Information regarding walk-in test chambers, their use, and manufacturers
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Walk-in test chambers are test chambers designed to simulate the conditions of a specific environment, such as temperature, moisture, humidity, and other crucial factors. They are a necessary part of determining product quality, durability, and service life. The success of walk-in test chambers is due to their airtight interior, which enables them to create climatic conditions that would affect the performance of a product. They are used when stability, shelf life, and age testing of a product is required.
Unlike reach-in and benchtop test chambers, walk-in test chambers are large enough to accommodate people and the testing of large products. They can have workspaces with sufficient flexibility to adapt to various types of testing conditions. In most cases, walk-in test chambers are customized to meet the requirements of a client. They can be assembled to meet any dimensional specifications with or without internal test benches.
The size of walk-in test chambers enables researchers to perform several different types of tests, including stability, aging, accelerated shelf life, and for the cultivation of various types of bacteria. As with all forms of testing, walk-in test chambers enable researchers to control environments by changing temperatures, levels of humidity, vibrations, and other factors that interfere with a product's life cycle. The primary function of walk-in test chambers is to assess and examine the stability, reliability, and durability of products by producing conditions products will encounter during their use.
Walk-in test chambers come in a wide variety of sizes and models capable of meeting the requirements of any testing specifications. They are large enough for testing any sized product or batches of products. The design of walk-in test chambers enables them to combine a set of test conditions to the necessary performance levels of a particular product. Customization features include access ports, heavy floor loading, various wall thicknesses, quiet packages, different styles of doors, windows, and safety options.
A walk-in test chamber is an insulated box that can be configured to produce specific environmental conditions for product reliability and validation testing. They can be easily assembled using foam panels that lock together to create different box sizes or have sealed welded panels. Some varieties of walk-in test chambers can be large enough for testing cars and trucks.
Modular walk-in test chambers are prefabricated test chambers that are easily configurable. They can be quickly assembled to meet the needs of any test or size requirements. Although modular walk-in test chambers can be assembled on demand, they still have all the features of permanent test chambers, including refrigeration, air circulation, electrical components, and other standard features. The main concept behind modular walk-in test chambers is easy installation without disturbing the work environment.
As with all forms of walk-in test chambers, modular walk-in test chambers can be very small with room for one or two persons up to very large. They are often used when there is restricted access to assembly areas or cost is a consideration. The structure of the modular panels for a modular walk-in test chamber includes sectional panels that have a metal inner layer and outer skin bonded to a core of insulation with cam action locks to connect each panel. The size of the panels vary in accordance with the size of a walk-in test chamber.
Solid walk-in test chambers are welded to form a single unit that can withstand high temperatures, rapid temperature changes, combined environments, and high humidity. Unlike modular walk-in test chambers, solid walk-in test chambers are constructed as a single unit that is hermetically sealed around a steel frame. In some cases, due to placement restrictions, solid walk-in test chambers are produced in sections that are welded together on placement.
The design of solid walk-in test chambers allows them to test heavy, oversized products. They can withstand high humidity conditions that create increased pressure. The strong tight seal of solid walk-in chambers provides the necessary structural strength to endure the pressure. Angle iron frames of solid walk-in test chambers makes it possible to fully open the door of the chamber for easy loading and provides more floor space.
The two basic types of walk-in test chambers come in a wide variety of sizes with each chamber being chosen for its applicability for a particular testing function. In many cases, due to the nature of the tests that are required for a product, custom designed walk-in test chambers are used. The types of testing of walk-in test chambers necessitate that manufacturers and their clients work closely together during the selection process. The importance of the data collected by walk-in test chambers requires that the chambers be carefully planned and engineered.
An important aspect of the development of products is the determination of a product’s life cycle, endurance, strength, and resilience. Although it is possible to test them in real time conditions, such testing takes time, expense, and may lack reliability. Walk-in test chambers play a key role in determining the quality of a product and its service life in controlled conditions that can be manipulated and adjusted to imitate any environment.
With a walk-in test chamber, engineers can create conditions that a product may encounter. They allow companies to customize their products to meet the environments of different parts of the world and provide data regarding the stability of the components of a product. Although walk-in test chambers can be initially expensive, the data and information they provide eliminates the disasters associated with the failure of a product.
