ARS | Publication request: The controlling effect of temperature in the application of permeation tube (PT) devices in standard gas generation

Submitted to: Journal of Chromatography A
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 19, 2011
Publication Date: February 17, 2012
Citation: Susaya, J., Kim, K., Cho, J., Parker, D.B. 2012. The controlling effect of temperature in the application of permeation tube (PT) devices in standard gas generation. Journal of Chromatography A. 1225:8-16.

Interpretive Summary: Permeation tube devices are used to generate trace gases for calibrating air quality instruments used for odor and chemical emissions analyses. Concentrations in the parts per million to parts per billion ranges are achieved by adjusting the temperature or air flow rate across the permeation tube. While previous research has been conducted on how air flow rate affects gas concentrations, little research has been conducted on the effect of temperature. Laboratory experiments were conducted to assess the accuracy of permeation tubes devices at temperatures of 30 to 100C. New equations were derived using regression analyses to predict gas concentrations as a function of temperature and air flow rate. The new equations greatly improved the accuracy of permeation tube devices.

Technical Abstract: In this study, the performance of permeation tube (PT) devices for the generation of VOC calibration gas was examined by successively generating BTX gas at five temperatures (30, 50, 70, 80, and 100C) and two flow rates (400 and 800 mL/min). A distinct relationship was observed between temperatures and permeation rates (PR) (or generated BTX concentrations). We examined the reliability of the manufacturer’s PR formula when operating at chamber temperatures different from the manufacturer reference temperatures for each PT device. Bias of the actual PR from the theoretical PR values became significant as PT devices were operated at temperatures beyond their optimum operating range (e.g., maximum bias of BTX as 141, 87.2, and 85%, respectively). Through a derivation of empirical formula, we were able to predict PR values of the target compounds more accurately as evidenced by significant bias reduction at all temperature points (e.g., maximum bias of BTX as 10.9, 21.1 and 20.6%, respectively).