Calibrating Water Permeation Tubes Using Saturator-Based Primary Trace Humidity Standards

Published

May 1, 2003

Author(s)

Gregory E. Scace, Joseph T. Hodges

Abstract

H₂O-containing permeation tubes are a key component of permeation tube humidity generators (PTGs). These devices are widely used for calibrating atmospheric pressure ionization mass spectrometers (APIMS) and for calibrating other trace humidity analyzers. Here we describe a new calibration service enabling the measurement of PTG permeation rates directly in terms of NIST primary standards of trace humidity generation. Rather than using commonly employed gravimetric methods for permeation tube calibration, the method applied here links the permeation rate of the permeation tube to the thermodynamic properties of ice. We describe the calibration system and demonstrate its performance. Based on a month-long series of calibrations of a single permeation tube maintained at 50 C and with a nominal permeation rate of 37 ng min-1, the measured permeation rate was reproducible to within 0.6 % (standard relative uncertainty).

Citation

Proceedings of Semicon West 2003 Technology Symposium

Pub Type

Journals

Keywords

calibration, humidity, permeation tube

Citation

Scace, G. and Hodges, J. (2003), Calibrating Water Permeation Tubes Using Saturator-Based Primary Trace Humidity Standards, Proceedings of Semicon West 2003 Technology Symposium (Accessed May 22, 2025)