Stability walk-in test chambers are designed to maintain a steady, consistent temperature and humidity level in a controlled environment for an extended period of time. They use a combination of heat and cooling with water to replicate conditions. For humid conditions, water is heated to create steam that is pumped into an airtight walk-in test chamber. This factor is not present for temperature only chambers. Depending on the quality of a walk-in test chamber, the level necessary to test a product may take a while to achieve.
Once the necessary levels are reached, they are maintained to assess how well a product or device is capable of withstanding the created conditions. For testing products against cold temperatures, fans are used to blow in cold air. The key to creating both sets of conditions is a tightly sealed walk-in test chamber.
The quality testing provided by walk-in test chambers helps manufacturers to develop products that are resilient, strong, and long lasting. Testing the stability of a product helps determine the life expectancy of a product and its shelf life.
Thermal shock walk-in test chambers also test a product's reaction to temperature, like stability walk-in test chambers. The difference between the testing methods is in how the temperature is used. With stability walk-in test chambers, hot or cold temperatures are maintained for an extended period of time.
The key feature of stability walk-in test chambers is their ability to maintain a constant temperature for a long time. Thermal shock walk-in test chambers take the temperature gradient to another level by rapidly changing it between extreme highs and extreme lows over short periods of time to test the effects of thermal expansion and contraction on a product. The results of the testing help in the evaluation of a product's reliability and stability under extreme temperature variations.
Altitude walk-in test chambers are a combination of temperature and altitude test chamber. They are designed to control the temperature of the chamber as it produces altitudes up to 100,000 feet. The combining of the two conditions makes it possible to provide a precise simulation of conditions encountered at various elevations.
Referred to as pressure or altitude walk-in test chambers, altitude walk-in test chambers are an essential part of the testing of parts for aerospace where equipment, instruments, and materials are transported in low pressure environments. The range of tests that altitude walk-in test chambers are designed to create include vacuum, altitude, temperature, humidity, icing, and vibrations. Combining the various factors of high-altitude transport makes it possible to subject products to real world conditions that can affect their performance.
Walk-in altitude test chambers are large and able to accommodate items that are bulky. They are designed to endure pressure from ambient down to 10 mbar with a temperature range of -75°C up to 150°C (-103°F up to 302°F). Walk-in altitude test chambers can have rapid or explosive decompression and be configured for military use under MIL-STD-810G.
Sand dust walk-in environmental test chambers or dust ingress test chambers have equipment that replicates the effects of sand and dust particles on products. Products are subjected to testing that determines a product’s ability to resist particle access and how a product performs in dusty or dirty environments. The special design of sand dust proof walk-in test chambers enables them to generate and suspend dust particles in the testing space. The air circulation system filters ambient air to remove large particles to ensure particles in the chamber are of the same size.
The suspended particles in the chamber are blown and circulated by air blown up from the bottom of the chamber to replicate the conditions of a sandstorm or dust filled environment. The duration of the testing conditions is determined in accordance with the objectives of the tests. Each instance provides data to evaluate the durability, performance, and reliability of a product. Sand dust proof walk-in test chambers can have a capacity of 1500 L and 2000 L (396.26 gal and 528.344 gal).
Sand dust proof walk-in test chambers are designed to test the exposure of automotive and electronic components under extreme conditions and are certified by the International Electrotechnical Commission (IEC), the International Organization for Standardization (ISO), and the military.
Salt spray walk-in test chambers simulate the impact on metals that have been exposed to salt contaminated atmospheres that accelerate corrosion. The design of salt spray walk-in test chambers enables them to better emulate corrosive conditions caused by salt polluted environments.
The corrosion of metals is caused by many environmental factors and depends on the type of metal, the environment, and whether a metal has a protective coating. The creation of corrosive environments in controlled laboratory settings is difficult due to the many environmental factors that create such damage. Salt spray walk-in test chambers are able to create, simulate, and increase the environmental factors related to corrosion. In addition, they provide cyclic exposure to dry, humid, and hot conditions.
The results from salt spray walk-in test chambers provide valuable data in regard to the properties of metals that are exposed to salt pollution. They are used to test coatings and a component’s resistance to corrosion.
Environmental walk-in test chambers, also known as climatic walk-in test chambers or climate walk-in test chambers, are designed to simulate various climatic conditions in regard to temperature and humidity. The goal of environmental walk-in test chambers is to determine how products will react in an assortment of climates. They are a critical part of assuring product quality and determining product service life.
