Document 7X29v0z01o8K49344Ja50do6

Industrial Hygiene Digest December. 1962 PREVENTIVE ENGINEERING 1185 High Velocity Add MUti Collection. ft. W. Sexton. Am. Iitd. Hyg* Aeon. J. 3, 396*405 (Sept.-Oct. 1962). Efficient collection of odd and chemical masts at high gas velocities has been ob 4 tained by the development of equipment that will function mechanically at gae flow rates to 8S0 feet pee minute. The collector designed for multi-stage operation ueea a concurrent liquid wetting system with countercurrent stage operation* Numerous conditions affecting performance were explored such as selection of suitable gas sampling equipment and control led chemical feeding procedures. The investigation included studies with the following adds: sulfuric* hydrochloric* perchloric* acetic* phosphoric and chromic--as well as ammonia* chlorine gas* ethylenediamine and nitrogen dioxide. '* Author's abst. 1186 Recent findings in the Field of Wet Dust Scrubbers. K. Semrau. Suub 22, la-i-ld? (Miy 19o2). The efficiency of a dust scrubber on a given dust or mist is dependent upon the power dissipated in the gas liquid contacting process. Efficier.cv increases with an increase in (he power dissipation required to attain a givenefficiencv increase as the particle size of the dust or mist decreases* However* the efficiency is nearly independent of tbe size* de sign. and geometry of the scrubber, also of the method by which the power is applied to the contacting process. There are 33 references to the subject. -- APCA Abscs. 1187 Why Test Method is Important in Rating Air Filter Efficiency. Anon. Heating Piping and Air Conditioning JU' 42-41, 216. did (July 1962). Because of a lack of standardisation in regard to methods used to test (liters by various manufacturers* the purchaser has difficulty in determining the proper fitter for the task. Filter efficiency may be expressed as a percentage by weight, or number of particu lates* or by discoloration of the filter* To evaluate manufacturer's claims the type of dust* the point in the life of the filter* and the air velocity must be known. Since dusts are not uniform, there are factors wbich bias efficiencies by weight* Certain dusts agglomerate into much larger partielcs*which tend to increase tbe efficiency rating* The discoloration test is based on methods developed by tbe National Bureau of Standards known as the Dust- Spot, Photometric, Dill Test* or Blackness Test. Samples of cleaned and uneleaned air are drawn onto filter papers and compared in a photoelectric testez. The photocells oppose each other on a galvanometer. By adjusting flow rates of the samplers a null is reached* and (he efficiency of the filter is determined. Special tests involving POP (dioctylphtbalate smoke)* jet or cascade impactor, radioactive cute or mist, and microorganism techniques are dis cussed, - - Public HeaUh-Eng. Absts. I !| i; I % A k *4 A V- - - - - - - WHVCT ?-; -VJ.-.7 i4 Rk * " . . ' . * . , j , * .* ' ... ^ i{ ir W&P *. * *, * .* *_ ? * * i*. *, *'. * f*,i- ^.,