Handbook of Solvents - George Wypych - ChemTech - Ventech!

1230 Krzysztof M. Benczek, Joanna Kurpiewska
18.2.6 VERIFICATION OF THE METHOD
Emission measuring setup is given in Figure 18.2.2. Cyclohexane
was pumped (with E=6.123 mg/min) into glass bottle
(V=44.5 l) equipped with a fan. The air in the bottle was analyzed
by gas chromatography using a flame ionization detector
- OVA 118. After 20 min., when the concentration reached
2.250 mg/l, the pump was stopped and the decay of concentration
with time was measured.
Results are given in Tables 18.2.1 and 18.2.2 (value E
from the equation [18.2.2], q from the equation [18.2.4]).
The standard deviation of the sample was 0.0106, of the
method - 0.0102 and bias was 0.08 mg/min (1.3%).
Tests were then performed in the macro-scale - emission
of cyclohexane in a room, when the emission ended when the
process stopped. The estimate is precise when the room vol-
Figure 18.2.2. Emission measurume and ventilation flow rate are known.
ing setup.
The method was verified in the industrial environment in
automotive plant. Here, the hazardous substances continue to
be emitted to the air after the process had stopped. The concentration measured near the out-
Table 18.2.1. Emission of cyclohexane
t, min Ct, mg/l E, mg/min
1 0.138 6.210
2 0.273 6.212
3 0.405 6.213
4 0.533 6.201
5 0.659 6.201
6 0.780 6.184
8 1.020 6.200
10 1.250 6.212
12 1.465 6.200
15 1.770 6.188
20 2.250 6.218
E ave. - 6.203, σ n= 0.0102, σn-1= 0.0106
Table 18.2.2. Ventilation flow rate
t, min Ct, mg/l Q, l/min
1 2.200 1.000
2 2.215 1.011
3 2.100 1.024
4 2.055 1.008
5 2.010 1.004
6 1.965 0.993
8 1.880 0.999
10 1.800 0.992
12 1.720 0.996
15 1.605 1.002
20 1.435 1.000
q ave. = 1.0026, σn = 8.7103×10 -3 , σn-1 = 9.1354×10 -3
let of exhaust was 620 mg/m 3 , and because the exhaust flow rate was known to be 50
m 3 /min, the emission was precisely estimated according equation [18.2.2] as 31 g/min or
312.48 kg/week. This value was comparable with the average solvent loss - 326.22
kg/week.