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By F. P. Haver, M. M. Wong

When a mixture of chalcopyrite concentrate and lime is heated in air, the following reaction takes place: 2CuFeS2 + 4Ca (OH)2 + 8 ½ 02 ; 2Cu0 + Fe203 + 4CaS04 + 4H20. Ca (OH)2 is the only common reagent that will adequately control SO2 evolution in roasting. Other additives tried, including CaO, CaCO3, Na2CO3, NaOH, MgO, Mg (OH)2, and MgCO3, were not effective. All reacted with sulfur, but not to the extent that will be required to meet the new control regulations for sulfur oxide emissions. For example: when the concentrate was heated with the theoretical amount of limestone (CaCO3), about 55% of the sulfur was retained in the calcine; whereas use of the stoichiometric amount of Ca (OH), converted approximately 99% of the sulfur to CaSO1. In most of the experiments, Ca(OH)2 was formed by adding CaO to concentrates containing enough water to simulate filter cake from flotation circuit. This eliminated the need for drying the concentrate and utilized the heat of hydration of CaO.

Jan 6, 1972

By S. Terry, W. Callender, R. J. Cornelius

When a dry ball-mill grinding circuit was in- stalled at the pellet plant of Hamersley Iron Pty. Ltd., it was something of a pioneering venture, since this was one of the first instances where such a circuit had been applied to iron ore on a major scale. The Hamersley pellet plant is located in Dampier on the coast of Western Australia. The feed for it consists of -8mm fines produced as a screened product at the Mt. Tom Price mine 186 miles inland from Dampier. It was these fines that encouraged the choice of a dry grinding facility for the plant. At the outset, tests had shown that the fines could not be filtered satisfactorily with a wet grinding system. At the pelletizing plant, the fines are stockpiled, reclaimed, dry ground in ball mills, formed into pellets on balling discs, hardened on an indurating line, and stockpiled for shipment overseas. These operations are shown in Fig. 1.

Jan 7, 1969

By M. F. Smith

BELOW the nose of the bainitic C curves in isothermal transformation diagrams, the rate of the austenite-to-bainite transformation usually decreases with decreasing temperature. However, in some steels and iron-carbon alloys, there is a noticeable acceleration in the initial reaction rate at temperatures just above Ms. Such speeding-up of the bainitic transformation would be understandable at temperatures just below Ms because of the catalytic effect of the martensite formed,' but the reversal in isothermal kinetics just above Ms seems quite anomalous. This behavior was observed by Howard and Cohen' in a 1.35 pct C steel and, on the basis of metallo-graphic examination, it was attributed to the formation of a thin plate-like product not belonging in the bainitic sequence. More recently, schaaber2 found two-stage reactions occurring in the vicinity of Ms in a number of steels, and suggested that the first stage might be the isothermal formation of marten-site, preceding the isothermal formation of bainite in the second stage. A decrease in the bainitic incu-

Jan 1, 1960

By H. J. French

At the request of a committee of the Engineering Division,' National Research Council, a study of the properties of boiler plate at various temperatures up to about 900' F. (482" C.) has been instigated. The following is a report of preliminary tests made on two grades of 1/2-in. plate and includes a description of the apparatus used in the determination of the proportional limit. Detailed reference to- the many published investigations in connection with the properties of steel at various temperatures will be omitted from this report. Suffice to state that results obtained for variation in tensile strength, elongation, and reduction in area with temperature are in substantial agreement with the effects now generally considered to be correct. Comparison of proportional limit values with results obtained by other investigators will be found in the conclusions. Materials Used The steels tested were $1/2-in. (12.7 mm.) open-hearth boiler plate of firebox and marine grades. The specified tensile strength and the analysis for each are shown in Table 1. In the manufacture of this material, a

Jan 1, 1922

By H. J. French

At the request of a committee of the Engineering Division,' National Research Council, a study of the properties of boiler plate at various temperatures up to about 900' F. (482" C.) has been instigated. The following is a report of preliminary tests made on two grades of 1/2-in. plate and includes a description of the apparatus used in the determination of the proportional limit. Detailed reference to- the many published investigations in connection with the properties of steel at various temperatures will be omitted from this report. Suffice to state that results obtained for variation in tensile strength, elongation, and reduction in area with temperature are in substantial agreement with the effects now generally considered to be correct. Comparison of proportional limit values with results obtained by other investigators will be found in the conclusions. Materials Used The steels tested were $1/2-in. (12.7 mm.) open-hearth boiler plate of firebox and marine grades. The specified tensile strength and the analysis for each are shown in Table 1. In the manufacture of this material, a

