Experimental Evaluation of Oil Mists Using a Semivolatile Aerosol Dichotomous Sampler

Abstract

The sampling performance of the semivolatile aerosol dichotomous sampler (SADS) was tested and compared with existing vapor and particle sampling methods: filtration, electrostatic precipitation, and vapor adsorption. Seven different test fluids were used to generate test droplets, and their concentrations and composition in each phase were evaluated using gas chromatography. The amount of wall loss inside the SADS was also evaluated. Combined vapor and particle concentrations for each test aerosol were not statistically different from one another as a function of test method. However, the particle concentrations estimated using the SADS were statistically higher than those from the other methods. In experiments with hexadecane, the particle concentrations estimated using the SADS, an electrostatic precipitator, and a glass fiber filter were 2.50 mg/m3, 0.05 mg/m3, and 0.01 mg/m3, respectively. For commercial metalworking fluid (MWF) droplets, compounds having low molecular weight were more prevalent in the vapor phase than those compounds with high molecular weight. The compositions of the particle phase were similar to those of the original fluids. The wall losses of hexadecane and bis(2-ethylhexyl) sebacate (BEHS) were 0.25% and 26.5% of combined vapor and particle concentrations in the SADS sampling, respectively. Because it can avoid evaporative losses, SADS will sample semivolatile aerosols more accurately than common filtration methods and may often yield higher particle concentrations than can be measured using the other methods.

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“…(15,19,36,37) Volckens and Leith (38,39) later reported that electrostatic precipitators have the potential for chemical artifact formation, especially with chemicals containing double bonds in their structure. Reaction and degradation due to ozone and corona-related ions in ESPs has been reported in other literature.…”

“…In the laboratory test of SADS using oil mist, the sampling media were charcoal tubes which can be connected almost directly to the outlets of SADS using a short Tygon tubing. (19) Due to the wide opening of the OVS tube, some extra interface between the tube and SADS is inevitable. A male piece of a quick disconnect couplings was inserted into the inlet of an OVS tube and then a short $1\frac{1}{4}$-inch Tygon tubing connected between SADS and the disconnect.…”

“…The flow rates for the vapor and particle outlets were 0.2 and 1.8 l.min −1 , respectively, to give a total flow rate of 2.0 l.min −1 and a vapor flow fraction of 0.1 of the total, per previous studies. (18,19) Flow rates were maintained by two mass flow controllers (GFC17, Aalborg Instruments & Controls, Inc., Orangeburg, N.Y.).…”

“…(19) The mass collected on each OVS tube attached to the particle flow side (M OVSp ) of the SADS includes both particle mass and mass collected from the vapor-phase (and thus the vapor phase mass must be subtracted from the total to obtain the particle mass in equation 2). This mass, and the mass of vapor only from the vapor flow side (M OVSv ) were obtained from analytical report.…”

“…SADS was tested in laboratory settings for oil mists and worked well. (19) Separation of particles from aerosols using SADS minimizes evaporative loss during sampling and the apparatus is less affected by temporal variation of the phase distributions. The SADS was designed for personal sampling and optimized to accommodate the pressure drops typically encountered with sampling media.…”