Document 3ewJQdwBRR0bY5VrnKYKQGROa

MR. T. B. BONHEY - PITTSBURGH OFFICE August % XgS? State of Bev York Deportment tf TaVy Division of Industrial hygiene Has Review - Engineerix Section 00 Centre Street Bev York, H.Y. 10013 EE* AP5EK0YED PIA8S EB-9I^5 & SF-9^5 (MB-499-65 & EAP-5QO-65) for AXCQ&* j&sseha cmmxm, vm or iftsasaA, sr. iahhebce, Hraamas izk-c & i2*wi, coHKxaoR AocesscBr ransh agaiflas Gestleae&t In a letter (dated 7/32/65) written by as at the refuteat of the Engineering Staff of Alcoa's Main Office In Plttrfbasgfr, jour approval ass sought concerning the removal of the rectangular cross "Section ductwork frees the outlet of the collectors* exhausters to the outside stacephere shown on our drawings &-65757-J and B-^S47^T* Your notices of approval tar the shove captioned plans reflected your decision regarding this request at that tins. Conditions of approval #5 (ESaa EP-^-05) and #3 (Idea EB^dL^^) stated that *$ischwg0 to the outdoors is required. Recirculation of the exhausted air can he permitted if & properly sized doth collector le used la place of car in addition to the unit indicated." 1 have sent copies of your approval notices to the Pittsburgh. Office, and they have replied with information not available to me before, and the request to further pursue this natter with you. Through the information which X have received from Hr. Ray W. Andrews, IT. of the Mechanical Engineering Division, in Pittsburgh, end from Hr. Thomas B. Bonney of the Msdlcal Department - Industrial Hygiene Division, also in Pittsburgh, they have indicated that approval for removing thin ductwork, without the additional cloth collectors, may still be possible. The Pittsburgh Office feels that, although the quantity of discharge ductwork is relatively small, in order to provide infixham safety cod health considerations this ductwork should be eliminated. Their opinion is based on tests conducted by Aiwa in the past which have sham type K Roto-Clcne Collectors, which we intend to use, to be at least 99.9^ efficient in removing the combustible dust from the sir stream. Their measurements indicate that more than 99$ f the air borne dust should be composed of particles about 2 microns in diameter. Further, they feel that at least 60$ would be above 325 mesh (*6p0. Roto-Clone type K units will remove 97$ of particles above the 2p. size, and do a very respectable Job on the smaller. ARCH 18601 State of liev York Deportment of Labor 8-9-65 2 This efficiency is such that it will mid the dost concentrations of the discharge air well below the threshold limit value of the material or 50 -jrapcfS end actual neagurecggta have shown the concentratim to be oa the order of cce (l) $pcf or less at the discharge of the unit. This would aeeaa to virtually eliminate any environmental prOhlaaa which had been envisioned. In addition/ the Pittsburgh Office feels that since the dost is comprised mainly cf the alaainaa pfftfflffrt lad atoainnw oxide abrasive* the dust would have a very lotr tcadeify and would be Classified as a ^nuisance dust." Since thoeeparticles that escape collection ere extremely thsy vill tend to collect on the walls of the exhaust duet. & is their opinion that the potential explosion hazard presented by an acciaaalatloa of dust on the duet vails (which, My be appreciable) is of infinitely greeter concern than the dischargins of insignifi cant anoints of taxlcolmlcally "inert" dust into the voddng area* la regard to the above, it was pointed out to the Sithdaugh Office that la the past Hr. J. Baliff, Ur. A. y. Barks, Hr. Arthur C. Stern, and Or. Leonard Oreeubexg of the Departaeat of Labor were consulted cn several occasions regarding situations. These cOMoltations inycdved A1cq&s MgaaelnB tOundyy at I68O Ktemood Avenue In Buffalo, the Aloes Cutlery Ccegmayet OLean and the Case Cutlery CCK&aqr in Bradford, Iteaesylnrania. As a result of tests and studies aade in reference to the above approval for the removal of jh?on -typo H Boto-Clone units was granted in the cases in Question. The alternate suggestion of using doth type collectors is ccwajdered to be extremely dangerous Men used with coMustlble dusts. It was mentioned that such * wait used to collect coabustible metal dust In ft fiarld fer H factory building resulted in an explosion which claimed two (2) lives in Binghamton, 'Sev Yack, in 19^6. Cm the basis of the aftnre-o&tioned arguments, * feel that stipulations #3 and #5 should be deleted. However, if this Information proves to be insufficient in arriving at a farther decision in this case, X an sure that representatives from our Pittsburgh Office would be pleased to meet with you to further discuss and clarify this matter. Very truly yours, AHMETUM COHOST OF AMERICA C. F. Ames 2. Mechanical Eng CM CC; Ifcssrs. H.H .Redder Pittsburgh H.W.Andrews, Jr. - tf T.B.Banney II FJi.Illlg IV File copy routed - DJi .Little - CJEJx&g W. Barr C.T.Bardo - Massene. U aRCH 18602