HH WE m OuMwIlffWIJi '--. ■wm : ♦♦ w <• <£. o • » * A 40. v v . t • . / V^ f V V*^V V^ f '> K v #T ^V ^ o~ - » • ^°*. ** % *o$ :<^Hk*. "^o< :A^ *bt* ;^ ^0^ v : .w>* \w/ v™ ^^t% * -Ufa °* ^^k% /-i^,* o o ^.^A o^; r: ^°^ *. ♦ «5^ •M* V^ *bK ^ v % w ^ S V ^^P* : ^ v \ : -^^* ; **% 1%P* ; ^ v -\ J 9 . ■ V % *tt\v *$- v ^ * h r» * ^^ . « • "■> ?v -.f».- ^\ -.wag: j\ -mm: ^% \wm- A -mm: PI Is . -Sis* «5» S V ".WW ^ v ^. j .»^» .c.9^. 'oWi: A vX :^^: ^ «^i SAfVf C^^ .1 ^ t 9' '•/» " • " ° ' A ,* v -^ V W O <<* » " o . %A _*k ... »1» A % F ^ J. * • • • «W O *o » » * ,A, V . t • , ^.^ ■••'" ,V v«0 <£°* * "#> * -J. ^ * 1 * "* ^ X •'ff a* ^ ' ifl? ^ * °^. *»Vo 9 .0 c v ♦ • • • * ^0 C> ' o . » ^0 ^ X, Bureau of Mines Information Circular/1987 Performance Evaluation of Two Light-Scattering Dust Monitors By R. P. Vinson and K. L. Williams UNITED STATES DEPARTMENT OF THE INTERIOR Information Circular/9162 Performance Evaluation of Two Light-Scattering Dust Monitors By R. P. Vinson and K. L. Williams UNITED STATES DEPARTMENT OF THE INTERIOR Donald Paul Hodel, Secretary BUREAU OF MINES David S. Brown, Acting Director Library of Congress Cataloging in Publication Data: \\z°& \& Vinson, Robert P. Performance evaluation of two light-scattering dust monitors. (Information circular ; 9162) Bibliography: p. 9 -10. Supt. of Docs, no.: I 28:27: 9162. 1. Mine dusts -Measurement -Instruments. I. Williams, Kenneth L., 1952- II. Title. III. Series: Information circular (United States. Bureau of Mines) ; 9162. TN295.U4 [TN312] 622 s [622'.8] 87-600188 CONTENTS Page Abstract 1 Introduction 2 Test equipment and procedures 2 PDS-1 and PCD-1 dust monitors 2 Aerosol chamber 5 Reference measurements 5 Other dust measurements 6 Results and discussion 7 Reference measurements 7 PDS-1 response 7 PCD-1 response 8 Effect of particle size distributions 9 Conclusions 9 References 9 Appendix A. — Manufacturer specifications 11 Appendix B. — Total dust concentrations 12 Appendix C. — PDS-1 and PCD-1 test data 13 ILLUSTRATIONS 1. PDS-1 Personal Dust Sensor and MDM-1 Mini Dosimeter 3 2. MDM-1 and portable computer 4 3. PCD-1 digital dust indicator 4 4. Aerosol chamber, sectional top view 7 5. PDS-1 readings versus gravimetric concentrations for coal dust 8 6. PDS-1 readings versus gravimetric concentrations for ARD and coal dust... 8 7. PCD-1 readings versus gravimetric dust concentrations for ARD and coal dust 9 TABLES 1. Reference respirable dust concentrations 6 2. Ratios of total dust concentrations to reference respirable dust concentrations 7 B-l. Total dust concentrations 12 UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT ft foot mg/m 3 milligram per cubic meter h hour min minute in inch mm millimeter lb pound ym micrometer L/min liter per minute mV oz millivolt ounce m 3 /mln cubic meter per minute pet percent mg milligram s second PERFORMANCE EVALUATION OF TWO LIGHT-SCATTERING DUST MONITORS By R. P. Vinson 1 and K. L. Williams 2 ABSTRACT The Bureau of Mines evaluated two real-time light-scattering dust monitors by measuring their response to Pittsburgh Seam coal dust and Arizona road dust (ARD). Both monitors, the model PDS-1, a personal dust sensor, and the model PCD-1, a digital dust indicator, are made in Japan by Sibata Scientific Ltd. Tests were conducted inside a labora- tory aerosol chamber designed to maintain a uniform spatial distribution of the test dust. PDS-1 and PCD-1 measurements of concentrations for each test dust were averaged over 4-h test periods and compared with simultaneous gravimetric measurements. Both dust monitors responded linearly with mass concentration with both coal dust and ARD. However, the linear response of the PDS-1 dif- fered from that of the PCD-1 for both dusts. 