copy in exact detail the procedure recommended by the U. S. Public Health Service, then iightfield counts must be made. The Bureau of Mines recommends a micro-pro jection method for impingcr counts'*. The konimeter, recommended by the Bureau of Mines for control sampling, is used in South Africa, where it originated, with dark-field, while the Bausch & Lomb counter is.available with dark-field only. Owens samples can be counted by either light- or dark-field. Gas Sampling Gas concentrations commonly met in sanitary air analysis are very low. Concentrations that men may breathe usually are given in parts per million by volume (P. P. M.), or in milligrams per liter, or per cubic meter under specified temperatures and pressures. Some gases and vapors, notably carbon monoxide, hydrogen sulfide, and mercury, in minute amounts, give strong chemical reactions which makes possible rapid estimations and still better, continuous records of pollution. However, the great bulk of gases and vapors from organic solvents, such as benzene, carbon tetrachloride, and carbon disulfide, cannot be caught effi ciently unless sampled at slow rates, such as Vt to X liter per minute. Some of them, such as benzene, can be absorbed directly in special solvents or adsorbants, like charcoal or silica gel, or can be converted into another compound which can then be estimated by an appropriate method. The greatest difficulty in estimating organic vapors in air occurs when mixtures of vapors are present. Unfortunately, this is all too often the case. Then, the devising of short cuts in itself offers a major problem, but local conditions sometimes permit the approximations of the proportions of the several ingredients in the collected sample and calculation of the total by estimating only the most easily-determined single constituent. Condensation The general availability of "dry ice" (temperature = --79" C.) makes convenient the routine collection and estimation of volatile compounds, like gasoline, for which liquid air (temperature = --192" C.) formerly was used. A convenient cooling mixture is made by pouring ethyl alcohol or gasoline on cracked dry ice. The condensation apparatus is then immersed in the cooling mixture. Liquid air is available in most large cities and offers a convenient cooling medium, but it should be remembered that it forms explosive mixtures with inflammable dusts or gases. 6 Vapor-Pressure Measurements If only one substance 5s present--ami that in a high degree of purity-- measurements of concentration can be made conveniently and quickly by condensing the vapor with the dry-ice mixture and then estimating the con centration by the Burrell-Jones vapor-tension method1'. This procedure is not in common use in industrial hygiene problems and needs further study. Routine Sampling ant! Recording of Air Impurities If control equipment has been installed, samples should be taken period ically for check-ups. This is 'He best way to tell whether the equipment is functioning as it should. If concentrations obviously are high, it is usually a waste of time to take the sample and to estimate it. For instance, a leaky elevator in a crushing plant or a defective rattler or an unhooded swing grinder in a foundry may cause such high dust concentrations that an impinger sample will be turbid in a few minutes. Little is gained by going through the sampling routine in such cases, unless one wishes to have records before and after repairs have been made. Today, many plants operate crushing units and other dust producers at night to take advantage of reduced power rates and to stagger employment over twenty-four hours. During the night shift, dust inspections can be made rapidly, using nothing but the beam from an