1、07842b5 05Lh934 b50 STD-AWS LVOS-ENGL 1982 0784265 051b935 597 D Laboratory Validation of Ozone Sampling with Spill-Proof Impingers Research performed by the Southern Research Institutes, Bir- mingham, Alabama, under contract with the American Welding Society and supported by industry contributions.
2、 Performed By: Performed For: H. Kenneth Dillon Marynoel M. Graham Merry B. Emory Southern Research Institute Birmingham, AL 35255 The American Welding Society 550 N.W. LeJeune Road Miami, Florida 33126 July 1982 Prepared for: Safety and Health Committee AMERICAN WELDING SOCIETY 550 N.W. LeJeune Roa
3、d Miami, FL 33126 International Standard Book Number: 0-871 71-224-5 American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126 1983 by American Welding Society. All rights reserved. This report is published as a service and convenience to the welding industry and is the product of an independ
4、ent contractor (Southern Research Institute) which is solely responsible for its contents. The materials in this report have not been independently reviewed or verified and are only offered as information. AWS assumes no responsibility for any claims that may arise from the use of this information.
5、Users must make independent investigations to determine the applicability of this information for their purposes. Printed in the United States of America . STD*AWS LVOS-ENGL 1782 078q2b5 05Lb937 3bT Contents Personnel v Acknowledgements vii Abstract ix I . Background and Research Approach 1 A . Back
6、ground . 1 B . Research Approach 1 2 . Literature Search 2 3 . Protocol . 2 1 . Purpose and General Considerations . 1 II . Construction and Evaluarion of an Ozone Test Atmosphere Generator . 5 A . Construction of the Generator . 5 B . Evaluation ofthesystem . 7 III . Development of a Prototype Samp
7、ler . 9 A . Choice of Candidate Tubing and Filter Materials . 9 B . Screening Tests 9 1 . Evaluation of Tubing 9 2 . Evaluation of Filter Materiais 1 1 3 . Assessment of the Effect of Nitrogen Dioxide and Nitric Oxide Upon Ozone Stability Inside Flexible Tubing During Sampling . 12 4 . Determination
8、 of the Effect of High Relative Humidity Upon the Transport of Ozone Through a Recommended Sampling Device 14 Teflon Filter and Bev-A-Line IV Tubing . 14 C . IV . Laboratory Evaluation of the Modified Sampling and Analytical Method.for Ozone 17 A . Calibration of the AKI Procedure . 17 B . Determina
9、tion of the Accuracy and Precision of the Developed Sampling and Analytical Method 18 1 . Validity of the Reference Analytical Method 18 2 . Accuracy and Precision Tests With Prototype Samplers 19 C . Determination of the Storability of Impinger Solutions Exposed to Ozone 20 1 . ProcedureNo . i 20 2
10、 . Procedure No . 2 21 3 . Summary and Conclusions of Storability Tests 22 V . Initial Field Evaluation of the Prototype Sampler 23 A . Description of Welding Test Conditions 23 B . Description of Sample Sets. 23 1 . Sample Set No . 1 . 23 2 . Sample Set No . 2 . 24 . 111 Contents (continued) C . D
11、. Processing Of Samples 24 Results and Discussion 24 1 . Ozone Determinations 24 2 . Additional Characterization of the Welding Environment 25 VI . Additional Field Evaluation of the Prototype Sampler . 27 Welding Test Conditions . 27 Air Sampling and Analytical Procedures . 28 1 . Evaluation of the
12、 Effects of Fume On Ozone . 28 2 . Evaluation of the Developed Personal Sampling Method . 28 I . Evaluation of the Effects of Fume on Ozone 29 2 . Evaluation of the Developed Personal Sampling Method . 30 VII . Summary and Conclusions 33 A . B . C . Results and Discussion 29 VIII . Acknowledgements
13、35 IX . Bibliography . 37 Appendix A: Summary of Statistical Terms and Formulas . 39 Appendix B: Tentative Sampling and Analytical Methodfor Ozone Inside a Welding Helmet . 41 2 . Range and Sensitivity . 41 3 . Interferences . 41 4 . Accuracy and Precision 41 5 . Advantages and Disadvantages of the
14、Method 42 6 . Apparatus . 42 7 . Reagents 42 9 . Calibration and Standards . 44 1 1 . References 44 1 . Principle ofthe Method . 41 8 . Procedure . 43 10.Caiculations 44 . - STDOAWS LVOS-ENGL L782 0784265 05Lb939 II32 Personnel AWS Research Committee Di. A. N. Ward, Chairman K. L. Brown, Vice-Chairm
15、an M. E. Kennebeck. Jr., Secretary Caterpillar Tractor Company Lincoln Electric Company American Welding Society J.S. Gorski Kemper Insurance Companies E. Mastromatteo INCO, Ltd. P. W. Ramsey A.O. Smith Corporation C.E. Wiggs The Heil Company Acknowledgements Our gratitude is extended to the Command
16、er, Anniston Army Depot, Anniston, AL and to Union Carbide Corporation in Birmingham for use of their facilities for field tests. Ken Brown, Kevin Lyttle and Dan Voss of the Safety and Health Committee, American Welding Society, provided invaluable guidance and help throughout the study. Funds for t
17、his project were provided by the American Welding Society. The American Welding Society gratefully acknowledges the financial support of the program by industry contributions. Supporting Organizations Air Products and Chemicals, Incorporated Airco Welding Products Allis - Chalmers Alloy Rods Divisio
