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By Francisco Alberto Marreiros da Rocha Filho

No processo de laminação a quente ocorre ocasionalmente a perda de ductilidade a quente que pode causar o fenômeno denominado como “abertura de cabeça” da barra durante a sequência de passes. Essa perda de ductilidade a quente pode ser severa e causar interrupções no processo produtivo. Esse fenômeno pode estar associado a diversos fatores entre eles: composição química do aço; defeitos presentes no tarugo; condições do processo de laminação; e temperatura do aço durante o processo, principalmente nos passes de desbaste e intermediários de laminação. No processo em estudo, a perda de ductilidade a quente ocorre associada à laminação de vergalhões a partir de tarugos oriundos diretamente do lingotamento contínuo. O presente trabalho tem como objetivo avaliar a influência da temperatura e da microestrutura formada ao longo do processo na perda de ductilidade a quente das barras através de um exame comparativo entre os vergalhões laminados com e sem o uso da etapa de reaquecimento.

Oct 30, 2017

By D. J. Schmatz, H. I. Aaronson, H. A. Domian

Diffusion kinetics in disordered hcp Cd-Mg alloys have been investigated by means of the Kirkendall effect and concentration-penetration curves determined with an electron-microprobe analyzer. Self-diffusion coefficients of both species were determined at the three marker compositions obtained, averaging 27.6, 46. 7, and 78.1 at. pct Mg, by means of the Darken analysis. These coefficients were then corrected for the unequal and concentration-dependent partial molar volumes of the two elements with the Balluffi analysis, and for the vacancy flux effect by the Manning analysis. The latter correction reduced the Balluffi correction produced larger changes in the self-diffusiv-ities; neither, however, produced statistically significant changes in the Do's or the H'S. The most striking result of this investigation is that at all three compositions and at all temperatures studied both the uncorrected and corrected self-difjusivities of magnesium are higher than those of cadmium. The Cd-Mg system is the first one found in which the higher melting, lower vapor pressure element diffuses more rapidly. Both an empirical correlation due to Toth and Searcy and considerations of the atomic mechanism of diffusion indicate that this anomaly is probably due to a comparatively low value of the activation energy required for a magnesium atom and a vacancy to exchange sites, perhaps occasioned by the higher compressibility of magnesium atoms. KIRKENDALL effect studies have been previously reported for only two hcp solid solutions: the E phase of the Zn-Cu system1 and the a phase of the Cd-Hg system.' In neither investigation were the marker-movement studies supplemented with the concentration-penetration curve determinations necessary to evaluate self-diffusivities by means of the atano and the Darken analyses. The present program was undertaken to obtain both types of data on a hexagonal solid solution in order to provide more detailed information relevant to the mechanism of diffusion in this type of lattice. The Cd-Mg system was chosen for this study because the disordered solid solution extends across the entire phase diagram at temperatures above 253"c5 and the substantial difference in the melting points of the component pure metals promised that marker movements would occur at reasonably rapid rates should the diffusivities of the two species be as unequal as might be anticipated. The experimental convenience of the relatively low melting points of cad-miun and magnesium and the availability of extensive and accurate activity data6 (required for application of the Darken analysis) were additional reasons for selecting this alloy system. Since the anisotropy of diffusion is not large in either pure cadmium7 or pure magnesium,' the diffusion couples were prepared from polycrystalline components. The presence of a well-defined texture in the couples—the c axis of individual crystals tended to be normal to the diffusion direction— however, provides a fair degree of crystallographic definition to the data obtained. The principal (and entirely unexpected) finding of this investigation, that magnesium, the high-melting low-vapor pressure element, diffuses more rapidly than cadmium, in contradiction to a broad range of results in fcc and bcc alloys, as well as in the previously studied hcp alloys,172 makes the self-diffusivity determinations of immediate interest in understanding the origin of this anomalous result. EXPERIMENTAL PROCEDURE The cadmium (Belmont Smelting and Refining Co.) and magnesium (Dow Chemical Co.) used in this study were both of 99.99 pct purity. Alloys containing 51.0 and 65.6 at. pct Mg were prepared from these materials by melting under a MgC12-base flux in a high-purity graphite crucible. These alloys were subsequently hot-worked and then homogenized in a helium atmosphere at temperatures close to their solidus points. Sandwich-type diffusion couples of the type g/d/g were prepared from the pure metals by solid-state diffusion. Two-piece alloy couples of Mg/65.5 at. pct Mg (Mg/gCd) and Cd/51.0 at. pct Mg (Cd/CdMg) were welded by a liquation technique. The individual components of both types of couple were initially cylinders 1.27 cm in diam and in length; the ends of these cylinders were machined accurately flat and parallel. For both welding techniques, the pure cadmium cylinders and the alloys were chemically polished in a mixture of 40 pct ethyl alcohol, 40 pct hydrogen peroxide (30 pct conc), and 20 pct nitric acid,g while those of pure magnesium were polished in a solution of 10 pct nitric acid in ethyl alcohol.' Immediately afterwards, both metals were rinsed in freshly distilled acetone, and then in similarly purified methanol.' The Mg/Cd/g couples were assembled in a carefully cleaned stainless-steel welding fixture, in which a screw operating through a self-centering arrangement permitted a controlled pressure to be exerted upon a couple prior to welding.'' Tungsten marker wires 0.005 cm in diam were placed at the d:g interfaces of some of these couples, and imbedded in the couples during the application of pressure. As soon as a couple had been assembled, the welding fixture was inserted into a Pyrex capsule containing a packet of zirconium chips at each end. The capsule