Jan 1, 1922

By G. W. Healy, W. D. Forgeng, N. R. Griffing

The liquidus surface of the C-Cr-Fe system to 1900°C has been mapped from carbon solubility and freezing point measurements, metallographic observations, and published data. In the graphite field, the surface drops precipitously to meet a slope descending from the Cr3C2-C join through the mixed carbide fields to a meandering eutectic valley; this flows from the Cr-C to the Fe-C edge. On the low-cavbon side of the valley, the surface rises to the chromium corner. 1 HE purpose of this inquiry was to gain a more complete knowledge of the C-Cr-Fe liquidus surface. This required an extensive study of carbon and chromium-rich alloys which, in the past, have received the least attention. Sanbongi el al.1 measured the solubility of carbon in liquid alloys containing up to 25 wt pct Cr at temperatures of 1460" and 1545°C and found that it increased with chromium content and temperature. Lucas and wentrup2 also made solubility experiments in graphite crucibles, but at higher chromium contents in the range of 38 to 80 pct and at temperatures of 1550" to 1700°C; however, their experiments were relatively few, and the effect of temperature was not consistent. The present investigation included compsitions ranging from 0 to 94 pct Cr and 1.4 to 11.7 pct C at temperatures up to 1800°C. Saturation experiments in graphite crucibles, thermal analyses during freezing, and metallographic and X-ray diffraction studies were employed to obtain desired information which, together with published data from other investigations about the binary edges and the ternary system at lower carbon levels, made possible the construction of a comprehensive C-Cr-Fe liquidus surface. C-CR-FE LIQUIDUS SURFACE The derived ternary liquidus surface is shown in Fig. 1 where the solid curves are liquidus isotherms. The dashed curves and the binary edges are the liquidus field boundaries of the primary crystals, the arrows along these boundaries indicating their direction with decreasing temperature. Each intersection of three internal boundaries is the composition of liquid involved in four-phase isothermal equilibrium with the three primary crystals whose liquidus fields touch there. It may be observed that a total of six four-phase equilibria occur at melt temperatures. The general topography of the liquidus surface consists of a eutectic valley sloping down from the Cr-C edge at 3.2 pct C to the Fe-C edge at 4.25 pct C. The liquidus surface rises in two directions from the valley, one hillside terminating at the Cr-Fe edge while the opposing hillside rises toward the carbon corner out beyond the top edge of Fig. 1. Both hillsides are interrupted by intersections of surfaces or joints representing the liquid colmpositions of various three-phase equilibria. Seven primary crystals occur, namely a(bcc), ?(fcc), graphite, (Fe, Cr)3C capable of dissolving as much as 15 pct Cr, and three different chromium carbides in which iron is partially soluble by substitution for chromium. The composition ranges of the primary l~hases at melt temperatures are shown

Jan 1, 1962

By W. Chubb

FOR the past several years there has been considerable interest in the development of zirconium and zirconium alloys for application in nuclear reactors. In a portion of the development work being conducted, attention has been given to the development of high-strength zirconium alloys. One of the most outstanding alloys developed in the course of this work is Zr-4 wt pct Sn-1.6 wt pct Mo.' Fabrication and Test Methods Over 50 ingots of zirconium containing either tin and molybdenum or both have been evaluated in the process of selection of an optimum composition. Most of these were prepared as 20-g are-melted buttons; a few were prepared by induction melting. All ingots were prepared by the me of Foote Mineral

