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An angled, front-left view of the Auto Technology C Series corrosion test chamber, showing the integrated touch screen controller, air pressure gauge, and durable fiberglass construction.

ASTM G85 Cyclic Salt Fog Chamber – C Series Size 20

The Auto Technology C Series Size 20 is a configurable ASTM G85 cyclic salt fog chamber providing approximately 20 ft³ (594 L) of usable test volume. It supports Annex A1, A2, A3, and A5 with touchscreen controls, an integrated solution reservoir, baffled fog distribution, wet/dry cycling, purge-air control, and a valve that bypasses the bubble tower when unhumidified atomizing air is required.

  • Supported Annexes: A1 Acetic Acid, A2 Cyclic Acidified Salt Fog, A3 Acidified Synthetic Sea Water, and A5 Dilute Electrolyte Fog/Dry
  • Bubble-Tower Bypass: Routes atomizing or purge air around the saturator when required by the selected annex
  • Fog System: Venturi atomizer with a baffled dispersion tower
  • Control System: 6-inch touchscreen for fog, purge, soak, dry-off, temperature, alarms, and cycle timing
  • Solution Storage: Integrated 60-gallon reservoir

ASTM G85 Annex A4 requires controlled SO₂ dosing and is not offered in the C Series. Annex A4 configurations are available in the M Series or appropriately equipped A and X Series chambers.

SKU: ASERIES20-ASTM-G85 Categories: , Tag:

Description

The C Series Size 20 ASTM G85 Cyclic Salt Fog Chamber is configured for laboratories performing acidic, cyclic, synthetic-seawater, and dilute-electrolyte corrosion testing under
ASTM G85.
It provides approximately 20 ft³ (594 L) of usable test volume and supports Annexes A1, A2, A3, and A5 through controlled fog generation, bubble-tower conditioning, dry-air purge, high-humidity soak, and fog/dry cycling.


Auto Technology C Series Size 20 ASTM G85 cyclic salt fog chamber
Auto Technology C Series corrosion chamber with touchscreen controls, integrated solution storage, and a non-corrosive molded cabinet.

Four ASTM G85 Annexes
Configurable for Annex A1, A2, A3, and A5 without presenting the chamber as capable of unsupported SO₂ dosing.

Bubble-Tower Bypass
A dedicated valve routes air around the saturator tower when the selected cycle requires unhumidified atomizing or purge air.

Touchscreen Cycling
The controller sequences fog, purge, soak, dry-off, temperature changes, alarms, and repeat cycles.


Request an ASTM G85 Size 20 Quote

Specify the required ASTM G85 annex, material or coating, solution chemistry, specimen dimensions, loading quantity, and any governing product specification.

ASTM G85 Annex Capability

ASTM G85 contains five mandatory annexes with different solution chemistries, temperatures, humidity conditions, purge requirements, and cycle sequences. The required annex must be identified by the governing material, coating, product, or customer specification.

Annex Procedure C Series Size 20
A1 Acetic Acid-Salt Spray (Fog) Supported
A2 Cyclic Acidified Salt Fog Supported with timed fog, dry-air purge, and high-humidity soak
A3 Acidified Synthetic Sea Water (Fog) Supported with cyclic fog and high-humidity soak
A4 Salt/SO₂ Spray (Fog) Not available in the C Series. Requires an SO₂-equipped M Series or appropriately configured A/X Series chamber.
A5 Dilute Electrolyte Cyclic Fog/Dry Supported with unhumidified atomizing air and alternating fog/dry operation

Annex selection matters: ASTM G85 is not one generic acidic salt-fog test. A chamber configured for A1 must not be assumed to be running A2, A3, or A5 without changing the solution, temperature, airflow, humidity, and cycle settings required by that annex.

Bubble Tower and Bypass Valve

In normal salt-fog operation, clean compressed air passes through the heated bubble tower, where it is humidified before reaching the venturi atomizer. ASTM G85 Annexes A1, A2, and A3 specify bubble-tower temperatures as part of their operating conditions.

The C Series G85 package adds a bypass valve that changes the compressed-air path when the selected annex requires unhumidified air or direct purge air.