The use of walk-in test chambers for product testing is due to the chamber’s ability to ensure homogeneous climate conditions in terms of time and space. Their flexibility enables them to replicate a variety of environmental conditions including temperature, humidity, pressure, and lighting. The chambers are equipped with sensors and various instruments to monitor and regulate conditions in the testing chamber, which allow researchers to assess how products react, age, and are able to function over time.
Walk-in environmental test chambers are made of stainless steel that is powder coated against corrosion. An essential part of the structure of environmental walk-in test chambers is their insulation that ensures a tight seal to the chamber. As with many walk-in test chambers, environmental test chambers have shelves for products to be tested. Components include heaters, refrigeration systems, dryers, and condensers, which are critical to simulating various environments.
The walk-in test chambers described above are the most common and a sampling of the many walk-in test chambers that manufacturers offer. In many cases, manufacturers and their clients work together to choose and develop a walk-in test chamber that best meets a client’s application. A wide variety of custom-built walk-in test chambers are offered by manufacturers to meet the needs of new and unique products.
Walk-in test chambers have become an important aspect of manufacturing since they help guarantee the quality and durability of products. Many industries rely on walk-in test chambers in the development of new products and for testing old products as they are adjusted to meet new requirements.
The viability of walk-in test chambers is dependent on the quality and effectiveness of their components. The critical nature of the data provided by walk-in test chambers requires the most efficient, durable, and reliable components to ensure data and results are accurate and consistent. Although there are several varieties of walk-in test chambers, there are aspects of each type that are similar due to the nature of the test they perform.
The main features of all walk-in test chambers, solid or panel, is their tight seal, which guarantees the accuracy of the collected data. The concept behind walk-in test chambers is the creation of environmental conditions that match real world conditions that products will face during their use.
Walk-in test chambers are divided into panel and solid with panel walk-in test chambers being composed of insulated panels that interlock to form a sealed chamber. This method of construction varies from solid walk-in test chambers that are welded one-piece units made of highly resilient steel. An essential component for both types of walk-in test chambers is their doors, which require tight secure seals to ensure the integrity of the testing environment.
The requirements for doors for walk-in test chambers are somewhat similar to those established for cleanrooms in that doors for walk-in test chambers are required to have an exceptionally tight seal to prevent ambient atmospheric conditions from entering the chamber. Walk-in test chamber doors are made of materials that are similar to the structural materials of a walk-in test chamber. Doors can be made of steel, aluminum, glass, or plastic, with steel being the most reliable and common.
Windows in the chamber and the edges of doors are sealed with gaskets that are able to endure the conditions created in a walk-in test chamber. Gaskets are made of several types of sturdy materials with silicone being the most common.
Panel build is one of the two options for the construction of walk-in test chambers. This type of construction allows for greater flexibility and makes it easier to fit a walk-in test chamber in limited space. As with welded walk-in test chambers, panels for panelized walk-in test chambers begin with a steel interior skin that is attached to a polyurethane core and frame. The steel interior skin provides the stability and strength necessary to seal a walk-in test chamber while the polyurethane exterior makes the panels easy to handle and maneuverable.
Welded permanent walk-in test chambers have a solid construction with interior steel walls and exterior steel or metal walls with foam insulation between the interior and exterior walls. The interior walls, floor, and ceiling are welded to form a completely sealed compartment. Windows may be added for observation purposes that are sealed with durable, long-lasting material. The configuration of welded walk-in test chambers enables them to quickly change temperatures, endure the pressure of high humidity, and provide resistance to explosions.
Although the research performed in walk-in test chambers is the same for panelized and welded chambers, certain experiments require the use of welded walk-in chambers due to the increased stress created. When conditions require high humidity or pressure, welded walk-in test chambers are the better choice.
The common factor for all forms of test chambers is their control systems, which program the various testing environments. State of the art control systems make it possible to have easy operation and flexibility. In the modern era, control systems are intuitive, user friendly with touch screen interfaces. They allow monitoring of processes and operating walk-in test chambers using drag and drop to build profiles. A microprocessor with secure firmware supports high speed data transfer in megabytes.