ordinary flash light to detect dust leaks. In the case of some gases and vapors, one's sense of smell often permits detection of gas concentrations which exceed desirable limits. Such a test - is quite unreliable unless one returns frequently to clean air or carries with him a respirator with an activated charcoal cartridge through which he takes several breaths before attempting to gauge the strength of the odor. One becomes used to even such dangerous or disagreeable odors as hydrogen sulflde in a few monments and it is, therefore, risky to estimate their strength by smell. Such crude tests do not take the place of regular sampling technic. How often the routine samples should be taken depends entirely upon local conditions. In some places, they are taken daily, while in others, several times a year is enough. It is well to play safe and to take them too often rather than too seldom. The men quickly become used to such sampling and pay no attention to the procedure. Obviously, the sooner'the sampler has the man's interest in his results, the better will be the outcome. It is com mon for the workmen to ask what the results are and to see to it that the samples in their particular departments are satisfactory. ' We know of one mining company whose concentrating plant is equipped for the taking of monthly dost samples. Various sampling stations have compressed air piped to convenient points and each station has an arrange ment for holding the hnpinger bottles. In this plant, it is usual for one operator to take, at the same time, samples on four floors of a single building. Samples should be taken wherever men work. It is a mistake to ignore places where one believes that there is no dust or gas. The samples are about the only proof that the employer can bring forth that he has taken proper precautions to prevent a disease, such as silicosis or a chronic poison ing from benzol. The mere statement that he or anyone else thought the atmosphere sufficiently dean is not enough. It is advisable to plot the results of periodic samples with the days or 7 months as abscissae and the concentrations or dust counts as ordinates. Such plots can be made conveniently on a master sheet, comments noted on the plot which is blue printed with each new hatch of samples, and the prints given to the appropriate departments. ' Continuous Records It is obvious that continuous records of either dust or gaseous impuri ties are more informative than occasional or intermittent records. It is possible to take continuous records of relatively heavy pollution, as in the stacks of power pianos, and also of ordinary atmospheric pollution which is of relatively low concentration. It is understood that Mine Safety Appli ances Company, Pittsburgh, will offer shortly a dust recorder that may prove useful in common sanitary air analyses. As noted previously, gases that give strong chemical reactions, particu larly those involving pronounced heat or color changes, are suited to estima tion by continuous recorders. A carbon monoxide recorder (j), which meas ures the heat liberated by a catalytic combustion reaction, is in wide use today. A recorder for mercury vapor (f) has also found considerable appli cation. The applicability of recorders in sanitary air analyses has hardly been touched upon and it is reasonably certain that others will be developed as need arises. Photographs It is common practice in power-plant operation automatically to take photographs at regular intervals of the smoke escaping from the stack. Such records provide useful evidence if the plant is accused of faulty operation. Occasional photographs of various plant and mine operations are often of greater practical usefulness than are records of dust