Document zQZdqxzJV1dma6KRZy2EpYnk0

iI i | ii !; X. B. BONNET PITTSBURGH OFFICE MR. G. D. BRUNO WENATCHEE WORKS December 19, 1967 CONFIDENTIAL RE: INDUSTRIAL HYGIENE_______________ Concerning our recent phone conversation, you mentioned that the Marinite sawing operation on the unventilated Carpenter Shop Circular Table is a regular Job. It entails perhaps 1 1/2 -- 2 hrs. per day. Because of the regularity of the Job, we feel that the dost generated should be controlled by exhaust ventilation; especially in view of the bad favor in which asbestos is present ly being held. . Respiratory protective devices have serious limitations and to use them as primary environmental control measures is poor industrial hygiene practice. Their applications are intended for experimental or infrequent operations and, in the case of regular jobs, where the contaminants cannot be adequately con trolled by other means. . Ventilation systems are commonly used on table saws such as you described. I have enclosed an example of one taken from the ACGIH Industrial Ventilation Manual. Even in the light of your recent dust survey, we recommend that the feasibility of venti lating the saw be examined. I spoke to Dr . Colwell concerning the asthmatic who works in this area. He stated that dust of any type will tend to irritate an asthmatic, however, would appear that this man is not sensitive to the Marinite components. If effective engineering controls are installed, he will probably tolerate his environment quite well. If the man is sensitized to Marinite, he and everyone else will be aware of it, and the man won't be able to tolerate a minimal amount, even after installation of control methods. Dr. Colwell feels that it would not be wise to have the man make a special visit to discuss his problem with Dr. Miller. However, if your local physician already is familiar with the case,' Dr. Colwell would like to discuss the case with him and suggests that Dr. Miller give him a call at his convenience. Concerning the degreaser din the Mold Maintenance room, it would appear that the degreaser hood is not ideally located. Apparently, the canopy hood carries the solvent vapors past the worker's nose. I've also enclosed a drawing of a ventilation scheme (slot venti lation} commonly used on degreaser units. I might also add that, quite often, it is possible to operate small degreasers (e.g. less than five square feet surface area) without any ventilation control whatsoever. This requires that ARD 042665 Mr- G. D. Bruno December 19, 1967 Page 2 the degreaser be maintained according to the manufacturer's recommendations, be located in a large room (e-g. more than 20,000 cu.ft.) with few drafts and not be used for parts whose configuration cause the liquid solvent to be carried out. If your operation can meet these qualifications, you may be able to attain better control with the canopy hood removed, (see the enclosure from the ASTM Vapor Degreasing Handbook) I spoke to Mr. Small about the ventilation of the table saw and v; degreaser. Should your engineering people desire any assistance from Pittsburgh Environmental Control Engineering, they will be pleased to help out in any way they can. Finally, a word about the collection and evaluation of coal tar pitch volatiles. Glass fiber filters do not tend to pick up nwch . moisture from the air as does filter paper. If the sample you collect is lO milligrams or less, you will probably wish to desiccate the glass fiber filter before weighing--both prior to and after sampling. If your sample weight is more than lOO mg., you can forget the desiccation step unless you have reason to suspect that you have collected water with your pitch fume sample. If the sample weight is somewhere between lO and 100 mg., you'll have -to play it be ear. Whether or not you make a correction for water pick-up will depend on tow well you like the uncorrected concentration value. If, by any chance, you get into any benzene extraction of the collected material, a blank on an unused filter is a must. I have seen reports that some of the blanks run pretty high. If they are high and variable, washing them with benzene (i.e. prior to the initial weighing) may be helpful. Hope the enclosures prove useful to you. Best wishes for the holidays. Thomas B. Bonney TBBimh Enclosures*- cc: D. W. Hitson - Attn: B. R. Small, Pgh - 2 M. O. Colwell, L. V. Cralley, file (T) 1~IC> VS-5o 1 VS-7 oZ rv\ cr^\l x_ ' ARD 042666 5-68 INDUSTRIAL VENTILATION Blade width, Exhaust volume, cfm inches ' Bottom Top Total Opto? over 2 to 3 over 3 to 4 over 4 to 6 over 6 to 8 350 350 550 550 550 350 550 BOO /too 1400 700 900 1350 1650 1950 Duct velocity - 3500 fpm. Entry loss - f.O duct VP AMERICAN CONFERENCE OF GOVERNMENTAL INDUSTRIAL HYGIENISTS BAND SAW DATE !~64 ~1 VS-706 ARD 042667 SPECIFIC OPERATIONS 5-47 Slot velocity- IOOO fpm maximum Entry loss -1.78 slot VP +0.23duct VP Also provide: ' l Separate due for combustion products ifdirect- fired unit. 2. For deoniig operation, on air-tine respirator is necessary. 3. Forpit units, foepit shouldbe mechanically ventilated. NOTE: Provide downdraft grille lorparts foot cannot be removed dry; 0=50 cfm/sq ft grille area. . Property operated, property located degreasers maynot require ventilation in rooms over 20,000cu ft in volume. rC Astm Oy <J*y+r AMERICAN CONFERENCE OF . GOVERNMENTAL INDUSTRIAL HVGIEN1STS SOLVENT DEGREASING TANKS DATE }-S4 t VS-sol ARD 042668 5-70 : - INDUSTRIAL VENTILATION Table, rip, mitre and variety saws. Saw diameter, inches Exhaust volume, cfm Up to 16 inch over 16 to24 incL over 24 variety with dado 350 440 550 550 Duct velocity - 3500 fpm Entry toss - t.O slot VP + 0.25 duct VP > AMERICAN CONFERENCE OF GOVERNMENTAL INDUSTRIAL HYGIENISTS PATE TABLE SAW 1-64 I VS-FOB ARD 042669 . used in 'n r r.on. to and oilers in io drain :'iuld be -<tvc on -old be' ' qrace i.il the piston place. 