Search Documents

By Naoki Hosoya, Setsuo Maeda

This paper addresses establishment of an experimental system for measuring biodynamic response (BR) of hand-arm system at the NIIH in Japan. BR measurement system at the NIIH is nearly equivalent to NIOSH installed system. The feasibility of the system is examined through the apparent mass (AM) measurement of the empty handle and a set of calibration masses. Apparatus The grip force was measured by using the handle shown in Fig. 1. The handle has two force sensors (KISTLER, 9212) and one accelerometer (PCB, 356A12). A low-pass filter with 5 Hz cut-off frequency was used to the grip force from measured force signal. Figure 2 shows BR measurement system in this study. The push or pull force at the handle was measured by using the force plate (KISTLER, 9286AA). The grip force and the push / pull force were displayed on a monitor. The shaker (IMV, VE-100S) is used to vibrate the hand-arm system along the forearm axis (Zh direction) (ISO 10068, 1998; ISO 5349-1, 2001). In most situations force actions for operating tools are expressed by grip, push, pull and combined these actions. These actions can be simulated in the test system. AM was obtained by performing H1 estimator in the PULSETM system (B&K, 3109) and it is denoted at the one-third octave band center frequencies. [ ] Methods In order to investigate the reliability of the system, AM measurement of the handle was performed. It is assumed that the handle is rigid in the upper limit of adoptive frequency range in this study. This assumption is validated in AM measurement of the empty handle. A pseudo-random vibration in the frequency range of 10 to 1,250 Hz was used and its amplitude is 1.0 (m/s2)2/Hz with a flat power spectral density (PSD) in the experiment. Measured AM includes the mass effect of the measuring cap in a subject experiment. Compensated apparent mass AMc(?) is obtained by Eq. (1) 1-2.

Jan 6, 2006

The National Institute for Occupational Safety and Health (NIOSH) National Personal Protec-tive Technology Laboratory (NPPTL) and the Mine Safety and Health Administration (MSHA) conduct a Long Term Field Evaluation (LTFE) program to evaluate deployed self-contained self-rescuers (SCSRs). The objective of the program is to evaluate how well SCSRs endure the under-ground coal mining environment with regard to both physical damage and aging when they are deployed in accordance with Federal regulations (30 CFR 75.1714). This report presents ?ndings of the combined eighth and ninth phases of the LTFE. For these phases, over four hundred SCSRs were evaluated. The units tested include the CSE SR-100, Draeger Oxy K-Plus, MSA Life-saver 60, and the OCENCO EBA 6.5. The OCENCO M-20 was evaluated only in Phase 9. Testing was per-formed between December 2000 and April 2004. Results of the evaluation indicate that all SCSRs experience some performance degradation due to the mining environment. Observed degrada-tion varies from elevated levels of carbon dioxide, high breathing resistance, and reduced capacity. Mechanical degradation to the SCSR components included breathing hoses, chemical beds, outer cases and seals. The LTFE tests discussed in this report are different from tests performed for SCSR certi?cation to the requirements of 42 Code of Federal Regulations, Part 84 (42 CFR, Part 84). LTFE tests reported here are conducted to an end point, oxygen depletion, to enable comparison of the duration of new and deployed SCSRs. The method for obtaining deployed SCSRs for this evalua-tion was not a random selection from the deployed population of SCSRs. Although the results of these tests are useful for observing performance of the tested SCSRs, they are not representative of all deployed SCSRs. A new evaluation protocol, with revised sampling strategies, test methods, and reporting procedures, is currently being designed to enhance the generalizability of the results. This program will be implemented following completion of Phase 10 of the current LTFE protocol.

Jan 10, 2006

By A. R. Taylor

Using solution calorimetry, the following heats of reaction were determined: (1) NaCN(c) + 1/Cu20(c) + 129H20(l) ? CuCN(c) + NaOH?128.5H2O ?H = -13.44±0.10 kcal/mole, (2) HCN(2) + NaOH?128.5H20 ? NaCN(c) + 129.5H20(l) ? = -2.52±0.02 kcal/mole. From these reactions, the heats of formation for CuCN(c) and HCN(2) were calculated to be 22.7±0.4 kcal/mole and 24.9±0.4 kcal/mole, respectively. Reaction 2 was made to check the consistency of literature values for heats of formation of HCN and NaCN. Adiabatic calorimetric measurements between 10° and 400° K showed the entropy and heat capacity of CuCN(c) to be 21.51±0.06 eu and 14.58±0.04 cal/mole deg, respectively, at 298° K. A broad anomaly in the heat capacity was found in the temperature range 285°-320° K. The heat of transition associated with this anomaly was less than 1 cal/mole, the sensitivity of the measurements.

