Test Chamber

Chapter One – What is a Test Chamber?

A test chamber is a managed and controlled environment used to test the endurance, stability, and practicality of equipment, products, and chemicals. It is a controlled enclosure that mimics the effects of environmental conditions a product may encounter during its usage. Programmed test chambers create extreme temperature variations, moist or humid conditions, and radical altitude variances.

Aside from environmental conditions, test chambers can be designed and set to push the limits of a product through the use of physical forces such as inertia, vibration, and destructive impact.

The burst test, seen in this image, determines the amount of resistance pressure this sample of cardboard can endure before it fails, an example of the endurance testing performed in test chambers.

Some of the other purposes for test chambers are:

• Prepping a product for additional testing
• Stand-alone testing for combinations of different materials
• Stress screening to help identify product issues while still at the prototype stage

Chapter Two – Designs of Test Chambers

Test chamber designs vary depending on the types of tests they perform, which can either be very complicated or extremely simple. They come in various sizes to suit the manufacturer’s needs and the desired test conditions; for example, they could be the size of a bench top for testing small items or room-sized to fit a car.

Though size and types of environments are a factor, modern test chambers have technological controls that can provide instantaneous data and read-outs that allow technicians to adjust and change conditions in the middle of a process. In a steady test chamber, pictured below, a specific set of variables are programmed into the chamber and remain unchanged for extended periods.

Steady test chambers are specially designed to maintain a constant and accurate temperature as a part of age testing. They have ducts and electrical control systems that can sustain an environment for long intervals.

Factors in the Design of a Test Chamber:

Test Chamber Size

The size of a test chamber depends on the type of product to be tested. Sizes vary from one cubic foot to 12,000 cubic feet, large enough to fit an airplane. Below are images of two types of test chambers. The first is an ISO small environmental test chamber for industrial hot air dryer testing. The second is a walk-in that creates various temperature levels and humid conditions. It is 8‘x4‘x4‘ and has a wind-driven rain machine with a wind turbine that can produce winds up to 160 mph (257 kph).

Test Chamber Controllers

Test chamber controls allow technicians to monitor testing from their desktop computer or laptop. Views of set points, temperatures, and humidity are readily available with preset graphics or ones that can be customized to a customer's special conditions. Unlike older model test chambers that provide data at the end of a test, new technology allows users to monitor and adjust test conditions while the test is in progress. As seen on the controller display below, it is possible to monitor air temp, product temp, and humidity digitally and graphically, with data being sent every second.

Test Chamber Automation

Automated test chambers can be programmed in a variety of ways to produce multiple environmental conditions in succession. A series of steps can be programmed into the chamber, such as ramp, soak, jump, and auto stop and start. The purpose of an automated chamber is to test the endurance and durability of a product. Its system depends on a ruggedly built Programmable Logic Controller (PLC) designed to perform in industrial settings.

Photostability Testing

Photostability testing creates exposure levels to the full spectra of light a product can experience during its use. The testing chamber precisely analyzes of the effects of sunlight, UV rays, and various colored lights, which can cause color fading or product deterioration. Data is provided regarding visual color assessment, comparison of color variations, and detection of metamerism (in colorimetry, the matching of colors with different spectral power distributions).

For critical health products like medications and drugs, photostability chambers create forced degradation in extreme conditions beyond the normal environment. Photostability testing has become common since 1990 in the pharmaceutical, paint, ink, and dye manufacturing industries.

The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) has specific standards for photostability testing under provision Q1B, which allows for two light source options for pharmaceutical testing. The Q1B test indicates that there are no unacceptable changes from a light source.

Pictured below is a photostability test of golf-ball-sized spherical sensors to measure the effects of UVA and visible light (VIS).

Chapter Three – Types of Test Chamber Tests

In the R and D (research and development) stage of product development, prototypes of a product are subjected to tests to determine its reliability, durability, resistance to various climactic and environmental conditions, and behavior during normal use. Any failure at this stage causes engineers to examine the product's defects and work on correcting the problem.

The type and number of tests vary depending on the industry. For example, some segments of the auto industry may emphasize the durability of paint, while other departments test stress and perform structural analysis. Testing has become essential in modern industry. Below is a list of common forms of testing.

Testing has become essential in modern industry. Below is a list of common forms of testing.