12 ft just being -team -team' <1 for f- ssure -'lould > side. rs.. an old be -)tT the 'wling -i ronve the lid the -.- bulb future ievice . v rercset;ed to .1 coils *ndenI oiler k pres-r. traps lory. is I min ty pilot wn of all ' failure. >r the fi HANDBOOK OK \APOK DeCKKASIXO 15 machine is being cleaned out, all gas, with a'connecting chamber^! otic end, including the pilot, should be shut off. are used. The connecting chandler is Thermostatic control should be provided provided wish a take-otf for local exhaust to shut off all gas if the boding tetnpera- or for a separate motor and blower. Ex ture of the liquid gets beyond a preset haust rates an- generally of 4he 'magni temperature.'Otis and greases dissolved tude of 60 cu ft per min per square foot of in the solvent raise the boiling point, evaporative area with velocities at the and this rise should be limited.. For tri- slot of 500 to 1200 ft per nun. However, chlorcthylene, a setting of 235 to 240 K local laws should be chccked'Mlxhaustiiig is recommended, with 295 F for per- of conveyorized units , is generally by cblorcthylcne machines. In normal opera means of an indraft intothc work open tion, the degreasers should be cleaned - ings so as to create a movement of air out before becoming this heavily con into the hoods. Exhaust rates will vary taminated, as discussed later under De from 50 to 100 cu ft per min-per square- greaser Operation. The high tempera foot of work opening and are mol based tures possible with gas make such control on the area of the vapor level within the mandatory and it should be of the unit. Care should be exercised in locat manual reset type. An automatic valve ing vcntilation exhaust stacks to ensure or device should be installed in the gas that exhaust gases do not return to the supply fine for shutting off the gas in case building. ' .' of excessively high vapor level. This should be of'the manual reset type calling Safety Precautions: . for investigation of the cause of .high 1.. Means tor cleaning put the degreas vapor level and then manual resetting of ing equipment without any one having the valve. ' . to enter should be incorporated in ihe 3. Electrically Heated Degreasers.-- dcstgn insofar as possible. Except for the small laboratory units, all 2,' Amply sized - cleanout %<loor plate-1 electrically heated degreasers should be strategically locafed, steam coils on re provided with thermostats to shut off- movable cleanout plates, electric heating heat due to excessively high vapor level, elements on removable-cleanout plates, or elevated temperature of the boiling and removable plates near spray -zones, liquid, and if possible a device for shut in.the case of a spray unit, are essential. ting off heat in case of low liquid level. Ji. A' permanent caution sign about A low liquid level device can be thermo conditions under which entryis possible static. or of the mechanical float type. In should be affixed to' all such openings. all cases,the wiring should be for manual .4. Covers should be provided for all resetting. . . _____ open tank units so that when not in use Mechanical Vettiilaiian: the equipment is covered completely. 5. .Safe handling procedures are cov-.. Mechanical ventilation should be con ercd^jn^dctail in the.section on General sidered for tanks having an open area of Hazards.of Terchlorethylcne-and Tri- 5 sq ft or more and installed in a room 'aiSfSSjiede.' : ; smaller than 20,000 cu ft- The ventilating system is best designed and provided by the manufacturer of the degreasing I-ocatiox or Solvent "'DDGRr-AStxG'' ' Hqum-men-t V equipment. Where exhausting is applied . While usually the sequence of work to open tanks, suction slots running the l flow through the plant is the prime length of the two opposite longer sides ' factor in determining the location of a. d. bhobo W2HAICHEE WORKS COHFXDSHTIAL This copy for Dr. L. V. Crallev - Pittsburg Office MR. V. E. MWHEWS VEHAICHES WORKS December 22, 1967 BKt MAKOmK 8AWIB0 - CAHFKHTSa SHOP At the request of Mr. Karrie, an air teat sea conducted In the Carpenter Stop on Wednesday, December 1J, 196?- She purpose of the test was to detenalne air loading by Marlnlte dust after searing operations. Bie results of the test shoved that the lnerease In dust loading caused by Marlnlte sawing vas substantially below the $ a^ef threshold limit value established by the American Conference of Governmental Industrial 3rglenlsts, 1967. The test results ranged trom. 0.07 appcf to 2 n5)pcf. The test covered a time period of about an hour end a half. Baaed on the examination of the work cycle, the materials involved, and the test results, there does not appear to be a significant hazard In the Carpenter Shop which can be associated with Marlnlte, provided that conditions remain the asms es those encountered daring the test. Workmen should, of course, continue to wear adequate personal protection [dost easts] during the actual saving of Marlnlte. If you have any questions, please coll me. O. D. BHOHO QOBiaea cei J. . Barrie K. C. Doerschuh/B. V. Stephena Dr. L. Y. Cralley - Pittsburgh Office ARD 042671