Product Description

The constant temperature and humidity test chambers ST-TH25L is mainly used to simulate extreme high temperature, low temperature, humid heat and alternating hot-humid environments that electronic instruments, new materials, electrical appliances, vehicle parts, metal products, aerospace materials and other items may encounter during transportation, storage and operation. It is applied to test the high temperature resistance, low temperature resistance and moisture resistance of materials, components and equipment, as well as to assess potential damage and service life degradation caused by harsh environmental conditions.

Product Features

2.1 Chamber Structure

Inner chamber: Made of SUS304 stainless steel plate, featuring acid resistance, corrosion resistance and easy cleaning.
Outer cabinet: Cold-rolled steel plate with baking finish treatment.
Door handle: Explosion-proof handle with anti-rebound design for simple operation and high safety.
Thermal insulation system: The insulation layer is filled with superfine glass fiber. Non-metallic high and low temperature resistant materials are adopted for joints between inner and outer cabinets to reduce heat conduction effectively. The door is sealed with high-grade silicone rubber, which resists aging and hardening under extreme temperatures for reliable sealing. Isolated humidification design is applied.
Moving & positioning device: Equipped with high-quality lockable PU casters at the bottom for convenient movement and fixed placement.
Sample rack: Mesh structure made of bent and punched SUS304 stainless steel. The spacing between racks is adjustable. Two racks are supplied as standard, with a uniform load capacity of 25 kg for samples.
Test port: A Φ50 mm test port is reserved, equipped with matched thermal insulation accessories and dedicated sealing soft plug.
Observation window: Double-layer vacuum tempered glass. The inner side is coated with conductive film for electric defrosting, enabling clear observation of the testing process.

2.2 Refrigeration System

The refrigeration unit adopts Nidec hermetic compressor, a leading brand in the global hermetic refrigeration compressor industry. It is charged with DuPont eco-friendly refrigerant R404A. A two-stage low-temperature circuit design is adopted, allowing different compressors to work in different temperature ranges to improve overall equipment performance.
Temperature and humidity are controlled coordinately via PID + SSR synchronous control system with automatic calculation function. It can instantly correct temperature and humidity fluctuations to achieve high precision and stable control.
High-precision controllers are configured for temperature and humidity. The set value and actual value are displayed accurately, with a resolution of 0.1°C.

2.3 Heating & Humidifying System

Heating element: High-speed heating nichrome wire.
Independent high-temperature heating system.
Humidifier: Stainless steel tube built-in nichrome heating wire and high-temperature magnesium oxide powder, featuring fast response and long service life.
The heating and humidifying systems are completely independent. An automatic water replenishment device is equipped for humidification.

2.4 Control System

High-precision LCD programmable temperature controller.
Intelligent digital PID microprocessor temperature and humidity controller.
Touch setting panel with direct digital display. Humidity is displayed in percentage. PT100 platinum resistance sensor is used for temperature measurement.
Temperature is regulated by thermal balance control mode.
Supports programmed tests with multiple groups and segments. Constant value mode and program mode are optional, and the running time can be set freely.
Main electrical components such as circuit breakers and AC contactors are CHNT brand; other electrical accessories adopt well-known domestic brands.
Powerful data processing function: Connectable to printer or RS232 communication interface, equipped with USB port for data transmission via U disk. It can display and print temperature-humidity & time curves on computer, facilitating data storage and review during tests.

2.5 Protection System

The equipment is provided with comprehensive protection functions including over-temperature protection, fan overheat protection, phase loss/reverse phase protection, refrigeration system overload protection, compressor over-pressure protection, timing function, electric leakage protection and operation indication. The unit will stop automatically once a fault occurs and trigger an alarm.

