title: Estimation of Organic Vapor Breakthrough in Humidified Activated Carbon Beds: -Application of Wheeler-Jonas Equation, NIOSH MultiVapor™ and RBT (Relative Breakthrough Time).
abstract: OBJECTIVE
  In the use of activated carbon beds as adsorbents for various types of organic vapor in respirator gas filters, water adsorption of the bed and test gas humidity are expected to alter the accuracy in the estimation of breakthrough data. There is increasing interest in the effects of moisture on estimation methods, and this study has investigated the effects with actual breakthrough data.
  
  
  METHODS
  We prepared several activated carbon beds preconditioned by equilibration with moisture at different relative humidities (RH=40%-70%) and a constant temperature of 20°C. Then, we measured breakthrough curves in the early region of breakthrough time for 10 types of organic vapor, and investigated the effects of moisture on estimation using the Wheeler-Jonas equation, the simulation software NIOSH MultiVapor™ 2.2.3, and RBT (Relative Breakthrough Time) proposed by Tanaka et al.
  
  
  RESULTS
  The Wheeler-Jonas equation showed good accordance with breakthrough curves at all RH in this study. However, the correlation coefficient decreased gradually with increasing RH regardless of type of organic vapor. Estimation of breakthrough time by MultiVapor showed good accordance with experimental data at RH=50%. In contrast, it showed discordance at high RH (>50%). RBTs reported previously were consistent with experimental data at RH=50%. On the other hand, the values of RBT changed markedly with increasing RH.
  
  
  CONCLUSIONS
  The results of each estimation method showed good accordance with experimental data under comparatively dry conditions (RH≤50%). However, there were discrepancies under high humidified conditions, and further studies are warranted.
authors.affiliation: Work Environment Research Group, National Institute of Occupational Safety and Health, Japan (JNIOSH).
authors.forename: Hironobu
authors.initials: H
authors.lastname: Abiko
authors.forename: Mitsuya
authors.initials: M
authors.lastname: Furuse
authors.forename: Tsuguo
authors.initials: T
authors.lastname: Takano
mesh_terms: D000327:Adsorption; D000392:Air Movements; D002244:Carbon / Q000737:chemistry*; D005740:Gases / Q000032:analysis*; D006801:Humans; D006813:Humidity; D008422:Materials Testing / Q000379:methods*; D008432:Mathematical Computing; D008962:Models, Theoretical; D009314:National Institute for Occupational Safety and Health, U.S.; D013997:Time Factors; D014481:United States; D055548:Vapor Pressure; D014835:Volatilization; D014867:Water / Q000032:analysis*
chemical_list: D005740:Gases; D014867:Water; D002244:Carbon