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Analysis of temperature and relative humidity control in auto-cyclic corrosion test


Perhaps the standard for a cyclic automotive corrosion test lab is to use a chamber with relative humidity control and an air cooling and dehumidification system, whether or not the standard specifically requires it. This ensures repeatability and reproducibility of the test. The cyclic salt spray corrosion test chamber can be used for the cyclic corrosion test of automobiles. Our Company Shanghai QINSUN Precision Electromechanical Technology Co., Ltd. is the manufacturer. Welcome customers who need to inquire.

Relative humidity in corrosion standards: what are the needs?

In the cyclic corrosion test, the working condition of the test box is complex, and there are many techniques for measuring temperature and relative humidity. Now we can extend it to the auto-cyclic test. A common feature of these tests is what GMW 14872 calls the environmental phase, which is part of a test cyclewhich is developed in a control of temperature and relative humidity.ed room. The temperature at this stage was 25 ± 3°C and the relative humidity was 45 ± 10%. Different tolerances were used for the Ford and VW ambient stages at 23°C and 50% relative humidity. A source of confusion and some disagreement is whether a corrosion test chamber designed to perform these tests should be able to control relative humidity. This answer depends on whether the laboratory installing the test chamber can reliably meet the specified conditions.

If the laboratory is precisely controlled for the environmental conditions stated in the standard, the exposure of the samples to these conditions by applying room air to the samples in the chamber, etc., an equilibrium is achieved between the inside and outside of the chamber, eliminating the need to measure the relative humidity in the chamberto adjust and regulate. However, laboratory conditions are rarely controlled with the precision required for these experiments, especially in corrosion testing. Therefore, it is a practical practice to replace the laboratory with a variable environment by controlling the relative humidity in the test chamber, which is necessary in the world market. In addition, this standard also demonstrates that proper control measures are needed to achieve the required mass loss by measuring the mass loss of corrosion coupons. In some corrosion tests it is very important to properly control the relative humidity, so there is still a trend to use standard corrosion plates.


For these mutable labs One of the The main difficulty that test chamber manufacturers face when designing test chambers is that in many environments it is difficult to control the temperature and relative humidity required for the ambient phase. For example, if the laboratory temperature is kept at 25°C and the relative humidity rises to 60% (such as during the summer months, when the outside dew point is relatively high), the air entering the corrosion chamber must be dehumidified to maintain the required relative humidity. humidity of 45 ± 10%. When the laboratory temperature reaches 29°C, the air must be cooled to achieve ambient conditions. For these reasons, many test chamber manufacturers have designed chillers and dehumidification systems to meet the required conditions.

Test Standard: Future Perspective

Cyclic Corrosion Test Has A History Of A Century, Relatively Relative Humidity Controls Are A Relatively New Feature . As in many areas, there is a balance between standards and the capabilities of the test equipment for sale. Test chambermanufacturers and standards writers have to work hand in hand. For decades, both sides have developed methods without relative humidity control in the equipment, but a growing number of automotive OEMs consider this test method unreliable. As more relative humidity control devices enter the market, stand still, and writers must also modernize test methods to take advantage of better testing techniques while maintaining hardware-neutral standards so that the market is open to competition.

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