Document OEkO5boNJE8JbbqVzYrZ71VYK

Industrial Hygiene Digest February. 1956 PREVENTIVE ENGINEERING 281 Performance of Automatic Louvers in Industrial Ventilating Systems. I. Kingsley. Monthly Rev.. N. Y. State Dept. Labor 34. 37.39 (Oct. f, 43, 44 (Nov. 1955). The industrial codes in New York State contain regulations prohibiting the use of louvers in exhaust systems. However, they may be desirable in some cases, and an Invest!, gatloa o( the performance of louvers under actual operating conditions is m order to determine whether they may be used under specific conditions. The tests are described and results are reported. In summary; (1) the pressure drop through clean louvers appears to he excessively high, and this may result in increased expenditure for larger fans and motors or cause inadequate control at the operation; (2) automatic louvers should not be used on the discharge dusts of dry spray painting exhaust systems on account of the excessive pressure drop caused by the deposition of oversprayed material on the. louver; (3) louvers should not be used in any exhaust system in which a tacky, sticky, linty, flammable, or corrosive material may be deposited on or cause corrosion of the louver; -and (4) the only systems la which automatic louvers appear to be feasible are tow velocity systems handling air or essentially air. Even then, the temperature should not be so high and the nature of any gaseous materials carried should not be such that corrosion will occur. 282 The Efficiency of Cyclone Dust Collectors. J. Dauphin. Genie chim. T3, 121.129 (1955). French. Earlter theories of cyclones are discussed and a new theory is developed. The forces on particles in the upper and lower roues of the cyclone are analyzed by using the concept of the stationary particle, which is that particle sire which will have no radial force component at r (rhoj^ the arithmetical average of the radii of the separator *"d the concentric exit duct, because the radial component of the air drag on the stationary particle is equal to its centrifugal force. The date of ter Linden (lost. Mech. Engrs. Froc. 160. 223, 1949) have suggested that at r0 there is no vertical velocity component is the air, the vertical velocity being downward at a radius higher than r0 and upward at a radius higher than r0. Equations for the separation are developed for particles larger and smaller than the stationary particle. The calculated efficiencies are in accord with the date of - tar Linden. -- Chem. Abets. 283 A Unique Wet Collector for Lightweight Aggregate Dusts, H. E. Seifert sad J. K. Fauaey, Jr. Am. lad. Hyg. Assn. Quart. 1&, 301-306 (Dec. 1955). The lightweight aggregate industry is comparatively new and In the production of this material the emission of atmospheric dust can be a serious problem. The amount of effluent from the kilns of the plant described was approximately 50,000 c. L m. Although several collectors were tried, including one commercial wet type, none of them operated successfully for more than a few weeks because of the abrasive action of the dust or the sulfur content of the gas. The temperature of the effluent from the kilns wns approximately 500*F. In order to adequately control the dust from the kiln, a dust collector built of spe* cially treated wood for resistance'to heat and acid wns constructed. A series of baffles and nosxles were installed to Increase the collection efficiency. Over 90? of the.atmospheric dust was eliminated and no complaints have been received since this collector was put into operation. -- Authors' summary 284 Role of Electric Forces in the Filtration of Aerosols by Fiber Filters. T. Gillespie. J. Colloid Sci. 10, 299-314 (June 1955). The net electric charge on the fibers of various filters and the electric charge distribution of typical test ae^qst&slwere measured. A simple theory of filtration which included electrical ae well as mechanical effects was developed la order to apply 31. 11 206 1390