counts or of gas or vapor concentrations. AS an exhibit on the company's bulletin boards, photo graphs are effective warnings to the men to clean up. In routine sampling, they should certainly be taken occasionally and incorporated as part of the inspector's report. . i J i 1 i 8 01034 TABLES I. Summary of Industrial Hygiene Activities in States and Cities in the United States from June, 1033. List fur nished by the Division of Industrial Hvgier.e, U. S. Public Health Service, Washington, D. C. II. Concentrations of Inflammable Vapors, Suggested by the U, S. Bureau of Mines, and Limits for Practical Control, Suggested by the Massachusetts Division of Occupational Diseases. III. Analytical Procc'dures in Current Use in Industrial Hygiene. IV. Firms Supplying Equipment Mentioned in this Bulletin. 9 / / O' V a% t 1 3 3 < H t 0i036 { t 1 l n 01037 TABLE II CONCENTRATION'S OF INFLAMMABLE VAPORS, SUGGESTED BY THE U. S. BUREAU OF MINES, AND LIMITS FOR PRACTICAL CONTROL, SUGGESTED BY THE MASSACHUSETTS DIVISION OF OCCUPATIONAL DISEASES CAS OR VAPOR Lower Limit, by Volume *,i Maximum Concentration Suggested by Massachc-...*** GAS OR VAPOR P. P. M. Ammonia ..................................... -...... Acetaldehyde .......................... .... Acetone ....................................-.......... Acetone (turbulent mixture)..... Acetylene ......... Acetylene (turbulent mixture)..., Benzene ........................................ Benzine .......... Blast /uniacr pns ---------------------- Butane ...... Butyl acetate (30* C.) -----------.... Carbon disulfide .................... Carbon monoxide .......... Cylclohexanc ...................... Dirhlorethylene ........... -........-.... . Ethane ....................... -- - Ethyl acetate ........... Ethyl alcohol ............... -.......... Ethyl bromide ...................... .......... Ethyl chloride ............................... . Ethyl ether ............................ -......... Ethyl formate .......... - Ethvl nitrite ................... ..... --.----- Ethylene ..........................-........ ........ Ethylene dichlorifle ............. .... ..... Ethylene oxide ...............--.......... Furfural (125' C.) ............ - Gasoline ......................... -....... --..... Hydrogen _____ 16 4 3 2.5 3.0 2.3 1.4 1.1 35 1.9 1.7 1.0 12.5 1.3 10 3.2 2.5 4 7 4 1.7 3.5 3 3.0 6 3.0 2 1.4 4.1 Illuminating Gas ............. 5.3 Methane .............................. 5.3 Methane (turbulent mixture)___ 5.0 Methyl acetate .................. 4.1 Methyl alcohol ........................... Methyl bromide ................................... 33.5 Methyl chloride .............................. 8 Methyl cyclohexane ......... 1.2 Methyl ethyl ketone ______________ 2 Methyl formate ............... ............... 6 Natural gas --............ 4,8 Pentane __--............ ................. -..... 1.45 Propane ..................... ..................... -- 2.4 Ptouyl acetate ................ Pyridine (70* C.) ----- 2.0 1.8 Toluene ........................ 1.4 Vinyl chloride ... ...................... Water gas --............ ...................... fl to 9 Ammonia ..................................... 100 Amyl acetate ..----------- ------ ------ 400 Aniline --..................................... Arsine ....... ........................................ 5 1 Benzol __________ ___ ___ _______ 75 CAdmiuni .................................. Butyl acetate ...... ........................ Carbon bisulfide ............... ............ Carbon monoxide ..... .................. Carbon tetrachloride ................. Chlorine __________ ___ _________ Chlorodiphenyls ........... ................ Chtoronapluhalenes --........... . Chromic acid -...................... ...... Dlchlorbcnzene .