Document DXMVZvbjXodK5aY7E72abJYn

1 3M Organic Vapor Monitor Sampling Rate Validation Protocol Another Step Towards Better Occupational Health and Safety R-35VF<61.1)R1 Occupational Health and Safety Products Divisi n/3M 220-7W 3M Center St. Paul. MN 55144 3M 007674 utno in U S A Sampling Rate Validation The sampling rates for the (*) contaminants were determined by sampling a known air concen tration in a laboratory generator-dilution system. This system consisted of a calibrated dry air gas meter, a syringe drive mechanism to deliver the liquid contaminant to a heat manifold, and an exposure device to hold six (6) monitors. The air concentrations of the contaminant were generated by delivering the contaminant at a known rate to an air flow through the heated manifold. For the exposure period, the air concentration can be determined by measuring the total air volume and the initial and final weight of the syringe containing the contaminant. Five concen trations at one-tenth, one-half, one, two and four times the permissible exposure limit (PEL) were generated to measure the sampling rates. For the sampling rate validations, six samples at each of the five concentrations were collected. The recovery coefficients were determined by spiking the monitors with known amounts of the contaminant at the level cor responding to amounts collected when sampling air concentrations ranging from one-tenth to four times the permissible exposure level (PEL). Results from the 18 spiked samples (3 sets of 6 samples) and the 30 exposure samples results were used to form the basic statistical set of data. In the sampling rate validation exposure, the monitors sampled known air concentration con taining three to five contaminants. The length of the exposures were: 2 Hrs. -- .1 PEL 2 Hrs. - .5 PEL 2 Hrs. -- 1 PEL 1 Hr. - 2 PEL .5 Hr. - 4 PEL The validation results were treated according to the statistical protocol outline in the Documentation of the NIOSH Validation Tests DHEW No. 77-185. The validated sampling rat s are tabulated for each contaminant as the mean of 30 samples with the variation reported as the precision of the sampling rate. These results along with the diffusion coefficients as calculated by the Hirschfelder equation are tabulated in Tables I, II and III. The technique for calculating the diffusion coefficient according to the Hirschfelder equation is outlined in Ap pendix A. In Figure 1, the validated sampling rates are plotted as a function of the calculated diffusion coefficients for alcohols, aliphatics, cellosolves, esters and ketones. From a least squares fit of the data, the variation of sampling rate is 5%. In Figure 2, the validated sampling rates are plotted as a function of the calculated diffusion coefficient for aromatics and other cyclic compounds. In Figure 3, the validated sampling rates are plotted as a function of the calculated diffusion coefficient for the halogenated compounds. For the compounds in the Sampling Guide and Analysis Guide other than those tabulated in Tables I, II and III, the sampling rates were determined from the diffusion coefficients calculated according to the Hirschfelder equation as outlined in Appendix A and the empirical relationships defined in Figures 1, 2 and 3. By this technique, it is possible to determine the sampling rates with an accuracy of at least 5%. 