Different methods are used to chart and track the data depending on the type of test. The critical nature of the tests performed by walk-in test chambers requires precision control of temperatures, humidity, and other factors. For enhanced and efficient data recovery, control systems are equipped with sensors and actuators that regulate environmental conditions to ensure the conditions are consistent and maintained.
The forced air circulation of walk-in test chambers is created by heavy duty motors that power fans with protectors and stainless steel shafts. As air is circulated, plenums are used to create airflow patterns to meet the requirements of the product being tested. The plenums used for walk-in test chambers come in several different forms including internal or external and horizontal, vertical, or a combination of both. Customized plenums can be designed to increase the even distribution of air for temperature control and limit noise.
As can be determined by the nature of the work performed by walk-in test chambers, proper air circulation is critical. The heating, cooling, and air circulation systems work in unison to create forced convection that simulates real world conditions. The speed of the airflow allows for quicker temperature adjustments with 1000 feet per minute (FPM) being the highest recommended airflow rate.
The three basic elements of walk-in test chambers are heat, cold, and airflow, which are monitored, controlled, and adjusted through the chamber’s control system. Heating systems consist of electric heating elements placed near the ventilation systems or plenums. Airflow and fast reacting heaters provide accurate control of temperatures. The placement of the heating system is a design feature that prevents items being tested from direct radiation, which can taint test results.
The heaters for heating systems can be sheath bare wire heaters that provide temperatures up to 180°C (356°F). For tests involving higher temperatures, manufacturers advise the use of other options. Heat in testing requires precision control to ensure accurate results. Since data regarding the characteristics of products is essential, engineers carefully monitor the provided heat such that it is consistent with the parameters of the research.
Cooling systems are essential to the creation of simulated environmental conditions. Cooling for walk-in test chambers is provided by refrigeration systems mounted on top, behind, beside, or remotely, depending on space requirements. Remote units can be installed outside a facility to save interior space. Cooled air enters through an evaporator that draws in the air using impellers. The temperatures that refrigeration systems can achieve can be as low as -70°C (-94°F). Lower temperatures are possible through the use of cryogenic gases, which can be pumped into the refrigeration system to create temperatures below -100°C (-148°F).
Extremes in temperature necessitate the use of welded walk-in test chambers, which have the durability to withstand such radical conditions. Hermetically or semi-hermetically sealing refrigeration systems lowers the need for maintenance and ensures longer run times. Sealing, also, saves on energy costs, reduces noise levels, and lowers the walk-in test chamber’s carbon footprint.
The generating of humidity is a key feature of walk-in test chambers and is created in several different ways. The most common methods are steam generators, ultrasonic nebulizer, or heated water bath. Steam generators are used for high temperature, high humidity testing and high-volume testing. The steam generator process involves bringing a tank of water to its boiling point and releasing the tank’s steam into the test chamber. This method increases the heat in the chamber, which can be a problem for temperature control.
Ultrasonic nebulizers are ideal for limited space walk-in test chambers where precision temperature control is essential. With ultrasonic nebulizers, vapor mist is generated and released into the test chamber. Heated water baths are a basic method for generating humidity. They consist of a water pump placed below the air handling system that is heated releasing water vapor through the air circulating system.
Humidification systems are sized to a walk-in test chamber’s size and the available work space. Humidity generated by a system can range between 20% up to 85% with an error of +/-2% Relative Humidity (RH). The use of a dry air purge can increase the humidity range by 5% RH. For a humidification system to be effective, it must be able to consistently maintain a stable RH range.
The reversal of humidification is dehumidification, which is achieved by removing the moisture generated by humidification. A cooled pipe or coil placed in the air circulation system causes the water vapor in the chamber to condense on the cooled pipe and drain away.
Vacuum systems are necessary to replicate the effects of high altitude on products. They are an essential feature of walk-in test chambers for aerospace and provide data regarding the harsh conditions of space travel. Vacuum walk-in test chambers create low pressure environments where temperatures and humidity vary at different altitudes.