Jan 1, 1967

By L. Béjar-Gómez

The aim of this research work is to study and characterize the precipitates in structural microalloyed steel by transmission electron microscopy and analysis by low resolution. Microalloyed steel with niobium was produced by casting in an electrical induction oven of 25 Kg capacity. Carbon content in steel was less than 0.1 % and 0.036% of niobium. Steel was processed thermomechanically; reheated to 1250 °C and hot rolled on a laboratory mill to a 13.0 mm thick plate with a finish rolling temperature of 900ºC and a thickness reduction of 80% . This work shows what precipitates are present in steel, the type of precipitates and their morphology. Analysis by transmission electron microscopy of low resolution was applied to obtain the chemical analysis of precipitates and the matrix. Spectroscopy of dispersive energy (STEM - EDS) was applied to obtain the element profile of precipitates. Particles of precipitates of NbC were found; with cubic morphology and size from 70 to 130 nm, circular morphology and size from 10 to 70 nm, polygonal morphology and size from 10 to 80 nm.

Jan 1, 2006

Provide exhaust face ventilation to remotely-controlled continuous mining machines making extended advances without exposing workers to unsupported roof. Approach Modify the sprayfan to move additional air to and from the coal mine face. Unmodified, sprayfans are capable of ventilating the face with 20-foot brattice setbacks. Additional sprays on the rear of the mining machine allow setbacks to be extended up to 40 feet.

Jan 1, 1988

By K. Schwerdtfeger

Data are presented on the effect of iron oxide on the electrical conductivity of CaO-SiO2-FeO-Fe2O3melts, and on limiting current and impedance in direct current or alternating current charge transfer at iron electrodes. The strong influence of iron oxide content can be utilized for in situ determination of total iron oxide content and Fe3+/Fe2+ratio. The possible probe designs are presented and the principles and procedures of the measurements are explained. Keywords: in situ probe for iron oxide determination in steelmaking slags, electrical conductivity of CaO-SiO2-FeO-Fe2O3slags, direct current over voltage and alternating current impedance at iron/slag electrodes.

Jan 1, 2004

By Russell B. Cornell, William B. Plank

AT the close of the academic year 1940-'41 the largest number of students ever recorded received their first or bachelor degree in the mineral technology schools of the United States. The total of men thus prepared to enter their professional careers in the mineral industries was 1601, a number nearly 12 per cent larger than two years ago and nearly 75 per cent larger than four years ago. Notwithstanding this increase in the number of graduates and as had been predicted in the preliminary report in February, there was a slight decrease in the total student population of the schools in both the United States and Canada. During the college year 1940-'41, 9133 students were enrolled in the 54 schools of the United States and 764 in six of the seven schools of Canada.

