G4 MULTI-GAS & SO₂ TEST CHAMBERS
The Auto Technology G4 is a 300-liter gas dosing chamber for moist sulfur dioxide and custom corrosive-gas exposure programs. A measured quantity of gas is introduced into the chamber and combined with controlled temperature, moisture, and exposure time to reproduce the conditions required by the test method.
Measured Gas Dosing
Introduces a known gas volume into the chamber for repeatable
fixed-volume corrosion exposures.
300-Liter Test Volume
Sized around the reference chamber volume used by ASTM G87 and
ISO 22479 moist SO₂ methods.
Up to Four Gas Inputs
Multiple gas connections support SO₂ and custom single- or
multi-gas dosing programs.
Gas Dosing and Mixed Flowing Gas Testing
Corrosive-gas testing generally uses one of two approaches depending on the specification. The G4 is designed for measured gas dosing, where a defined quantity of gas is introduced into a known chamber volume. This is the approach used by moist SO₂ methods such as ASTM G87, ISO 22479, and DIN 50018.
Tests based on a continuously flowing mixture of low-level pollutant gases use a Mixed Flowing Gas (MFG) chamber . MFG systems continuously deliver the test atmosphere while controlling gas flow, chamber air exchange, temperature, humidity, and gas concentration as required by the method.
G4 Gas Dosing
- Measured quantity of gas
- Known 300-liter chamber volume
- Moist SO₂ and custom dosing programs
- Gas-volume metering
- Temperature and timed exposure control
Mixed Flowing Gas
- Continuous low-level pollutant gas flow
- Controlled chamber air exchange
- Temperature and relative-humidity control
- Gas-concentration measurement
- Long-duration electronics and connector exposures
Moist SO₂ and Gas Dosing Standards
The G4 is built around fixed-volume gas dosing methods in which the quantity of gas introduced, chamber volume, water quantity, specimen loading, temperature, and exposure time work together to establish the test environment.
ASTM G87
Moist sulfur dioxide corrosion testing using a nominal 300-liter chamber, measured SO₂ delivery, water in the chamber base, heating, and either continuous or alternating exposure.
ISO 22479
Sulfur dioxide corrosion testing in a humid atmosphere using the fixed gas method. A measured volume of SO₂ is introduced into a fixed-volume cabinet at the beginning of the test cycle.
DIN 50018
Humid-atmosphere sulfur dioxide testing using AHT 1.0 S and AHT 2.0 S exposure conditions with defined SO₂ additions and a heated, condensing environment.
300-Liter Reference Chamber
The G4's 300-liter chamber volume closely follows the reference apparatus used by the principal moist SO₂ standards. Gas dose, water quantity, specimen loading, and test conditions are defined around this chamber size, making the relationship between the specified exposure and the chamber configuration straightforward.
| Standard | Exposure Method | SO₂ Dose for 300 L | Exposure Temperature |
|---|---|---|---|
| ASTM G87 | Measured SO₂ dose into a fixed chamber volume | Typically 0.2, 1.0, or 2.0 L as specified | 40°C ±3°C |
| ISO 22479 | Fixed gas method | 0.2, 1.0, or 2.0 L | 40°C ±3°C |
| DIN 50018 | Measured SO₂ addition into humid chamber | 1.0 or 2.0 L for AHT 1.0 S / AHT 2.0 S | 40°C ±3°C during the first test section |
The governing material or product specification establishes the selected SO₂ dose, exposure sequence, number of cycles, specimen preparation, and evaluation requirements.
How the G4 Gas Dosing System Works
Measured Gas Delivery
Gas is supplied through the selected inlet and the required volume is measured as it is introduced into the chamber. The dosing arrangement is selected around the gas, required quantity, and applicable test method.
ASTM G87 and ISO 22479 describe gas delivery using appropriate regulating and volume-measuring equipment such as a calibrated flowmeter. Once the required quantity has entered the chamber, the programmed exposure proceeds according to the selected method.
Moisture and Temperature
Water placed in the chamber base provides the moisture used to develop the humid, condensing environment. Chamber heating raises the exposure space to the specified test temperature and supports the moisture conditions required for the corrosion reaction.
The angled chamber roof directs condensate away from the specimens, helping maintain consistent exposure without direct dripping from the chamber ceiling.
Multiple Gas Connections
The G4 can be equipped with up to four gas inlet connections. This provides flexibility for laboratories that run SO₂ along with other custom gas-dosing programs or programmed sequences.
Typical Moist SO₂ Cycle
- Add the specified quantity of water to the chamber.
- Position the specimens according to the test requirements.
- Close and seal the chamber.
- Introduce the specified measured volume of SO₂.
- Heat the chamber to the required exposure temperature.
- Maintain the specified exposure period.
- Vent or transition to the next condition as required.
- Renew the water and gas before the next cycle when specified.
Chemical-Resistant Construction
The exposure area uses a washable PVC lining selected for aggressive humid and acidic environments. Gas-contact components and seals are selected around the gases and exposure conditions specified for the chamber.
Technical Specifications
| Feature | Specification |
|---|---|
| Chamber Type | Measured-dose gas corrosion chamber |
| Internal Volume | 300 L (approximately 10.6 ft³) |
| Gas Inputs | Up to 4 distinct gas inlet connections |
| Primary Application | Moist SO₂ and custom measured-dose gas exposures |
| Gas Delivery | Measured-volume dosing through appropriate regulating and gas-metering equipment |
| Maximum Gas Supply Pressure | 10 psi |
| Moist SO₂ Exposure Temperature | 40°C ±3°C |
| Cycle Control | Programmable chamber temperature and exposure time with gas dosing performed according to the selected method |
| Observation | Dual shatter-resistant Plexiglas viewing ports with gasketed seals |
| Interior | Washable chemical-resistant PVC-lined exposure area |
| Condensate Management | Angled roof directs accumulated condensate away from specimens |
Specimen Loading and Placement
Specimen loading is part of the test condition in moist SO₂ testing. The amount and type of exposed material affect how sulfur dioxide is absorbed and consumed inside the chamber, so the standards define both total exposed surface area and specimen placement.