Types of Tests:

• Temperature Testing is the most common product stress test since fluctuations in temperature cause a product to expand or contract. The type of product being tested determines rates of temperature changes. Temperatures can range from a -112° F to 482° F (-80° C to a +250° C).

• Humidity Testing is the second most common form of environmental stressor that can affect the internal workings of a product. Moisture or leakage can lead to oxidation and corrosion.

• Accelerated Age Testing uses a set of atmospheric conditions to speed up the aging process to determine how long the product will last. It is mainly used with new products that have not been through the normal aging process. The full spectrum of tests is used, from temperature and humidity to shake and vibration. The chart below is a graph of the aging process of the luminous flux of a LED light.

• Agree Testing combines temperature and humidity testing with vibration testing. It creates rapid temperature changes with varying humidity. The vibration test measures a product's reaction when being shipped or moved.

• Thermal Shock Testing is testing that verifies the reliability of a product during rapid changes in temperature, which are more severe than the expected range a product may experience. It is used to determine the cracking and strength of bonding materials.

• Altitude Testing tests the adaptability and reliability of a sample under low pressure, high temperature, and high altitude while measuring electrical performance parameters. These test chambers test vehicles, computers, and electronic components for high mountain conditions as well as packaging for air transport.

• Moisture Testing simulate soaking and rainy conditions. They use watertight chambers for water spray testing and have self-contained recirculation systems. Water is injected by nozzles with flow meters to adjust the water supply.

• Electrodynamic Vibrations or Shaker Systems conduct shock, vibration, and stress screening for failure analysis of electric PCB boards, mobile phone chips, aerospace equipment, military aircraft, automotive parts, tanks, and heavy weapons and equipment.

• Electromagnetic Radiation Testing tests for the flow of electromagnetic waves from a product, is required by several nations, and must be repeatedly performed on production models.

• Cyclic Corrosion Testing accelerates the corrosion process in laboratory conditions and is widely used in the auto industry. Materials may be submerged, dried off, or sprayed. The test is complicated and involves multiple exposure processes.

• Salt Spray Test is another accelerated corrosion test that exposes a sample to a salt spray or salt fog. The test chamber subjects the sample to a constant and continuous indirect application of fog or spray.

• Climactic Testing is testing that creates a controlled setting for all types of weather conditions to determine the reliability and longevity of a product. Climactic testing includes many of the other forms of testing, such as temperature, humidity, corrosion, and sand and dust.

• Sand and Dust Testing is a form of testing that circulates sand, dust, and other possible contaminants at high speeds in the testing chamber. Particulate count and speeds are adjusted in accordance with per preset specifications for the tested material.

• Vacuum Testing is mainly performed on equipment used in outer space or processes that include vacuum drying or coating

• Cytogenetic Testing is designed for slide drying tests for the creation of in situ and non-in situ cell samples. For the best results, control of the temperature and humidity must duplicate the environment conditions for chromosome spreading. The results of a chromosome analysis greatly depend on the conditions where the evaporation of the methyl acetate or ethyl acetate fixatives happens.

• Stability Testing is a type of test designed to present evidence on how the quality of a drug will change over time under the influence of a variety of environmental and atmospheric factors. The most common factors are temperature, humidity, and light. The results of the test outline recommendations for storage conditions, when to retest, and shelf life. The guidelines for testing are outlined in Federal Drug Administration (FDA) Q1A(R2) titled "Stability Testing of New Drug Substances and Products." Aside from photostability testing, other drug stability tests include accelerated, intermediate, freeze and thaw, bulk holding, and period after opening (PAO). A further requirement of the FDA is expiration dating, which has to be supported by real-time (RT) stability testing.

• Excursion Testing is a time temperature-sensitive pharmaceutical product test where the product is exposed to temperatures outside the normal range provided for transport and storage. The difficulty of excursions is that they can happen at any time, which means that transport is the most vulnerable time for pharmaceutical distribution. The difficulty of excursion testing is that there aren‘t any possible means for predicting what conditions will create an excursion. Disasters, weather changes, and improper handling can all lead to excursions. The best tests increase the rate of chemical degradation or other possible change by radically adjusting and modifying possible storage conditions as part of the stability test.

• Stress Screening or Environmental Stress Screening (ESS) All products must maintain high performance during their cycles of usefulness and maintain their original performance parameters. In ESS testing, products are exposed to thermal tests to force the exposure of latent defects, production errors, or infant mortality of the product. It is a process completed upstream of production to correct problems and improve product quality.