Jan 1, 1941

By J. S. Osoba, J. G. Richardson, F. M. Perkins

Laboratory experiments have shown profound diffcrences in the behavior of so-called "fresh cores" from the East Texes field and of the same cores after ex~ractio~l with organic solvents. The residual oil satura/ion remaining after waterflooding fresh cores was appreciably lower than the corresponding saturations after flooding extracted cores. This behavior was also reflected in the water-oil relative permeability-saturatiorl relations, which were more favorable for high oil recovery from the fresh cores. These differences were evident not only in the amount of residual oil left after wafer flooding, but also in the saturation water remaining in the core after displacernent by oil. Residual water saturation after displacernetzt of water by oil was higher in the fresh cores than in the extracved core,. Capillary pressure-saturation relations were also different for the fresh crnd extracted cores. Imbibition experiments indicated that both fresh and extracted Bast Texas cores imbibed water spontarteOLISIY, but- the rate of imbibition of water was higher for samp1es after. extraction than it was for fresh core. material. INTRODUCTION Several years ago a series of waterflooding tests was made in the laboratory on a number of Woodbine core samples from the East Texas field. These samples had been stored in containers open to the air and were extracted with organic solvents before they were subjected to the laboratory tests. After water flooding, the residual saturation of kerosene, which was the oil used in the tests, was found to average about 30 per cent. This saturation was higher than expected. In investigating the circumstances which might have been responsible for such a high residual oil saturation, attention was given to possible changes in wetting properties of the rock brought about by the procedure employed in extracting the cores. Preliminary results indicated that the explanation for the high residual oil saturation lay in the wetting behavior of the cores, though what effect extraction had on this behavior was not clear. In consequence, the work described in this report was undertaken in an attempt to investigate the mechanism responsible, and to ascertain the actual residual oil saturation to be expected in the reservoir after water flooding. It was soon found that there were profound differcnces in the behavior of so-called "fresh cores" from the East Texas field and of the same cores after extraction with organic solvents. These differences were evident not only in the amount of residual oil left after water flooding, but also in the saturation of watet remaining in the core after displacement by oil. The complete explanation of this behavior is not yet apparent. The description of work and results described in following sections, therefore, must be considered as an interim report presenting facts which must await additional information before they can be fully interpreted.

Jan 1, 1956

By Joseph D. Davis

Selection of a suitable coal or coals for the manufacture of coke of desired quality with due consideration of the purpose for which the coke is intended requires careful thought, and often it will pay to go to considerable expense in testing such coals as may be available. In general it will

Jan 1, 1942

By Stephen L. Chryssoulis, Daniela Venter, Stamen Dimov

"Comparative surface analysis of floated and rejected free gold grains from a number of full scale benefication plants and from pilot plant testwork, has shown silver (the most common impurity in gold) and sulphur invariably in greater concentration on floated gold grains, implying that they assisted gold flotation (gold activators). Collector loading measurements on individual gold grains from concentrates of staged rougher flotation tests on a cyclone U/F product of a pyritic gold ore, revealed first progressively lower concentrations of the collector monomer on gold from each follow-up concentrate and secondly a direct proportionality between the surface concentration of silver and the collector monomer. These two observations leave no doubt that silver activates gold and that collector monomers play a significant, previously not fully recognized role in gold flotation.INTRODUCTIONGold to some degree is naturally floatable in industrial systems, which means that it can be recovered without collector addition (Marsden and House, 1992). This is due to the adsorption of hydrocarbons and deposition of sulphur, which are dependent on the metallic properties of gold, particularly its high electrical conductivity, which allows surface electrochemical reactions to occur catalytically and selectively. Cyclic voltammetry has shown that gold can be rendered hydrophobic by deposition of a surface layer of sulphur (Sº) from S2- and HS- solutions (Walker et al., 1984). Twenty monolayers of sulphur were required to produce a hydrophobic gold surface.However, no sulphide flotation plant relies solely on the natural floatability of gold for its recovery. Gold hydrophobicity is enhanced by the addition of flotation collectors such as xanthates (X), dithiophosphates (DTP), dithiophosphinates (DTPI), mercaptobenzothiolates (MBC) etc., as used in sulphide mineral flotation (Dekok, 1973: Adams et al., 1986). The mechanism invoked in enhancing the hydrophobicity of pure gold with the aforementioned four groups of collectors is similar to that of pyrite, whereby collector anions are oxidized at the gold surface to form dimers (Groot, 1987; Marsden and House, 1992; Basilio et al., 1992) As an example, xanthate ions are oxidized at the gold surface to form the neutral dimer dixanthogen (X2):"