ISO 22479 Specimen Area
ISO 22479 specifies a total exposed specimen surface area of:
0.5 ±0.1 m² per 300 ±10 L
The required exposed surface area is adjusted proportionally for chambers of other volumes.
When the actual specimens provide less exposed area, substitute specimens of the same material are used to bring the total loading to the specified level.
ASTM G87 Specimen Placement
ASTM G87 also uses approximately 0.5 ±0.1 m² of total exposed specimen area unless otherwise agreed.
- Minimum 20 mm between specimens
- Minimum 100 mm from chamber walls and ceiling
- Minimum 200 mm above the chamber water
- Specimens arranged so condensate does not drip onto lower specimens
- Near-vertical orientation generally used unless otherwise specified
Controlling the specimen load helps keep the relationship between gas dose, chamber volume, exposed material, and corrosion severity consistent from one test to the next.
Applications
The G4 supports materials, coatings, components, and assemblies evaluated in humid sulfur dioxide and other compatible measured-dose corrosive-gas environments.
Coatings and Corrosion Protection
Evaluate painted, plated, coated, and otherwise protected metal surfaces for coating defects, blistering, substrate attack, and corrosion produced by humid SO₂ exposure.
Metals and Alloys
Compare metals, alloys, and corrosion-protection systems under controlled gas dose, moisture, temperature, and exposure time.
Components and Assemblies
Test manufactured components and assemblies when humid corrosive gas exposure is part of a product qualification, development, or comparison program.
Custom Gas Dosing Programs
Multiple gas connections support project-specific exposures using compatible gases, measured dosing, programmed sequences, and customer-defined test conditions.
Moist SO₂ Contract Testing
Auto Technology also operates an A2LA-accredited corrosion testing laboratory for customers that want test data, additional capacity, or help establishing a moist-gas test program before bringing the capability in-house.
Common Test Programs
- Material and coating qualification
- Product development and material comparisons
- Failure analysis and corrosion investigation
- Production or supplier verification
- Temporary or supplemental test capacity
- Test-program development before equipment purchase
Laboratory Capabilities
- ASTM G87 moist SO₂ testing
- ISO 22479 fixed-volume SO₂ testing
- DIN 50018 sulfur dioxide testing
- Specimen loading and fixture support
- Custom gas-dosing programs
Send the applicable standard, specimen dimensions and material, required exposure, and number of cycles for review.
Frequently Asked Questions
How does the G4 dose sulfur dioxide?
A measured volume of sulfur dioxide is introduced into the 300-liter chamber at the beginning of the exposure cycle. The required quantity comes from the governing test method or product specification.
ASTM G87 and ISO 22479 commonly use 0.2, 1.0, or 2.0 liters of SO₂ for a 300-liter chamber. The gas quantity is measured with appropriate calibrated gas-metering equipment before the exposure proceeds.
Why is the G4 a 300-liter chamber?
ASTM G87 and ISO 22479 use a 300-liter chamber as the reference basis for moist sulfur dioxide testing. Gas quantity, water quantity, specimen loading, and other test conditions are defined around this chamber volume.
The G4 follows that established chamber size so the specified gas dose and specimen loading can be applied directly.
What is the difference between G4 dosing and mixed flowing gas testing?
The G4 introduces a measured quantity of gas into a fixed chamber volume. This approach is used for moist SO₂ methods such as ASTM G87, ISO 22479, and DIN 50018.
Mixed Flowing Gas testing continuously supplies low-level pollutant gases while controlling chamber air exchange, temperature, humidity, and gas concentration throughout the exposure. Auto Technology builds dedicated MFG chambers for those methods.
How is the gas dose measured?
The gas supply uses regulating and measuring equipment selected for the required gas and dose. ASTM G87 and ISO 22479 describe volumetric gas measurement using calibrated equipment such as a flowmeter.
The objective is to introduce the specified volume of gas into the known chamber volume at the start of the exposure.
How much specimen material can be placed in the chamber?
Specimen capacity is based on exposed surface area and placement as well as physical dimensions. ISO 22479 specifies 0.5 ±0.1 m² of total exposed specimen area for a 300 ±10 L chamber.
ASTM G87 also uses approximately 0.5 ±0.1 m² unless otherwise agreed and establishes spacing from adjacent specimens, chamber surfaces, and the water in the bottom of the chamber.
Why does specimen loading matter?
Sulfur dioxide is absorbed and consumed by the materials exposed inside the chamber. The total specimen area and the material being tested therefore affect the chamber atmosphere and resulting corrosion exposure.
Maintaining the specified specimen load helps produce comparable results from cycle to cycle and between laboratories.
Why is the chamber interior lined with PVC?
Moist sulfur dioxide creates an aggressive acidic environment. The washable PVC-lined exposure area provides a chemically resistant chamber surface suited to repeated moist-gas testing and routine cleanup between exposures.
Can the G4 be configured for gases other than sulfur dioxide?
Yes. The G4 can be built with up to four gas input connections for compatible custom gas-dosing programs. Gas selection, materials compatibility, dosing requirements, chamber controls, exhaust, and facility safety requirements are reviewed for the intended exposure.
How are gas exhaust and operator safety handled?
The system is integrated with the customer's laboratory ventilation and gas-handling setup. Exhaust routing, gas regulators, backflow protection, purge procedures, and other facility requirements are established around the gases used in the test program.