A dew point analyzer measures the amount of moisture present in a gas to determine the theoretical temperature at which the moisture in the gas will condense (the saturation point).
Although dew point is related to the temperature and the pressure of the gas, the dew point of a gas remains the same regardless of the actual temperature of the gas. For example, a gas at room temperature (70°F, or 21.1°C) with a dew point of 40°F (4.4°C) will cause condensation if it is cooled to a temperature below 40°F. This can be seen in the summer when the ambient temperature in the evenings drops below the dew point temperature of the air, causing water droplets to form on any surface that cools to a point below the dew point temperature.
Knowing the dew point of a gas in a heat treating environment can be beneficial in either determining the carbon potential of the gas, or determining the purity level of the incoming process gases.