Jan 1, 1971

By R. K. Koch

The vapor pressures of liquid columbium and liquid hafnium were deter-mined by the Langmuir free evaporation method as a part of the Bureau of Mines program on the study of transition metals. An electron-beam furnace with a water-cooled copper crucible was used for melting. Temperature was measured with a two-color ratio pyrometer. Least-squares analyses of the vapor pres-sure data gave the following equations: [Logp (atm) = 5 .429 -31,310 T] for liquid columbium in the range 2,740° - 3,140° K, and [Log p (atm) = 5,690 28 T] for liquid zirconium in the range 2,500° -2,810° K. Third-law evaluations of each data set gave mean heats of sublimation (298.15° K) of 175.1±3.2 kcal/mole and 148.3±1.2 kcal/mole for columbium and hafnium, respectively. Second-law standard heats of sublimation determined from sigma plots and from sigma-prime plots agreed fairly well with the third-law values. The sigma-prime plots gave standard entropies of sublimation of 30.96±0.84 eu and 33.S6±0.44 eu for columbium and hafnium, respectively.

Jan 1, 1968

By J. W. Walkiewicz

One of the objectives of the Bureau of Mines is to develop substitution technology for scarce materials. In accordance with this goal, alloys containing lanthanum, cobalt, copper, and magnesium were investigated for fabrication of rare-earth-cobalt (RE-Co) permanent magnets. A complete substitution of lanthanum for samarium and a partial substitution of copper for cobalt was accomplished. Magnets of La-Co and La-Co-Cu-Mg alloys were fabricated by powder metallurgy techniques and evaluated. A maximum intrinsic coercivity of 23.2 kOe was obtained with a La-Co-Cu-Mg alloy. In comparison, maximum values of 9.3 kOe and 11.6 kOe were obtained with La-Co and La-Co-Cu alloys, respectively. The substitution of copper and magnesium for part of the cobalt resulted in a large increase of intrinsic coercivity, similar to the results of Bureau research with mischmetal-Co-Cu-Mg alloys. Unlike the mischmetal-Co-Cu-Mg magnets, the La-Co-Cu-Mg magnets showed signs of physical deterioration on exposure to air. The effects of fabrication parameters on the magnetic properties of the La-Co-Cu-Mg alloys were also determined.

Jan 1, 1982

By Alla D. Mah

Heat content and entropy data at high temperatures were obtained for cuprous oxide (Cu2O) and cupric oxide (CuO). Experimental results and smooth values are reported. Equations are given for heat content increments and heat capacities above 2980 K. Low-temperature heat capacity data were obtained for cuprous oxide. Evaluation of the 2980 K entropy gave, S°298.15(Cu2O) = 22.08 ± 0.10 cal/deg mole. Heat of formation values were determined for cuprous and cupric oxides. The values are: AH°298.15(Cu2O) = -40,830 ± 300 cal/mole, and AH°298.15(CuO) = -37,230 ± 150 cal/mole.

Jan 1, 1967

By H. C. Ko

Heats of solution of calcium carbon-ate (calcite) and calcium oxide in hydrochloric acid were determined by solution calorimetry. Combination of these two heats yields a value of 42.643±0.024 kcal/mole for the enthalpy of calcination of calcite at 298.15 K. Literature data on ?H°298.15 of calcination of calcite were reviewed and compared. Thermodynamic properties for the calcination process were calculated from 298.15 to 1,500 K using Gibbs energy functions. This research was undertaken by the Bureau of Mines as an effort to provide thermodynamic data for the advancement of minerals technology, energy conservation, and environmental preservation.

Jan 1, 1982

By Elger. G. W.

The Bureau of Mines investigated preheating of continuously fed, fragmented ferrous scrap charges by furnace offgases and utilizing substitutes for imported fluorspar to condition electric steelmaking slags. Three types of continuous scrap charging procedures were investigated to determine electrical energy consumption in a I-st (short ton) electric arc furnace. Cold and preheated scrap charges were continuously fed at rates averaging 37.5 and 43.7lb/min, respectively. The feed rate varied appreciably from test to test owing to hangup of the scrap in the charge bin. Approximately 7 pct less electrical energy was consumed in melting scrap preheated to 8400 to 1,1100 F by furnace off-gases than in melting cold scrap. Overall energy consumptions were 888 kW'h/st for cold scrap, 829 kW'h/st for preheated scrap" and 637 kW'h/st for conventional backcharged scrap. Stack gases from scrap preheating averaged 1200 F and a flow rate of 1,615 scfm compared with 2200 F and 1,302 sefm for cold-charged scrap. Slag conditioners tested included synthetic fluorspar, boric acid, hydroboracite, used aluminum potlining wastes and aluminum anode tailing wastes, and Sorelflux B. The boron-containing conditioners fluidized the slags the best, followed in order by the conditioners containing fluorine and titanium.