Jan 1, 1958

By E. J. Horwood

The varying physical character and large extent of the Broken Hill lode necesarily involve the employment of a variety of underground methods. The lode had its origin in an extensive fault plane traversing metamorphosed schists conformably, as a rule, with their beds of stratification. The underground waters carrying minerals in solution deposited their contents in the original cavities formed by the faulting action, and in the enlargements of these cavities due to dynamic forces brought to bear on the rocks, more especially on the hanging-wall side of the fault. This deposition was supplemented by metasomatic replacement of a portion of the original rock contents by the argentiferous sulphides of lead and zinc which form the staple products of the district. Although the orebody is practically continuous throughout the mines, its width varies greatly, ranging from a few feet to about 350 ft. The widest portions occur in conjunction with huge folds in the inclosing country rock, almost exclusively on the hanging-wall side. The ore in these folds pitches to the south in the southern half of the field, and to the north in the northern half; there are, however, undulations in these ore channels evidently due to compression of the rocks in the direction of the channels. In the earlier days, before the orebodies had been opened up, vertical cross-sections across these bulges in the hanging wall gave the lode the appearance of the "saddle formation," so well exemplified at Bendigo in Victoria; but subsequent development of the ore channels has long since proved that the formations in the two districts are entirely different. The depth reached by the zone of complete oxidation of the sulphides varies from about 259 to 550 ft, from the original outcrop, while partial oxidation extends in places below the 1,000-ft. level. The result of oxidizing influences has been the production of ore of every grade of cohesive-ness, from that of dry sand to that of hard compact rock. The methods of mining followed in this field, and even in individual mines, are varied in accordance with the character of the ore. The general practice of the field is to sink vertical shafts, generally on the foot-

Jan 1, 1916

By R. S. Archibald

The subject of this paper is particularly appropriate, since Daniel C. Jackling was active in early exploitation of taconites on the Mesabi Range and contributed greatly to their later economic development. After his success in developing the low grade porphyries in the West he looked for more worlds to conquer, and so undertook the concentration of low grade taconites, from which he hoped to produce commercial ore. Mesabi Iron Co., organized in 1919, actually did produce merchantable sinter from taconites in 1922. The enterprise did not prove commercial at the time, as cost of production was high and the surplus of iron ore in the Lake Superior District already contributed to a low market price, but this same property has since been developed by Reserve Mining Co. The work done by Jackling had much to do with the success of this later venture. Iron ore was first discovered on the Marquette Range in Michigan in 1845. The first ore from this range came from the old Jackson mine in Negaunee in 1848. During these early years this property and others on the Marquette produced limited tonnages for transportation to Lower Lakes and for consumption by charcoal furnaces in the area, where a plentiful supply of hardwoods furnished the charcoal for iron smelting. The Marquette and other ranges tributary to Lake Superior did not produce much ore for transportation to Lower Lakes until the locks at Sault Ste. Marie were constructed, but from the time the first lock at the "Soo" was completed in 1855 these ores were transported through the locks to consumer centers in the East. The Marquette Range has a history of continuous production from 1848 to the present day. In 1877 the Menominee Range was discovered at the location of the old Penn Mines near Vulcan, Mich. There were further discoveries of ore on the old Menominee Range and at Florence, Wis., in 1880 and at Iron River and Crystal Falls, Mich., in 1882. Penn Mines continued in operation from the date of their discovery until they were finally exhausted by Pickands-Mather in 1945, but operations still continue on the Menominee in the Crystal Falls and Iron River districts. Ore is shipped to a lake port at Escanaba, Mich.

