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PLAINTIFFS j EXHIBIT i OOl^Koo Hr# Kay 19, 1954 Bunt Counting Equipment Hr. Cilloy hns roquoatod that on Invaotigation be Bads of the duat counts throughout tho sd.il and possible methods of reducing the nnount of dust for improved hygonic conditions. Hill oanagoaant io ever vorking on this problsm and dust counts are periodically made by tho Buroau of Industrial Hygicna. Tho problem of dust counts and methods of reducing came are imdor active study b7 tho Air l^rglcno Comittoo of tho Asbestos Textile Institute. Tho first stop in any duct "count program io to aelect suitablo equipment. Thoro appoarn to bo a dlfforenco of opinion relativo to equipment as" tho lapingor collector io generally used hero vblle tha tbormal prooipitator is uaoc in England for collecting tho dust particloo. It 1# understood Hr. Luttenberg is arranging a conforonce vith Dr. Shilca of the Pennsylvania Bureau of In dustrial Hygiene for a discussion cf dust counting oquipxcnt. Also, dust counts will undoubtedly be diccunood at tho June meeting of tho Air Hygiene Ccsnaittoo of the Asbestos Textile Institute. For background information, a brief litomturo sosrch vas made in Chemical Abstracts on dust counts, in vhich tho folloving facts voro rioted relativo to tho oporutiou, limitations, and comparisons among various typos of instruments Many- typos of equipment for determining dost counts or dust ccncentra tione bavo boon dovolopod. Tho total nnount of duct in air can bo dotsrminod tj drawing a known amount of air through a suitablo filter and the amount of dust determined by weighing (1), Stokingor and La skin (2) roport tha oloctroetatic precipitator in which the dust particlas are made to sottlo out by an electric field is boot suited for tho determination of dust concentrations. Eovover, it Is not suited for aizo--distribution of most particulates becauss of size sogrogntlon along tho collecting surfc.es, and because of aggrogaticn of particloa. Several types of apparatus aro suitable for dust counts. In tho impingor typo (3) tho air is drawn through c jet to impinge on wntor. The dnot is rotained as a suspension fron vhich it io allowed to Bottle out on n special type of aicroccopo olido end tha duat particlco countod. Its officiency Increases vith tho oenpling volooity vhich is normally about 23 liters par minute. Its officiency is about 40. Chorabury of Penn State rciporto (4) tho nldgot inpingor oothod of collecting, analysing, and evaluating dust lfl_puxely amplrlcal~t:nd~glves "only relative PLAINTIFFS EXHIBIT W-008M2 Kr. B. L Hooro - 2 repulto which aro subject to orroro ia IntorprotJitloa If considerations aro not givon to limitations oonccmod with tho ability of tho apparetuo to draw dust Into tho nozslo tube,. tho lcaa _of_thqjaus_t_by__tha .liquid, tho chattorlng >#> of tho fluat cnlaplngeocnt, tho stability of the duot la tho liquid.~the sloe range of tho duot, eta. Vhcn tho accessary corrections aro applied, tho midgetiaplngor aothod yields rooulto comparable vith other aothoda of evaluating dust. In tho caocado inpcctor ll), tho air lo paceod consecutively through four Jets of docrcaotng oico onto a glass nil do contod with an adhcaivo. It 13 reported (2) to hare given excollont particlo-sizo analyses in tho size rango of C.2 to 50 nicronc. It yioldc rapid and roliablo results in the characterization of duet and can bo used for tho si 10 distribution analyses of nixturoo of ducts. Dolov tho uooful rango of tho cascade inpoctor (2), tho thomal precipitator io tho coot usoful instrument; This instrunont (5) oakos usa of tho faot that thore io a dust freo space around a hot body, in this caoo an electrically hooted viro placed between rsioroDCopo covor alides on which the dust is deposited Toots show that tho instrucont collects almost 100$ of the dust particles in the air. A vory slow eanpling rate, normally 7 ec/nin., la required. Hagill in describing techniques for snog analysis (6) reports a cascade inpaotor vab used to collect conploo ovor brief perioda of time and to follow atcorphorio changes oloooly. A thermal precipitator is advantageous in that it ap pears to colloot all fine particles, but it xuot bo operated at very lev air flow rates. fevaral photoolectrio dovicon and dust caserss for nensuring directly the concen tration of duet particles in tho nir have boon reported. These aro based cm tho Interference of a bean of light by dust particles in the air. For accurcto dust counts, cpacinl attention oust be givoa to campling techniques as, the solection of location, tho uoo of nixing baffloo, and tho need of lsokinotio csapling (7). Since it_hac bccn_roportcd_that_thoro is no _unfa*rarable_ physical reaction frra . . aobostoo duot_ln tho lmga which lo undor 10 nicrons or ovor 0 nicronc in *-- length,~our eapbaein should bo directed toward counts in that size rangoV" This appoaro to bo tho range in which the caocado ir.paator or inpingor Is moot effecti' vhJLl# tho thermal procipitator is Root effsctlTo for finer particloo. There for*, tho cascade ixp&ator is given first choice and tho inpinger aocond choice. Tho accuracy of any ovist counts will dppaod core on tho car of taking the easpic and asking tho counts than on tho typo of apperatun casd. a* cc- Mosers. Cillcj i-- I-uitcnbergor Stall , H. S. Kalor "- REFERENCES - (X) Dust In Indnotrial Atmoapheraa. Determination of aaoa concentration by the Volatile Filtor Method. P. F. holt., Natallurgia 44,- 52-4, 1951. (2) Air Pollution and partiolo-alcc toxicity problooa. H. E. Stokingor and S. Laokln, nucleonics, 6, Ho. 3, 15-31, 1950. (3) Duct in Industrial Atcoopheros. Tho inpingor and oascads impactor. P. F. Holt, Ketallurgia, 43, 25G-9, 1951. (4) Tho uas and limitations of tho aidgot lmplngor for counting dust. H. D. Chanibuxy, Proc. national Air Pollution Symposium, 1949, pg. 184-92. (5) Dust in Industrial Atcoophoro*. Determination of tho particle count. P. F. Holt, MotallurgLa, 43, 151-2, 1951. (6) Techniques employed in tho analysis of Loo Angelos Saog, P. L. Hag-ill, Proc. Rational Air Pollution Synpoaium, 1949, pg. 61-3. * (7) Sampling of dust-laden gnaoo. C. J. Stalnaand, Trans. Inst. Chanical Enginoore, 29, 1951,!, ?g 15-44. portlnont Artloloa An appraisal of proaont-day field iaotruaento. A. 3. Sottorlind, An. Ind. Hygiene Assoc. (quarterly 9, 35045, 1948. Relation betvoen and proolsion of dust counts. C. F. Brovn end U. H. Schrcnk, 0. 3. Bureau of Minas Report, Investigation Ho. 4568, 1949 (35 pp).