Monday, March 2, 2009

Testing your Products using a Temperature Chamber

By Peter Brown

Temperature testing your product using a temperature chamber can prevent failure in the field and is a necessity today. Mostly these chambers are manufactured in the U.S.A.

Chamber manufacturers produce other types of chambers beside just temperature chambers. These will included: Liquid Carbon Dioxide Cooled Chambers Temperature Humidity Chambers Altitude Chambers Salt Spray Chambers Temperature Plates Liquid Nitrogen Cooled Temperature Chambers AGREE Temperature Chambers Space Simulation Chambers HALT Test Chambers Industrial Ovens

Here are some well known brands of temperature chambers: Thermotron Tenney Environmental Associated Environmental Blue M Espec Bemco Lunaire Despatch TestEquity Sigma Systems ESS Cincinnati Sub Zero Delta Design Ransco Russells

Every temperature chamber has a specified temperature range. The temperature range of the chamber will depend on the type of refrigeration used to cool it. If the chamber is cooled using Mechanical Refrigeration Compressors, the maximum temperature range is normally -70C to +170C when two compressors in a cascade configuration are included. If on one compressor is used, then the temperature range will most probably be about -35C to +170C.

Another method to cool Temperature Chambers is CO2 or LN2. Normally a temperature range of -70C to +170C can be obtained by using these cooling methods.

Most temperature testing includes temperature cycling. This will subject the product being tested to a range of temperatures in a specified time period. Most mechanically cooled temperature chambers have a temperature ramp rate (both up and down) of about 2C per minute (air air temperature) for a specified maximum product load. Should temperature ramp rates beyond this be required, this can be achieved by using larger compressors or CO2 or LN2. It is not unusual for a chamber using larger compressors or CO2/LN2 to achieve temperature ramp rates of up to 15C per minute or more.

Programmable controllers are standard on just about every temperature chamber manufactured today. This enables temperature cycling to be done automatically. A typical programmable controller would be the Watlow F4 controller. Some manufacturers even build their own OEM controllers. Options normally available for programmable controllers are RS-232 Interface and IEEE-488. Sometime extra event outputs can also be provided.

Most temperature chambers are offered with the following optional items: Window in the Door Circular temperature chart recorders Feed-Through Ports Castors for easy movement of the chamber Water or air cooled compressors Dryer package to remove moisture and prevent condensation when chamber is cooled - 15437

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