*.......... ................ Dichlorethyl ether__ ____ ._____ Ether. 0x1* 400 15 100 100 1 1* 1 to 51 0.1* 75 15 400 Ethylene dlchlorfde __________ 100 Formaldehyde ........... --__ ________ "0 Gasoline ________ 1000 Hydrochloric acid ................... 10 Hydrogen cyanide ..................... 20 Hydrogen fluoride ___________ 3 Hydrogen sulfide___......_________ 20 Lead __________ ______ __________ 0.15* Mercury ....... ............ ......... ............. 0.1* 7 Methanol _______________ 200 Monochlorbenzene __________ ,__ 75 Nitrobenzene __________________ Nitrogen oxides ...................... Ozone _________________ Phosgene _________________ Phosphine Sulfur dioxide ____________ Tetrachlorethane ___________ Tetrachtorethylene .................. 4 Toluol ________________ Trlchlorethylene ______________ Turpentine ____________ Xylol, coat tar naphtha________ S5inc oxide fume_____________ 5 10 1 1 2 30 10 200 200 200 200 200 15* * Milligrams/cu. meter 12 0iJ38 TABLE III ANALYTICAL PROCEDURES IX CURRENT USE IN INDUSTRIAL HYGIENE The substances listed in the following table are more or less commonly found in industrial atmospheres. Methods of deter mination which are suggested have all been used by laboratories in this country and found to be satisfactory. Not all of the methods listed, hpwwv are specific. It is assumed that the user of this table is familiar with common analytical procedures and with the general methods of sampling or collecting atmospheric impurities. For example, lead as a dust, such as lead arsenate, would be caught by impinger; lead fume from lead burning by electric precipitator; while lead tetraethyl would be collected by means of a bubbler. Differ ent rates of flow would be used in each case. MATERIAL Acetone Ammonia Aniline Arsenic (dust) Arstnc (gam) Benzene Bromine Method ot Collection Draw air through bubbler containing H-O. Draw air through H,50, so lution in gas wash bottle. * Low Cone. Draw air through bnbblcr containing acidified <H;SO,) dist, water and methyl red indicator. Continue to end point. Cone'. Greater Than 1% Draw air through bubbler containing 50 cc. of a satur ated solution of boric acid. Draw air through bubblers containing 10U 11-SO,. Draw air through impinger containing water. Draw air through bubbler containing alcoholic KOH. Draw air through nitrating acid. Draw air through Indicating Instrument. Draw air through bubbler containing I- solution in KI with starch. Method of Determination Modified iodometrlc Determine XH, by A. p. H. A. Standard Method . Calculate XH- concentration as in ordinary acid linetry. Titrate with o.o;; X. Jf-SO, using methyl red indicator. Depends- upon reaction of aniline with Br. using sodfum indigo disulfonate as an indi cator ". Iodometrlc. Modified Gutzelt, vwiwi iii7suv vi vviumeinc determination as dlnitrobenzene. Ref.: Air Hyg. Bull. No. 2, Part 1 (Jan., 1938). Equipment from (j). Iodometrlc. 13 MATERIAL Carbon dioxide Carbon disulfide Carbon disulfide and hydrogen sulfide in presence of each other Carbon monoxide Chlorine Chlorinated hydrocarbons, general Carbon tetra chloride Chromic acid (mist) Method of Collection Draw ihronirh .1 ri! .tfler removing sv-i 1 tx-11 vapur on "drlerUe" and weigh. Draw nil' through bnhMrr ronir,:ni1U-.UiifLc ri-it NuIH't V solution and phouolsul|ilKinophthnleiu indicator. Gas-collccting bottlc-s. Draw nir through nlcohnlir KOH to form potassium ethyl xanthate. ' Draw air through 10% CdClsolntion. then through 2.5% H-SO, and through 5% acohnlie KOH. Low concentrations. Id to 1,500 PPM, by heat liberated from combustion with Unp- cailte ns catalyst. Concen tration on dial of a mflllam- meter. High concentrations. 