1 9 Supervisory physical scientist. Physicist. Supervisor; Pittsburgh Research Center, Bureau of Mines, Pittsburgh, PA. INTRODUCTION One of the primary objectives of the Bureau of Mines is the elimination of coal miners' pneumoconiosis ("black lung") by reducing exposure to harmful dusts. Dust monitoring is critical to reducing respirable dust levels in mines. Most of the dust sampling in U.S. coal mines is done to determine compliance with dust standards. Measurements to determine compliance are made periodi- cally, usually every two months, with an approved sampler. Federal regulations (1_) 3 require gravimetric dust samples to be taken over an 8-h work shift. With gravimetric samplers, respirable dust particles are physically collected during the work shift and later weighed at a remote location. Since determination of compliance is based on the average of several shift-long measurements, the delayed analysis inherent in gravimetric techniques poses no problem. Further- more, since the standard is based on a 2mg/m 3 mass concentration, the gravi- metric approach is quite suitable. When operated carefully, these samplers can provide an accurate measurement of the average mass concentration of dust to which miners are exposed. Although gravimetric samplers (commonly called personal samplers) have been used for other than compliance purposes, they are often too slow and labor intensive for effective research or immediate dust control purposes. In an earlier Bureau study, it was found that a fast-response instrument is more effective for evaluat- ing dust control systems ( 2) . Timely adjustment of dust control system operat- ing parameters requires more immediate dust level information than is possible with the gravimetric sampler. Light-scattering techniques have made possible rapid, real-time measurements of dust concentrations. The Bureau has played an important role in developing real-time dust monitors. For example, in recent years the Bureau sponsored the development of two light-scattering real- time dust monitors, the RAM-1 (3) and the MINIRAM (4_). Many other light-scattering dust moni- tors are commercially available. The University of Minnesota evaluated several of these instruments for the Bureau in 1983 (_5). Two light-scattering instru- ments that were not available at the time of that evaluation have since been evalu- ated by the Bureau. The evaluation of these two monitors, the model PDS-1 per- sonal dust sensor and the model PCD-1 digital dust indicator, is the subject of this report. The report discusses the ability of these instruments to measure mass concentrations of Pittsburgh Seam coal dust and ARD. 4 No attempt has been made to assess the mine-worthiness of these instruments. TEST EQUIPMENT AND PROCEDURES THE PDS-1 AND PCD-1 DUST MONITORS The PDS-1 Personal Dust Monitoring System has three major components: The PDS-1 Personal Dust Sensor, the MDM-1 Minidosimeter, and a portable computer (Manufacturer specifications are listed in appendix A). The PDS-1 (fig. 1) is a portable, battery-powered, light-scattering dust detector. Dust particles diffuse into the PDS-1 sensing chamber, which contains a light source and detector. The detec- tor senses light scattered by particles passing through the light beam. The detected light is converted into an electric analog signal, which may be used to activate an audible alarm in the PDS-1 if the signal exceeds a preset level. The PDS-1 incorporates a reference light- scattering board which is a translucent material that scatters a portion of the Underlined numbers in parentheses re- fer to items in the list of references preceding the appendixes. 4 ARD is a carefully sized, commercial test dust used primarily to test the efficiency of air filters for internal combustion engines. FIGURE 1.