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: .u .WmNY TECHNICAL REPORT Addendum Report #3: Additional Studies on VCM Adsorption | tec*TiON " "-- M. M. O'Mara/G. A. Lees Avon Lake Technical Center i May 25, 1974 Typed: Mey 28, 1974 ko A number of VCM exposures involving new adsorbents, coanercial adsorbents at low VCM exposures, and a variety of exposure conditions have been carried out. During the course of this continuing study we have replaced the Century OVA with a Bendix Hydrocarbon Analyzer. Zn summary we have found*. (1) The Bendix analyzer far outperforms the Century analyzer in terms of stability, background and accuracy, (2) carbon remains to be the best adsorbent for VCM, (3) the life-time of the Welsh cartridge in terms of 1 ppm breakthrough ranges between 30 minutea and 90 minutes, <4) the Welsh canister outperforms anything evaluated to date* i J. L. Nelson E. W. Harrington G. D. Scheef B. A. DiLlddo . G. Schwaegerle "a. ' 1 ono*' ?ii.c *cc* c" E. M. G. Zwlcker H. Waltemate E. B. Katzenmeyer, Jr. F. E. Krause R. K. Kreager J. Pausch V. Zakrlskl A. L, Schultz R. W. Strassburg M. N. Johnson L. B. Cridar E. A. Collins L. A. Chandler R. J. Meyer C. Flynn D. L* Kent Plant Managers Plant Safety Engineers < i ' j | BFG24490 23223001 Introducti on Our last report (B.F.G. Technical Report, March 8, 1974) on the subject of VCM adsorption covered evaliatior* of new adsorbants and larger carbon canisters and cartridges* Since that, report we have continued our studies in this area and have also prepared VCM standards in support of other investi gations (gas chromatographic, chemical desorption, x-ray studies). This current report is a suxnaery of this work. A sunmary of all experiments is provided in Table I. No detail is given for the Analytical Gas Standards (A.G.S.) prepared for other studies; a permanent record of this work will be retained. During the course of this work we replaced the Century OVA with a Bendix Total Hydrocarbon Analyzer. One of the advantages with the Bendlx instrument is the ability to determine VCM breakthrough times below 75. An attempt was made to do this with the Century OVA at T#j (see #33, 34) but there is considerable error in the values. The main reason is due to the inherent 5-10 ppm background In the Century analyser. This background can be zero suppressed with the Bendlx instrument. Ve have also found that the baseline is much steadier with the Bendix instrument. Baseline drift is probably the greatest source of error with the Century OVA analyser, especially in the 0-5 ppm region. The agreement between the two methods considering the above limitations with the Century is not that bad. Testing the Welsh cartridge (7500-1) at 15 llters/mln. and 10 ppm of VCM we obtained the following breakthrough times (T jJ*for the two analysers; T * 162 (Century) and T e = 120 (Bendix) (see Experiments #33 and #63). 'Previously --' we had determined a 12% deviation in determining T$ with the Century analyzer. In Table 1, we have analysed the Welsh 7500-1 cartridge at 30 1/mln. and 10 ppm two times (#64 and #71) with the Bendix analyser* The average Tq is 50 i 4 minutes which represents an 8% deviation- In our next report we will broaden the data base on this deviation analysis but reproducibility seems better with the Bendix instrument. Effect of Rate on Breakthrough Time Comparing experiments #63 and #64 a significant decrease in Tq (initial breakthrough) takes place when the rate is increased from 15 1/min. to 30 1/min. A number of people have requested that more experiments be carried out at the 15 1/min. rate rather than the 30 1/min. rate. While the Information obtained at 15 1/min. is of interest, it should be remembered that in our approach we correlate to the 0SHA standard when we test at 30 1/min. not at 15 1/mln. Since final acceptance of any device is based on the OSHA standard, most of our testing should be in the 30 1/aln. range (or whatever rate best correlates to the standard). 