0.05 to 1.0% (500-10,000 PPM) use detector depending upon liberation of I3 from l.O. or color reaction with PdCl, ampoules. ' Details from makers of the above equipment <b) fe) (j). Draw air through O-lolidine reagent In special absorption tube. Draw air through 10% KI solution. . Physical method such as ab sorption on activated char coal or by use of Interfer ometer. Thermal decomposition meth od. (As above). Method of Determination Compare resulting color against standards. Ref.: Hig gins Sl Marriott, J. Am. Chem. Soc., vol. 52, p. 3S o9ii). Volumetric gas anal, method. Ref.: 11. S. Bureau of Mines Ttullctln Xo. j;., and I. C. 7(117 (li'SS). Determine xanthate lodometrically. Kef.: Matusaak. M. P.: ind. Kng. Chem., Anal. Ed., vol. 4, pp. SS-120 (1932). lodometrlc. Determine CS, ns above. Ref.: Barthclemy, H. L.: Tubiie Chatillon Corp., Rome, Ga., or Dlv, of Ind. Hyg., X. V. State Dept, of Labor, SO Centre St., New York. Ref.: U. S. Bureau of Mines. Tech. Paper 5S2. Also: Drinker, C. K,: Carbon Monoxide Asphyxia. Chapt. S by Sendroy. Oxford Univer sity Press. New York, 1933. Transfer sample to Xessler tube and compare with stan dards after standing. lief.: Porter: J. Ind. Eng. Chem.. vol. IS, p 730 0920). Jodomefrtc. Ref.: Air Hyg. Bulletin Xo. 2, Part 3 (March, 193SL Equipment from (1) (m). Implngcr with approximately normal KaOH. or with elec tric precipitator. . 14 Iodometric. Ref: Bloomfield and Blum: U. S. Pub. Health Rep., No. 43. p. 2330 (1923). Determine chromate with xdlphenylcarbasldc os indi cator. Ref.: Toe, J. H-: Photochem ical analysis. 2 vois. tvilcy & Sons, New York. 192S-1929. OiOiO material Esters Ethyl bromide Ethyl chloride Formaldehyde Hydrocarbons, genera! Hydrochloric acid Hydrofluoric acid Hydrogen cyanide Hydrogen ulfide Method of Collection Method of Determination Gas-collecting bottles. Hydrolyze with NnOTf, bad; titrate excess XnOH, Ref.: Pattv, Yam ami Pclirenk: U. S. Ptib. Hc:<i:!i Rep. No. 51, p. ill (1P35). See MeBr. l'niw air through bubbler containing water. fl) Zeiss portable interfer ometer. (2) Absorption on solid ma terials, sucli as activated charcoal or silica m 1t-\ Gas-coliectinjr bottle. Self-contained inslntments operate on tbe heat of com bustion principle and give readings of the percentage of the lower explosive limits di rectly on dials. Special cali brations of the dials can be obtained depending on the application. Draw .air through glycerol potassium carbonate-water sotn. of the ratio 1:1:1. Draw air through bubbler containing KOH. Draw air through bubblers containing O.ST KOH. Colorimetric Indicator. See also carbon disulfide. Draw air through activated alumina coated with AgC.X or PbAc. Instrument using this method sensitive to 25-4VQ PPM. in strument for colorimetric method using test paper sen sitive to fl.OSTr supplied by Colorimetric method usin Schift's soln. -Also, Denig method. Chapin, R. M.: J. Ind. Eng. Chem., vol. 13. p. tlSil). Full Information from (n>. Volumetric gas analysis method M. Also, U. S, Bureau Mines I. C. 7017 (133S). Equipment from (b) (c) fj) fD. Determine chloride Ion by Volhai'd method. Ref.: Hel ler: Gesimd. Ingenieur. vol. 53. p. 201 (1S32). Chem. Abst., vol. 27, p. 155 flf'33). Distill fluorides as hydroftuosllictc acid. Titrate fluorides .in distillate with thorium nitrate suln. using sodium alizarine sulfonate as indi cator. Ref.: Willard, and Winter: Ind. Eng. Client., Anal. I'd., vol. 5. p. 7 01*33). Itoruff and Abbott, (ibidl, vol. 5, p. 235 (1'.>33). Titrate with AgXO-,, Range of SO-1 .Wf* PPM. Equipment frc.m CJ). Conrentrntion fs Indicated by length of color change. Ref.: I.ittleficld, Yant and Pa-rger: If. S. Bureau Mines. R. 1. Xo. 3276 (June. 35>::.l. See also: Reed. J. D.: -T. Roc. Chem. Ind.. vol. 37. in'- 43- U tl!'3S). Draw nlr through bubbler containing is soln. in KI with stnrch. 