3M 007675 2 Compound Ketones Acetone Diisobutyl Ketone Methyl Butyl Ketone Methyl Isobutyl Ketone Methyl Ethyl Ketone Methyl Propyl Ketone Alcohols n-Amyl Alcohol i-Amyl Alcohol Butyl Alcohol Diacetone Alcohol i-butyl Alcohol Propyl Alcohol Aliphatics Heptane Hexane Nonane Octane Pentane Cellosolve Butyl Cellosolve Cellosolve Cellosolve Acetate Methyl Cellosolve Methyl Cellosolve Acetate Esters n-Amyl Acetate s-Butyl Acetate Ethyl Acetate i-Butyl Acetate Methyl Acetate Propyl Acetate Hirschfelder Diffusion Coefficient (cm2/sec) .1096 .0606 .0756 .0761 .0943 .0838 .0787 .0790 .0879 .0707 .0908 .1004 .0721 .0796 .0617 .0664 .0864 .0681 .0820 .0682 .0911 .0740 .0668 .0728 .0883 .0793 .1009 .0793 Table I Measured Sampling Rate (cc/min + s.d.) 40.1 .9 24.6 + .8 29.7 .7 30.0 + .4 36.3 .9 33.0 + .5 31.2 + .4 32.3 .4 34.3 .7 28.2 + .4 35.9 .7 39.7 .7 28.9 + .7 32.0 + .7 24.6 + .6 26.6 + .6 34.5 .8 28.2 + .6 32.4 + .9 26.6 + .4 36.3 + .4 29.0 + .5 26.0 + .5 28.6 + .4 34.5 + .6 31.0 + .3 37.0 + .6 30.1 i .5 3M 007676 3 Aromatics & Other Cyclic Compounds Benzene p.tert-Butyl Toluene Cumene Mesitylene Alpha Methyl Styrene Styrene Toluene Xylene Cyclohexanone Isophorone Cyclohexane Cyclohexene Methyl Cyclohexane Cyclohexanol Compound Halogenated Carbon Tetrachlordie Chlorobenzene Chlorobromomethane o-Oichlorobenzene 1,2 Dichloroethylene Ethyl Bromide Ethylene Dibromide Ethylene Dichloride Methylene Chloroform Methylene Chloride Perchioroethylene Propylene Dichloride 1,1,2 Trichloroethane Trichloroethylene Hirschfedler Diffusion Coefficient (cmz/$ec) .0947 .0599 .0690 .0660 .0700 .0764 .0827 .0748 .0802 .0635 .0851 .0876 .0769 .0760 Hlrschfelder Diffusion Coefficient (cm2/sec) .0857 .0812 .1005 .0732 .0992 .1013 .0824 .0973 .0855 .1102 .0786 .0833 .0836 .0874 4 Table II Measured Sampling Rate (cc/min s.d.) 35.5 .6 20.7 .4 24.5 .9 26.3 .7 25.0 .5 26.8 .8 31.4 .6 27.3 .5 28.9 .3 21.7 .7 32.4 .7 32.3 .4 28.9 .4 29.5 .3 Table III Measured Sampling Rate (cc/min t s.d.) 30.2 + .4 29.3 + .6 34.4 .9 27.8 + .6 35.2 .5 36.4 + .3 29.6 -t .4 33.2 .7 30.9 .3 37.9 .3 28.3 .5 30.6 - .4 29.7 + .6 31.1 .2 3H Figure 1 Sampling Rate As a Function of Diffusion Coefficient U1 8 CP 0s0i .070 .080 .090 .100 Calculated Diffusion Coefficient (cm2/sec) Sampling Rate As a Function of Diffusion Coefficient Calculated Diffusion Coefficient (cm2/sec) Appendix A Calculation of Diffusion Coefficient Because diffusion coefficients are not available for alt contaminants from the same experimen tal determination, it is therefore desirable to use accurate estimations as determined from the Wilks and Lee modification (Ind. Eng. Chem. 47,1253 [1955] of the equation by Hirschfelder, Bird and Spots (Trans. Am. Soc. Mech. Engrs., 71,921 [1949] as outlined in J. H. Perry, Ed. [Chem. Engrs. Handbook]). It has been shown that excellent empirical correlation can be achieved between measured sampling rates and the calculated diffusion coefficients. Therefore, the sampling rates which were not measured can be determined with an accuracy of 5% from the calculated diffusion coefficients using the emplirical relationship. The following outlines the Hirschfelder equation and defines the neccesary parameters