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

摘要

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° 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.