Comprehensive guide to constant temperature and humidity test chamber: purpose, principle, parameters and advantages

A constant temperature and humidity test chamber is a device that can accurately simulate specific temperature and humidity environments. It is widely used in many fields such as electronics, automotive, aerospace, and biopharmaceuticals. It helps researchers, engineers, and quality control personnel to assess the performance, reliability, and stability of products under harsh conditions. It provides an important testing means for product research and development, production, and quality assurance.

I. Equipment Overview
The constant temperature and humidity test chamber is an industrial-level testing device that simulates the changes in natural environment temperature and humidity. It provides a reliability verification platform for products by accurately controlling the temperature (-70℃ to +300℃) and humidity (20%–98% RH). Its core functions include:
Environmental Simulation: It can simulate extreme conditions such as high temperature and high humidity, low temperature and low humidity, and rapid temperature changes.
Performance Verification: It tests the durability, stability, and failure modes of materials, components, and complete machines in complex environments.
Quality Control: It provides a standardized testing basis for research and development, production, and quality inspection.
II. Technical Principles and System Composition
The constant temperature and humidity test chamber is composed of six core systems, and each system works together to achieve precise control of environmental parameters:
Refrigeration System
Core Components: It uses double-stage compression refrigeration technology (some high-end models use cascade refrigeration). A closed loop is formed by the compressor, condenser, expansion valve, and evaporator.
Low-Temperature Control: It can achieve a low-temperature environment below -70℃, meeting the special needs of military and aerospace industries.Heating System
Heating Method: Nickel-chromium alloy electric heating tubes are used, combined with a PID intelligent temperature control algorithm to achieve a temperature fluctuation of ±0.1℃.
Rapid Heating: It can heat from -40℃ to +85℃ in just 30 minutes, meeting the needs of rapid temperature change testing.
Humidification System
Steam Humidification: An external stainless steel boiler-type shallow surface evaporator is used. Steam is generated by heating the water tank.
Humidity Control: The humidity sensor has an accuracy of ±2% RH and can simulate a high humidity environment of 95% RH, which is suitable for drug stability testing.
Air Circulation System
Circulation Fan: A multi-blade centrifugal fan is used, with adjustable wind speed to ensure the uniformity of temperature and humidity in the box is ≤±2℃.
Duct Design: The optimized duct structure reduces turbulence and improves test accuracy.
Control System
Control Mode: It supports constant temperature and humidity, program segment operation, cyclic testing, and other modes.
Intelligent Functions: It is equipped with a 7-inch TFT color touch screen, which supports remote monitoring, data storage, and fault self-diagnosis.
Safety Protection System
Multiple Protections: Over-temperature protection, compressor overload protection, leakage protection, low water alarm, etc.
Safety Design: The box is made of fire-resistant materials, and the observation window is made of double-layer tempered glass to ensure operational safety.

III. Core Application Fields
Electronics and Electrical Industry
Testing Projects:
High-temperature and high-humidity storage (e.g., 85℃/85% RH, 1000 hours) to verify the aging resistance of circuit boards.
Low-temperature and low-humidity testing (-40℃/10% RH) to evaluate the response speed of displays.
Typical Case: Testing the lifespan of mobile phone buttons in a tropical rainforest environment (40℃/95% RH).
Automotive Industry
Testing Projects:
Alternating wet heat cycle (-40℃–+120℃) to test the expansion and contraction rate of rubber seals.
Condensation water protection test (30℃/95% RH) to verify the sealing of car lights.
Typical Case: Verification of the insulation performance of new energy vehicle battery packs under extreme temperature and humidity conditions.
Biomedical Field
Testing Projects:
Drug stability testing (25℃/60% RH, long-term accelerated testing).
Material compatibility testing of medical devices (e.g., dialyzers) in high-humidity environments.
Materials Science
Testing Projects:
Hygroscopicity analysis of polymers (30℃–90% RH gradient change).
Adhesion testing of coatings in alternating wet and hot environments.
Aerospace Field
Testing Projects:
Low-pressure testing (simulating an altitude of 15,000 meters, pressure 5.4kPa) to verify equipment sealing.
High and low-temperature alternating testing (-60℃–+150℃, 10℃/min) to test the thermal expansion coefficient of materials.
IV. Operating Standards and Maintenance Guidelines
Operating Procedure:
Preprocessing:
Clean the box to ensure there are no residual pollutants.
Check the water tank level (for humidification type) and refrigerant pressure.
Sample Placement:
The spacing between test items should be ≥10cm to avoid blocking the air duct.
Liquid samples should be sealed to prevent evaporation from affecting humidity control.
Parameter Setting:
Set the temperature and humidity curve according to the test standard (e.g., stage heating, constant humidity holding).
Start Monitoring:
Observe data fluctuations in real time and record any abnormalities.

Common Fault Handling:
Humidity not reaching the standard: Check the water supply pipe of the humidifier or replace the humidity sensor.
Slow cooling: Clean the condenser dust or replenish the refrigerant.
Frequent alarms: Calibrate the sensor or check the circuit grounding.
Routine Maintenance:
Weekly Maintenance: Clean the humidification water pan and replace the filter.
Monthly Maintenance: Calibrate the temperature and humidity sensors (professional calibration is needed if the error is >5%).
Annual Maintenance: Replace the compressor lubricating oil and check the electrical system insulation.
V. Selection and Procurement Guide
Clarify Testing Requirements:
Temperature and Humidity Range: Determine according to product standards, such as -40℃–+150℃ for electronic components.
Volume Selection: Small bench-top models (below 50L) are suitable for laboratories, while large walk-in models (above 10m3) are suitable for vehicle testing.
Accuracy Requirements: For high-precision testing, choose devices with ±0.1℃/±2% RH.
Key Parameter Comparison:
Temperature and Humidity Fluctuation: ≤±0.5℃/±2% RH is the industry benchmark.
Heating/Cooling Rate: For rapid temperature change testing, it should be ≥5℃/min.
Uniformity: The difference in temperature and humidity at different points in the box should be ≤±2℃.
After-Sales Service:
Service Content: Warranty period, repair response time, spare parts supply capacity, etc.
VI. Future Development Trends
Intelligent Upgrade: AI algorithms predict equipment failures, and the Internet of Things (IoT) enables cluster control of multiple devices.
Green and Energy-Saving: Environmentally friendly refrigerants (R513A) replace traditional Freon, and heat recovery technology reduces energy consumption.
Modular Design: Users can customize and expand composite testing modules such as light exposure, vibration, and salt spray.
The constant temperature and humidity test chamber is a core device for industrial product quality assurance. Its technological development directly promotes innovation in high-tech fields. Enterprises need to choose the right equipment according to their own needs and ensure the reliability of test results through standardized operations and maintenance. With the advancement of intelligent manufacturing, the intelligence, energy-saving, and integration of test chambers will become the mainstream direction in the future.