Method of and apparatus for measuring very low water content in gas
US5052818A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | May 18, 1989 |
| Grant date | Oct 1, 1991 |
| Priority date | — |
| Expiry date | May 18, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N25/68
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An improved method of and an apparatus for measuring a very low water content in a non-condensible gas which has a dew point in the range of from ordinary temperature to -80.degree. C. or less. The gas to be measured is pre-cooled to a temperature slightly higher than that of the dew point, and is then blown against a reflecting mirror whose surface is cooled down to the dew point temperature of the gas. A condensed light having high luminance is projected toward the reflecting mirror. When the gas is blown against the mirror and cooled down to the temperature of the dew point, thereof a dew or frost is formed on the mirror, and the amount of scattered light reflected from the mirror is increased by the dew or frost. This increase in scattered light is detected by a photodetector. A silicon wafer which is polished to have a surface precision of 1/4 or less that of the wavelength of the condensed light is employed as the mirror to enable measurement of dew points of -80.degree. C. or less.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.