Jan 1, 1987

By E. G. King

THIRD-LAW entropy data for zirconium-containing compounds are sparse. Kelley a lists entropies at 298° K. for the oxide, tetrachloride, nitride, and silicate, as well as for the metal. The present paper presents heat capacities between 51° and 298° K. and entropies at 298.15° K. for the zirconates of the alkaline-earth metals-calcium, strontium, and barium. The authors believe magnesium zirconate does not exist as a stable compound at room temperature. Entropies of formation from the constituent oxides also are given. MATERIALS The materials used in this investigation were synthesized and analyzed in the Berkeley Laboratory of the Bureau of Mines. Calcium zirconate was prepared by heating an intimate mixture of reagent-grade calcium carbonate and pure zirconia for 30 hours between 1,200° and 1,300° C. and for 32 hours between 1,400° and 1,500° C. As part of the heating schedule, the sample was ground and mixed seven times. Periodic analyses and minor adjustments of composition were made. Analysis of the final product gave 31.19 percent calcium oxide (theoretically 31.28 percent) and 68.67 percent zirconia (theoretically 68.72 percent). The X-ray diffraction pattern agreed with that in the ASTM catalog.

Jan 1, 1960

By L. Garner McDonald

The U.S. Bureau of Mines, under contract to the U.S. Department of Energy, investigated the erosive-wear properties of seven commercial alloys with potential applications as valves for coal-conversion plants. A dry particle, jet-erosion apparatus was used to determine the wear of seven materials: 316 and 440-C stainless steels, K-68, K-701, and K-801 cemented tungsten carbides, HC-250 white cast iron, and Haynes 6B. The alumina abrasive entrained in the nitrogen gas jet had particle sizes of 27 or 50 µm, the abrasive velocities were 55 to 170 m/s, and the particle impingement angles were 15° to 90°. The maximum specific wear for ductile materials was found to occur at impingement angles of 15° to 30°, and the minimum specific wear occurred at 60° to 90°. For the brittle materials, maximum specific wear occurred at impingement angles of 50° to 85° and minimum specific wear was at the lowest angles. As the velocity and erosive particle size increased, the specific wear increased. The specific wear was related to the velocity by the power function WocAVn, where n was 1.8 to 3.9 for ductile materials and 1.8 to 3.6 for brittle materials.

Jan 1, 2010

By E. G. Davis

As a result of interest by the U.S. Department of Energy, the Bureau of Mines conducted studies on comminution of bituminous coal to the 2-um particle size range using the Bureau-developed turbomill. Both "plant grind" size (80 pct minus 75 um) and microsize (minus 10 um) coal can be produced in a single step with the Bureau's turbomill. In 15 min, minus 2.4-mm coal milled in water with steel shot was reduced tc 65 pct minus 75 m and 26 pct minus 2 m, with an energy requirement of 139 kW^h/mt coal. Plant-grind size coal milled in water, with Ottawa sand as the milling medium, was reduced to more than 45 pct minus 2 m in 15 min, at 175 kW?h/mt. Plant-grind coal milled with steel shot was reduced to 57 pct minus 2 um in 15 min, at 138 kW?h/mt. When diesel fuel was substituted for water, the milling of the coal was less effective and less energy efficient. Keeping the pulp dispersed was critical. Without an effective dispersant, the slurry became very viscous with increased milling time, resulting in higher energy requirements, low heat dissipation, and poor grinding efficiency.

