Gas analyzer
US4730478A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 17, 1986 |
| Grant date | Mar 15, 1988 |
| Priority date | — |
| Expiry date | Jun 17, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/0256
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for determining the proportion of a given gas component in a gas mixture, comprising a piezoelectric crystal provided with a surface layer containing a substance capable of selectively and reversibly adsorbing said gas component, and being so arranged that the gas mixture can be brought into contact with said surface layer. The crystal is incorporated in an oscillator circuit which produces an output signal representing the oscillating frequency of the crystal, and therewith the proportion of the given gas component in the gas mixture. For compensating the temperature dependency of the surface-layer adsorption of the relevant gas component, a thermistor (R.sub.T) is arranged to be influenced by the same temperature variations as the piezoelectric crystal. Further, the output signal (S) of the oscillator circuit is connected to the input of an amplifying circuit, which incorporates the thermistor (R.sub.T) and is so constructed that the degree of amplification of the circuit is dependent on the resistance of the thermistor in a manner such that the output signal (V.sub.U) deriving from the amplifying circuit is substantially independent of temperature variations of the sur…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.