Document jmEEMMj26nG3QbrVGVzpOODZN
3M Organic Vapor Monitor
Sampling Rate Validation Protocol
3H 006177
SAMfUKfi ms VALIDATION
The sampling rates for the () contaminants were determined by sampling a known air concentration 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 devloe 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 oan be determined by measuring the total air volume and the Initial and final weight of the syringe containing the contaminant. Five concentrations 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 eaoh of the five concentrations were collected. The recovery coefficients were determined by spiking the monitors with known amounts of the contaminant at the level corresponding 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 containing three to five contaminants. The length of the exposures were:
2 Hrs. 2 Hrs. 2 Hrs. 1 Hr. 5 Hr.
- .1 PEL - .5 PEL - 1 PEL - 2 PEL - 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 rates 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 coefficent according to the Hirschfelder equation is outlined in Appendix A.
In Figure 1, the validated sampling rates are plotted as a function of the calculated diffusion coefficients for aloohols, aliphatlcs, 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.
3M 006178
For the compounds in the Sampling Guide and Analysis Guide other than those tabulated in Tables 1, II and III, the sampling rates were determined from the diffusion coefficients oaloulated according to the Hlrsohfelder 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 aoouraoy of at least + 5%.
3H 006179
able I
COMPOUND
Ketones
Acetone Diisobutyl Ketone Methyl Butyl Ketone Methyl Iosbutyl 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-Hutvl Acetate Methyl Acetate Propyl Acetate
Hirschfelder Diffusion Coefficient
(cm vsec)
.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
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 7.0 + , (> 30.1+ . r>
3H 006180
^able II
Aromatics & Other Cyclic Compounds
Benzene p.tert-Butyl Toluene Cumene Mesitylene i-Methyl Styrene Styrene Toluene Xylene
Cyclohexanone I .sophorone
Cyclohexane I'yc 1 ohexeni; Methyl Cyclohexane
Cyclohexanol
H i. r:;chf elder
Bit fusion Coefficient
(cm /min)
Measured Samplinq
Rate (cc/min+
.0947 .0599 .0690 . 0660 .0700 .0764 .0827 .0748
.0802 .0635
.0851 . 0876 .0769
.0760
35.5+.6 20.7+.4 24.5+. 9 2G.3+.7 25.0+.5 26.8+.8 31.4+.6 27.3+,5
28.9+.3 21.77.7
32.4+.7 32.37.4 28.9+.4
29.5+ . 3
3H 0061si
COMPOUND
Halogenated
Carbon Tetrachloride Chlorobenzene Chlorobromomethane o-Dichlorobenzene 1,2 Dichloroethylene Ethyl Bromide Ethylene Dibroraide Ethylene Dichloride Methylene Chloroform Methylene Chloride Perchloroethylene Propylene Dichloride 112 Trichloroethane Trichloroethylene
"able hi
Hirschfelder Diffusion Coefficient
(cm /sec)
.0857 .0812 .1005 .0732 .0992 .1013 .0824 .0973 .0855 .1102 .0786 .0833 .0836 .0874
Measured Sampling
Rate (cc/min+ s.d.)
30.2+.4 29.3+.6 34.4+.9 27.8+.6 35.2+.5 36.4+.3 29.6+.4 33.2+.7 30.9+.3 37.9+.3 28.3+.5 30.6+ . 4 29.7+.6 31.1+.2
3M 006182
SAMPLING RATE AS A FUNCTION OF DIFFUSION COEFFICIENT
CALCULATED DIFFUSION COEFFICIENT (cm2/sec)
SAMPLING RATE AS A FUNCTION OF DIFFUSION COEFFICIENT
CALCULATED DIFFUSION COEFFICIENT (cm2/sec)
0
aH
s
o o
W
<
O i--
Pk
<
Oi GO
SAMPLING RATE AS A FUNCTION OF DIFFUSION COEFFICIENT
. -|...................i
.060
*|-----------------1----------------1----------------1----------------[----------------r--------------------------------1--------------|-------------r '
.070
080 .090 .100 .110
CALCULATED DIFFUSION COEFFICIENT (cntfsec)
04
F ig u re
Appendix A
Calculation of Diffusion Coefficient
Because diffusion coefficients are not available for all con taminants from the same experimental 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 empirical relationship. The following outlined the Hirschfelder equation and defines the necessary parameters needed for calculating the diffusion coefficient according to this technique.
Hirschfelder Equation
D <3
Where D*
9 B
gas diffusivity(cm2/sec)
T * absolute temperature (K)
M1'M2 " molecule weights of components 1 and 2 P absolute pressure (atm)
collision diameter (A)
(r, + r2)/2
collision integral for diffusion, function of kT/g.^ (see Table I-Appendix A)
3M 006186
*
Boltzmann constant 1.38 x 10 erg/K
l12
T
energy of molecular interaction (ergs)
1.15 T. 1.92 Tm
temperature of component boiling point (K)
m temperature of component melting point (K) Combining and simplifying the above expressions:
- air value (97K)
ih2 kT
= ^j(97K) (1.15 *h)
a f
7TO (1.92 Ttti )
as 298.15
V(97K) (1.15 Tb)
= 28.2
From this value, the collision integral, I., can be found from the interploted 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
V2
rl 2
12
- 1.18 (V) J = ^ vatomic (see Table 11 Appendix A)
3.62
1/3 62 + 1.18 V2
2
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By combining all of the above expressions and values, the first equation can be expressed as the following;
Dg = [22.03 - 5.07 -\J. 0345 + l/2] [iy .0345 + 1/fU
Id (3.62 + 1.18
)2
Example Calculations;
ot
Methyl acetate CH^-C-O-CHj Molecular weight - 74 Boiling point (Tj;>)'-331#K (58*C)
i.T
Tu
xd
28.2 V33r
1.55
m .5914
V2 ' 3(14.8) + 6 (3.7) + 7.4 + 7.4 81.4
y3,_r__2 . 4.33
Dg
(22.03-5.07 V. 0345 + 1/74) ( V7o345 + 1/74) (.5914) [3.62 + 1.18 (4.33)]
2
Dg .1016 cm /sec
3H 006188
i t /. u*
1.')!) .01 .02 .03 .04 .03 .06 .07 .08 .09
1.10 .11 .12 .13 .14 .15 .16 .17 .18 .19
1.20 .21 .22 .25 .24 .25 .26 .27 .28 .29
1.30 .31 .32 .33 .34 .35 .36 .37 .38 .39
1.40
Appendix A TABLE I
INTERPOLATED VALUES Of LULL ISION INTEGRAL
I
M /
I
0 12 0
0.7197 .7165 .7132 .7100 .7067 .7035 .7003 .6970 .6938 .6905
0.6873 .6846 .681* .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
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
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 006189
Appendix A TABLE II
LeBas Additivity Values & Rules - V2 * ^ vatomic
Element
Carton
Chlorine Terminal as in R-Cl Medial as in R-CHC1-R
Fluorine
Hydrogen
Iodine
Nitrogen In primary amines in seaondary amines
Oxygen
Q
Doubly bound -C-
0
In aldehydes & ketones RC-H,R-C-R
in methyl esters CH.-O-C^-R
In methyl ethers CH^-O-R
p
In higher ethers & esters R-O-C-R
0 R-O-R
In acids R-C-OH
In union with S,P,N
Sulfur
Special Rules; (1) Deduct 6 for three mattered ring (2) Deduct 8.5 for four membered ring (3) Deduct 11.5 for five membered ring (4) Deduct 15.0 for six numbered ring (5) Deduct 30.0 for naphthalene ring
Atomic Volume (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
3H 006190