Jan 1, 1987

By A. R. Taylor

In recent years, thermodynamic data have been used to a greater degree than ever by the chemical and metallurgical engineer as a means of predicting and controlling chemical reactions. To satisfy the spiraling demand for basic physical data needed for the calculations, the Bureau of Mines is studying the heat capacities of a variety of chemical compounds at high and low temperatures. This paper is one of a series presenting such data. The heat capacities of two alkaline earth compounds, strontium bromide and strontium nitrate, were measured in a temperature range of 60° to 300° K. in an adiabatic calorimeter and at temperatures of 300° to about 1,200° K. in a Bunsen ice calorimeter. The construction and operation of the calorimeters are discussed in other reports.3 4 The heat-capacity data presented in this report were extrapolated to 0° K., and smooth values of heat capacity, entropy, enthalpy function, and free-energy function were calculated and tabulated at even 10-degree intervals. The enthalpy data were fitted with algebraic equations by applying the method of least squares; calculations a£ heat-capacity values, entropy, enthalpy function, and free-energy function were made at even 50-degree intervals. The heat and entropy of fusion of strontium bromide were calculated from the enthalpy measurements.

Jan 1, 1962

By M. Hertzberg

Results of a comprehensive study of the absolute spectral radiance of the infrared emissions from methane-air explosions are reported. The spectral growth of these expanding flames were recorded with a time resolution of 1 msec in the spectral range of 1.7 to 5.0 µm. Time-resolved spectra were obtained for methane-air mixtures as a function of stoichiometry, nitrogen dilution, and Halon dilution, in a 9-liter vessel under different venting conditions. Data are also presented for coal dust-air explosions. Temperatures, obtained from the absolute radiances and from a band ratio technique for methane-air, are internally consistent and are generally 50° to 200°K below adiabatic flame temperatures. All near limit mixtures gave essentially the same flame temperatures (1,500° to 1,600° K) regardless of whether the limit was obtained by dilution with excess air, excess methane, excess nitrogen, or Halon. The coal dust explosion spectrum is essentially a blackbody continuum at 1,500° K with some selective emission at 4.4 µm from hotter CO2. The data are analyzed in terms of the radiative dynamics of a sperically expanding flame zone. The importance of radiative transport is assessed. An equation is derived which relates the instantaneous fraction of combustion power radiated to adiabatic variables.

Jan 1, 1973

By W. W. Weller

Thermodynamic values for scandium and its compounds are very sparse. This is evident upon examination of any of the commonly used compilations of thermodynamic data. For example, National Bureau of Standards Circular 5004 lists only four heat of formation values, two free energy of formation values, and four heat-capacity values for scandium compounds. The entropy of crystalline scandium is one of the most fundamental values that has been lacking. This Bureau of Mines paper reports heat-capacity data for scandium metal in the temperature range from 50° to 298° K., together with the entropy value at 298.15° K. derived from these data through application of the third law of thermodynamics.

Jan 1, 1962

By Harry R. Nicholls

The objectives of this investigation were to determine the strain propagation laws for a strain pulse in salt and to compare the seismic effects from the detonation of different explosives in salt. The investigation showed that a strain propagation law of the type, e = K(R/W 1/3 ) n, and a strain energy propagation law of the type, Ea/W 1/3 = K(R/WI/3)b , are valid in salt. A change in the regression law coefficient, n , was noted with strain level. A similar change in b was inferred because strain energy is proportional to the square of strain amplitude. Particle velocity data may be used interchangeably with strain data under the test conditions.

Jan 1, 1962

By K. O. Bennington

The thermodynamic properties of synthetic acmite, NaFe3+Si206, were determined by the Bureau of Mines. The enthalpy of formation was determined by hydrofluoric acid solution calorimetry. The values of the standard enthalpy of formation at 298.15 K, ?Hf°298.15, from the elements and from the oxides, ?H°298.15, are ?Hf°298.15 = -615.87 ±0.71 kcal/mole, ?H°298.15 (from oxides) = -32.08 ±0.53 kcal/mole. Various experimental data were combined with other data from the literature to calculate all the related thermodynamic properties in the range of 298 to 1,263 K. The standard Gibbs energy of formation is ?Gf°298.15 = -575.8 kcal/mole.

Jan 1, 1981

By E. G. King

This paper reports measurements of low-temperature heat capacities and entropies at 298.15° K. of two copper ferrites (CUFe204 and CU0.75Fe2.2504). These substances, which occur in copper-smelting slags, have not been sujected to any previous direct thermodynamic investigation. The two copper ferrites are spinel minerals of the variate class. In previous investigations similar data were obtained for 13 other spinel minerals -7 of the normal class and 6 of the variate class. The entropies at 298.15° K. of these minerals have been compiled and revised as necessary in the light of present knowledge regarding structural randomness; entropy values, recommended for use in thermodynamic calculations, are listed.

