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Bau und Wirkungsweise der Apparate und Vorrichtungen zur Abscheidung von Staub und feinen Flussigkeitsteilchen werden beschrieben. Die theoretischen Grundlagen fur die Abscheidewirkung werden angegeben. Fur die verschiedenen Abscheider werden die auf die Gasleitung bezogenen Kosten, die ungefahren Grenzen der Abscheidemoglichkeit, der Druckverlust und die Preise fur amerikanische und deutsche Verhaltnisse angegeben.

A water-soluble fluorescent-dye aerosol has been used successfully as a meteorological tracer. Because of simple instrumental analysis of field samples and great sensitivity, the technique offers large savings in the cost of tracer studies. The aerosol consists of 2- to 10-micron particles of uranine, generated by pneumatic atomization of a solution. The analysis is based on the fluorescence of a uranine-water solution. The sensitivity of the analysis is 10−10 g (corresponding to a single 5-micron particle) and samples as small as 10−9 g have been analyzed readily. The technique has been applied to a field program involving evaluation over distances up to 8 miles during periods of maximum atmospheric diffusion.

The collection efficiency of glass fiber pads was investigated with a super cooled liquid aerosol. A filter-velocity range of 0.02 to 20 ft./sec. was covered with filter pads having a bulk density ranging from 1 to 10 lb./cu. ft. and a fiber diameter ranging from 1 to 30 μ. For the aerosol employed the results showed a minimum collection efficiency at a velocity of 2 to 5 ft./sec., dependent on fiber size. At the lower velocities, where diffusion is controlling, collection efficiency increased with decreased velocity; at higher velocities, where inertia is controlling, efficiency increased with increased velocity. For purposes of generalization the data were correlated in terms of dimensionless parameters which allow for the combined effects of flow-line interception, inertial interception, and diffusinal deposition. Evaluation of the data in terms of existing theories of deposition indicated nominal agreement with the theory of Langmuir, as modified by Natanson, for diffusional deposition. For inertial deposition the measured collection efficiencies were considerably lower than would be predicted from the theoretical values reported by Langmuir and Blodgett for potential flow around the fibers, presumably because of the viscous-flow (low Reynolds number) conditions that prevailed in this study.

(1950). Gravity and Centrifugal Separation. American Industrial Hygiene Association Quarterly: Vol. 11, No. 1, pp. 40-48.

Discharge coefficients were determined in a standard 1-in. pipe for thick-plate and knife-edge orifices of 1/32-in. to 3/4-in. diam, and for critical (sonic) flow nozzles of 1/32-in. to 1/4-in. diam. With properly constructed knife-edge orifices the discharge coefficients were established within ±0.5 per cent for all sizes, but, with small orifices of 1/4 to 1-hole-diam thickness, the discharge coefficients were not reproducible. Thick-plate orifices (1-hole-diam thick) were found to be as good or better than nozzles in constancy of discharge coefficients when used under critical-flow conditions.

The purpose of this study was to determine the effects of sulfuric acid (H(2)SO(4)) alone and with ozone (O(3)) on rats. To accomplish this, rats were exposed for 8 hours daily to an atmosphere containing either nebulized H(2)SO(4), H(2)SO(4) plus 0.9 ppm O(3), or 0.9 ppm O(3). The atmosphere in the exposure chambers was maintained at a fairly constant temperature and humidity. Nebulized H(2)SO(4) was delivered uniformly to provide a particle size of about 0.3 micron mass median diameter (MMD) and a mass concentration of 2 mg/m(3). In preliminary experiments, animals exposed to 2 mg/m(3) of H(2)SO(4) daily for 82 days showed very slight morphologic injury to the respiratory tract. In contrast, biological effects were readily demonstrable in rats exposed to H(2)SO(4) plus O(3) or to O(3) alone, possibly with some enhancement of effect in animals exposed to the mixture. The effects observed were characteristic of the response to O(3) alone.

A detailed research plan was established after review and evaluation of current data for simple chemical compounds at high pressure and high temperatures. Apparatus has been designed and is being constructed to recover particles produced by a shock and to minimize the probability of reagglomeration or further collisions. It is hoped that the apparatus can permit a permanent record of the particle distribution if this should be desirable. Theoretical considerations indicate that giving aerosol particles a net unipolar charge will increase the rate at which an aerosol cloud issuing from an apparatus will expand for reasonable aerosol concentration and charge levels. The prime uncertainty rests with the difficulty of achieving the desired charge levels. A laboratory nozzle has been designed and fabricated to permit direct assessment of this concept, using corona for charging. The project on the dissemination of hydrophobic powders has been divided into two tasks. Task 1 is a study of the behavior of solids subjected to shock loading. Task 2 is an investigation to determine whether electrically charged particles of CS agent can be used to improve the effectiveness of the dissemination process.

A study was conducted to critically review and evaluate literature in the field of atomization. The literature survey yielded 955 pertinent references which have been summarized together with abstracts where available. The more important correlations presented in the literature for the various mechanical atomizing techniques (hydraulic or pressure, pneumatic or two-fluid, and rotary or spinning disk) have been summarized and analyzed. The best agreement was shown by the data for hydraulic swirl nozzles, where discrepancies were nominally not over twofold to threefold. The largest discrepancies, tenfold in some cases, were found for simple hydraulic nozzles. A large part of the discrepancy is attributed to shortcomings in the drop size analysis techniques, including sampling.

A technique was developed for measuring electrical mobility distribution of an aerosol and average effective size at each mobility level. An aerosol is passed through a purifier and a narrow mobility channel. The purifier removes charged particles from all but a thin central stream that enters the mobility chamber halfway between electrodes. Particles are deposited on an insulating surface according to their mobility. Total charge distribution on the walls was determined by a special scanning probe; mass distribution was determined by chemical or colorimetric analysis. Tests to determine mobility distribution of a uranine aerosol generated by atomizing and evaporating a dilute water solution yielded fairly consistent results. Results were consistent with expected magnitudes; average particle diameter (volume-to-diameter mean) was 0.8 micron, and particle charge levels ranged from 0.05 to 1 volt/micron specific particle surface gradient. Remaining problem areas are listed and suggestions are given for improving the technique and extending its usefulness.

This bibliography represents a survey of published information relevant to the manner in which electrostatic phenomena might influence dissemination of chemical warfare agents, covering both the open literature and reports of government-sponsored research. Abstracts are included for most of the 1028 references cited.