Jan 1, 2003

By C Reed

Titaniferous magnetite deposits are a significant source of vanadium for use in high strength steel alloying and other chemical applications. The mineralogy of the deposits varies markedly and the ore characteristics strongly influence the process route selected and the metallurgical outcomes. Characterisation of the ores reveals the presence of magnetite, ilmenite and other minerals such as spinel hematite and goethite with variable degrees of weathering along with weathered products of host rock. The standard processing route is to crush, grind and magnetically recover a concentrate for salt roasting to produce a soluble vanadate. Ore beneficiation is practised to generate an iron based mineral concentrate containing much of the vanadium with low silica levels of two per cent. Typical processing problems encountered are fine liberation size, over grinding of the magnetite and variable response to magnetic separation resulting from the weathering profile. Beneficiation options are restricted, and generally focused on producing a combined iron and titanium rich concentrate containing vanadium due to the fact that ilmenite and magnetite and their products of weathering are magnetic and have similar specific gravities making their separation difficult. The ilmenite usually contains low levels of vanadium making its separation highly desirable from the iron mineralisation containing higher levels of vanadium. Salt roasting of vanadium ores followed by water leaching has been the standard processing route for many years. The cost of suitable sodium salts, availability of capital and increasing energy costs and energy availability are critical factors in determining the viability of aspiring vanadium producers. To date, only Windimurra has acquired full capital funding, secured energy and sodium salt supplies at suitable cost that enable the construction of the project. Low overall recoveries of vanadium to concentrate roasting at up to 1200¦C are critical cost issues. In this paper, factors influencing the recovery of vanadium are reviewed and emerging processing trends explored. The important features of the processing of titaniferous magnetites have been condensed from the literature, published works, company websites, our own work and personal communication.

Jan 1, 2008

By JeffreyS. Vipperman, Daniel R. Babich, EricR. Bauer

In response to the continuing problem of noise induced hearing loss NIHL among mine workers, the National Institute for Occupational Safety and Health NIOSH has conducted numerous noise surveys in coal preparation plants. The research, consisting of worker dose monitoring, task observations, and equipment noise profiling, was completed in eight separate preparation plants. Worker dose monitoring was conducted for three shifts in most cases. Workers experiencing higher than allowable doses were task-observed for one full shift to correlate dose to noise source(s). Finally, noise levels on all floors, and in lunchrooms and control rooms, were characterized. Results indicate that only workers who routinely spend a significant portion of their shift in the plants (away from the control rooms) are susceptible to overexposure from noise. Certain pieces of equipment (screens, centrifuges, sieve bends) are the loudest primary noise sources responsible for the worker noise exposures.

By Robert A. Jankowski, Natesa I. Jayaraman, Jay F. Colinet

The U.S. Bureau of Mines evaluated the dust control effectiveness of two-phase flow systems in a full-scale model mine using a mockup of a Joy 14CM continuous mining machine. In a two-phase flow system, air and water flow simultaneously through the nozzle. Air pressure varies from 10 to 60 psi, and water at 30 to 50 psi. Coal dust was introduced at the face, and dust concentrations were monitored at the operator locations and in the return. When compared with a conventional spray system, a symmetrical two-phase flow system reduced dust levels during the box cut by 43 pct at the operator location, and 30 pct in the face return. Dust levels, however, increased at the off-operator position during the slab cut. A directional two-phase flow system reduced dust levels at both operator locations by more than 90 pct in the box cut mode. While the use of two-phase flow systems will reduce respirable dust levels and water usage, it requires an air supply to the miner. Moreover, the ability of the two-phase flow system to redirect the dust cloud makes nozzle orientation a critical factor.

Jan 1, 1991

An integrated palynological and sedimentological investigation of four wells from the eastern margin of the Gippsland Basin has resulted in a scheme for classification of palynofacies in this area. Thirteen different palynofacies assemblages are recognised and assigned to particular environments based on the enclosing sediments, which range from alluvial, through coastal barrier to continental shelf environments. Close correlation is observed between the interpreted energy regime of the palynofacies assemblage, and that of the enclosing sediments. Assemblages characterised as reworking surfaces can be correlated with unconformity producing events (ie tectonic activity associated with the opening of the Tasman Sea), and some of the minor eustatic sea level Changes.

