Study of low hydrogen flows into high-vacuum systems

A study is made of a scheme providing spectrally pure, low hydrogen flows i nto a high-vacuum chamber through the use of a palladium membrane with a wo rking surface of 20 cm(2) and ethyl alcohol vapors (scheme combining the pr ocesses of hydrogen generation and admission). It is demonstrated that at a n optimum alcohol vapor pressure and a membrane temperature of 973 K this s cheme can provide specific hydrogen flows of about 5 x 10(-2) Torr.1/s cm(2 ). The hydrogen permeability is limited in this case by the processes occur ring at the entrance surface of the Pd-membrane. (C) 1999 International Ass ociation for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.