An environmental test chamber is a system that allows a user to control the environmental conditions of an enclosed space to run controlled tests on a subject.
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.
To create temperature and temperature humidity conditions, environmental test chambers use electric heaters to create temperature and refrigeration systems 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. To boost the humidity range of the test chamber 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 with its clear walls allowing total product visibility during testing.
Diving in further, there are multiple 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 and 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 failures and as well as testing your products ability to cope with the different climatic zones.
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 but where they deviate is the time it takes to reach those extremes.
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 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 a real world situation. By using a salt spray environmental test chamber, our customers 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 and 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 organization that have standards for salt spray testing are American Society for Testing and Materials (ASTM) and the United States Department of Defense (MIL-STD). By creating test standards, it allows 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. Especially for products going to the Department of Defense, it allows the military to know 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 metals, alloys, and coatings, whereas ASTM-B117 does not have specific test specimen and is a broad spectrum standard.