Operating mode Air path
A1/A2/A3 fog generation Compressed air passes through the heated bubble tower before reaching the atomizer
A2 dry-air purge Air bypasses the bubble tower and atomizer and enters the chamber directly to remove fog and dry the specimens
A5 fog period Atomizing air bypasses the bubble tower but continues directly to the spray nozzle without being humidified

A5 concentration control: ASTM G85 A5 specifically states that the atomizing air must not be saturated with water. Humidifying the air would work against the intended change in electrolyte concentration as the specimens cycle from wet to dry.

ASTM G85 Annex A1 Acetic Acid-Salt Spray

Annex A1 is a continuous acetic acid-salt spray procedure. The sodium chloride solution is acidified with acetic acid, and the chamber maintains the specified exposure-zone and bubble-tower temperatures.

Solution Sodium chloride solution acidified with acetic acid
Solution pH 3.1–3.3
Exposure-zone temperature 35°C ±2°C
Bubble-tower temperature 47°C ±1°C

ASTM G85 Annex A2 Cyclic Acidified Salt Fog

Annex A2 uses a repetitive six-hour sequence combining acidified salt fog, direct dry-air purging, and a closed-chamber high-humidity soak.

Cycle step Duration Chamber operation
Acidified salt fog 45 minutes Fog generation using conditioned atomizing air
Dry-air purge 2 hours Air bypasses the bubble tower and atomizer and enters the chamber directly
High-humidity soak 3 hours 15 minutes Specimens remain in the closed cabinet until the next fog cycle

Solution pH: 2.8–3.0

Exposure-zone temperature: 49°C ±2°C

Bubble-tower temperature: 57°C ±1°C

ASTM G85 Annex A3 Acidified Synthetic Sea Water

Annex A3 uses acidified synthetic sea salt solution and alternates fog exposure with a high-humidity soak. The governing material or product specification establishes the appropriate exposure-zone temperature.

Solution Synthetic sea salt with 10 mL glacial acetic acid per liter
Solution pH 2.8–3.0
Cycle 30 minutes fog followed by 90 minutes soak above 98% RH
Bubble-tower temperature 47°C ±1°C at a 35°C cabinet setting; 57°C ±1°C at a 49°C cabinet setting

ASTM G85 discusses different temperature ranges for aluminum heat treatments and organic coatings. The applicable product specification or agreement between purchaser and supplier determines the required temperature.

ASTM G85 Annex A5 Dilute Electrolyte Fog/Dry

Annex A5 alternates one hour of dilute-electrolyte fog with one hour of dry-off. Unlike conventional salt-fog operation, the atomizing air is not saturated with water. The C Series bypass valve routes compressed air around the bubble tower and directly to the spray nozzle.

Cycle step Duration Conditions
Dilute-electrolyte fog 1 hour No cabinet heat; room conditions of 24°C ±3°C and below 75% RH
Dry-off 1 hour Fresh-air purge; chamber reaches and remains at 35°C ±1.5°C within 45 minutes of switching to dry

Sodium chloride: 0.05% by mass

Ammonium sulfate: 0.35% by mass

Collected-solution pH: 5.0–5.4

Room conditions affect A5: The fog portion is performed without cabinet heating at controlled indoor ambient conditions. Different room temperatures can produce different results.

ASTM G85 Annex A4 Requires an SO₂-Equipped Chamber

Annex A4 combines salt fog with periodic introduction of sulfur dioxide gas. The procedure requires an SO₂ source, controlled gas flow, an inert solenoid valve, compatible tubing and fittings, and uniform gas distribution through the chamber.

C Series limitation: The C Series Size 20 does not include the SO₂ dosing equipment required for ASTM G85 Annex A4. Specify an SO₂-equipped M Series chamber or an appropriately configured advanced A or X Series system when Annex A4 is required.

The required annex must be confirmed before quotation. A chamber capable of Annexes A1, A2, A3, and A5 should not be represented as an Annex A4 chamber without the required gas-dosing system.

C Series Fog Generation and Distribution

The C Series combines a venturi atomizer with a tall baffled dispersion tower. The aerosol passes through the tower and baffle before entering the specimen area, helping reduce large droplets and direct impingement.


Interior of C Series Size 20 ASTM G85 cyclic salt fog chamber
Standard interior layout of the C Series Size 20 chamber.

Water-fog demonstration showing C Series atomization and dispersion. Water is used so the airflow and droplet movement remain visible on video.

