Environmental chambers are used to test products under controlled conditions of temperature and humidity. Refrigerated test chambers have the advantage of reaching lower temperatures and a bit of dehumidification. For low humidity, a separate dehumidifier can be purchased. As well, some biological incubators can be used as environmental chambers if the narrower range of temperature and humidity suits the laboratory protocol. Some cabinets are used as stability chambers to test product shelf life at a constant temperature and humidity over weeks or months. Others have controllers that allow measured ramping of parameters, or even cycling between set conditions with specified holding times at each stage.
Factors to consider in selecting a chamber are: external size, internal capacity, number of shelves, temperature range, humidity range, rate of temperature change needed, possible heat load generated by the produce under test, access ports for running cables or hoses through the walls, power requirements .. Note that the water supply may need to be distilled water, deionized water, or even tap water in a few cases. A drain will also be needed for condensate and excess water from the humidification process.