Chapter Four – Types of Test Chambers

Most test chambers are designed to perform more than one type of test to save money and time. Specially designed chambers test the viability of a new product that is about to be introduced. The majority of chambers do temperature and humidity testing or stress and vibration endurance testing. A select few perform highly accelerated stress screening (HASS) or Highly Accelerated Life Testing (HALT).

The use of test chambers has become a critical part of modern product development, testing, and marketing. Listed below are a few of the different types.

Anechoic or EMC Test Chambers

Anechoic or EMC test chambers are lined with sound and electromagnetic absorbing material to shield against attenuated electromagnetic interference. They test the radiated emissions of a product or its immunity to radiation emissions. Since the chambers are shielded against outside interference, an operator receives an accurate measure of the EMC field generated by a device and can determine if a piece of equipment complies with emission standards. The image below is of the interior of an anechoic chamber.

Cryogenic Test Chambers

Cryogenic test chambers create extremely low temperatures. Using liquid nitrogen or helium, a cryogenic chamber can reach temperatures as low as -238° F or (-150° C). They are time-consuming and costly since the temperature must to be lowered very slowly.

Mechanical Test Chambers

Mechanical test chambers perform mechanical tests, such as hardness, shock, vibration, impact, fracture, and fatigue. In some industries, they are known as shakers. The image below is of a tensile testing machine.

Modular Test Chambers

Modular test chambers are pre-engineered and prefabricated to meet any type of testing need. They include modular electrical temperature control systems that can be adapted to meet any desired conditions.

Pressure Test Chambers

Pressure test chambers place products under extreme pressure. They simulate static and changing pressures at high altitudes and ocean depths. Pressures can reach as high as 60,000 psi or be reduced to create a vacuum.

Reach-in Test Chambers

Reach-in test chambers are a form of portable remote conditioner that can simulate any form of environmental conditions. They are very convenient method for botanical and biological research.

Remote Conditioners

Remote conditioners can be used with large or hard-to-reach products. They have flexible temperature settings for secluded locations, can create temperature variations and humid conditions, are cost effective.

Stability Test Chambers

Stability test chambers have a controlled environment where all variables are held constant except for the specific ones modified for testing. They are primarily used to test temperature and humidity ranges but can also do shelf-life testing for drugs, nutraceuticals, personal care products, and food & beverage follows ICH Q1A requirements.

Steady Test Chambers

Steady test chambers perform long-term shelf life material testing and can simulate a wide range of humid environments and temperatures. Types of tests include accelerated aging, packaging, life science, storage, and research.

Tabletop Test Chambers

Tabletop test chambers are designed to test small items but have the same functionality as larger chambers with variations in temperature and levels of humidity. They come in a variety of sizes, from one to four cubic feet.

Vacuum Test Chambers

Vacuum test chambers remove air and pressure from a sealed compartment to evaluate the effects of a vacuum. Testing by a vacuum test chamber is a required by the aerospace and defense industries. Spacecraft engineers use it for testing electronics, circuits, lenses, filters, and structural materials.

Walk-in Test Chambers

Walk-in test chambers are large enough for a person to walk into. They vary from the size from a small closet to sizes that can fit a car or truck, and they can complete the full range of tests, from thermal shock and salt spray to humidity and temperature variances. This YouTube video shows a Ford testing center performing a cold-weather test on trucks and cars.

Welded Test Chambers

Welded test chambers are ideal for applications that require high temperatures over 200° F (93° C), high humidity, rapid temperature changes, and altitude simulations. They have one-piece construction and a hermetically sealed steel frame.

Chapter Five – Test Chamber Industry Applications

For several decades, test chambers have been used to study products for aerospace, artificial intelligence, automotive, electronics, solar cell, medicine, and industrial research. They offer a convenient, economical, and efficient method for studying products during development, production, and distribution.

Since their development, test chambers have found use in almost every aspect of manufacturing. Below is a brief sampling of industries that use testing chambers.

Industrial Applications

• Auto industry - In the auto industry, test chambers provide artificial space to recreate possible conditions vehicles and their parts may confront during their lifetime. Test chambers allow engineers to accelerate conditions to determine the resilience of materials.