15 lodmnetriv. -T-H material Method of Collection Method of Determination Lead, as dust or fume Mercury Methane Tmpinger nr electric precipi tator. Draw air against SeS coated paper Lampshade detector (using SeS) available from (f) (j). Freeze vapor with dry Ice. Gas-collecting bottle. Combustible pan indicator from (b) <c) (3) (1). Flame Safety lamps from (b) (c) (j). See Air Hyp. Bulletin No. 3, Part G (1938). Compare color change against standards. Ref.: Xordlandcr, B. TV.: Ind. Blip. Chem., vol. 19, p, 522 (1327). Ref.: Fraser: J. Ind. Hyp. & TOX., vol. 1G, p. 67 (1934). Vol. gas anal, method Ref.: Hoey-et- Fene. Currie. U. S. Bureau Mines Buli. No, 331 (1930). See also: U. S. Bureau Mines I. C. No. 33 (1937). Methanol - Draw air through bubbler containing water. Collect sample In partly evacuated bottle. Absorb McOH in distilled water by thorough agitation of water in the bottle. Discussion. Ref.: Wright, L. O.: Ind. Eng. Chem., vol. 19, p, 750 (1927). Oxidize to formaldehyde and determine colorimetrlcally (Denlgc method) u. See alse: Formaldehyde, Chapin's method. Detenu ine by mod! lied Denigc method. Re!.: Selirenk and Yant: U. S. Bureau Mines, Personal communication (1933). Methyl bromide Methyl chloride Ethyl bromide Ethyl chloride Collect samples by He dis placement. Analyze volu metrically by slow combustion with a white-hot platinum coil and large excess of O*. P.of. iPayers, Yant, Thomas, and Berger. U. S. Public Health Bull. No. 185 (1923). For YleBr see also: Busbey and Drake: Ind. Bng. Chem., Anal. Bd., vol. 10, p. $90 (1938). Nitric acid Draw air through an acidi Determine NaOi with phenol- fied 6(1 HlO; bubbler followed sulfonic acid by A. P. H. A. Nitrogen by 2 or 3 5(4 KOH H-O; bub Standard method11- Ref.: tetroxide blers. Drinker and Snell: J. Ind. Hyp. & Tox., vol. 20, p. 331, <- (1938). 1- Draw air through liquid air Oxidize as above and deter trap. mine by n I iron acetate method. Ref.: Coitman: J. Ind, Hyp. & TOX., vol. JO, p. 289 (1938). Oxygen Gas-collecting bottle. 16 Vol, gas anal, method >*. TJ. S. Bureau Mines I, C., 7017) (1938). 0 -10*2 MATEBlAb Ozone Phenol Phosgene Phosphorus trichloride Radioactive substances Sulfur chloride Sulfur dioxide Sulfuric acid (mist) Toluol Trtchlor- ethylene Method of Collection Method of Determination Partially evac. bottles con taining starch-Kt .solution. In presence of XaO(, collect by liquid air. Draw air through bubbler containing NaOli solution. . Draw afr through bubbler containing aniline water sat urated with dlphcnyl-urea. Draw air through bubbler containing Br water. Physical methods using elec troscope. Draw air slowly through HXOj solution of AgXOj. Draw air through I--KX starch solution. Partially evacuated bottle containing 1-KI starch soln. Draw air automatically through acid BrV-. Draw air through XaOH in impingcr. Draw air through fuming HNOj. Draw air through specially designed absorption tube containing absolute EtOH. Combustion method for chlorinated hydrocarbons. fodoinctrlc K. Ref.: Coltman and McPher son, J. Ind. Hyg. S: Tox.. VO). 20, p. 465 (193S). Determine colorimetvlcally l!. Kilter oft precipitate of di phenyl-urea in tared Gooch crucible, dry and weigh, dis solve diphenyl-urea with alcohol dry, r.r.i . ".";igh. Ref.: Yarn, et al.: Ind. Eng. Chom.. Anal. Ed., vol, S, p. 20 (1936). Boll and determine P by colorimetric molybdate meth od". Ref.: Schwarts, el al.: J. Ind. Hyg. & Tox., vol. 15, p. 362. 