— PDS-1 Personal Dust Sensor and MDM-1 Mini Dosimeter. light beam. Each time the board is in- serted into . the light beam, the same amount of light is scattered to the de- tector. The gain of the instrument can then be adjusted to indicate some arbi- trary value. The manufacturer calibrates the instrument to directly indicate the mass concentration for ARD. By inserting the reference board and noting the instrument reading, the manufacturer de- termines the numerical value that should be indicated whenever the board is in- serted in the future. The predetermined reference value is supplied with each unit. The analog signal from the PDS-1 can also be sent to the MDM-1 Mini Dosimeter (fig. 1), which is a battery-powered data acquisition system capable of storing 800 1-min dust concentration averages. A digital display on the MDM-1 is contin- uously updated to indicate the current dust concentration. Data stored in the MDM-1 can be retrieved by a small por- table computer (fig. 2) that is program- med to do elementary statistical analyses on the dust sampling data. Three PDS-ls were made available and used for this evaluation. This improved the statisti- cal validity of the test data. The PCD-1 digital dust indicator (fig. 3; specifications in appendix A) is a battery-powered, light-scattering dust monitor with a built-in air pump and microprocessor. Dust-laden air is drawn into the PCD-1 sensing chamber where, as in the PDS-1, dust is detected by light- scattering techniques. The microproces- sor contains user-friendly, menu-driven software that gives the PCD-1 great versatility. A keypad on the top of the PCD-1 allows the operator to program the PCD-1. In operation, the PCD-1 aver- ages the signal for a preset averaging interval and then stores that value in memory. The averaging interval can be adjusted from 6 s to 10 h> A maximum of 6,200 6-s averages can be stored in mem- ory. The total sampling time may also be programmed, in 1-min increments, for up to 620 min. Because the response of light-scattering dust monitors often de- pends on the properties of the dust being measured, a calibration factor (called FIGURE 2.— MDM-1 and portable computer. FIGURE 3.— PCD-1 digital dust indicator. the "K Factor") may be entered into the microprocessor so that the true mass con- centrations are displayed and stored in memory. The PCD-1 also features a RS232C port, which is a digital interface, used for communicating with other computers. AEROSOL CHAMBER All tests were conducted in an aerosol chamber designed specifically for evalu- ating dust sampling instrumentation. The chamber is similar to the one used by the University of Minnesota to evaluate the other light-scattering dust monitors (5- 6_). (See the introduction to this re- port.) The hexagonal 8-ft-high chamber is supported by a 2-ft high triangular base. Dust-laden air, produced by the dust generating system, passes through a krypton-85 5 particle-charge neutralizer and enters the top of the chamber through a 1-5/8-in-diam pipe. At the top center of the chamber, the dust-laden air first strikes a special target that evenly dis- perses it, then passes it through a honeycomb flow straightener designed to minimize turbulence. Drawn by a blower at the base of the chamber, the dust- laden air then passes the sampling in- strumentation, which is located on a round, rotatable table near the base of the chamber. The air finally passes through a perforated metal instrument table and is collected by a large, highly efficient filter located just above the blower. The aerosol chamber's dust generation system consists of a f luidized-bed aero- sol generator and a dilution-air system. The f luidized-bed aerosol generator can disperse dry powders with particle sizes from 0.1 to 20-ym-diam. Air blown through the bottom of a small cylinder containing bronze beads produces a fluid- ized bed. A loop of continuous ball c — — Krypton-85 gas, sealed in a small tube, emits beta and gamma radiation to ionize air molecules in a larger con- centric tube through which the gener- ated dust must pass. Charged particles passing through the ionized air sur- render much of their charge to the ionized air molecules. chain carries the dust from a reservoir into the fluidized bed of bronze beads. The motion of the beads breaks apart any dust particle agglomerates. Air blown through the bed then