With increasing demands for product quality across industries, environmental test chambers have become essential tools for ensuring product performance and reliability. Industries such as aerospace, military research, weapons development, 5G semiconductors, and electrical and electronic sectors all require environmental testing under specific conditions to verify product durability and functionality. However, due to the complexity of these chambers and the numerous technical specifications involved, some crucial factors are often overlooked. This article outlines Key Considerations for Selecting an Environmental Test Chamber to help you make an informed decision.
Temperature Range
Currently, single-stage refrigeration systems typically operate within a temperature range of -40°C to 150°C, while two-stage refrigeration systems can extend this range to -70°C to 150°C. Unless specific testing requirements dictate otherwise, it is not advisable to unnecessarily increase the upper temperature limit. A higher upper limit increases the temperature gradient between the chamber interior and exterior, which can reduce airflow uniformity and effectively decrease the usable test volume. Additionally, raising the temperature limit demands more advanced insulation materials and higher manufacturing costs. Similarly, lowering the minimum temperature beyond what is required can also lead to unnecessary expenses. For example, if -40°C suffices for a test, setting the lower limit to -50°C would be unnecessary and could force an upgrade from a single-stage to a two-stage system, increasing costs. Therefore, it is essential to define the temperature range based on actual testing needs to ensure both functionality and cost efficiency.
Load Considerations
Proper load configuration is crucial in testing procedures, as it significantly impacts stabilization time, calibration accuracy, temperature uniformity, and heating/cooling efficiency. Loads can be categorized into non-heating loads and heating loads. Non-heating loads refer to test specimens that do not emit heat when powered on, directly affecting the chamber’s heating and cooling time. Heating loads, on the other hand, involve specimens that generate heat, which impacts both temperature and humidity levels. A lack of understanding of load effects can lead to issues such as failure to reach the set temperature, insufficient cooling, or slow temperature transitions. Providing accurate data on specimen material, weight, and heat output ensures precise, reliable test results and enhances efficiency in product development and quality control.
Effective Test Volume
Due to thermal conduction effects, airflow temperature near the chamber walls can initially differ from that in the center. When testing large specimens, this can affect environmental uniformity. According to the GB/T 10592-2023 standard for high-low temperature test chambers, the total load volume should not exceed 1/5 of the working space, and in any cross-section perpendicular to the primary airflow, the total load area should not exceed 1/3 of that section’s area. Additionally, specimens must not obstruct airflow, and the total mass of the load should not exceed 80 kg per cubic meter of test volume.
Chamber Size Selection
Many users are unsure how to determine the appropriate environmental test chamber size. Below are common sizes and their typical applications:
60L Chamber
Suitable for testing small samples like plastic sheets, mechanical test strips, color panels, and textile materials.
225L Chamber
Accommodates small batteries, automotive parts (e.g., cup holders, map pockets), phone cases, and small PCB boards.
800L Chamber
Designed for testing components such as vehicle lights and battery cells.
1400L Chamber
Can accommodate monitors and automotive components.
40m³ Test Room
Suitable for instruments, seats, battery trays, and large batteries.
168m³ Test Room
With a working space of 8000x6000x3500mm (168m³ volume), it can test entire vehicles. A 120m³ chamber can also serve this purpose.
Reproducibility
While it is impossible to perfectly replicate natural environmental conditions in a test chamber, it is feasible to simulate these conditions within an acceptable tolerance. This means that the environmental conditions created around the test specimen must comply with test standards and tolerances. For instance, military-grade temperature chambers must meet national military standards (GJB150.3-86, GJB150.4-86) concerning uniformity and temperature control precision.
Repeatability
Environmental test chambers may be used for multiple tests on the same product type, or a single product may undergo testing in different chambers. To ensure comparability of test results under the same specifications, the chamber must provide repeatable conditions. This means the applied environmental stresses (e.g., thermal, vibrational, electrical) must be consistent with test standards. Compliance with national calibration regulations ensures this consistency, with required recalibration intervals (e.g., vibration tables typically require recalibration every two years).
Controllability
The environmental conditions provided by a test chamber must be both observable and controllable. This ensures test condition reproducibility and repeatability while preventing damage to the specimen due to uncontrolled environmental factors. Most test standards require measurement accuracy to be at least one-third of the permissible error margin.
Exclusivity
Each environmental test must strictly control environmental factors, values, and tolerances while eliminating unwanted influences. For example, in vibration testing, parameters such as magnetic leakage, acceleration noise ratio, and harmonic distortion are regulated to ensure the integrity of test conditions.
Safety and Reliability
Reliability testing, particularly for high-value military products, often involves extended test cycles. Test personnel frequently operate around the chamber during these tests, making safety a critical concern. Environmental chambers must be safe, user-friendly, and durable. Protective mechanisms, alarms, and interlock systems should be in place to safeguard personnel, test specimens, and equipment.
Choosing Between a Constant Temperature & Humidity Chamber and a Thermal Shock Chamber
Some users struggle to decide whether to purchase a constant temperature and humidity chamber or a thermal shock chamber. Here’s how to choose:
1. Primary Functions
Constant Temperature & Humidity Chamber
Simulates different temperature and humidity environments to observe long-term performance changes.
Suitable for stability and aging tests, such as material heat-humidity resistance and long-term electronic stability.
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Tests a product’s durability under extreme temperature fluctuations by rapidly transferring specimens between high and low temperatures.
Suitable for thermal stress and crack resistance tests on electronic components, plastics, and metals.
2. Applicable Industries
| Chamber Type | Industries | Typical Tests |
| Constant Temperature & Humidity | Electronics, Automotive, Chemicals, Pharmaceuticals, Textiles | Material aging, humidity stability, textile moisture performance |
| Thermal Shock | Automotive, Aerospace, Military, Semiconductors, Plastics | PCB solder reliability, metal stress resistance, plastic cracking |
3. Purchasing Recommendations
Choose a constant temperature & humidity chamber for long-term temperature and humidity stability testing (e.g., aging tests).
Choose a thermal shock chamber if your tests involve rapid temperature transitions (e.g., stress and impact resistance tests).
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