Environmental Test Chambers: Temperature Range

The range of temperatures that may be produced inside a chamber is one of the most important characteristics that distinguishes one type of chamber from another.

High Temperature

Common upper-range (high) temperatures offered by most chamber manufacturers are 177 degrees C to 190 degrees C; this range is especially common in reach-in and walk-in types. Using special construction and insulation, temperatures up to 593-degrees C may be attained.

Here is some more detailed information on high-temp chambers.

Low Temperature and Cooling

Cooling environmental temperature chambers can be done in a number of different ways. The two most commonly used ways are:

• expendable refrigerants -- liquids/gasses that are injected into the space being cooled. As refrigerant liquid enters a chamber (directly or via a fin coil) it absorbs heat and flashes to gas. The gas is then vented out side the chamber (and out of the building). Liquid nitrogen and liquid carbon dioxide are the two most popular refrigerants. Cryogenic temperatures down to -184 degrees C can only be attained using liquid nitrogen. Liquid carbon dioxide (CO2) can't produce temperatures below -68 degrees C. Both liquid nitrogen and liquid CO2 are environmentally safe and may be vented to the atmosphere. However, it's very important that these gasses be vented outdoors -- they displace oxygen, which can lead to asphyxia if the chambers is not properly vented.
  
  
• mechanically-cooled refrigeration -- these type of chamber cooling systems are similar to those found in common refrigerators. A compressor is used to circulate refrigerant in a closed-loop system. The lowest temperature required by one's testing goals determines the type of refrigeration system needed. Single-stage systems can drop a chamber's temperature down to -34 to -40 degrees C. For continuous operation at and below -40 degrees C, most manufacturers recommend a cascade refrigeration system. Cascade systems are comprised of two separate cooling systems to cool the chamber to a maximum low of around -85 degrees C.

Here is some more detailed information on low-temp chambers.

Read more about Temperature Change Rate.

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