carries the dust particles out of the fluidized bed to the aerosol chamber. The amount of dust introduced into the chamber can be varied by changing the chain speed or airflow rate through the bed of bronze beads. Changing these parameters, however, can change the par- ticle size distribution of the dust that enters the chamber. Since the response of a light-scattering instrument is often affected by changes in particle size dis- tribution, random changes could introduce error into the determination of instru- ment response. Thus, whenever possible, an adjustable diluter was used to vary dust concentrations in the chamber with- out changing the dust generator operating parameters. First, the generator was allowed to stabilize at a high dust gen- eration rate. A diluter system was then used to divert a selectable portion of the dust-laden air, filter the dust par- ticles from that portion, and return the filtered air downstream of the dust generation system. The diluter thus re- duced the dust concentration entering the aerosol chamber without varying the oper- ating parameters of the f luidized-bed generator. The dust concentration could be further reduced by feeding a con- trolled amount of filtered dilution air with the dust-laden air into the aerosol chamber. The addition of the dilution air, however, increased the total airflow rate through the chamber, thereby in- creasing the velocity of air past the sampling inlets of the instrument being tested. REFERENCE MEASUREMENTS Gravimetric dust samples were collected during each test to provide reference measurements for comparison to measure- ments made by the light-scattering in- struments. Five preweighted 37-mm-diam polyvinyl chloride (PVC) membrane filters in cassettes were connected to the out- lets of five cyclones. Chamber air was sampled through the cyclones at 2 L/min, this flow caused the respirable fraction of the dust to be deposited on the pre- weighted filters. After sampling, the filters were removed and weighed. The average respirable dust concentration in the chamber during the test period was calculated as C = M/(F-T), where C = concentration, mg/m 3 , M = mass of collected dust, mg, F TABLE 1. - Reference respirable dust concentrations ' and sampling flow rate (0.002 m 3 /min) , T = sampling time, min. The calculated values of C for each of the five cassette samplers were then averaged. The standard deviation for each test was also calculated. The co- efficient of variation (CV) was then calculated by dividing the standard deviation by the average concentration for each test (table 1). The average concentration for each test was then com- pared to the time-averaged value indi- cated by each of the light-scattering monitors during the same test period. OTHER DUST MEASUREMENTS Several filter samples were collected during each test without cyclone precol- lectors to provide a measure of the total dust concentration 6 in the test chamber (table B-l, appendix B). These samples were collected at three locations in the test chamber, at 2 L/min, with the same type filter cassettes as were used for collecting the respirable samples. The inlets of these filter cassettes were faced downward during sampling. The ratio of the reference respirable 6 The term total dust refers to all dust particles in the aerosol chamber, both respirable size and larger. In essence, total dust is all dust collected by the filter cassettes without any size- selective precollector. Test Number of samples Mean, mg/m 3 Standard deviation ARD CV, pet 1 5 1.829 0.194 10.6 2 5 2.256 .159 7.1 3 5 2.241 .163 7.2 4 4 .810 .022 2.7 5 5 .728 .044 6.0 6 5 .348 .021 6.0 7 5 3.403 .319 9.4 8 5 4.619 .294 6.4 9 5 3.532 .259 7.3 10 5 4.593 .334 7.3 COAL DUST 11 5 2.459 0.095 3.8 12 5 2.073 .130 6.3 13 4 2.115 .054 2.5 14 5 2.492 .031 1.2 15 4 2.555 .062 2.4 16 5 2.600 .035 1.4 17 5 2.246 .051 2.3 18 5 .446 .020 4.5 19 5 .393 .027 7.0 20 5 .431 .015 3.6 21 5 5.517 .129 2.3 22 5 5.451 .151 