In most cases, vacuum walk-in test chambers are solid welded walk-in test chambers to be able to endure the created pressure. The size of vacuum walk-in test chambers is influenced by the types of items to be tested and can be as large as 65 cu ft. Vacuum pumps are used to create the required testing vacuum level and remove particulate matter and moisture. Vacuum systems require close monitoring to help maintain proper pressure levels, which requires the vacuum pumps to operate continuously and is turned on and off as required.
| Pressure Variations at Different Altitudes | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pressure(kPa) | 1 | 2 | 4 | 8 | 15 | 25 | 40 | 55 | 70 | 84 |
| Altitude (m) | 31200 | 26600 | 22100 | 17600 | 13600 | 10400 | 7200 | 4850 | 3000 | 1000 |
Since the introduction of walk-in test chambers in the 1950s, they have become a stable part of product production and introduction. In many ways, walk-in test chambers help manufacturers to produce successful and profitable products by providing data in regard to a product's longevity, usefulness, stability, and resilience. The use of walk-in test chambers helps in product development by providing data for adjustments and improvements that make a product appealing to the market.
There is a long list of products that are examined using walk-in test chambers, which runs the gamut from small commercial products to critical components for space exploration. The true value of walk-in test chambers is in the guidance they provide and helping industry leaders avoid errors in marketing unreliable products. The primary use of walk-in test chambers is in the pharmaceutical, medical technology, food and beverage, and cosmetics industries in regard to product stability, shelf life, and aging. The wide use of walk-in test chambers is due to the space they provide compared to other forms of test chambers. The floor space of walk-in test chambers enables manufacturers to test large quantities or bulky items.
The concern for the safety of drugs has necessitated the inclusion of stability testing to determine a drug's expiration date and the behavior of drugs over time. Tested products are stored in climate walk-in test chambers under programmed conditions for temperature and humidity. The conditions of the testing are defined by the guidelines from ICH and are required to be strictly followed. The testing determines the shelf life of a drug and specifies a drug’s duration when stored under controlled conditions. The accuracy and precision of the tests are followed to meet the stringent conditions outlined by the ICH.
As with drug testing, medical instruments are required to meet the highest standards and be extensively examined before being used. Walk-in test chambers before a variety of tests on instruments to guarantee their safety and stability. The various tests are designed to examine the performance of instruments in simulated real time environments. The types of tests include humidity, temperature, light, moisture, pH, agitation, strength, quality, and purity. These walk-in test chamber tests are performed for life sciences, chemicals, medical devices, and in vitro diagnostics.
Food testing involves accelerated shelf life testing (ALST) under differing conditions to determine before dates. The use of walk-in test chambers provides immediate and fast results where simulations of temperature, relative humidity, and light are tested for their effects on the quality of foods. The different temperatures used to store samples include 20°C, 30°C, and 40°C (68°F, 86°F, and 104°F) during exposure to high levels of intense light. In addition, color loss is measured as changes in hue (ΔH) vary with changes in light and temperature. Chemical, microbiological, and physical changes are measured at various intervals until a product is no longer viable.
Cosmetics are tested in regard to their formulation and packaging under specific climatic and environmental conditions. The testing is designed to meet necessary physical, chemical, and microbial quality standards to ensure the integrity of products and their packaging. In addition, due to the nature of cosmetics and their wide use, the different tests are designed to determine the safety of cosmetics and their potential negative effects. Products are exposed to differing high temperatures, humidity, and intense light of varying degrees.
Microbiological experiments require consistent conditions in order to provide the necessary data. Any fluctuations, changes, or contamination can significantly damage results and end an experiment. Walk-in test chambers, with their versatility and adaptability, create environments that make it possible to grow cultures with controlled humidity to prevent dishes from drying out. The chambers can be used to breed insects or plants where changes in airflow are a necessity. In addition, the successful growth of cultures requires a controlled light source and ventilation. As with other forms of uses for walk-in test chambers, heat has to be minutely controlled such that the illumination from the light source does not damage the conditions.
The nature of the work completed by walk-in test chambers requires the oversight of several organizations and agencies. The nature of their work and the significance of the testing necessitates guidelines and standards for the safety of the public, researchers, and products. The stipulations for walk-in test chamber use include the ICH, Good Laboratory Practice (GLP), Good Manufacturing Practices (GMP), American Society of Testing and Materials (ASTM), Federal Drug Administration (FDA), and the International Organization for Standardization (ISO).
The specific stipulations are:
Before a walk-in test chamber can be used or certified, manufacturers must prove adherence to the stipulations in the above regulations in regard to the products being tested. The validation process includes installation qualification (IQ), operational qualification (OQ), and performance qualification (PQ).
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