Test results reveal things like product decay and degradation and, conversely, product effectiveness and durability.
Environmental test chambers allow researchers to use a wide variety of test methods and tests. Such tests are related to circumstances like: sudden environmental temperature change and temperature extremes, humidity and moisture, salt spray, UV rays, airborne and structural vibrations, corrosion, EMI and more. Researchers may also use test chambers to conduct overall durability testing. Using test results, researchers can predict potential useful lifespan, tweak product formulas and fix errors before a product goes to market.
Products you may use every day undergo this testing. Examples include: car parts, cell phones and other electronics, kitchen appliances, makeup, and hand soap. Some of those countless industries that rely on environmental testing include: medicine, pharma, food processing, food packaging, consumer goods and services, automotive, engineering, and construction.
The first environmental test chamber was built in Holland, Michigan in 1951 by Charles Conrad. Conrad was a self-taught innovator, who began working in climatic simulation after high school. He created his test chamber by modifying a home freezer. The industrious Conrad, who had been commissioned by H.E. Morse Company to create a low temperature processing system, literally assembled it on his front porch. His first system could generate temperatures as low as -125°F.
After his successful invention, he founded his own company, Conrad, Inc. He received a patent for the test chamber in 1954. In 1962, after selling his stock in Conrad, Inc., Conrad founded another company, Thermotron Industries. This company was the first truly focused on environmental testing chamber manufacturing. It became one of the biggest players and innovators of the industry.
Since the invention of environmental test chambers, engineers have made many improvements that have allowed them to serve even wider purposes. For instance, modern test chambers are increasingly portable and can now be purchased in miniature forms. In addition, they can test a wider range of temperature humidity than ever.
Test chambers are often built for specific purposes, and so have specific names, such as AGREE, cryogenic, altitude, salt spray, vacuum, thermal shock, temperature test, humidity test, walk-in and reach-in chambers.
The “AGREE” in AGREE test chamber is an acronym for Advisory Group on Reliability Electronic Equipment, which was a group within the Defense Department of the United States that worked to create the AGREE chamber to perform tests on military hardware. AGREE chambers can produce fast-acting temperature extremes; they can jump from 41℉ to 104℉ (5℃ to 40℃) within 60 seconds, even with large loads. They also have removable floors so that they can enact vibration shock test systems. Today, AGREE chambers not only test military hardware but also automotive, electronic, and telecommunications equipment.
Cryogenic Test Chamber
Cryogenic test chambers test products that must face temperatures between -238-degree Fahrenheit to absolute zero. Applications that often undergo cryogenic testing include flash-freezing and long-term food chilling, metal strengthening, medicine preparation, and preservation and the production of rocket fuel from liquid gases.
Altitude chambers, or hypobaric chambers, test the effects of low-pressure on products, packaging, and electronics that will be exposed to high altitudes. They can also be used for testing human respiratory and circulatory response to altitudes up to 200,000 feet above sea level. Human testing is for specialized professions and activities, like astronaut and pilot training and athletic training.
Salt Spray Chamber
Salt spray chambers, also called fog chambers, test corrosion resistance by hanging an object from a rod as the chamber introduces a salty residue that creates fog. This process is relatively inexpensive and used by a number of industries, including aerospace, automotive, construction, and industrial manufacturing.
Vacuum chambers are testing chambers from which almost all matter, including air, has been removed. This is mostly used for aerospace and aviation applications.
Thermal Shock Chamber
Thermal shock chambers test the effect sudden temperature changes have on a product, since thermal shock can cause faulting or cracking along stress lines. Many industries rely on chamber thermal testing. Ceramics and glass rely on it especially, though, because, due to low thermal conductivity and a tendency to expand and compress unevenly, they are at-risk for thermal shock.
Temperature chambers are self-explanatory; they test the effect of different temperatures. They’re often used in conjunction with other testing processes, like vibration testing and altitude testing. Because of their varying applications, temperature test chambers also vary in length, width, and design. For instance, some chambers are large enough to drive into, while others contain only a simple desktop.
Humidity Test Chamber
A humidity chamber is used to simulate a wide range of humidity conditions, so that researchers can test the effects of different types of humidity on their products and learn about humidity control. Most often, humidity testing is conducted in the service of specific biotech and industrial applications.
These chambers are relatively huge, big enough to drive vehicles into them. They majorly are either modular or welded. For construction of modular type chambers, prefabricated modules or panels are used, lined with urethane foam insulation. The construction limits the temperature and humidity range that can be attained; the maximum high temperature it can reach is between 100℃ and 121℃. The humidity range is 70℃ with 95% relative humidity (RH).