18、n, The Chernetron Corporation AWS Detroit Section AWS New Orleans Section Arcos Corporation The Binkley Company Caterpillar Tractor Company Chicago Bridge and Iron Company Grove Manufacturing Company, Division of Kidde, Incorporated General Electric Company The Heil Company Hobart Brothers Company H
19、untington Alloys, Incorporated Lincoln Electric Company Miller Electric Manufacturing Company National - Standard Company A.O. Smith Corporation Teledyne - McKay, Incorporated Trinity Industries, Incorporated Truck Trailer Manufacturers Association Walker Stainless Equipment Company Weld Tooling Cor
20、poration Many other organizations have made contributions to support the ongoing program from May 1979 to the present. vii This report describes the adaptation of an existing air sampling and analytical method for ozone to the personal monitoring of employee exposures to the substance inside a weldi
21、ng helmet. The Saltzman iodometric method was modified to accommodate helmet sampling. The personal air sampler that was developed consists of a Teflon filter in a polystyrene holder joined with flexible tubing to a spill-proof impinger containing an alkaline potassium iodide solution. The sampler i
22、s compatible with a personal sampling pump capable of an air flow rate of 2.0 L/ min. The overall method was evaluated in the laboratory with 110-L test atmosphere samples at an ozone concentration of about O. 1 ppm (0.2 mg/ m3 at 25 C) and with 40-L test atmosphere samples over the concentration ra
23、nge of 0.3 to 5.1 ppm (0.6 to 10 mg/m3 at 25 C). The average bias relative to an independent sampling method was about -10% for determinations near O. 1 ppm and about +7% for determinations in the range of0.3 to 5.1 ppm. The relative standard deviation at O. 1 ppm was 6.6% and the pooled relative st
24、andard deviation for concentrations in the range of 0.3 to 5.1 ppm was 7.7%. Field tests of the method were not as successful. The ozone concentrations determined with the developed method were much lower than those simultaneously determined with a chemiluminescent monitor and those determined by an
25、other iodometric impinger method, the boric acid/ potassium iodide method. Loss of ozone as a result of reaction with welding fume present in the air samples or as a result of the catalysis of other reactions of ozone by the fume may have contributed to the observed discrepancies. A tentative person
26、al sampling and analytical method was recommended based on the boric acid/ potassium iodide procedure. ix - STDmAWS LVOS-ENGL 1982 = 07842b5 051b942 727 Laboratory Validation of Ozone Sampling with Spill-Proof Impingers I. Background and Research Approach A. Background All arc welding operations pro
27、duce ultraviolet radiation; in turn, the ultraviolet rays with wave- lengths 24 2 13 24 2 13 24 2 13 24 2 a. Each filter holder was attached to a 2-ft length of 0.25-in.-o.d., 0.125-in.4.d. Bev-A-Line IV tubing. b. Bev-A-Line tubing alone. STDmAWS LVOS-ENGL 1982 E 07842b5 05Lb952 b7b E 12/ LABORATOR
28、Y VALIDATION OF OZONE SAMPLING WITH SPILL-PROOF IMPINGERS sampling device and tubing, the sampling stream was split by means of a nylon tee between the monitor (sampling at about 0.2 L/min) and a critical orifice connected to a vacuum pump (sampling at about 1.8 L/ min). The monitor signal was recor
29、ded for about 30 min. The filter holder was then removed from the sampling line, and the experiment was repeated. The results indicated that the styrene filter holder did not retain a significant quantity of ozone. At the 95% confidence level, the observed ozone concentra- tion with no filter holder
30、 in the sampling line was O. 11 1 f 0.003; with the filter holder present, but with no filter, the observed concentration was O. 114 f 0.002. The styrene filter holder was, therefore, deemed to be suitable for the sampling device. The affinity of the filter materials for ozone was then determined by
31、 a similar procedure: Generator effluent containingabout O. 1 ppm of ozone was sampled at 2.0 L/min through a 37-mm polystyrene filter cassette in tandem with a 2-ft length of 0.25-in.-o.d., O. 125-in.4.d. Bev-A-Line IV tubing. Downstream from the filter holder and tubing, the sampling stream was sp
32、lit as before between the monitor (sampling at about 0.2 L/ min) and a critical orifice connected to a vacuum pump (sampling at about 1.8 L/min). The sampling was performed for at least 20 min. In each of three sampling sets, a reference monitor signal was first established with no filter disc mount
33、ed in the filter holder. The procedure was then repeated two or three times with a different candidate filter material mounted in the holder each time. The results of these tests are presented in Table IV. The apparent loss of ozone that occurred when PVC and cellulose ester filters were exposed was