• Aerospace industry - The aerospace and aviation industries use test chambers for testing atmospheric conditions for adherence to stringent SAE standards. The three critical factors for testing aerospace equipment are quality, reliability, and safety. The nature of aerospace manufacturing requires producers to follow a variety of regulations and requirements.

• Pharmaceutical industry - The main forms of pharmaceutical testing are steady, accelerated aging, shelf life, and expiration date. As with the aerospace industry, pharmaceutical companies have very stringent regulations determining their production methods. Testing of medicines is one of the most crucial factors.

• Battery industry - The battery industry uses testing chambers to test their products for vulnerability to humidity, heat, and vibration. HASS and HALT testing is used to simulate types of failure conditions. The fragile nature of batteries requires high-precision testing and assessment. To ensure quality, batteries are put through every possible test, from altitude simulation to thermal shock.

Chapter Six – Test Chamber Standards

Standards and regulations regarding the production of industrial equipment determine the quality of the data and the safety of users. Unlike other products, test chambers have a long list of certifying organizations that specify the requirements and specifications for test chamber classifications. The best-known and most commonly used designations have been developed by the International Organization of Standardization (ISO).

Companies can choose the set of standards they will follow. Critical industries involved with public safety are required to meet specific regulations. Most manufacturers work to get approval from as many certifying organizations as possible.

Below is a list of a few of the certifying organizations.

ISO

The International Organization of Standardization is an independent, non-governmental membership organization and the world's largest developer of voluntary international standards. The ISO specifications for test chambers are 10605 for electrostatic discharge, 16428:2005 for surgery implants, 16525-7:2014 for adhesives, 7137:1995 for airborne procedures, and 9022-20:2015 for optics and photonics.

AECTP 100

The North Atlantic Treaty Organization (NATO) provides guidance for the handling of military equipment in the Allied Environmental Conditions and Test Publication (AECTP) 100, Environmental Guidelines for Defense Material. AECTP 100 includes a list of requirements regarding for handling of various types of ordinance.

ASTM

The American Society for Testing and Materials creates the standards for aerospace, automotive, building and construction, chemicals, consumer products, food processing, medical devices, IT, telecommunication, manufacturing, pulp & paper, safety & security. ASTM was developed in the United States to address manufacturing quality issues. It has expanded to 140 countries and has 1,150 participating organizations.

FDA

The United States Food and Drug Administration was legislated to protect the public. It specifies requirements regarding the quality and purity of products.

IEC

The International Electrotechnical Commission publishes standards for electrical, electronic and related technologies.

JEDEC No. 22-A104D

The Joint Electron Device Engineering Committee develops standards for microelectronics. Its goal is to oversee microelectronics technology. In its sixty years of existence, it has developed testing methods and product standards for the semiconductor industry.

MIL-STD

MIL-STD was developed by the United States Department of Defense. The purpose of MIL-STD is to provide suppliers with a set of standardized directions for the production of military weapons and equipment.

RTCA

Radio Technical Commission for Aeronautics is dedicated to bringing organization to the complex issues regarding the aviation industry. It has published standards regarding every advancement in aviation and methods for testing aerospace instruments and equipment.

SAE

The Society of Automotive Engineers International focuses developing of standards for the transportation industries. Most testing organizations that supply the automotive, truck, and aircraft industries strive to get SAE certification.

SR-332 (Telcordia)

Issue 4 of SR-332 provides methods for predicting the reliability of hardware. Known as the Telcordia Reliability Prediction Procedure, it uses data collected from major companies to develop ways to predict the success of equipment.

UL

Underwriters Laboratories conducts research and analysis regarding safety for developing standards to guide the commercialization of technology. It provides safety certifications, validations, testing, inspection, auditing, advising, and training.

UN/DOT 38.3

UN/DOT 38.3 is a set of regulations regarding the transportation of lithium batteries. It has been adopted as a global standard.

Conclusion

• Test chambers are a managed environment designed to test products in a controlled environment.
• A wide spectrum of tests that can be performed in a test chamber, with temperature and humidity being the most common.
• Test chambers come in a variety of sizes, from one cubic foot to several thousand and can fit on a counter top or in an airplane hanger.
• Product testing has become essential as customer demand rises and products become more technical.
• Testing of products has become more essential as the demands of customers have risen and products have become more technical.
• TA wide array of organizations have developed standards for test chambers.
• Every industry has invested in test chambers for the testing of products from development through production.