needed for calculating the diffusion coefficient according to this technique, Hirschfelder Equation BtWi/M, + 1/Mj Prf; lD Where gas diffusivity (cmJ/sec) B JTo.7 2.46V1/M, + 1/mTJ x 10 4 T absolute temperature (K) M,,M, = molecule weights of components 1 and 2 P absolute pressure (atm) 0 collision diameter A (r, + r2)/2 Ig = collision integral for diffusion, function of kT/C,? (see Table 1-Appendix A) k = Boltzmann constant = 1.38 x 10-8 erg/K ,2g = energy of molecular interaction (ergs) | = 1 15 Tb - 1.92 Tm temperature of component boiling point (K) temperature of component melting point (K) 8 3H 007681 4 Combining and simplifying the above expressions: ^ = air value (97K) f1 = -V(97K)(1.15Tb) = "V(97 K) (1.92 Tm) kj _ 298.15 "V(97K) (1.15 Tb) = 28.2 From this value, the collision integral, ld, can be found from the interpolated values tabulated in Table I of Appendix A. The radius (r) can be determined from the summation of the atomic volumes tabulated in Table II of Appendix A. r = 1.18 (V) 1/3 v* = 2vatomic <See Table II Appendix A) r, = 3.62 r,/ = [(3.62 + 1.18 By combining all of the above expressions and values, the first equation can be expressed as the following: Dg = (22.03 -- 5.07 y.0345 + i/mJEv/BMS- +~7M2 ld(3.62 + 1.18 V/T 3w 007682 9 Example Calculations: Methyl acetate CH,-C-0-CH, Molecular weight - 74 Boiling point (T^) 331 K (58C) KI = 28.2 e,2 AA131 = 1.55 ld= 5914 V2= 3(14.8) + 6(3.7) + 7.4 + 7,4 = 81.4 Dg Dg -- 4.33 (22.03 - 5.07 "\A0345 + 1/74) (V0345 + 1/74) -------------------------------------------- --------- -------- (.5914) [3.62 +1.18 (4.33)]2 .1016 cnWsec 3W 0076S3 10 kT/e,, 1.00 .01 .02 .03 .04 .05 .06 .07 .08 .09 1.10 .11 .12 .13 .14 .15 .16 .17 .18 .19 1.20 .21 .22 .23 .24 .25 .26 .27 .28 .29 1.30 .31 .32 .33 .34 .35 .36 .37 .38 .39 1.40 Appendix A Table 1 Interpolated Values of Collision Integral *D 0.7197 .7165 .7132 .7100 .7067 .7035 .7003 .6070 .6938 .6905 0.6873 .6846 .6819 .6791 .6764 .6737 .6710 .6683 .6655 .6628 0.6601 .6578 .6554 .6531 .6507 .6484 .6461 .6437 .6414 .6390 0.6367 .6347 .6327 .6307 .6287 .6266 .6246 .6226 .6206 .6186 0.6166 kT/Gu 1.40 .41 .42 .43 .44 .45 .46 .47 .48 .49 1.50 .51 .52 .53 .54 .55 .56 .57 .58 .59 1.60 .61 .62 .63 .64 .65 .66 .67 .68 .69 1.70 .71 .72 .73 .74 .75 .76 .77 .78 .79 1.80 *D 0.6166 .6148 .6131 .6114 .6096 .6078 .6061 .6044 .6026 .6008 0.5991 .5976 .5960 .5945 .5929 .5914 .5899 .5883 .5868 .5852 0.5837 .5823 .5810 .5796 .5783 .5769 .5755 .5742 .5728 .5715 0.5701 .5689 .5677 .5665 .5653 .5640 .5628 .5616 .5604 .5592 0.5580 3H 007684 11 Appendix A Table II LeBas Additivity Values & Rules V2 = vatomic Element Carbon Chlorine Terminal as in R-CI Medial as in R-CHCI-R Fluorine Hydrogen Iodine Nitrogen In primary amines In secondary amines Oxygen Q Doubly bound -C- 99 In aldehydes & ketones R-C-H,R*C-R In methyl esters CHj-O-C^-R In methyl ethers CHj-O-R ,0 In higher ethers & esters R-O-C-R O R-O-R In acids R-C-OH In union with S,PtN Sulfur Special Rules: (1) Deduct 6 for three membered ring (2) Deduct 8.5 for four membered ring (3) Deduct 11.5 for five membered ring (4) Deduct 15.0 for six membered ring (5) Deduct 30.0 for naphthalene ring Atomic Volue (V) 14.8 21.6 24.6 8.7 3.7 37.0 15.6 10.5 12.0 12.8 7.4 7.4 9.1 9.9 11.0 12.0 8.3 25.6 12 3M 007685