2.8 23 5 5.230 .140 2.7 CV 'As sampl Coefficent of variat measured by gravi es. ion. metric cassette dust concentration to the total dust concentration provided a crude measure of the particle size distribution of the test dust in the chamber (table 2). Finally, the RAM-1 7 a light-scattering dust monitor previously characterized by the Bureau (_7 ) , was used to monitor the behavior of the dust generator before and during each test period. The data gathered by this instrument was helpful in determining when the dust concentra- tion in the chamber had stabilized after startup of the dust generating system and in detecting unexpected changes in the generator output. 'Reference to specific products does not imply endorsement by the Rureau of Mines. TABLE 2. - Ratios of total dust concentrations to reference respirable dust concentrations (T/R) Test Concentration, mg/ Respirable Total 2 T/R Test Concentration, mg/m Respirable Total 2 T/R ARD COAL DUST 1, 2, 3, 4, 5. 6. 7. 8. 9. 10. 1.829 2.256 2.241 .810 .728 .348 3.403 4.619 3.532 4.593 5.998 8.121 NA 3.307 1.257 .743 10.538 16.036 13.959 15.971 .28 .60 NA .08 .73 .13 .10 .47 .95 .48 11 12 13 14 15 16 17 18 19 20 21 22 23 table B-l, 2.459 2.073 2.115 2.492 2.555 2.600 2.246 .446 .393 .431 5.517 5.451 5.230 5.501 2.24 5.799 2.80 5.669 2.68 6.034 2.42 6.516 2.55 6.537 2.51 5.278 2.35 1.155 2.59 .877 2.23 1.175 2.73 9.668 1.75 9.954 1.83 9.322 1.78 NA Not available. From table 1. "From RESULTS AND DISCUSSION REFERENCE MEASUREMENTS Table 1 lists the respirable dust con- centration data used to evaluate the light-scattering monitors. In table 1, entries under the heading "Mean, mg/ra 3 " represent the mean of the reference ves- pvvabZe dust concentration measurements from the five previously described gravi- metric cassette samplers. For ARD, these means ranged from 0.35 to 4.62 mg/m with .PDS-1 MDM Aerosol chamber walls Instrument table Impactor Gravimetric total dust sampler Gravimetric respirable dust sampler (cassettes) FIGURE 4.— Aerosol chamber, sectional top view. CV's between 2.7 and 10.6 pet. Since each of the five respirable dust cassette samplers was located in a different position (fig. 4), the low CV's indicate that the ARD was fairly evenly dis- tributed in the aerosol chamber. (Table B-l, appendix B) lists the total ARD reference measurements. The respirable coal dust concentration data are also listed in table 1. Mean coal dust concentrations ranged from 0.39 to 5.52 mg/m 3 with CV's ranging from 1.1 to 6.9 pet. Again, dust concentrations were fairly uniform in the aerosol cham- ber. Table B-l lists the total reference coal dust concentrations. PDS-1 RESPONSE Figure 5 is a plot of the readings from each of the three PDS-1 units versus the mass concentration of respirable coal dust determined gravimetrically for ref- erence. (The plotted PDS-1 data are listed in appendix C.) The PDS-1 values are time-averages of the instrument read- ings over the test period. Each corres- ponding gravimetric reference value is the mean of five measurements determined from filter samples taken during the test period, as previously described. I 2 3 4 5 6 GRAVIMETRIC RESPIRABLE DUST CONC, mg/m 3 FIGURE 5.— PDS-1 readings versus gravimetric concentra- tions for coal dust. I 2 3 4 5 6 GRAVIMETRIC RESPIRABLE DUST CONC, mg/m 3 FIGURE 6.— PDS-1 readings versus gravimetric concentra- tions for ARD and coal dust. Agreement between the readings from units A, B, and C was good (fig. 5). Regression lines were calculated for each unit to fit the equation y = Mx, where y = PDS-1 reading, mg/m 3 , M = slope, and gravimetric respirable dust concentration, mg/m 3 . This calculation forced the regression line for each unit through the origin. The response of each unit to mass concen- tration is represented by M. The values for M ranged from 2.00 to 2.06, repre- senting response variations of only a few percent. These results imply that if PDS-1 units are calibrated with the ref- erence