Jan 1, 1992

By Bruce I. Thomas

Reconnaissance studies of beach sands along the eastern part of the Gulf of Alaska were conducted by the Bureau of Mines to determine if any of these coastal areas warranted investigations as possible sources of valuable minerals. Because of difficult access and limited transportation facilities only a minimum of sampling, surveying, and camping equipment is utilized to obtain spot samples from key areas as well as information indicating the location, size, and character of the deposits. Such data were obtained from beaches located along approximately 247 miles of the Gulf of Alaska coastline during parts of the 1957 and 1958 field seasons. A total of 201 3-inch-diameter auger holes, spaced roughly at 1 mile intervals, were bored by hand methods to depths ranging from 3 feet to 27 feet; also 33 shovel samples were collected from selected localities. Samples were reduced to a rough concentrate in the field by panning; the rough concentrates were shipped to the Bureau of Mines laboratory at Juneau for further concentration and for petrographic and chemical analyses. Particular attention was given to the heavy-mineral content of the concentrates, although the types and relative amounts of rock-forming minerals were also determined. The reconnaissance indicated that, generally, the valuable mineral content of the beach deposits was too low to be of further interest except in the vicinity of Yakutat and Lituya Bays where erratic but possibly significant concentrations of magnetite and/or ilmenite were found. At Yakutat, about 20 miles of beachline extending southeasterly from Ocean Cape, yielded samplas containing from 1 pound to over 300 pounds of iron and from a trace to over 100 pounds of titanium dioxide (TiO2) per cubic yard of beach material. However, the higher grade samples represented local concentrations of minor importance. The general tenor of the Yakutat beach, as indicated by the airthmetical average of 27 auger-hole samples, is about 35 pounds of iron and 20.5 pounds of titanium dioxide per cubic yard of beach material. Ilmenite is the predominant heavy mineral of the beach deposits in the vicinity of Lituya Bay, but it was found in concentrations only in limited areas near the

Jan 1, 1962

By Paul J. Axtell

Two new railroad bridges in Kansas City, Missouri are founded on drilled shafts embedded into the soil and underlying shale. The uncertainty arising from the non-homogeneous, anisotropic nature of most shales, and the variability of shales across the U.S., makes it a difficult material to assign appropriate design properties. As was the case on this project, the uncertainty of foundation performance in shale can lead to overly conservative designs, particularly with drilled shaft foundations. An extensive Statnamic axial testing program was performed to verify that the load-settlement behavior of the drilled shafts would be acceptable for the intended railroad traffic. Axial Statnamic testing was applied in three increasing cycles of 927 kips, 1007 kips, and 3177 kips, respectively. The maximum movements recorded at the shaft head during each of the loadings were 0.052 inches, 0.062 inches, and 0.257 inches, respectively. The loads applied in each of the respective Statnamic tests were not sufficient to reach the capacity of the shaft; so direct comparison of measured and calculated capacities is not possible. However, evaluation of the estimated design capacity can be accomplished based on results from the Statnamic testing program by utilizing normalized load transfer relations presented by O?Neill and Reese (1999). Such comparisons necessarily require extrapolation of the data measured in the Statnamic tests following typical load-displacement response. Results indicate the Kulhawy and Phoon (1993) method for estimating side resistance in Pleasanton shale rock sockets, assuming a smooth socket, appears to agree well with observed behavior during Statnamic testing. Accordingly, the O?Neill and Reese (1999) method for estimating the toe resistance in intermediate geomaterials, assuming cohesive rock with Rock Quality Designation (RQD) between 70 and 100, appears to agree well with observed behavior during Statnamic testing. Finally, based on Statnamic testing at varying load magnitudes and normalized curves developed by O?Neill and Reese (1999), the contribution of side resistance to the capacity of a deep foundation can be determined assuming no load is transferred to the base of the foundation during lower magnitude testing. Furthermore, higher magnitude testing can provide a means to evaluate the accuracy of design end bearing calculations.

Jan 1, 2006

Provide low-cost fire protection for big bulldozers. Approach A fire protection system, previously used on mobile logging equipment and adapted to surface coal augers, has now been adapted for use on large mining bulldozers. How It Works Heat sensors mounted in the engine compartment and hydraulic hose areas detect the fire, usually before the operator does. This causes the system to automatically discharge A-B-C class dry chemical extinguisher through a fixed piping system. The system can also be manually activated from either the opera-tor's cab or ground level. Location of the principal components of the system are shown in the drawing The heat sensors of the sys-tem consist of bimetallic strip switches which operate at about 10000F temperature. Switch operation results in release of compressed gas from a small storage cylinder. The gas expands to blow the dry chemicals out of the nozzles, in a spray that lasts about 15 seconds. The compressed gas used is usually nitrogen, although carbon dioxide is also used.

