||Annular Denuders for Use in Global Climate and Stratospheric Measurements of Acidic Gases and Particles (Abstract Only).
Stevens., R. K. ;
||Environmental Protection Agency, Research Triangle Park, NC.;National Aeronautics and Space Administration, Washington, DC.
Atmospheric composition ;
Chemical composition ;
Climatic changes ;
Gas analysis ;
Nitric acid ;
Sulfur dioxides ;
Air pollution detection ;
||Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy.
||Measurements of acidic and basic gases that coexist with fine particle (less than 2.5 micron) may be useful for determining the impact of these species on global climate changes and determining species that influence stratospheric ozone levels. Annular denuders are well suited for this purpose. A new concentric annular denuder system, consisting of a three channel denuder, a Teflon coated cyclone preseparator, and a multistage filter pack was developed, evaluated, and shown to provide reliable atmospheric measurements of SO2, HNO2, HNO3, NH3, SO4(=), NH4(+), NO3(-), and H(+). For example, the precision of the annular denuder for the ambient measurements of HNO3 and nitrates at concentrations between 0.1 to 3 microgram/cu m was + or - 12 and 16 pct., respectively. The 120 x 25 mm three channel denuder is encased in a stainless steel sheath and has annular spaces that are 1 mm wide. This design was shown to have nearly identical capacity for removal of SO2 as conventional 210 x 25 mm single channel denuder configurations. The cyclone preseparator was designed and tested to have a D sub 50 cutoff diameter of 2.5 micron and minimal retention of HNO3.
||In NASA. Ames Research Center, International Workshop on Stratospheric Aerosols: Measurements, Properties, and Effects p 41.
||55E; 55C; 68A
||(Order as N91-32528/2, PC A05/MF A01)