Multiple volatile organic compound vapor chamber testing with a frequency-agile CO 2 DIAL system: field-test results

Multiple volatile organic compound vapor chamber testing witha frequency-agile CO2 DIAL system: field test resultsLewis Carr, Russell Warren, Clinton Carlisle, Sylvie Carlisle, David Cooper, and Leland FletcherGeoscience and Engineering Center, SRI International, Menlo Park, California 94025Steve Gotoff and Felix ReyesEdgewood Research, Development, and Engineering Center, U.S. Army,Aberdeen Proving Ground, Maryland 21010-5423ABSTRACTMany of the 189 Hazardous Air Pollutants (HAPs) listed in the Environmental Protection Agency regulations can bemonitored by Frequency Agile CO DIAL (FACD) systems. These systems can be used to survey industrial and militaryinstallations and toxic waste repositories at ranges of a few kilometers from emission sources. FACD systems may become avaluable tool for detection and estimation of a wide array of HAPs. However, in most cases, several of the listed HAPs will bepresent simultaneously and discrimination of one HAP from another based on differences in spectral characteristics can bechallenging for FACD systems. While FACD hardware is mature and is capable of addressing these discrimination issues,multiple-contaminate separation algorithms will need to be developed. A one week field test was conducted at Los Banos,California, to gather multiple HAP data that will be used for future algorithm development. A vapor chamber was used tocontrol disseminated concentrations of each HAP and reduce effects of atmospheric turbulence and wind direction and speed.Data was collected for several chemicals injected into the vapor chamber simultaneously. The data and results from the fieldtest are presented and calibration issues are discussed.1. INTRODUCTIONPrior to 1990, the Clean Air Act (Section 1 12) National Emissions Standards for Hazardous Air Pollutants (NESHAP)provided regulatory guidance for seven hazardous air pollutants (HAPs): arsenic, asbestos, benzene, beryllium, mercury,radionuclides, and vinyl chloride. Title III of the CAAA expands this list to 189 HAPs. The limits-on-emission standards forthese HAPs are defined by the potential for adverse health effects from threshold concentration levels and the maximumavailable control technology (MACT) standards. The MACT component of the new standards is based on the measurementcapabilities of the top 12% of control technologies and is therefore independent of the standards' health-based componentFrequency-agile CO DIAL (FACD) technology has the potential to provide EPA and industry with characterization data formany of the 189 HAPs in ways that may someday designate it as an MACT technology. FACD systems can be housed inmobile platforms and can provide real-time data analysis, wide-area surveillance, and multimaterial measurement analysis ofvolatile organic compounds (VOCs) that are of primary concern at government and commercial industrial and waste disposalsites. For example, these systems can determine if suspected areas of contamination exceed predefined thresholds, monitorprocess streams for contamination beyond predetermined levels that have potential for accidental releases of designated VOCs,and monitor clean-up and remediation procedures that may potentially involve releases of VOC contamination into theatmosphere. These VOCs can include trichioroethylene (TCE), perchloroethylene (PCE), dichloroethane, benzene, toluene,xylene, acetone, and methyl ethyl ketone (MEK). Sensitivities for these materials as well as several other materials listed asCAAA HAPs are provided in Table 1. The values in Table 1 are based on absorbance data gathered in a laboratory settingwith an VFIR and a predicted minimum signal-to-noise ratio (SNR) at which the FACD system can accurately perform aconcentration pathlength (CL) measurement. In Table 1 ,this