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LABORATORY AND FIELD EVALUATION OF CRYSTALLIZED DOW 704 OIL ON THE PERFORMANCE OF THE PM2.5 WINS FRACTIONATOR
Citation:
Vanderpool, R, M. Labickas, A. Leston, M. Tolocka, F. McElroy, R. Murdoch, S. Natarajan, C. A. Noble, L. Byrd, R W. Wiener, AND E. Hunike. LABORATORY AND FIELD EVALUATION OF CRYSTALLIZED DOW 704 OIL ON THE PERFORMANCE OF THE PM2.5 WINS FRACTIONATOR. Presented at Symposium on Air Quality Measurement Methods and Technology, Research Triangle Park, NC, April 20-22, 2004.
Impact/Purpose:
Develop and evaluate methods for the sampling and analysis of PM in ambient air, with emphasis on FRM/FEM for PMc, measurement of carbonaceous aerosols, measurement of biogenic aerosols, comparisons measurements from the STN and IMPROVE monitoring networks, and continuous methods for PM mass and its chemical components.
Description:
Subsequent to the PM2.5 FRM's 1997 promulgation, technicians at the CT Dept. of Env. Protection observed that the DOW 704 diffusion oil used in the method's WINS fractionator would occasionally crystallize during field use - particularly under wintertime conditions. While the frequency of occurrence on a nationwide basis was judged to be low, concerns were raised that crystallization of the oil during a given sampling event may adversely affect the event's data quality.
In response to these concerns, the USEPA and the CT Dept. of Env. Protection conducted a specialized series of tests to determine if crystallized oil adversely affected the performance of the WINS fractionator. In the laboratory, an experimental setup using dry ice was used to artificially induce crystallization of the diffusion oil under controlled conditions. Standard size selective tests of the WINS fractionator were then conducted using primary calibration aerosols. Test results showed that neither the position nor shape of the WINS fractionation curve were substantially influenced by crystallization of the DOW 704 oil.
Wintertime field tests were then conducted in Windsor, CT using collocated FRMs equipped with both crystallized and non-crystallized oil. As predicted by results of the laboratory tests, crystallization of the oil did not adversely affect measured PM2.5 concentrations. In 33 collocated PM2.5 tests, regression of crystallized DOW 704 versus liquid DOS (dioctyl sebacate) produced slopes, intercepts, and R2 values of 0.98, 0.1 ug/m3, and 0.997, respectively.
In 45 collocated PM2.5 tests conducted at three U.S. cities, regression of liquid DOS versus liquid DOW 704 produced slopes, intercepts, and R2 values of 0.995, -0.006 ug/m3, and 0.999, respectively. As a result of these tests, DOS oil has been approved by EPA as a substitute for the ' DOW 704 oil. Users of this alternative oil have not reported any operational problems associated with its field use.
This is an abstract of a proposed presentation and does not necessarily reflect the United States Environmental Protection Agency (EPA) policy. The actual presentation has not been peer reviewed by EPA. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.