board to the manufacturer's recom- mended value, they will agree well with each other. Figure 6 compares the response of one PDS-1 unit with corresponding gravimetric values, using both ARD and coal dust. (See appendix C, data for unit.) Again, each PDS-1 response value represents a time-average of the output, and again, the reference gravimetric measurement is the mean of five measurements. The PDS-1 response to ARD was significantly different than the PDS-1 response to coal. The M value was 0.59 for ARD, as opposed to 2.06 for coal dust. These data imply that the response of the PDS-1 depends significantly on characteristics of dust particles other than mass, such as size and index of refraction, as is the case for other instruments based on light-scattering (_5, 7^). Nevertheless, for a particular dust, the response was linear with mass concentration over the ranged tested. For both coal and ARD, the coefficient of determination (r ) was greater than 0.9 when the data were fitted to the equation y = M/x. PCD-1 RESPONSE Since only one PCD-1 unit was available for testing, inter-unit comparison was not possible. Figure 7 shows the response of the PCD- 1 versus corresponding gravimetric values, for both ARD and coal dust. (See appendix C for the PCD-1 data. ) Again, the response to ARD was different than the response to coal dust. The values of M were 0.22 for ARD and 0.16 for coal dust. Again, the response was linear with mass concentration for each dust. The slopes (M) of these responses could have been changed by entering a "K fac- tor" into the PCD-1 's microprocessor. For these tests the "K factor" was kept I 2 3 4 5 6 GRAVIMETRIC RESPIRABLE DUST CONC, mg/m 3 FIGURE 7.— PCD-1 readings versus gravimetric dust con- centrations for ARD and coal dust. at unity. The value of r was 0.84 for ARD and 0.97 for coal dust. For the PCD- 1, the slopes of the curves show the re- sponse to ARD was greater than the re- sponse to coal. For the PDS-1, the situation was reversed. EFFECT OF PARTICLE SIZE DISTRIBUTIONS In the absence of impactor data, ratios of total to respirable dust concentration measurements (T/R) provided some indica- tion of the particle size distribution. Table 2 shows the T/R ratios for both the ARD and coal dust tests. Some variability existed in the size distribution, as indicated by the T/R ratios. Variability also existed in the responses of the light-scattering instru- ments, as indicated by the ratios of the PDS-1 and PCD-1 readings to the gravi- metric determinations of mass concentra- tion (M). Nevertheless, no statistically significant correlation could be found between changes in particle size distri- bution and the responses of the instru- ments. Theoretically, particle size can have an effect on the response of light-scattering instruments. More careful measurement and control of par- ticle size distributions during similar tests would be needed to confirm size dependence. CONCLUSIONS Both the PDS-1 and the PCD-1 responded linearly with mass concentration for both ARD and coal dust over the range of about 0.3 to 5 mg/m 3 . However, the instruments' responses to ARD and coal dust were different. The PCD-1 's response to ARD was greater then its response to the coal dust. The situation was reversed for the PDS-1. The major difference between the two instruments is that the PCD-1 draws air into its light-sensor chamber with an air pump, whereas the PDS-1 has no air pump. As is the case with scattering dust monitors, pends on characteristics particles other than mass, response differences observed using ARD and coal dust probably resulted from dif- ferences in the indexes of refraction of these two dusts. However, this could not be determined by the data collected dur- ing these tests. many light- response de- of the dust The apparent REFERENCES 1. U.S. Code of Federal Regulations. Title 30 — Mineral Resources; Chapter I — Mine Safety and Health Admin. , Department of Labor; Subchapter — Coal Mine Safety and Health; Part 70 — Mandatory Health Standards — Underground Coal Mines, Sec. 70.100 (a); July 1, 1985. 