Jan 1, 1978

By Wilson A. F

The use of stable isotopic measurements as a technique for elucidating the origin and history of the water in hydrothermal fluids is relatively new. Recept studies have emphasized the importance of meteoric water in the formation of many hydrothermal ore deposits including many epithermal gold-base metal deposits which occur in faulted volcanic terrane. Other vein-type gold ores are believed to have formed from fluids of magmatic or metamorphic origin and exhibit characteristic d18O values. Preliminary oxygen and carbon isotopic data for some important gold deposits of eastern Australia have emphasized the diverse origins of their ore fluids.The Mount Morgan gold-copper orebody is shown to be of the volcanogenic massive sulphide type with ore fluids predominantly of sea water origin. The Charters Towers fissure veins formed during hydrothermal activity associated with intrusion of Lolworth Igneous Complex equivalents. Oxygen isotopic studies of the quartz reefs at Stawell and Gympie have been inconclusive. The ore fluids have a d18O value of about 7 per mil and may be of magmatic or metamorphic derivation.

Jan 1, 1981

By Daniel Brutto

Environmental considerations are a key driver within the marine mining consenting process across different national and international legislative regimes and are critical in shaping the global public perception of the industry. As a result, it is vital that mining companies seeking to operate within marine environments establish a robust understanding of the sensitivities of the seabed environments in which they are active, the impacts of their activities and the ability of the environment to recover from these impacts. The significant risks of failing to do so include an inability to either obtain or maintain operating permits. The risks can be mitigated by the common application of existing seabed biological expertise in baseline assessment and monitoring. The key ingredients of a fit-for-purpose, cost-effective seabed ecological assessment include early consideration of ecological issues within the project life-cycle through undertaking detailed desk-top studies as-wellas the multiple-use of data that have been acquired as a consequence of prospecting processes, with such data including remote acoustic data, seabed imagery and sediment samples. These data can be used to inform the design of robust benthic baseline surveys which provide adequate information on the ecological character of the environment in question and habitats and species of conservation importance - decreasing project risk and increasing the likelihood of securing consent.

Sep 14, 2011

By K. Tajrych

Time and again, lives are lost in underground cave-ins only be- cause there is no quick, sure way of locating the victims. When such accidents happen, rescuers must usually depend on the testimony of eye- witnesses for information on the whereabouts of trapped miners. Seldom is this information reliable. The witnesses themselves have just been through a traumatic experience that has distorted or destroyed their sense of time and place. A far more reliable method of finding men underground has recently been developed by the Coal Mining Research Institute of Ostrava, Czechoslovakia. With this system, a miner can be located with adequate precision even if he shows no sign of life. For the system to work, the miner need only have his electric cap lamp somewhere nearby. The system consists of a minute radio transmitter operated by the lamp battery (Fig. 1). This tiny transmitter continuously emits high- frequency electromagnetic waves that can be picked up by a sensitive direction-finder receiver in case of accident.

Jan 8, 1969

By W. P. Yant

The hazard to health from contamination of air by a noxious gas depends not only on the potential harmful response attending exposure, but also on the warning properties, which in effect may be termed the "accompanying warning response," This warning may be manifested as an odor, taste, irritation of the eyes, nose, or throat, or perhaps headache, vertigo, or nausea. These manifestations may be painful and even slightly harmful, but to a much lesser degree than the primary injury of exposure. The warning response mitigates hazards directly in proportion to the degree of Intolerability which accompanies injurious exposure, and accordingly its absence augments hazards. This accounts for the fact that the actual health hazards from a non-odorous or non-irritating gas or vapor of comparatively low toxicity sometimes equal or exceed the hazard from a considerably more toxic substance, but one which possesses a marked odor or produces eye, nose, or throat irritation in advance of harmful exposure. When a substance lacks the properties for giving warning, it is often possible to impart them by the addition of a small amount of another substance which has an exceedingly high warning intensity. The vapors of this substance, commonly termed a "warning agent" or "tracer gas," escape and mingle with the gas or vapor which lacks warning properties and thereby apprises persons of the latter's presence. The amount of the warning agent added is that which will give adequate warning in advance of serious physiological harm from the dangerous gas or vapor.

Jan 1, 1930