title: The use of permeation tube device and the development of empirical formula for accurate permeation rate.
abstract: A series of laboratory experiments were conducted to assess the accuracy of permeation tube (PT) devices using a calibration gas generator system to measure permeation rate (PR) of volatile organic compounds (VOCs). Calibration gas standards of benzene, toluene, and m-xylene (BTX) were produced from PTs at varying flow rates (FR) of 20-1200 mL min(-1) and constant temperature (30°C). Results indicate that changes in flow rate greatly affected the permeation rate of each VOC at this temperature. This paper presents experimental approaches to accurately measure actual permeation rate (APR) and the derivation of empirical equations for predicted permeation rate (PPR). If the magnitude of bias is defined as the difference between PPR and the manufacturer's permeation rate (MPR), the bias was typically 19-40% for toluene (T) and 31-54% for m-xylene (X). Benzene (B) exhibited the least bias of 1.4-18.8%, nevertheless our PPR values for benzene were more reliable at lower flow rates (0.75-1.20%). This study highlights the importance of flow rate and associated pressure changes as a key to accurate permeation rate estimation from permeation tube devices.
authors: Department of Environment & Energy, Sejong University, 98 Goon Ja Dong, Seoul 143-747, South Korea.
authors: Janice
authors: J
authors: Susaya
authors: Ki-Hyun
authors: KH
authors: Kim
authors: Jin Woo
authors: JW
authors: Cho
authors: David
authors: D
authors: Parker
mesh_terms: D000465:Algorithms; D001554:Benzene / Q000737:chemistry; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D004867:Equipment Design; D005740:Gases / Q000032:analysis; D010539:Permeability; D012015:Reference Standards; D012044:Regression Analysis; D015203:Reproducibility of Results; D014050:Toluene / Q000737:chemistry; D055549:Volatile Organic Compounds / Q000737:chemistry*; D014992:Xylenes / Q000737:chemistry
chemical_list: D005740:Gases; D055549:Volatile Organic Compounds; D014992:Xylenes; D014050:Toluene; D001554:Benzene