This study was to evaluate the efficiency of diffusive monitor using activated carbon fiber(ACF, KF-1500) in measuring airborne organic solvents. The following characteristics were identified and studied as critical to the performance of diffusive monitor; recovery, sampling rate, face velocity, reverse diffusion and storage stability. For the evaluation of the performance of this monitor, MIBK, PCE, toluene were used as organic solvents. In the sampling rate experiments, eight kinds of solvents (n-hexane, MEK, DIBK, MCF, TCE, CB, xylene, cumene) as well as the above solvents were used.
The results were as follows:
1. The desorption efficiencies(DE´s) of ACF diffusive monitor ranged from 83 % to 101 %. In contrast, those of coconut shell charcoal ranged from 78 % to 102 %. Especially, the DE´s of ACF for the polar solvents such as MEK were superior to those of charcoal.
2. Experimental sampling rates on ACF were average 42 ㎖/min(37-46 ㎖/min) for 11 organic solvents at 24±2℃, 50±5 %RH. However ideal sampling rates(DA/L) were 33 %, higher than experimental sampling rates.
3. The initial response(15∼16 min) of the testing monitor was 2 times higher than the actual concentration determined by the reference methods at 24±2℃, 8±5 %RH. and 80±5%RH. Within 1 hours, the curve reached a linear horizontal line at low humidity condition. But sampling efficiencies decreased with respect to time at high humidity condition. And sampling efficiencies were higher at high humidity condition than low humidity condition for MIBK.
4. At very low velocity (less than 0.02 m/sec), the concentration of ACF diffusive monitor were poorly estimated. But ACF diffusive monitor were not affected at higher velocity(0.2 m/sec-0.6 m/sec).
5. There was no significant reverse diffusion when the ACF monitors were exposed to clean air for 2 hours after being exposed for 2 hours at the level of 1 TLV.
6. There was no significant sample loss during 3 weeks of storage at room temperature and 5 weeks of storage at refrigeration.
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