2. U.S. Bureau of Mines. Instantan- eous Sampling Improves Longwall Dust Con- trol. Technol. News 134, Feb. 1982, 2 pp. 3. Lilienfeld, P. Improved Light Scattering Dust Monitor (contract HO377092, GCA Corp.). BuMines OFR 90-79, 1979, 48 pp.; NTIS PB 299 938/AS. 4. Lilienfeld, P., and R. Stern. Per- sonal Dust Monitor — Light Scattering (contract HO308132, GCA Corp.). BuMines OFR 95-83, 1982, 40 pp.; NTIS PB 83-205435. 10 5. Marple, V. A., and K. L. Rubow. Respirable Dust Measurement (contract J01 13042, Univ. Mn.). BuMines OFR 92-85, 1984, 154 pp.; NTIS PB 85-245843/AS. 6. . An Aerosol Chamber for In- strument Evaluation and Calibration. Am. Ind. Hyg. Assoc. J., v. 44, May 1983, pp. 361-367. 7. Williams, K. L. , and R. J. Timko. Performance Evaluation of a Real-Time Aerosol Monitor. BuMines IC 8968, 1984, 20 pp. 11 APPENDIX A.— MANUFACTURER'S SPECIFICATIONS Range: Sensitivity: Particle size range: Calibration: Power source: Operating time: Dimensions: Weight: PDS-1 Personal Dust Sensor 0.01 to 10 mg/m 3 or 0.1 to 100 mg/m 3 0.01 mg/m 3 0.01 to 10 pm Built-in reference board Rechargeable Ni-Cd batteries 9 h 4-3/8 by 3-1/2 by 1-1/2 in 1 lb 7 oz MDM-1 Mini Dosimeter Input range: Resolution: Precision: Data acquisition: Display: Data output: Power source: Operating time: Dimensions: Weight: Range: Sensitivity: Particle size range: Power source: Operating time: Dimensions: Weight: to 1000 mV 1 mV ±0.5 pet full scale 180 data points per min; stores 800 1-min averages 3-1/2-digit mass concentration from to 10.00 mg/m 3 Serial (ASCII) TTL level Rechargeable Ni-Cd batteries 12 h 3-3/8 by 1-3/4 by 6-1/8 in 10 oz PCD-1 Digital Dust Indicator 0.001 to 9.999 mg/m 3 0.001 mg/m 3 0.01 to 10.00 pm Rechargeable Ni-Cd batteries 10 h 11 by 3-1/2 by 5-3/4 in 8 lb 12 APPENDIX B. — TOTAL DUST CONCENTRATIONS Table B-l lists the means of several total ARD and coal dust concentration measurements. The means for ARD ranged from 0.743 to 16.036 me/m 3 with CV's to 16.036 mg/m J , with TABLE B-l. - Total dust concentrations ranging from 0.6 and 9.3 pet. The coal dust means ranged from 0.877 to 9.954 mg/m 3 , with CV's ranging from 1.0 and 13.2 pet. Test Number of Mean, Standard rev, Test Number of Mean, Standard CV, samples mg/m 3 deviation pet samples mg/m 3 deviation pet ARD COAL DUST 1 1 5.998 NAp NAp 11 3 5.501 0.221 4.0 2 1 8.121 NAp NAp 12 3 5.799 .559 9.6 3 2 NA NAp NAp 13 3 5.669 .122 2.1 4 3 3.307 0.309 9.3 14 3 6.034 .059 1.0 5 3 1.257 .063 5.0 15 3 6.516 .399 6.1 6 3 .743 .027 3.6 16 3 6.537 .405 6.2 7 3 10.538 .424 4.0 17 3 5.278 .694 13.2 8 3 16.036 1.333 8.3 18 3 1.155 .046 4.0 9 3 13.959 .715 5.1 19 3 .877 .031 3.5 10 3 15.971 .094 .6 20 3 1.175 .062 5.3 21 3 9.668 .641 6.6 3 9.954 .654 6.6 23 3 9.322 .504 5.4 NAp Not applicable. 'As measured by gravimetric cassette samplers. 2 Lost sample. APPENDIX C.~ PDS-1 AND PCD-1 TEST DATA (Milligrams per cubic meter) 13 Test PDS-1 PCD-1 Test PDS-1 PCD-1 Unit A Unit B Unit C Unit A | Unit B Unit C ARD COAL DUST 1 ] NA NA 0.740 0.489 4.661 3.982 3.520 0.265 1.695 NA 1.271 .609 12 3.959 3.353 2.872 .214 NA 1.392 1.560 NA 13 2.410 3.407 3.485 NA 4 NA .521 .526 .232 14 4.370 4.759 4.649 NA 5 NA .658 .749 .321 15 6.092 4.945 4.833 NA NA NA .343 .094 16 4.074 4.866 4.998 .396 7 NA NA 2.037 .487 3.862 4.307 NA .373 8 NA NA 3.053 NA 18 .582 .584 .622 NA 9 5.028 2.341 2.034 .942 .460 .471 .522 .072 NA 4.348 2.321 1.010 20 .629 .692 .735 .105 21 10.604 10.887 11.127 .883 13.674 12.153 12.670 .870 23 9.681 12.035 11.931 .851 Data not available because of malfunction of dust monitor. U.S. Department of the Interior Bureau of Mines— Prod, and Distr. Cochrans Mill Road P.O. Box 18070 Pittsburgh. Pa. 15236 OFFICIALBUSINESS PENALTY FOR PRIVATE USE. $300 ] Do not wi sh to recei ve thi s material, please remove from your mailing list. 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