23223002 Tx Values Our initial data Involving the Welsh cartridge at 10-2Cl ppm (30 1/min.) indicates that Tj. Is reached between l and If hours. Although ve have not yet S it T 5 is defined as the time to .5 ppm VCM/ BFG24491 Page 2 May 28, 1974 determined at 50 ppm, previous wo-k with the Century analyser at 50 ppm indicates a Tj * 41. We believe this vilue is high, again due to the inherent problems with the Century analyser at these low levels. Never theless in terms of the problem, the values (T^) indicate the approximate life-time of the Welsh cartridge. If the concern is worker exposure to 1 ppm of VCM, the Welsh cartridges exhibit a life of ^ to l hours depending on the concentration of VCM in tbs atmosphere. Welsh Canisters In our last report we showed tbs significant increase in protection offered by the Welsh canister (7800-1M). At 30 1/min. and 100 ppm, T5 was reached after 11 hours. Recent studies with this canister (Experiment #70) indicate that initial breakthrough, at 10 ppm and 30 1/min is almost 17 hours and is not reached until ~20 hours. To date we have seen nothing that approaches the performance of the Welsh canister. Other Adsorbents A number of other adsorbents involving a mnber of principles of chemistry were tried. Nothing, so far evaluated, approached the effective ness of carbon in scavenging VCM. In our last report we found that the coconut charcoal was not as effective as the petro-charcoal. Since that report. Harvard has also tested the coconut charcoal in their apparatus and have arrived at the same conclusion. Thus at this time, coconut charcoal offers no real advantage over the more abundant petroleum based charcoal. Future Studies We will continue our studies along the following lines: (1) determine reproducibility (Tq, T>5, T^> at the low (5-20 ppm) exposure concentration, (2) follow the Harvard work now in progress in which engineering redesign experiments with the entire masks are underway, (3) continue to evaluate new adsorbents, and (4) evaluate the standard cartridges and canisters at low levels of VCM (1-5 ppm). 23223003 ch Attachment M. M. O'Mars BFG24492 \ ~\ 'I Table 1 Experiment No. 31, 32 SMMfrv ef VCM Adsorption Data Obtained with the VCM Flow E*twrie*it TnY9lYiHB A.C.S. nov Uc* VCX Concentration * ... 'T' (minutes) 33 34 35 - 39 40 41 42 43 - 46 47 48 - 53 54 55 56 37 - 61 62 Walah 7500-1 Ha1th 7500-1L A.C.S. MSA Cartridge 44135 Willson 1-13 Willaon 1-21 calclia carbonate absorbent repeat of #42 (1-21) A.C.S. MSA Cartridge 459315 1CA Cartridge 459315 Willaon 1-25 Ti0a, Lead Acetate abaorhanct Walah 7500-1 63 Welsh 7500-1 64 65 M H 6. M 70 Welsh 7500-1 Walah 7300-1 Various carbon filters containing nixturea ef carbon and other adaorbaata; #67 la the control containing only carbon. Walsh canister, 7B00-1M 15 15 30 30 30 30 30 30 30 30 30 IS IS 30 30 30 30 30 30 30 71 Walah cartridge 75001 (repeat of #64) 30 10 10 100 100 100 100 100 50 100 100 100 20 10 10 20 100 100 100 100 10 10 t 3 162; Tj - 278 T#J - 291 13.0 0.0 57.0 aU 0.0 46.5 32.0 25.0 11.0 All 0.0 data in error; will be repeated T0 . 98, T , - 120; 148 T0 - 54, - 92 T0 * 35, Tt - 57; T5-77 13.0 32.0 12.0 0.0 Tfl > 1010, T. - 1220, tj 1335 T0 - 46, Ir - 81 i'-Ti-1'Tj it the cine (la minute*) la which the concentration of VCX dovnatrean from tba cartridge bccoaat 5 ppm, 0Analytical Cat Standard. 0Eun* 31 to 61 were nada vith the Century O.VJt. 00.0 Hiai lmediate breakthrough; no VCX adaorptlon vaa evident. (S)Macerial* submitted by L. Chandler for evaluation aa VCM adaorbaata. 0Runa 62 - 71 and all future experiments vara nada vith our nav Bendix total Bydrocarboa Analyser. BFG24493 23223004