Jan 1, 1960

By Nick Holonyak

Halogen vapor-transport synthesis of Ga(As,-,Px) and its preparation into laser junctions are described. Electrical and optical properties of Ga(As,-,PX) laser junctions are discussed. The present limitations in these properties are related to material proble?vzs and the very early state of development of Ga(As,-,PX), and are discussed in this context. Inhonzogeneity problems, fluctuation of As :P ratio, and problems with deep-level contaminants are described and related to Ga(As,-,PX) junction performance. Laser junctions are demonstrated which operate to wavelengths as short as 6470 A (77°K). The prospect that Ga(As,-,P,) will operate to wavelengths perhaps 100A shorter is mentioned. IN this paper we wish to describe some of the more important features of almost 1 year of experience in the preparation and properties of Ga(As,-,P,) p-n junction lasers. Because much data so far available are far from complete, some of the results still must be considered tentative and subject to correction and revision as work on Ga(As,-,P,) crystal problems progresses. Although the electrical, optical, and device properties of Ga(As,-,P,) junction lasers are understandably of considerable interest, the work to date points out that by far the most serious problems extant and those deserving first attention are problems involving the growth, doping, and perfection of Ga(As,-,P,) crystals. One of the most formidable of these is to grow Ga(As,-,P,) sufficiently free of deep levels, either due to contaminants or to structural imperfections, to allow fabrication of laser p-n junctions which can be cooled and not suffer from "freeze-out" of carriers on deep levels (and consequent double-injection behavior). In addition to the problems of growing crystals adequately free of deep levels and generally of the highest perfection, so that the best possible laser junctions can be realized, the further goal remains of increasing the phosphorus content well beyond 40 pct in an attempt to determine the practical lower wavelength limits of laser action in the Ga(As,-,P,) system. Even though the laser junctions prepared in Ga(As,-,P,) are of importance in their own right, we have considered them at this point mainly a means to study the growth and crystal problems of the material. It can be concluded that the laser junctions now available are almost completely limited by the purity and structural deficiencies of Ga(As,-,P,) crystals, and cannot be fairly compared with, for example, GaAs p-n junction lasers until Ga(As,-,P,) crystal growth has been more extensively developed. The basis for the statements above will become evident in the following sections which describe Ga(As,-,P,) crystal and junction preparation, and laser-junction properties. G(As,-,P,) CRYSTAL GROWTH As previously reported,2 we have found it convenient to employ the halogen vapor-transport process3 for synthesizing Ga(As,-,P,) crystals for use in laser junctions. Commercially available GaAs and Gap, separately prepared by halogen vapor tranport, are sealed in the desired ratio in a quartz vessel with a quantity of column-VI donor and a small quantity of metal halide which supplies the halogen for transport. The sealed ampoule, as shown in Fig. 1, is heated at a temperature in the range from 1025" to 1100°C at the position of the source GaAs and Gap. The GaAs and Gap are simultaneously vapor-transported and deposited as Ga(As,-,P,) at one end of the ampoule

Jan 1, 1964

D. C. JACKLING, the father of the porphyry coppers, has been honored for his pioneering in that field. There is another facet to Mr. Jackling's activities, one which now may prove an even greater monument than the big coppers-the story of his venture in taconite beneficiation. The essence of his porphyry development was mass handling of material. Not alone mining on a large scale, which was done on the Mesabi Range at the turn of the century, but the integration on a previously unknown scope of mining, milling, concentration, and in many cases, of final reduction to metal at the site. This was mass production applied to mining, treatment of a very low grade source material, previously considered submarginal.

Jan 1, 1954

By Earle E. Schumacher, W. C. Ellis, John F. Eckel

Copper-calcium alloys are of interest as materials for use in deoxidized conductors of high conductivity. That calcium is effective in deoxidizing and degasifying copper is well known. Brandenberg and Wiensl have described the use of calcium in the casting of sound copper and state that the deoxidation can be carried out without difficulty. The castings that they prepared were sound and sufficiently ductile to permit wire drawing. Pratt,2 in British Patent No. 1699 (1907), has claimed the use of calcium for the deoxidation and degasification of copper. Masing3