Applicable Test Standards

1. GB2423.1-2008 / IEC6008-2-1-2007

2. GB/T 2423.2-2008

3. GJB150.3A－2009

4. GJB150.4A－2009

5. GB2423.22-2008

6. GB/T 2424.5-2006

7. GB/T 10589-2008

8. GB/T2423.3-2008 (IEC68-2-3)

Technical Data

Item	Specification
Model	ST-TH25L
Nominal Internal Volume	25 L
Inner Chamber Dimension (W×H×D)	380 mm × 300 mm × 220 mm
Overall Dimension (W×H×D)	617 mm × 1033 mm × 765 mm
Temperature Range	-20℃ ~ +150℃
Control Accuracy	Temperature resolution: 0.01℃ Humidity resolution: 0.1%R.H Temperature deviation: ±2℃ Humidity deviation: ±2%R.H Temperature uniformity: ≤2℃ Humidity uniformity: ±3%R.H Temperature fluctuation: ±0.5℃ Humidity fluctuation: ±2%R.H
Temperature Change Rate	Heating rate (from -20℃ to +150℃): Average 3℃/min Cooling rate (from +150℃ to -20℃): Average 1℃/min
Refrigeration System
Compressor	Nidec fully hermetic compressor (Japan)
Refrigerant	Eco-friendly R404A / R23
Refrigeration Mode	Single-stage mechanical refrigeration
Air Circulation	Centrifugal fan with forced air circulation
Evaporator	Finned tube heat exchanger
Condensation Mode	Air cooling
Condenser	Stainless steel brazed plate heat exchanger
Filter Drier	Removes residual moisture and acidic substances in refrigerant, filters solid impurities and copper debris to prevent ice blockage and dirt blockage of expansion valve and capillary tube
Humidification System	Stainless steel humidifier
Heating System	Nichrome alloy stainless steel heater
Water Supply System	Front water tank with fully automatic water replenishment
Control System
Controller	Lugong controller
Display & Functions	1. Direct display of set value (SV) and actual value (PV) of temperature and humidity 2. Display program number, segment, remaining time, cycle times and running time 3. Program editing and curve display 4. Independent program editing page; 4 segments of temperature, humidity and time can be set per page 5. Display for constant value or program running status 6. Chinese / English language switching 7. 7-inch true color display screen
Program Capacity & Control Functions	1. Max. 120 programs; 1 program consists of 1~99 segments, total 1200 segments 2. Each segment can run up to 999 cycles; temperature & humidity slope can be set via timeline 3. Programs can be linked; dialog-style editing with functions of edit, delete and insert; group time signal output to control ON/OFF of test samples 4. 9 groups of PID parameters available 5. Segment skip and hold function during program operation 6. Power-off program memory; automatic resume after power recovery 7. Data acquisition, export and curve viewing 8. Automatic PID calculation and FUZZY control 9. Screen backlight adjustment and backlight timing setting 10. Screen display protection with timed or manual screen off 11. Program copy, link and test title editing 12. Scheduled start and shutdown function 13. Date and time adjustment 14. Key & screen lock function 15. Standby view and fault prompt
Communication Interface	RS232 / RS485; curve display and data acquisition; support monitoring and remote control
Operation Mode	Chinese / English interface, touch input
Running Mode	Program mode / Constant value mode
Setting Limit	±5℃ beyond maximum temperature range
Display Resolution	Temperature: 0.01℃; Time: 0.1 min
Power-off Memory	Optional recovery modes: Hot start / Cold start / Stop
Temperature Sensor	Platinum resistance
Data Storage	Standard configuration for test data and curve recording; data upload & download supported, expandable storage
Software Environment	IBM compatible PC, CPU above PⅡ, RAM ≥128M, Simplified Chinese Windows 2000 / Windows XP
Safety Protection	Over-temperature protection, fan overheat protection, phase loss / reverse phase protection, refrigeration system overload protection, compressor over-pressure protection, timing function, electric leakage protection, operation indication and automatic shutdown upon fault alarm
Cabinet Material	Outer shell: High-quality cold-rolled steel plate with electrostatic spraying Inner wall: SUS304 stainless steel plate Thermal insulation: 100mm rigid polyurethane foam + 100mm high-density glass fiber cotton
Standard Accessories	Φ50 mm test port, interior lamp, double-layer vacuum tempered glass observation window