Alternatively, in welded chambers, as the name suggests, the internal chamber is welded together, which gives it the ability to withstand higher humidity ranges and extreme temperature ranges. They are designed to withstand altitude conditions, and because of all these features, they are more expensive than a modular type.
Reach-in chambers are the most common type of remote conditioners or chambers. They come in a range of sizes, starting from 0.5 cubic feet to 70 cubic feet. These relatively portable chambers can simulate practically any environment condition, from temperature variations, to humidity, altitude, solar rain, or vibration. Specialized thermal shock chambers are also available in different sizes and configurations; they can change temperature condition from one to another a matter of seconds, checking the reliability in adverse conditions.
Environmental test chambers consist of a variety of different elements, depending on their type. For example, to efficiently alter environmental conditions within the chamber, test chambers feature cooling systems, such as freezers and heaters. Or, to simply control temperature inside the chamber, manufacturers include insulated wires and conductors. Meanwhile, to help adjust pressure, manufacturers place vacuums inside pressure chambers. Other common components include: viewpoints and video feeds, stainless steel interiors, reach-in gloves for test subject handling and a variety of control systems.
Primarily, two types of refrigeration systems are available: expanded refrigerant and mechanically cooled.
Expanded Refrigerant System
In refrigerant-based cryogenic chambers, temperatures can go down to –184℃, using liquid nitrogen. Alternatively, carbon dioxide can be used as refrigerant; however, it can only achieve temperature down to –68℃. These gases unlike, chlorofluorocarbon, are environmentally safe and can be vented directly to the atmosphere.
Mechanically Cooled System
Mechanically cooled systems follow the same principle that are used in home refrigerators. They are further classified as single-stage refrigeration and cascade refrigeration systems. A single-stage refrigeration system can bring down temperature to –34℃, and in some cases, 40℃, whereas cascade refrigeration systems have two separate systems that can cool the chamber down to –85℃. Single-stage refrigeration systems are less expensive and have fewer parts, which makes them more reliable.
These systems rely on another component, condensers. For this purpose, two types of condensers are available: air-cooled and water-cooled. Air-cooled condensers are further divided as integral and remote air-cooled condensers.
Integral Air-Cooled Condenser
Small chambers are generally installed with air-cooled condensers, so they can be moved conveniently from one area to another. However, some things need to be considered with air-cooled units. First, the area where the environmental chambers will be placed should be air conditioned, as chamber’s performance is reduced if the ambient environment goes above 30°C. The chamber may not work at all, in some cases. Second, to operate efficiently in a high ambient room condition, the condensers must be of higher capacity, which can affect the running cost.
Remote Air-Cooled Condenser
In remote air-cooled systems, condensers are placed at a remote place, away from the chamber, generally outdoors. The pro of these systems is the fact that they offer freedom from the noise and heat. The con is that remote conditioner systems are complicated and therefore expensive to install and maintain.
Water-cooled condensers cool refrigeration systems using water instead of a refrigerant. Water-cooled condensers are best paired with environmental test chambers that must operate at six horsepower or more. The most common problems with water-cooled systems are related to water flow and differential water pressure supplied to the chamber.
Note: Condensers are commonly installed near the floor, which allows them to get dirty easily. A dirty condenser can be clogged and eventually over time can trip the high-pressure safety. Remote air-cooled condensers or water-cooled condensers are the best choices for dirty locations.
Environmental testing is a necessary process for any business that hopes to be successful. By finding flaws and weaknesses before a product reaches the public, a company can save money on fixes and enjoy a reputation for quality. It can offer a better warranty and feel confident that it will not face high reimbursement costs. The long hours and expenses put into environmental testing are an investment worth your while.
How to Use It
To begin conducting tests using your environmental test chamber, you must first carefully open the machine, place the product you’d like to test inside and then close it again. Once your product is in place, you use the set-up controls to create the environmental conditions to which you’d like to subject your project. In addition, you can set how quickly the test chamber reaches this environmental threshold. After you’ve got the settings the way you want them, you push the start button and let the test begin. During the testing, you or another technician will usually watch the product as it undergoes testing, in order to note its reactions.
Design and Customization
When designing environmental test chambers, test chamber suppliers must make choices about chamber type, cooling/heating systems, chamber layout and accessories. For instance, to get accurate results, the chamber needs details such as a viewing area in which workers can monitor the tests. These typically manifest as viewing holes, video feeds or, occasionally, a stand-in area. Engineers must also consider whether control panels should be analog or digital.
