We were required to provide 2 environmental test cells to enable paint to be evaluated. One test cell had to be fixed at 25 degrees 50% RH with approx. 10% fresh air whilst the other had a variable set point from 5 degrees C 10%RH to 40 degrees C 80% RH and anywhere in between.
The Variable test cell was the real challenge as it meant the software had to perform at infinite set points and the turn down ratio of the equipment had to be such that it could cope with both ends of the scale.
The fixed booth could be achieved with an air handling unit, cooling coils, heating coils and humidifier whilst the variable booth required a desiccant wheel to provide the low RH temperatures.