34、 due in part to a small decrease (-7%) in the monitor sampling rate during the exposure of these filters; however, the filters did appear to sorb a large fraction of the ozone sampled. Of the other three filter materials, the Teflon fiber mat filters performed best and exhibited no measurable affini
35、ty for ozone. The Spectro Grade glass fiber filters sorbed 3 to 4% of the ozone sampled. The Teflon membrane filters indicated losses of 4 and 11%. From these results, the Teflon fiber mat (5-m pore size), which sorbed no ozone, was judged to be the most satisfactory filter medium. The Spectro Grade
36、 glass fiber filter also yielded acceptable results; it appeared that the Spectro Grade filter could be employed in a sampling device with only a small loss of ozone. 3. Assessment of the Effect of Nitrogen Dioxide and Nitric Oxide Upon Ozone Stability Inside Flexible Tubing During Sampling In subse
37、quent tests, we attempted to determine the effect of oxides of nitrogen upon the stability of ozone while the ozone was sampled through Teflon and Bev- A-Line tubing. The test procedure was as follows: A dilute standard gas mixture of either nitric oxide (3.3%, v/v) or nitrogen dioxide (1% viv) in n
38、itrogen was combined at a controlled rate with a stream of generator effluent containing ozone and air. The Table IV Determination of the affinity of filter discs for ozone Average Sample Observed ozone loss of set no. Filter disc concn? pprn ozone, %b I None 0.114 f 0.002 - PVC 0.020 f 0.006 82 Cel
39、lulose ester 0.003 f 90 o. 110 f 0.001 a. At 25 to 21 C. b. 95% confidence interval. c. 3 in. x0.25-in.-o.d. xO.16-in.4.d. d. 37-mm Teflon filter in polystyrene filter holder in tandem with2 ft of 0.25-in.-o.d., 0.125-in.-i.d. Bev-A-Line IV tubing. at the 95% confidence level between the monitor res
40、ponse with the short length of glass tubing and the response with the sampling line described above. At a relative humidity near saturation at 25 to 27“ C, the average monitoring reading observed with the sam- pling line was about 3.5% lower than the average reading observed with the glass tubing. T
41、hus, even under conditions of very high relative humidity, the effect was observed to be small. C. Recommended Sampling Device On the basis of the accumulated experimental data and other practical considerations, the following com- ponents of the ozone sampling device in the order of their occurrenc
42、e in the sampling train were re- commended: 1. A 37-mm Millipore Type LS (Mitex) Teflon fiber mat (Millipore Filter Corporation, Catalog 2. A two-piece closed-faced polystyrene filter cassette (Millipore Filter Corporation, Catalog No. M000-037-AO) to support the filter during sampling. 3. A nylon a
43、dapter (Millipore Filter Corporation, Catalog No. XXII-025-03) to attach the holder to the tubing described in Item No. 4. 4. A 2-ft length of Bev-A-Line IV (0.25-in.-o.d., O. 125-in.-.d.) plastic tubing (Cole-Parmer In- strument and Equipment Company, Catalog No. C-6490-12) to transfer sample air f
44、rom the filter to the impinger. Teflon tubing of similar dimensions may also be used if connectors can be found to ensure an airtight fit of the tubing with the filter holder and impinger (described below). 5. A nylon adapter (Gelman Sciences, Inc., Catalog No. 4222) attached to the downstream end o
45、f the 2-ft length of 0.25-in.-o.d., O. 125-in.-id. Bev-A- Line IV tubing. 6. A 1-in. length of 0.313-in.-o.d., 0.188-in.-i.d. Bev-A-Line IV tubing (Cole-Parmer Instrument and Equipment Company, Catalog No. 3-6490- 14) as a connector for the adapter described in Item No. 5 and the inlet of the imping
46、er des- cribed in Item No. 7. 7. Spill-proof impinger, 2-oz (Daco Products, Inc., Catalog No. SI-32). 8. A I-ft length of0.313-in.-o.d., O.lSS-in.-i.d. Bev- A-Line IV tubing to connect the outlet of the first impinger with the inlet of the backup impinger. NO. LSWP-037-00). 9. 10. 11. 12. STD*AWS LV
47、OS-ENGL 1982 A second 2-oz. spill-proof impinger. A length of any type of flexible tubing (Le., Tygon, polypropylene, rubber, etc.) to connect the impinger to the moisture trap and sampling pump. A moisture trap such as a 1-g bed of silica gel in a drying tube or a commercially available device. A p
48、ortable, battery-powered air sampling pump capable of maintaining a volume flow rate of 2 L/min for 8 h before recharging. A diagram of the prototype sampler is presented in Figure 3. Only one supplier of a spill-proof impinger (Daco Products, Inc. of Montclair, New Jersey) was found; however, the i
49、mpinger offered by DaCo appeared to be adequate for use in the ozone sampling device. This impinger is a plastic-coated glass bottle with an 07842b5 0536955 385 Recommended Sampling Device/ 15 impinging well and a T-tube that is adjustable in height. The impinger can be clipped to an individuals clothing for sampling. The device was available in various sizes; for the impinger to remain spill-proof, a maximum liquid capacity was recommended for each size. We chose the 2-02 size with a recommended capacity of 15 mL to accommodate 10 mL of the AKI absorbing solution, the vol