An important aspect of making reliable testing chambers is by maintaining consistency; engineers must avoid interfering and keep the process as uniform as possible. They also must take into account pre-existing variations of products and materials. With this strict level of control, engineers can make systems that are customized to your application and optimally useful.
Safety and Compliance Standards
Depending on the individual test chamber, your system will have different safety and compliance requirements. For example, cryogenic test chambers must pass OSHA standards for insulation on freezing chambers. Other environmental test chambers used in the United States must pass other OSHA requirements. They must also pass stress tests. In addition, walk-in chambers require an interior space permit, since it could contain a hazardous and potentially dangerous atmosphere.
Things to Consider
Guide to Buying
Many factors determine selection criteria, and price primarily determines the purchasing decision for many. This over the time can prove to be a costly mistake. To help you make the right decision, we’ve provided some questions to ask yourself and some points of interest to consider.
The primary questions that you should ask yourself are:
1. What will be tested in the chamber?
2. What should be the capacity of the chamber?
3. Should it be water-cooled or air-cooled?
4. What is the range of temperature you need?
5. What is the humidity range you require?
When it comes to environmental test chambers, humidity can be confusing. The humidity measure that you will see in the specifications is RH, which is temperature specific. The moisture in the air at 30℃ and 50% RH is not equal to 15℃ and 50% RH, the capability of air to hold moisture reduces, as the temperature goes down. This complicates the whole functioning. Instead of going into details, if you need to achieve lower humidity levels, ask for a chamber fitted with a dry-air purge system and refrigeration valves. In most temperature chambers, the common temperature–humidity range is 7℃ to 85℃, with 10% to 98% RH, which is limited by a 5℃-dew point.
Buying Used Test Chambers
Since environmental test chambers can be quite a pricey, a good alternative option for some shoppers is a used test chamber. If you plan on purchasing a used environmental test chamber though, you need to do your research. Testing equipment bought without proper research and insight can be a source of grief over time. With second-hand equipment, new issues generally accumulate, which negates all the benefits it gave at first. Maintenance and repair can easily drain all the money you saved on the purchase.
Before purchasing a used unit, evaluate it using the following questions:
1. Does the chamber provide the conditions you require?
If you buy a chamber and it does not provide the temperature or humidity range that you want, then the equipment is nothing more than junk. There are many types of environmental chambers, with varying degrees of temperature-humidity range. Check if the equipment reaches the temperatures and humidity levels that you need with your products, as heat, shape, and weight of the product can distort the performance of a machine, especially, the rate of change of temperature.
2. Is the manufacturer still operational?
All test equipment, new or old, needs repair and maintenance at some point. The cost of repair and maintenance can escalate quickly, if the original manufacturer has gone out of business, the spare parts will be difficult to find. Moreover, it will be difficult to find personnel with relevant expertise.
3. Does the chamber have proper airflow?
Inadequate airflow in environmental test chambers can lead to formation of hot or cold spots, which results in overheating and insufficient performance. Airflow is a major factor when the rate of change of temperature is higher. For high-performance application, 500 feet per minute (FPM) is considered effective, make it your benchmark and decide.
4. Is the mechanical structure rickety?
Rather than the external structure, you should be concerned about the main chamber, since that is where everything happens. The chamber is regularly bombarded with unfavorable environmental conditions, which take a toll on it. Presence of significant deposits or rust is a red flag. Moreover, check for the alignment of doors and panels, misalignment shows the modification done to structure.
5. What is the condition of the refrigeration unit?
The first thing you need to check is whether the unit has modern CFC-free coolants. Old CFC-based units do not pass the stricter regulations. The other thing that you have to consider is leaking; it is the most common problem with a refrigeration unit, which significantly affects the performance.
6. Does the chamber insulation work?
Only few temperature chambers are seam-welded, most are modular based. With the absence of welding, over time, moisture permeates into the insulation, which affects performance adversely. It is difficult to check for damp insulation, the only way is a visual inspection, check the internal chamber thoroughly for any gaps and abnormalities.
Choosing the Right Manufacturer
Finally, you need to choose the right manufacturer or supplier. The right manufacturer isn’t always the same for everyone. For example, if you require a highly customized system, a used testing chamber provider probably isn’t right for you. Or, if your needs are quite simple, you may be able to work with a supplier that offers more generic, less expensive models. The unifying factor when it comes to getting a quality system, though, is customer service. No matter your application requirements and no matter your budget, you should choose a provider that understands your requirements and seeks to attend them with care. With a provider like this, you can’t go wrong. Find the one for you among those reliable and high quality environmental test chamber companies that we’ve listed here right on this page.
Check out our Linear Actuators website
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Environmental Test Chambers Informational Video