Jan 1, 1930

By S. K. Tarby, W. O. Philbrook

The rate of FeO and MnO reduction from silicate and aluminate slags by carbon-saturated iron is dependent on both slag composition and temperature. Owing to variable stirring rules during- the course of reaction, the reduction processes occur in two stages in stationary graphite crucibles. In the first stage the slirring caused by CO evolution results in forced convection conditions in the slag. As the boiling action subsides during reduction, the flow conditions within the system become those defined by natural convection. Analysis of the data by an unsteady-state penetration model indicates that the rate of reduction is controlled by the rate of cocur-rent flow of' cations and anions from the bulk slag to the interface during both stages of reduction. The hearth reactions of the blast furnace have been extensively investigated from the viewpoint of equilibrium by deductions from controlled laboratory experiments. However, the literature contains relatively few studies that have been directed toward the area of slag-metal reaction kinetics, and the majority of these have been concerned with the rate and mechanism of sulfur transfer between iron and slag. More recently, attention has turned to the kinetic factors in the reduction of oxides from liquid slags. One of the first investigations in this field was conducted by Dancy1 on the reduction of pure liquid FeO and pure liquid Fe3O4 by carbon-saturated iron. The integrated form of the rate equation indicated that the reduction of FeO was of the first order up to 80 pct reduction. Over the initial 30 pct of reduction, the magnetite reaction was also interpreted as a first-order process. The rates of reaction were extremely rapid as indicated by a 30 pct reduction of the liquid magnetite in a time interval of about 1 to 2 sec. Phil-brook and irkbbride' studied the reduction of FeO from a lime-alumina-silica slag by carbon-saturated iron and solid graphite in stationary crucible assemblies. With the use of the differential form of the rate equation, the rate of the reduction reaction was found to be proportional to the second power of the concentration of the reactant FeO for both the slag-metal and slag-graphite reactions. These authors presented a number of comments in an effort to explain the difference between the molecularity of the above reaction and the observed second-order relation. One such argument, recently extended by Wagner,3 was that the rate-limiting step may well be one of transport control. A complete discussion of the proposed mass-transport control mechanism of this reduction reaction will be presented in a later section of this paper. Kinetic studies of the reduction of other oxide species, namely chromous oxide, titania, and silica, have also been reported. McCoy and philbrook4 used rotating crucible assemblies to investigate chromium reduction from Ca0-SiO2-A12O3 slags. First-order kinetic law was obeyed for the slag-metal reduction reaction as determined by the integration method of data analysis. Due to scatter of the data, any dependence of the rate constant on temperature or slag composition was obscured. Concentration-time data for the reduction of titania from blast-furnace type slags under reducing conditions were obtained by Delve, Meyer, and Lander.' The data were too few, however, for a formal kinetic interpretation. Kinetic data for the very slow reaction of silica reduction have been observed by McCoy and Philbrook6 and Fulton and chipman.7 The former experimenters found the reaction-rate constant for silica reduction by carbon-saturated iron to be 20 to 60 times less than the rate constant for chromium reduction. In their work on the reduction of SiO2 in mechanically stirred systems, Fulton and Chipman also found small values for the specific reaction rate and derived a high value for the energy of activation for the reaction. In both of these investigations, the reduction process was assumed to follow first-order behavior. schuhmann8 proposed that the rate-limiting step in this reaction is the diffusion of oxygen from the interface through a boundary-layer film to the bulk metal phase, and Rawling and Elliott9 have reported experimental confirmation of this hypothesis for temperatures below 1600°C. Turkdogan et a1.10 have also concluded that the rate of reduction of silica is a slow process and controlled by the diffusion of oxygen in the metal, but only in the absence of carbon monoxide bubbles at the slag-metal interface. In the presence of bubbles, achieved either by injecting carbon monoxide at the slag-metal interface or by blowing it through the metal and slag, these investigators found a rather rapid reduction of silica which appeared to be controlled by an interfacial reaction involving the de-sorption of silicate ions from the slag-metal interface to the metal phase as silicon and oxygen atoms. In view of the unresolved nature of the kinetics of FeO reduction and the lack of kinetic data for the manganese reaction,

Jan 1, 1968

H. W. Turner, Portland, Ore. (communication to the Secretary*) :—Mr. Brown's paper on the complicated groups of veins exposed in the workings of the Bodie mine forme a valuable contribution to the literature of the structural features of ore-depoeits. It is much to be desired that managers should put into print the results of their observations of the mines under their charge. These observations, as well as data of production, kind of ores, etc., usually accumulate for years, and unless the mining geologists of the Geological Survey happen along before the mine is worked out, such data seldom get into print. About the year 1899 I went through the mines at Bodie with R. C. Turner, then superintendent, and made some notes on the veins and gangue-minerals, and collected some specimens. Mr. Brown refers to crystals of feldspar (albite) found on fragments of quartz on the surface. I collected a number of specimens of these crystals, mostly from Queen Bee hill, and

Jan 1, 1909

By M. M. Fine

Normally the U. S. produces less than 10 pct of its annual manganese requirement. About 95 pct of domestic consumption is used by the steel industry.1 The strategic and critical nature of manganese has been recognized by its inclusion in the national stockpile and by intensified research directed toward cataloging and evaluating domestic manganiferous deposits. The USBM has participated in these activities for many years with field and laboratory studies to assess the extent and potential utilization of domestic manganese ores. One area of particular interest is in the vinicity of Batesville, Ark., where deposits have been mined since 1849 for both manganese and ferruginous manganese ores. Production is centered in Independence County, but deposits are also found in Sharp, Izard, and Stone counties in north- central Arkansas. Miser has described the geology and manganese mineralization in some detail.2,3 The rocks of the area are sedimentary, consisting of sandstone, limestone, shale, and chert. The two formations of greatest importance,4 Fernvale lime- stone and Cason shale, are host rocks of the primary manganese mineralization.

