Tuesday, February 17, 2009

Temperature Chambers - Information you Need to Know

By Peter Brown

Should you need your product to be reliable under any temperature conditions, you will need to test them using a temperature chamber. In the United States there are quite a few manufacturers of this type of equipment.

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

Temperature chambers have a temperature range depending mostly on the type of cooling provided. Mechanical refrigeration compressors can have a maximum temperature range of -70c to +170c if the compressors are in a a "cascade" configuration (two compressors). With only one compressor, the temperature range will be far less: Normally -35C to +170C.

Beside mechanical compressors, CO2 or LN2 can also be used to cool a chamber. The temperature range obtainable using CO2 or LN2 is normally -70c to +170c.

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.

Options offered for temperature chambers are normally the following: Window in the Door Water or air cooled compressors Circular temperature chart recorders Feed-Through Ports Dryer package to remove moist Castors for easy movement of the chamber - 15634

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