Equipment definition and corrosion principle:
The sulfur dioxide test chamber (also known as a gas corrosion test chamber) is designed to simulate acidic, sulfur dioxide-laden atmospheres—such as those found in industrial zones, areas affected by acid rain, or chemical plant vicinities. It accelerates the assessment of the resistance of metal platings, coatings, electronic contacts, and hardware components to sulfur-induced corrosion.
Corrosion mechanism:
Within the sealed chamber, a high-temperature, high-humidity environment is maintained. SO₂ dissolves in water vapor to form sulfurous acid, which further oxidizes into dilute sulfuric acid; this creates condensation on the sample surface, triggering electrochemical corrosion. This process reproduces—in a short timeframe—phenomena such as sulfur-induced rusting, blackening, and coating blistering or failure that would typically occur outdoors over several years.
Key applicable industries and test samples:
Hardware & Electroplating: Zinc, nickel, chrome, and gold plating,passivated parts; screws and fasteners
Electronics & Electrical: Connectors, terminals, PCBs, switch contacts, wire harnesses, metal housings
Automotive Parts: Chassis metal components, decorative plated parts, automotive connectors
Coatings / Building Materials: Anti-corrosion paints, sprayed aluminum profiles, curtain walls, outdoor metal components
Security: Outdoor surveillance housings, locks, electrical control cabinets
Applicable domestic and international standards:
Domestic standards (GB)
GB/T 9789-2008: Sulfur dioxide corrosion test under condensation conditions (standard coating test)
GB/T 2423.19-2013 (Kc): SO₂ corrosion test for electronic contacts and connections (equivalent to IEC 60068-2-42)
GB/T 2423.33-2021 (Kca): High-concentration sulfur dioxide accelerated corrosion test...
International standards
ISO 3231, ISO 22479, IEC 60068-2-42, ASTM G87
Standard test parameters
GB/T 9789 standard cycle (24-hour cycle)
- Temperature: 40°C ± 3°C
- Humidity: >95% RH (condensation state inside the chamber)
- SO₂ Concentration: 0.067% by volume (670 ppm)
- Standard Cycle: 8h gas exposure + 16h static exposure to ambient air; repeated cycles
Low-concentration SO₂ test (Kc) for Electronics
Temperature 20–30°C, humidity 75%–85%, low SO₂ concentration; continuous exposure for 4, 10, or 21 days; monitoring changes in contact resistance
High-concentration accelerated test (Kca)
Configurable high SO₂ concentration (0.1%–2%) for rapid screening of inferior protective coatings
Chamber structure
Corrosion-resistant Chamber: Inner liner made of PP/FRP Fiberglass-reinforced plastic (FRP) construction (acid-corrosion resistant, preventing leakage caused by SO₂ corrosion of metal casings); powder-coated cold-rolled steel exterior
Temperature and humidity control system: PID intelligent temperature control, humidification reservoir, heater, and fan circulation to ensure uniformity
SO₂ gas supply system: Standard SO₂ cylinder with pressure-reducing valve, precision inlet valve, sealed gas lines, and concentration monitoring
Sealing and exhaust system: Double-layer silicone door seal; automatic exhaust neutralization and discharge upon test completion (environmentally friendly, preventing toxic gas leakage)
Sample rack: Inclined hanging rack ensuring samples do not obstruct one another and allowing for uniform condensation;
PLC touchscreen controller: Settings for temperature, duration, and gas exposure time; automatic cycling; multiple safety protections (over-temperature/gas leakage);
Waste neutralization tank: Neutralization of exhaust gas using an alkaline solution for compliant discharge.
