Method for detecting methane in a gas mixture

US5635628A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Maximilian Fleischer · Ehrenkirchen, DE
• Hans Meixner · Haar, DE

Key dates

• Filing date: Apr 22, 1996
• Grant date: Jun 3, 1997
• Expiry date: Apr 22, 2016

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N33/0016
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and apparatus for detecting methane in a gas mixture that may contain commonly used solvents including alcohols and acetones is provided which measures a change in electrical resistivity, electrical conductivity or relative permeability caused by the presence of methane gas at a chemically active sensing structure. The apparatus includes two spaced-apart electrodes that are covered with a thin methane-sensitive semi-conductive metal oxide layer. The gas to be tested is heated to a temperature exceeding 740.degree. C. before it contacts the metal oxide layer. Alcohols, acetones and other solvents are oxidized to electrical carbon dioxide and water before they reach the metal oxide layer so that only the less reactive and reducing gas methane reaches the metal oxide layer where it is reduced and increases the conductivity of the metal oxide layer as measured between the two spaced-apart electrodes with an appropriate electrical meter instrument.