This paper presents the results of an evaluation of high-magnification microscopic techniques used to analyze fiber contamination in water conducted by an ASTM Task Group under Subcommittee E04.11 on Electron Metallography. These techniques offer a feasible means of measuring relatively low levels of fiber contamination in environmental water samples. Other bulk-type methods lack the needed sensitivity and selectivity. The transmission electron microscope is the best basic instrument for the analysis, particularly when it is equipped with selected area electron diffraction and energy-dispersive spectroscopy capabilities. The mean fiber concentrations by different groups agree within a factor of two. The interlaboratory reproducibility of 50% can be expected in relatively clean water samples unless the concentration is low. In samples with high concentrations of interfering solids, the precision will not be as good. Interlaboratory reproducibility of 25% is as good as the method can provide. When applied on a broad scale there are variable and significant losses associated with the condensation washing of samples containing amphibole. The losses are low and less varible when condensation washing is used to prepare samples containing chrysotile.
A Task Group of the Joint Committee on Effect of Temperature on the Properties of Metals (sponsored by the American Society for Testing and Materials, the American Society of Mechanical Engineers, and the Metal Properties Council) did an extensive study of methods for the extrapolation of short-time rupture data in an effort to decide if any one method might serve as a basis for a standard practice. Emphasis was on the time-temperature parameter. The following conclusions were reached: 1. Among the computerized techniques the newly introduced minimum-commitment method (MCM) is on the average about as good as the best of the four standard time-temperature parameters studied. 2. In addition, the MCM has other potential merits which make it a candidate for the sought-after standard. Further study and investigative work are required to realize this potential. 3. Experienced analysts can get good results by manual extrapolation methods. These methods are subjective, and because of the limited availability of experienced analysts such methods probably should not be considered for standard practice. Many recommendations are given in the report for future work toward the goal of defining a standard practice.
The application of a particle measurement computer (PiMc) system for measuring average fiber diameter and variability of wool and other animal fibers has been demonstrated. Three lots of wool top and three lots of scoured wool cores representing fine (19 to 20 µm), medium (27 to 28 µm), and coarse (34 to 35 µm) grades were used. Preparation of slides of cut wool fibers and different mounting media were tested. Based on analyses from results of two laboratories, testing six lots of wool, only one had a difference in average fiber diameter between methods that was significant at the 0.05 probability level. This difference was 0.32 µm. Also, the analysis did not detect any bias or systematic error attributable to the PiMc system, nor was the difference between laboratories using different machines significant. The system reproduced its measurement results very closely. In this study, there were 24 comparisons and all differences were within theoretical differences due to chance. The PiMc procedure of measuring fibers is over twice as fast as the microprojector and takes one less person. Alternative sampling procedures are presented showing how the sampling error can be reduced with a fixed number of fibers analysed. Based on these results, a standard computer program can be developed which generates summaries of the diameter and variability properties for wool and other animal fibers in a printout form suitable for a permanent record.
Measurements of heat transmission in a number of different loose fill cellulosic insulations have been made by heat flow meter and guarded hot plate methods. Effect of temperature and density have been studied together with a limited investigation on moisture effects. Variations of up to 18 percent occur in the same nominal materials from different sources. This fact indicates that the raw materials and their processing can have a significant influence on the heat transmission properties. For the optimum density range of 35 to 40 kg/m3 and above, the different materials have a very similar temperature coefficient of thermal conductivity. Lower density materials have a significant radiation contribution to their total heat transmission characteristics.
A rational system for monitoring atmospheres suspected of containing insoluble toxic particles requires a method that will provide a sample in which all particles are represented in proportion to their “respirable fraction,” that is, in proportion to the probability that they would be deposited in the nonciliated region of the lung, if inhaled by an average man. Various organizations concerned with occupational health have advanced formal definitions of respirable fraction, and samplers operating in accordance with those definitions are widely used for both personal and general area monitoring. In this discussion, quantitative descriptions of respirable fraction, the formal definitions derived from them, and the performance characteristics of respirable fraction samplers are reviewed. The samplers are shown to perform adequately for their respective definitions, but in general the definitions themselves significantly overestimate respirable fraction as determined from recent experimental data.
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