Document wrxd5oYo5v1KoYQoZ9EyRORa6

44i- ** nr* o fo'ur oh akooh rjr pak cmcnt a qum, no. ___E*8 Jatzenm< prom D/002Q - B/5-H FICLD POINT 04 AKRON DEPARTMENT ft .LOO. NO. ___J.C._McCool_ 4UB41CT D/0020 - B/5-H___________ MONITORING AMBIENT VCM LEVELS WITH A BULLARD DOSIMETER DATE TOUR LXTTEI DATE TMI LETTER V4/74 Objective Compare VCM levels measured by a Bullard Dosimeter with those measured by charcoal tube sampling. This instrument conceivably could be used a? a self-contained personal monitoring device. 1, Conclusuions 1) The Bullard Dosimeter has a possible application as a personal alarm to warn employees when ceiling levels of vinyl chloride have been exceeded. 2) It is quite unsuitable for use as a leak detector because of the long response time, CIO - 15 minutes), required to reach equilibrium. 3) . There is a correlation between the readout values measured on a Doslraett memory cell and the VCM values based on charcoal tube sampling; further work is indicated to provide a clearer evaluation. 4) The high cost of this apparatus ($1900.00) precludes its1 wide spread use, but it could be warranted as a means of backing up results of othei VCM analysis procedures. 5) The Dosimeter could serve as an area monitor because it is a self-contai unit, and would be readily located as desired. Recommendations Average another monitoring trial to compare the Dosimeter data with the char coal sampling results. Special attention must be given to proper calibration of the Dosimeter. Discussion This is a preliminary report of how the Bullard Vinyl Chloride Dosimeter per formed as a vinyl chloride monitoring device in poly bldg. 451 at Avon Lake. The results were compared with results obtained by charcoal tube sampling performed at the same time. The Dosimeter features a sensor which "breathes" vinyl chloride (for which the instrument is factory-calibrated). These vapor ' diffuse into a special solid state crystal, and the signals developed provide a measure of the VCM concentration. These signals can be divided into memory cells for specified sampling periods; based on the counts/hour, the VCM con centration (in ppm) can be graphically estimated. The Dosimeter could provid an immediate estimate of worker exposure to VCM, in contrast to the long time required to work up and analyze the VCM collected by the charcoal tube procedi Like the Charcoal tube approach, the Dosimeter is suitable for being used as FD-nU-a REV. Itfo MTHO. IN U.E.A. NGC 15421 2- D/0020 - B/5-H June 4, 1974 personal monitor for the employees who may be exposed to VCM. Hr, Lynn Willis (of ALGC) and 1 quickly established that the Dosimeter is quite unsatisfactory as an instantanious leak detector* We estimate that it takes 10 - 15 minutes for the Dosimeter vinyl chloride scale reading* to reach equilibrium. We fitted a poly cLeaner, (Hike Novotny), in Bldg* 451 with both the Dosimeter and the standard charcoal tube (5/8/74)* This was to compare how the total VQi values as measured by the two instruments. In both cases* the air samplec was taken from Hr. Novotny1a breathing zone* Results are shown in Table Is VCM Counts Time Counts/hr. TABLE 1 __________ Charcoal Tube 57 Air eampled(l) 35 min* mg* VCM in sample 98 35 1.2 ppm VQI* 8 ppm VCM ( * from graph) 13.4 Encouraged by these results, we repeated the comparison on 5/9/74 with another poly cleaner (J. Allgood). This test was performed to evaluate Dosimeter sensitivity - how short an exposure time was required to obtain a significant read out with the Dosimeter? Table IX shows the results of a 110* exposure as measured by the Dosimeter and by the charcoal tubes TABLE II OPERATION: J.'Allgood Bldg. 451 Poly 19 EXPOSURE TIME: 5/9/74 0925 to 1115 NQC 15422 VCM Dosimeter Charcoal Tube Counts Time Counts/hr ppm VCM 290 110 min. 158 13 Air sample (liters) VCM (mg) in.sample 110 5.6 ppm VCM 19.9 D/0020 - B/5-H June 4, 1974 At this point, we switched to a'new charcoal tube, and continued the monitor!: study. It is to be remembered that when the memory cell is read, the count then starts over. It had been hoped to integrate these readings or the dif ferent steps in the, poly cleaning operation. Unfortunately, this does not wor unless the electricity cell is purged after the memory cell is read* Bbr Whs Is worth, I am reporting the following results in Table III: TABLE III POLY CLEANER; Samble Time Time Jr. Allgood Bldg. 451 Count Readout Counts/hr. Poly 43 VCM Dosimeter pom* .Reading 1115 - 1240 85 min. 438 309 28 22 1327 - 1345 18 min. 46 153 13 25 1348 - 1410 22 min. 44 120 12 12 * VGM value from graph based on counts/hour. The charcoal tube covering the period from 1115 to 1410 gave a suspiciously low value, and is not reported here. It will be noted that in Table 3, nothing is reported for the interval betwee 1240 and 1327. This represents the poly cleaners lunch period. While I had discharged the memory cell at 1240 ( 438 reading), it was a complete surprise to me that when Mr. Allgood returned from lunch at 1327, the memory cell show< a count of 2901 It is very difficult fo me to see why this should be, since he supposedly was in a non-VCM area. It appears that the high gas concentrat: left in the cell at 1240, kept on diffusing, giving for the signals which resulted in the 290 value at 1327* This is why a purge would have to be used ( to draw out the vapors from the cell by heat), if our wished to make a seri< of integrated readings. I have seen enough of this instrument to feel that a repeat trial would be in order. The charcoal tube analysis situation now is in much better shape and we would get speed analyses to compare with the Dosimeter data. AI am con vinced that we should know more about the potentials of this direct read out instrument. ( In spite of its* $1900.00 price tag). elcv John C. McCool NGC 15423 D/0020 - B/5-H June 4 1974 ce: L.B. Crider E.tf. Harrington W. Waltornate F. Krause C. Lufter - P. Zakrieki L* Wallis NGC 15424