CRH Corrosion Testing Chamber Q-FOG-CRH

Technical Data

• Brand
  Q-Lab
• Capacity
  600L/1100L
• Models Available
  Two
• Temperature Range
  +20°C to +70°C
• Electrical
  3ph/24A/415V
• Castors
  Yes
• Humidity Range
  20 to 100%

Downloads

• Product Brochure
• Operating Manual
• Technical Data Sheets
• Thermoline Capability Statement

Support & FAQs

At Thermoline, we strive to supply helpful customer support to ensure that you get the most out of our products. We are committed to providing whatever support our customers need, wherever they are in the world. If you can't find your solution in the below FAQs or Knowledge Base, please contact our friendly support team.

What is Cyclic Corrosion testing?

Cyclic corrosion testing is intended to be a more realistic way to perform salt spray tests than traditional, steady-state exposures. Because actual atmospheric exposures usually include both wet and dry conditions, it makes sense to pattern accelerated laboratory tests after these natural cyclic conditions. Research indicates that, with cyclic corrosion tests, the relative corrosion rates, structure and morphology are more similar to those seen outdoors. Consequently, cyclic tests usually give a better correlation to outdoors than conventional salt spray tests. They effectively evaluate various corrosion mechanisms, including general, galvanic, and crevice corrosion.

Cyclic corrosion testing is intended to produce failures representative of the type found in corrosive outdoor environments. CCT tests expose specimens to different environments in a repetitive cycle. Simple exposures like Prohesion may include cycling between salt fog and dry conditions. More sophisticated automotive methods call for multi-step cycles incorporating immersion, humidity, condensation, salt fog, and dry-off. Initially, these automotive test procedures were designed to be performed by hand. Laboratory personnel manually moved samples from salt spray chambers to humidity chambers to drying racks, etc. More recently, microprocessor-controlled chambers have been used to automate these exposures and reduce variability.

Can the Q-Fog tester control relative humidity?

The Q-FOG model CRH can ramp to and maintain a defined RH value and temperature through the use of an air preconditioner, an air control module, and special atomizing humidification nozzles. Deionized (DI) water is required for proper operation. The Q-FOG model CCT has the capability of 95-100% humidity control.

What specimen mounting options are available with the Q-Fog?

Standard test panel racks are available to accommodate flat specimens, such as Q-PANEL standard substrates. Odd-shaped parts (e.g. large, three-dimensional specimens) can be mounted on special 20 mm hanging rods. A rack-level or diffusion-level grate kit may be used for extremely large or heavy three-dimensional objects (such as metal wheel rims, engine parts, etc.).

What if my test requires quicker heat up times?

Rapid Ramp Heater capability enables the performance of some corrosion tests that have very fast transition times.

What is Dew Point?

The dew point is the temperature at which dew (condensation) forms and is a measure of atmospheric moisture. It is the temperature to which air must be cooled at constant pressure and water content to reach saturation. Dew points are expressed as a temperature. Higher dew points correlate to higher moisture content, also known as absolute humidity.

The dew point represents the lowest temperature to which air with specific temperature and relative humidity (RH) can be cooled. At the dew point, air has a relative humidity of 100%, and additional cooling produces condensation rather than lowering the air temperature.

Why is Relative Humidity important in laboratory corrosion testing?

Corrosion is caused when a metal is in contact with water and an electrolyte, such as a salt. In this corrosive environment, metals react to form metal oxides. Except for noble metals such as gold, silver, and platinum, all metals exist as oxides in the environment. Corrosion is effectively nature’s way of returning refined metals back into their natural state.

Although this concept is simple, the practice of simulating outdoor corrosion in the laboratory is very difficult. Multiple oxides can form as a result of complex multi-step reactions that are dependent on specific environmental conditions. Environmental cycling of temperature and moisture is the main reason that outdoor corrosion mechanisms are so complex. In weathering, we often talk about dew (condensation) and rain as they relate to moisture. In corrosion, there is another term related to moisture, called deliquescence. This is the phenomenon where any salt will form a liquid solution when the environment exceeds a relative humidity threshold. This threshold is known as the deliquescence relative humidity (DRH) and varies for different salts. 

Deliquescence of salts can affect strongly the time of wetness of materials, which plays a major role in the corrosion experienced by specimens. To address this, temperature and humidity transitions specified in modern corrosion test cycles are usually controlled to ensure that the time above the DRH during a transition is consistent, regardless of which tester is used to run the cycle. Without controlled transitions, repeatability and reproducibility drop considerably.

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