3$S, 433 (1933). Dissolve th e precipitated AgC! in XH.OII again precipitat ing with HXOj15, Iodometrtc. Ref.: Griffin and Skinner, Ind. Eng. client., vol, .24, p. 362 (1932). Solution from sampling hottie brought to same intensity as a blank by addition of stan dard iodine solution. Ref.: U. S. Bureau Mines, R. I. Xo. 3003 (1930). Conductivity method with recorder. Ref.: Thomas: Ind. Eng. Chem., Anal. Ed,, vol. 4, p. 253 (1932). Acidify with HC1 and deter mine sulfate as BaSO,. Similar to U. S. Bureau Mines method for CH using KOH Instead of XaOH. Determine colorinietrteally -on reaction with pyridine and 50*5 sodium hydroxide. Ref.: Barrett: J. ind. Hyg. & Tox., vol. IS, p. 341 (1936). Air Hyg. Bulletin Xo. 2. Part 3 (March, 1933). . 17 Pit'/-? - * P f : t. 1 i 1 " j 1I i1 .r ! !lt' TABLE IV. FIRMS SUPPLYING EQUIPMENT MENTIONED IN THIS BULLETIN <a) Bausch & Lomb Company Rochester, New York. (b) E. D. Bullard Company 275 Eighth Street, San Francisco, California. (c) Davis Emergency Equipment Co. 65 Van Dam Street, New York. New York. <d) Detroit Air Meter Company Detroit, Michigan. <e> Fisher Scientific Co. 709-717 Forbes Street, Pittsburgh. Pennsylvania. (f) General Electric Company 1 River Rd., Schenectady, New York. : (g) E. V. Hill Co. 179 West Washington Street, Chicago, Illinois. (H) Illinois Testing Laboratories, Inc. 420 N. LaSalle Street, Chicago. Illinois. (i) Macalaster Bicknell Co. 171 Washington Street, Cambridge, Massachusetts. (j) Mine Safety Appliances Company Pittsburgh, Pennsylvania. ` (k) Pulmosan Safety Equipment Corp. ' 17G Johnson Street, Brooklyn, New York. a) Union Carbide Company--Linde Air Products, Inc. 30 East 42nd Street, New York, New York. Willson Products, Inc. Reading, Pennsylvania. (n) Zeiss Company 485 Fifth Avenue, New York, New York. 18 ! 01044 References 1. Report of National Silicosis Conference. U. S. Dept. Labor, Div. Labor Standards, Washington, D. C. 2. Industrial Code. Bulletin No. 33, New York State Dept. Labor. Rules Relating to the Control of Silica Dust in Rock Drilling (May, 1937). 3. Tentative Recommended Good Practice Code and Handbook on the Fundamentals of Design, Construction, Operation, and Maintenance of Exhaust Systems. American Foundrymen's Association, 222 W. Adams Street, Chicago, Illinois. Price S4.00. 4. Yaglou, C. P.: The lAnti-d Thermometer Anemometer. J. Ir.d. Ilyg. & Tox., 20: 497, 193S. 5. Brown, C. E.; and Schrcnk, H. H.: A Technique for Use of the Impinger Method.. U. S. Bureau Mines, I. C. 7026, June, 1938. 6. Drinker, P.; and Hatch, T.: Industrial Dust. McGraw-Hill Book Com pany, New York, N'ew'York. Price S4.00. 7. American Society of Mechanical Engineers: Fluid Meters, 4th Edition, 1937, 29 West 39th Street, New York, New York. Price S3.00. 8. Barnes, E. C.; and Penney, G, W.: An Electrostatic Dust Weight Samp ler. J. Ind. Hyg. & Tox., 20: 259-265, 1938. 9. The Vapor Pressure Method for Estimating the Concentration of Organic Vapors, such as Gasoline, in Air. U. S. Bureau Mines, Tech.' Paper No. 87 (1916). This Bulletin is out of print. . 10. Scott, W. W.: Standard Methods of Chemical Analysis. 4th Edition. Van Nostrand Company, New York, New York. 1927. 11. Standard Methods for the Examination of Water and Sewage. 9th Edition, 1936. American Public Health Association, New York, New York. 12. Zhitkova, A. S.; Kaplan, S. D.; and Ficklen, J. B.: Some Methods for the Detection and Estimation of Poisonous Gases and Vapors in the Air. A Practical Manual for the Industrial Hygienist. Service to Industry, Box 133, West Hartford, Connecticut, pp. 198. 13. Cook, W. A.*, and Coleman, A. L.: Determination of Solvent Vapors in Air by Means of Activated Charcoal. J. Ind. Hyg. & Tox., IS: 194-210, 1936. 14. Cook, W. A.: The Industrial Hygiene Laboratory. J, Ind. Hvg. & Tox., 18: 623-636, 1936. ' 15. Flury, F.; and Zemik, F.: Schadliche Gase. Julius Springer, Berlin (1931). 16. Gas Chemist's Handbook. American Gas Association, New York, New York. Revised from time to time. 19 0iJo