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CRH Corrosion Testing Chamber Q-FOG-CRH

Cyclic corrosion testing provides the best possible laboratory simulation of natural atmospheric corrosion. Research indicates that test results are similar to the outdoors in structure, morphology, and relative corrosion rates.

The Q-Fog CRH advantages include the elimination of manually moving test specimens from one chamber to another and the laborious spraying of test specimens while reducing variability in results from excessive specimen handling.


The Q-FOG CRH cyclic corrosion testers are the simplest, most reliable, and easiest-to-use RH-controlled corrosion chambers available. These cyclic corrosion chambers can perform traditional salt spray, Prohesion, and nearly all cyclic automotive tests. This salt-fog tester features fully-adjustable relative humidity and precise control over ramp times. 

Q-FOG CRH chambers are available in two sizes, 600L and 1100L, to fulfil a wide range of testing requirements. The Rapid Ramp Heater capability enables the performance of automotive corrosion tests that have very fast transition times.

The CRH tester features an advanced cleaning feature for spray nozzles that prevents the clogging frequently found in competitive chambers. Within one Q-FOG CRH chamber, it can cycle through the most significant corrosion environments. Even highly complex test cycles can easily be programmed with the Q-FOG controller.

The Q-FOG CRH can ramp to and maintain a defined RH value and temperature through an air preconditioner, an air control module, and special atomising humidification nozzles. Deionised (DI) water is required for proper operation.

The Shower Function in the Q-FOG CRH is used for some automotive test specifications. A user-adjustable volume of solution is uniformly sprayed onto specimens through specially positioned spray nozzles. The Shower Function offers the following advantages:

  • Nozzles are mounted to either a stationary shower module in the chamber centre or a top-mounted swaying shower bar.
  • The stationary shower module can be easily removed when using the Fog Function.
  • Spray droplets are much bigger, flow rates are much higher, and shower times are much shorter than the atomised solution mist in the Fog Function.
  • Shower on/off times can be directly programmed to allow for excellent control of corrosion rates

The Q-FOG CRH cyclic corrosion chamber has superior fog dispersion compared to conventional systems, which cannot vary volume and distance independently. A variable speed peristaltic pump controls the amount of corrosive solution delivered to the fog atomiser, while the air pressure regulator controls the distance of the "throw." Note that purified water is required for the proper operation of Q-FOG corrosion testers.

Space utilisation is maximised, and maintenance is minimised with the Q-FOG tester's internal solution reservoir. The 120L reservoir has enough capacity to run most tests for seven days or more. The reservoir has an integral salt filter and a built-in alarm to alert the operator when the solution is low. The integrated reservoir can optionally be connected to an external tank.

Q-FOG testers can change temperatures exceptionally fast because of their unique internal chamber heater and high volume cooling/dry-off blower. An additional air heater allows very low humidity dry-off exposures. Conventional chambers with water jackets cannot cycle rapidly because of the thermal mass of the water, nor can they produce low humidity.

If fast heating or dry-off conditions are required, as prescribed in test standards ISO 11997 and automotive CCT-type tests like JASO M609, the CRH model can be configured with Rapid Ramp Heaters. This Rapid Ramp Heater system enables quick temperature and relative humidity transition in a fully-loaded chamber in order to meet these demanding automotive test standards unconditionally.

The Q-FOG CRH tester's chamber temperature and RH sensors should be calibrated by the user every six months to ensure accurate and consistent results. Calibrating the temperature and RH sensors takes only a few minutes. It requires simple tools, a calibrated reference thermometer, and an insulated container.

A built-in microprocessor controls test conditions, time, and temperature. A remarkably simple user interface featuring dual, full-colour touch screens allows for easy programming. The operator can quickly create new cycles or run any of the pre-programmed cycles. The Q-FOG controller includes complete self-diagnostics, including warning messages, routine service reminders, and safety shutdown.

Q-FOG CRH units come equipped with a viewing window on the side of the lid and an interior light to allow easy monitoring of the test conditions.

Technical Data

  • Brand
  • Capacity
  • Models Available
  • Temperature Range
    +20°C to +70°C
  • Electrical
  • Castors
  • Humidity Range
    20 to 100%


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.