Osaka Sanso Kogyo Ltd.

Junichi Nishizawa

Takahiko Kijima

Akira Makihara

Edward Frederick Ezell

Hiroshi Nakamura

Shigeki Hayashi

Taichi Tagawa

Juinchi Nishizawa

Shigeru Kikuchi

Method of measuring the dew point or frost point of a gas having low

The invention relates to an apparatus for determining the frost point of a gas containing a very small amount of water. The apparatus comprises (I) compartment A made of a good heat conductor; (II) an inlet for the gas to be measured, which inlet is provided on compartment A; and (III) a heater for adjusting the temperature in compartment A, and a temperature sensor. The apparatus further comprises (IV) compartment B which is adjacent to compartment A. At least part of compartment B is made of a poor heat conductor. Further, the apparatus comprises (V) a hole at the interface between compartments A and B and (VI) a reflector mirror having a temperature sensor. The reflector mirror is provided on compartment B in such a way as to cover the hole is connected thermally to a freeze source in such a way that the temperature of the reflector mirror can be varied from room temperature to at least -80.degree. C. Also, the apparatus comprises (VII) a gas outlet provided on compartment B; (VIII) a small gap formed between the hole and the reflector mirror; (IX) a device that allows convergent rays of light or laser light to be emitted onto the surface of the reflector mirror; and (IX) a photodetector equipped with a condenser lens. The condenser lens condenses light from frost formed on the surface of the reflector mirror when said gas to be measured contacts said mirror and said water in said gas condenses as frost. Finally the apparatus comprises (XI) a detector device that senses the temperature at which frost occurs on the reflector mirror.

Apparatus for measuring the dew point or frost point of a gas having low

A method of determining the dew point of a gas containing a very small amount of water using (1) a reflector mirror the temperature of which can be varied from room temperature down to at least -80.degree. C.; (2) a source of condensed rays of light for irradiating the reflector mirror; and (3) a light recovering device that detects changes in scattered light due to condensation on the reflector mirror by exposing the mirror to the gas. The method comprises cooling the mirror and detecting the temperature at which the scattered light has a maximum intensity; slowly raising the temperature and detecting the temperature at which the scattered light has a minimum intensity and repeating the cycle until the temperature at which the intensity is a maximum and the temperature at which the intensity is a minimum are almost the same.

Method and apparatus for measuring the dew point and/or frost point of a

A method of cleaning a reflector mirror in an optical dew point meter that measures the dew point or frost point of a sample gas by a process including the steps of bringing the sample gas into contact with the reflector mirror whose temperature is variable, projecting condensed rays of light or laser light onto said reflector mirror, and detecting the change in the intensity of scattered light and/or reflected light on account of the dew or frost formed on said reflector mirror, characterized by bringing a CO.sub.2 gas or a CO.sub.2 containing gas into contact with the reflector while the latter is in a cooled state, thereby condensing CO.sub.2 on the surface of the reflector mirror, and the subsequent step of heating the reflector mirror to vaporize the CO.sub.2 is dischosed.

Method of cleaning the reflector mirror in an optical dew point meter

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.

Growing community of inventors

Hyogo, Japan

Takahiko Kijima