Psychrometrics, Dew Point and Condensation

Dry-bulb temperature, moisture content, relative humidity and dew point describe different properties of moist air. Changing one may change another without adding or removing water.

Dew point is the temperature at which the air becomes saturated for its current moisture content. A surface below that temperature can collect condensation.

Cooling coils remove moisture when water condenses on them. The same cooling can temporarily raise local relative humidity even while total water is being removed.

Heating air lowers relative humidity when moisture content remains constant, but it does not remove water. Product evaporation can then add moisture back to the chamber.

Cold walls, doors, products, ducts and evaporators can collect water that carries contamination or produces local wet surfaces and mould faults.

Measure temperature and humidity at representative locations, manage drainage and surface temperatures, and interpret controller readings using the loaded chamber rather than simple setpoint assumptions.