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Technician posing next to an environmental test chamber

What is an environmental test chamber?

An environmental test chamber is a system that allows users to control the environmental conditions of an enclosed space to run controlled tests on a subject.

Environmental test chambers can range in size from half-a-cubic-foot benchtop models all the way up to 12,000-cubic-foot, drive-in rooms.

There are also multiple environmental conditions that test chambers can recreate: temperature and humidity conditions, temperature only conditions, and corrosive conditions through the use of salt spray. You can explore our full selection of test chambers here.

How does a test chamber work?

To create temperature and humidity conditions, environmental test chambers use electric heaters to cool or remove temperature from the environment. The refrigeration systems can be either mechanical or a liquid-cooling-based system with pros and cons for each. To introduce humidity to the system, steam generators are used, and to remove humidity, a mechanical dehumidifying system is used. 

An air dryer can be added to allow the test chamber to reach a lower relative humidity. Learn more about AES’ wide line of temperature and humidity test chambers here. To create the salt spray, a salt solution is prepared and stored in the tank then compressed air is used to force it through a nozzle and create a mist in the test chamber. The MX Series chamber is a unique style of salt spray chamber. Its clear walls allow for total product visibility during testing.

There are different types of temperature testing and different test chambers built for those types of testing. Steady-state testing means the test chamber holds the environment at a certain temperature (and humidity if necessary) for a long period of time. Test chambers built for this kind of testing have a high-temperature control to ensure that the test is as accurate as possible. The LH Series is a good example of a chamber with this kind of testing capacity. 

Thermal cycling testing has the test chamber cycling from a selected temperature to another, with a focus on the ramp rate that it takes to reach those temperature levels. At AES, we have two styles of chambers for thermal cycling that will fit almost any lab space: The FD/HD Series is our floor-standing line, and the SD/BHD Series is our benchtop line. 

Finally, there is thermal-shock testing. This style of testing is when a product is quickly exposed to drastically different temperatures. At AES we use a two-zone test chamber in our SM Series to achieve this with one cool zone and one heated zone. The product is then transferred between the two zones via a pneumatic elevator. By rapidly exposing your product to two drastically different temperatures, you can test to find product fa

Thermal Cycling vs Thermal Shock

There are two types of temperature testing that, while similar in name, are very different in their actual procedures. Both thermal-cycling and thermal-shock testing require bringing a product to two different temperature extremes. Where they deviate is the time it takes to reach those extremes.

  • Thermal cycling is a slower process where the product is brought to the two temperature extremes over a period of time. The biggest factors in testing like this are the ramp rates of the test chamber to the two temperature extremes. Depending on how you want to test your product, you can vary the ramp rates to meet the level of stress you want to put on the product. Also, thermal cycling has long soak periods where the product is left at a certain temperature level to ‘soak’ in that thermal condition.

  • Where thermal cycling is a slower process, thermal-shock testing is much quicker in terms of introducing the product to the other temperature. In a multiple-compartment, thermal-shock test chamber, the chamber has two (or three) zones. One zone is the upper-temperature limit, and the other zone is the lower-temperature limit. The third zone can be added for ambient temperature exposure. A basket is then used to quickly and autonomously transfer the product being tested between the zones. This allows for the product to be taken from one extreme and immediately transferred to the other extreme. The biggest factor in this type of testing is recovery time. Recovery time applies to two areas in testing depending on what standard is being tested for. It can either apply to the product or the air. When it is air recovery it means that the air of the temperature has to recover to a set temperature when the product is introduced. Product recovery means that the product has to reach the set temperature in a certain amount of time after it was introduced to the zone.

 

Are there standards for these types of testing?

Depending on what you are testing, there are multiple standards that apply to each type of testing. There are JEDEC standards that apply for thermal cycling of microelectronics as well as ASTM standards for cycling photovoltaic modules. For thermal-shock testing, there are military standards for product testing for products entering the defense industry.

Salt Spray Testing

Salt-spray environmental test chambers are used to test the corrosive properties of products. Salt-spray test chambers are primarily used to test how well finishes, paints, and other products can last when exposed to real-world conditions. By using a salt-spray environmental test chamber, you can see years of corrosive exposure in a much shorter period of time.

Our salt-spray test chambers hold the internal testing environment at a constant 95ºF and the salt and the spray is generated by using compressed air to create a pressure differential in the nozzle. This pressure differential sucks salt solution into the nozzle. As it passes through the nozzle, the spray that saturates the interior of the test chamber is created.

There are many standards that apply to salt-spray testing and salt-spray test chambers. The two major organizations that have standards for salt-spray testing are the American Society for Testing and Materials (ASTM) and the United States Department of Defense (MIL-STD). These test standards allow for products entering those markets to be held to the same level of quality, and end-users know what level of scrutiny their product has passed through. That’s especially for products going to the Department of Defense—the military knows how much field stress they can put on products without them failing.

Two of the more common standards for salt-spray testing are ASTM-B117 and ISO 9227. Both specifications layout the apparatus, procedure, and conditions required to create and maintain the salt-spray test environment. ISO 9227 applies specifically to metals, alloys, and coatings, whereas ASTM-B117 does not have a specific test specimen and is a broad spectrum standard.

TEST CHAMBER USE CASES

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Research

Research is essential for the technology and engineering activities required to advance the design and development of products. Companies in almost every industry rely on research and development (R&D) to plan, design, and deliver new, innovative products. AES manufactures environmental test chambers to accommodate various aspects of R&D. Some examples are laboratory research, design of possible product alternatives, testing in search for or evaluation of product alternatives, construction, and testing of pre-production prototypes.

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Production

A product's reliability is based on measuring its stability and performance during a period of time under specific test conditions. AES test chambers are designed to enable our customers to conduct reliability and quality testing that guarantee the optimum operation and durability of their products. Reliability testing in an AES environmental test chamber makes it possible to examine the product's ability to endure environmental extremes as well as performance during or after subjection to particular or multiple environments, including the product's anticipated operational environment.

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Reliability Testing

Throughout the manufacturing process, functional testing verifies that the finished product conforms to its required specifications and validates product resilience. AES environmental test chambers are aligned with best production practices by verifying that an established set of product conditions and/or standards are met. This type of testing greatly reduces the risk of unexpected and costly product failures after the product has been released. Environmental testing of products also makes it possible to predict their life expectancy, set realistic customer expectations, and create cost-effective warranties. The result is increased customer satisfaction, reduced costs, and improved profitability.

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Quality

Quality assurance and quality control ensure the excellence of a product. Many products, components, and parts in different industries have specific environmental quality requirements. These requirements may be regulatory or may be an important aspect of the design or manufacturing specifications. AES environmental test chambers are used to measure whether quality requirements are met in different environmental conditions.

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Custom-Built Test Chambers

AES is proud to offer fully-customizable, environmental test chambers made to meet your needs. You get to work with a dedicated sales manager and AES engineers that love to tweak the old and redesign the new. AES engineers regularly modify existing standard test chambers with custom options specified and configured by your ideas or can design utterly custom test chambers to fit perfectly within your test parameters.