Jan 8, 1959

By Charles M. Brown, Russell Franks, W. O. Binder

Occasionally in the application of the austenitic chromium-nickel steels to corrosive conditions, failures have occurred by cracking without serious general over-all attack of the metal. As pointed out by Foyt and Scheil(1),2 and by Scheil, et al.(2) as well as by Hodge and Miller(3), the stress-corrosion failures that have occurred have been limited in number, and have taken place only when the steels were exposed to certain corrodents. These investigators have stated that while stress- corrosion cracking can be intergranular in nature and originate at the grain boundaries of the austenitic chromium-nickel steels, it can also take place in trans- granular fashion. They have shown that the cracking may be either initiated at the grain boundaries and may propagate along grain boundaries for some distance and then suddenly extend across grains, or it may begin in a transgranular fashion and suddenly proceed along grain boundaries until the cracking stops. Their data further show that when austenitic stainless steel is subject to intergranular attack, stress will concentrate and cause cracking in service. These investigators have studied the effect of the metals titanium and columbium which are added to the steels to impart immunity to intergranular attack, and molybdenum which is added to improve resistance to general corrosion.

Jan 1, 1945

By E. F. Evoy

The uranium deposit of Gunnar Mines Ltd. is on south shore of Crackingstone Peninsula in the Beaverlodge area of northern Saskatchewan. The property spans St. Mary's Channel, a narrow waterway separating the mainland from a group of islands in Lake Athabasca. The mine property, consisting of 12 claims and 7 fractions, was staked in July 1952 by A. O. Zeemel and W. J. Blair. Diamond drilling commenced in the fall of that year and continued until the spring of 1954. In that interval, some 70,000 ft of drilling outlined an orebody plunging from the surface south-ward to a depth of 1000 ft below the shore of St. Mary's Channel. The last 9000 ft of drilling was through lake ice, and when this was interrupted by spring breakup, sufficient ore reserves had been established to warrant the present operation. Surface drilling was therefore terminated.

May 1, 1956

One Hundred Sixteenth Meeting of the Institute, Monday, Feb. 18, to Thursday, Feb. 21, inclusive, 1918. Committee on Arrangements J. E. JOHNSON, JR., Chairman BRADLEY STOUGHTON, Vice-Chairman A. R. LEDOUX J. V. N. DORR L. W. FRANCIS F. T. RUBIDGE G. D. VAN ARSDALE MRS. S. J. JENNINGS E. M. SHIPP RALPH W. DEACON ARTHUR L. WALKER The program for the New York Meeting, in February, 1918, as planned by the Committee on Arrangements at meetings in the middle of December, and therefore subject to slight alteration in detail, is as follows: MONDAY, FEBRUARY 18 9 a. m. to 5 p. m. Registration at Institute Headquarters. 10 a. In. Technical Sessions. 12.30 p. in. Luncheon at Engineering Societies' Building. 2 p. m. : Technical Sessions. 8.30 p. m. War Smoker or Patriotic Meeting. TUESDAY, FEBRUARY 19 10 a.m. Annual Business Meeting, followed by Technical Sessions.

Jan 1, 1918

By John V. Beall

Early this year at the University of Arizona in Tucson, a survey was made of student opinion about the minerals industry. Over 100 of the three page questionnaires were completed and these were analyzed by the following categories: 40 Mining Engineering students, 20 Geological Engineering with 2 Geophysical Engineering students, 15 Geology students, 7 Metallurgical Engineering, 26 Underclassmen, 29 Graduate students and a composite of 84 total students. Not all of the results of the survey were predictable. After graduation there is a strong preference toward going to work in the mineral industries. The next most popular options, but trailing the first choice greatly, was graduate work or employment in another industry. A smattering of other choices were for teaching, government or research. None checked the box for drop out.

Jan 1, 1971

There's a right way and a wrong way to store diesel electric systems and similar equipment for generating on-site power, according to James Frankow, service manager for Allis-Chalmers Corp's Engine Division. In any event, the less storage the better. Many generating sets are stored before installation, especially when new construction is underway. Improper storage, or mothballing, can create initial reliability problems. Therefore; arrange for inside storage with no drastic extremes in temperature or humidity. If engines and alternators are stored in areas other than inside a dirt-free and temperature-controlled building, the unit or engine should be completely covered and protected against the environment. Before covering it with a canvas or with plastic, the unit should first be sealed at the following critical engine openings:

Jan 3, 1978