C Series Touchscreen Controls


C Series touchscreen for selecting ASTM G85 corrosion test methods
C Series touchscreen method-selection interface.

The 6-inch color touchscreen manages the selected ASTM G85 sequence and provides access to chamber status, alarms, manual functions, and stored test methods.

  • Fog and solution-system control
  • Bubble-tower temperature control
  • Bubble-tower bypass-valve sequencing
  • Dry-air purge and fresh-air dry-off
  • High-humidity soak timing
  • Exposure-zone temperature control
  • Status and alarm display
  • Optional data logging to the controller memory card

C Series Size 20 ASTM G85 Chamber

The Size 20 provides laboratory-scale capacity for coated panels, plated components, aluminum alloys, fasteners, production parts, and corrosion-control specimens. Racking is selected around the specimen geometry and required exposure angle without obstructing fog distribution or collection.


C Series Size 20 ASTM G85 chamber loaded with corrosion test panels
C Series Size 20 chamber loaded with corrosion test panels.

Usable test volume

Approximately 20 ft³

Approximately 594 liters

Base chamber footprint

Approximately 95 × 43 in

Approximately 242 × 110 cm

Solution reservoir

Integrated 60 gallons

Final installed footprint depends on exhaust routing, service clearance, solution-handling equipment, and selected options.

ASTM G85 Test Solutions

Auto Technology supplies premixed solutions for the ASTM G85 annexes supported by the C Series.

Part number Solution Link
C173330 ASTM G85 Annex A1 premixed solution View solution
C173332 ASTM G85 Annex A2 premixed solution View solution
C173331 ASTM G85 Annex A3 acidified synthetic sea solution View solution
C173334 ASTM G85 Annex A5 dilute-electrolyte solution View solution

Configure a C Series Size 20 for ASTM G85

Specify the required annex, test revision, material or coating, solution chemistry, specimen dimensions, loading quantity, exposure angle, and facility utilities.


Request Configuration Assistance

ASTM G85 Size 20 Chamber FAQ

What is ASTM G85?

ASTM G85 is a corrosion-testing practice containing five modified salt-spray annexes. The annexes use different acidic solutions, synthetic seawater, cyclic fog, dry-air purge, high-humidity soak, sulfur dioxide, or dilute-electrolyte fog/dry conditions.

Which ASTM G85 annexes can the C Series Size 20 perform?

The C Series Size 20 can be configured for Annex A1, A2, A3, and A5. It is not configured for the sulfur-dioxide dosing required by Annex A4.

Why does the G85 chamber need a bubble-tower bypass valve?

Annex A2 requires direct dry-air purging that bypasses the bubble tower and atomizer. Annex A5 requires unhumidified atomizing air, so the air bypasses the bubble tower and travels directly to the spray nozzle.

Does every ASTM G85 annex bypass the bubble tower?

No. Annexes A1, A2, and A3 specify heated bubble-tower conditions during fog generation. The bypass is used during the A2 purge and for A5 unhumidified atomizing air.

Can the C Series perform ASTM G85 Annex A4?

No. Annex A4 requires controlled SO₂ introduction and compatible gas-handling equipment. Auto Technology reserves this capability for SO₂-equipped M Series chambers and appropriately configured advanced A or X Series systems.

Is ASTM G85 Annex A5 the same as ASTM B117?

No. Annex A5 uses a dilute sodium-chloride and ammonium-sulfate electrolyte, alternates one hour of fog with one hour of dry-off, and requires unhumidified atomizing air. ASTM B117 is a continuous neutral salt-fog practice using different solution and operating conditions.

What is the capacity of the C Series Size 20?

The Size 20 provides approximately 20 ft³ or 594 L of usable test volume. Its base chamber footprint is approximately 95 × 43 inches, excluding final exhaust routing and service clearance.

Does the chamber include touchscreen controls?

Yes. The C Series uses a 6-inch color touchscreen for method selection, chamber status, alarms, manual functions, and control of the selected G85 sequence. Data logging is available as an option.

What information is needed to quote an ASTM G85 chamber?

Provide the required G85 annex, revision, material or coating, governing product specification, solution chemistry, specimen dimensions, loading quantity, exposure orientation, and available utilities.

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