Jan 1, 1959

By Seth C. Schaefer

The Federal Bureau of Mines studied the Gibbs free energies of formation of chromous fluoride (CrF2), chromic fluoride (CrF3), and chromium (II,III) fluorides (CrF2.40 and CrF2.45) with high-temperature galvanic cells employing calcium fluoride doped with 1 mole-pct yttrium fluoride as the electrolyte. Free-energy changes were obtained from open-circuit potential measurements for the following cells: Cr, CrF2 // CaF2 // NiF2, Ni (a) NiO, NiF2 // CaF2 // CrF3 , Cr203 (b) CrF2 , CrF2.40 // CaF2 // NiF2, Ni (c) and CrF2 ?45 , CrF3 // CaF2 // NiF2, Ni (d) with the following overall reactions Cr(s) + NiF2 (s) = Ni(s) + CrF2 (s) (1) 3NiO(s) + 2CrF3 (s) = 3NiF2 (s) + Cr203 (s) (2) 5CrF2 (s) + NiF2 (s) = 5CrF2.4O (s) + Ni(s) (3) and 3.64CrF2.45 + NiF2 (s) = 3.64CrF3 (s) + Ni (s) . (4) These results were combined with the best available literature values of ?Gf° of NiF2, NiO, and Cr203 to deduce Gibbs free energies of formation for the chromium fluorides expressed as follows: ?Gf°(CrF2) = -179.31 + 24.33 X 10-3T ± 0.43 kcal-mole. (5) (858.1 - 964.9 K) ?Gf° (CrF3) _ -226.16 + 1.82 X 10-3T ± 0.79 kcal/mole (6) (880.8 - 957.8 K) ?Gf°(CrF2.40) _ -213.65 + 32.14 X 10-3T ± 0.44 kcal/mole (7) (0053.9 - 936.8 K) and ?Gf°(CrF2.45) _ -176.17 - 12.67 X 10-3T ± 0.80 kcal/mole (8) (875.1 - 937.6 K). Free energies and equilibrium fluorine pressures for three univariant and one bivariant equilibria are illustrated.

Jan 1, 1976

By K. O. Bennington

The thermodynamic properties of two manganese silicates, pyroxmangite and fowlerite (zincian rhodonite), were experimentally determined by the Bureau of Mines. The standard enthalpies of formation were determined by hydrofluoric acid (HF) solution calorimetry, the low-temperature heat capacities by adiabatic calorimetry, and the high-temperature heat capacities by differential scanning calorimetry over the range 322 to 1,372 K. Data for the standard enthalpy of formation (AH298), the derived standard entropy (S298), and the standard Gibbs energy of formation (AGf 298) are as follows: Pyroxmangite [(Mn0.9554Cao,0446)(Si03)J- AHf298 319.668±0.46 kcal/mol AH298 (from oxides)... -7.215±0.11 kcal/mol 5295 23.785±0.048 cal/(mol'K) AGf298 -301.190±7.96 kcal/mol Fowlerite [(Mno.7o3Zno.0884Ca0.2086)(Sio3)]--AHf298 ?... -329.914±0.419 kcal/mol AH298 (from oxides)... -8.400±0.104 kcal/mol 5598 21.949±0.059 cal/(mol-K) AGf298 -310.716±7.99 kcal/mol These experimentally determined values were combined with data from the literature to calculate the Gibbs energies and equilibrium constants of formation over the temperature range of the measurements. Standard enthalpies, Gibbs energies, and equilibrium constants of formation are given as a function of temperature from both the elements and the constituent oxides.

Jan 1, 1987

By R. K. Koch

The vapor pressures of liquid titanium and liquid platinum were studied under the Bureau of Mines program for the determination of thermochemical data on the transition elements. Beating was done in a 2-kw electron-beam furnace with a water-cooled copper crucible to contain the melt. Temperature was measured with a disappearing-filament brightness pyrometer. The vapor pressure data for liquid titanium in the range 2,008° to 2,379° K are represented by the least-squares derived equation [log p (atm) = 6.268 - 22, T] Two series of determinations were made on liquid platinum. Results of the first series are expressed by the least-squares derived equation [log p (atm) = 8.240 - 30,460T] for the range 2,0860 to 2,4200 K. Results of the second series are expressed by the least-squares derived equation [log p (atm) = 7.795 - 29,580 T] in the range 2,045° to 2,442° K. Third-law evaluations of each series gave mean standard heats of sublimation of 112.4 kcal/mole, 133.3 kcal/mole, and 133.8 kcal/mole for titanium first series on platinum, and second series on platinum, respectively. Second-law heats of sublimation and equations for heats, free energies, and entropies of vaporization were obtained from sigma plots of each data set.

Jan 1, 1969