Water Condensation Test Chamber

The bottom of the test chamber is covered with demineralized water and heated up to 40°C. The water evaporates resulting in 100% condensing (or high) humidity inside the chamber. The thermal losses through the chamber walls produce temperature gradient and consequently the dew point is reached in the vicinity of specimens and the vapor starts condensing on the surface of the test samples.  

In addition to the high humidity (also known as Constant Humidity "CH") the DIN EN ISO 6270-2 defines two more variants:

• Alternating Temperature (AT): 8 h high humidity, 16 h cooling at room temperature
• Alternating Humidity and Temperature (AHT): 8 h high humidity, 16 h aeration with room air

The Water Condensation (High Humidity) test can be optionally extended with the Kesternich tests. This option introduces the prescribed volume of the SO₂ gas into the test chamber during the High Humidity phase. The Kesternich test gains on popularity due to the fact that the atmosphere in many industrialized countries is increasingly poluted with this gas.

In contrary to the Salt Spray Test where it is of interest that the test chamber is thermally perfectly isolated from the outside environment the proper Water Condensation test implies small but measurable heat losses particularly around the roof area. These heat losses result in a temperature gradient between the bottom and the roof of the test chamber which is required to reach the dew point inside the test chamber and consequently the water condensation.  

VLM's patented Controlled Water Condensation (CWC) system is able to accuratelly control the amount of heat losses through the roof resulting in the temperature gradient of exactly 1°C between the chamber roof and the its bottom.    

The CWC system is the main prerequisite for achieving high reproducibility of test conditions and achieving reliable test results. Moreover, the stainless steel design of the test chamber and the surface heating elements allow high thermal conductivity and very fast heat transfer into the chamber. The water in the bath is heated quickly and evenly resulting in even evaporates acrsoos the whole water surface. The unwanted air turbulence are avoided which is also an important condition for an uniform water condensation.

The combination of all above measures for the controlled water condensation combined with the salt spray test in a single test chamber results in highly reliable VLM test chambers for Cyclic Corrosion Tests (CCT).