The temperature chamber and the temperature humidity chamber are two important types of simulated enironmental chambers in envrionemntal chamber. These temperature humiditychambers is widely used in electronics, machinery, chemical, construction and other industries. It provides a reliable artificial environment for environmental adaptability research of various equipment, materials and components.
High low temperature chamber has been widely used in electronics industry and some industries with high precision requirements. However, as processes and technologies improve, the ability to test chamber is increasing. Many different testing requirements and testing indicators will be encountered during the testing process.
For example, the current constant temperature humidity chamber is required to be tested under low temperature and low humidity conditions. The thermal shock chamber requires temperature changes above 30 °C per minute and so on. This brings certain difficulties to the test and puts higher demands on the ability of the test equipment.
1. What is Temperature Overshoot?
Temperature overshoot is the phenomenon that when the temperature of the studio exceeds the set temperature by more than 5 °C for the first time, it is slowly lowered and stabilized at the set temperature. Some pharmaceutical, biological, chemical, food, electronics and other industries are relatively sensitive to this phenomenon.
2. Hazards of Temperature Overshoot
The product inspection practice tells us that the temperature overshoot generated by the temperature test chamber during the startup and each heating and heat preservation process is very harmful to the tested product. Especially for temperature sensitive products and gluing materials, transient overshoot temperatures can cause damage to the product and failure of the glue.
3. Cause of Temperature Overshoot
3.1. Wrong Usage of Environmental Chamber
Temperature overshoot also occurs in users who are not very clear about the use of the environmental chamber. For example, many domestic environmental chambers now use two sets of heaters for heating. This is provided by the manufacturer in order to distribute the heating power reasonably. Many users directly turn on two sets of heating during use of the environmental chamber. This causes the temperature to always be near the upper limit of the index.
If the accuracy of the environmental chamber’s control system is low, intermittent overshoot may occur. This makes the environmental chamber unstable at the set point. This situation is basically due to the overshoot of the temperature caused by the user’s lack of understanding of the environmental chamber, which is better solved. Just adjust the temperature chamber settings. However, it should be noted that it is best to adjust the temperature of the environmental chamber to the non-test temperature point during the adjustment process, and then let the temperature chamber work again. This effect is better, but also pay attention to whether the ability of the environmental chamber itself can meet the requirements of the test.
3.2. Instrument Accuracy of Environmental Chamber
The cause of temperature overshoot is also the problem of meter accuracy. The accuracy of the tables used by the general test equipment manufacturers is relatively low and the reaction rate is relatively slow. This caused the temperature inside the chamber to be already high, but the meter did not respond. In addition, many high temperature chamber are not equipped with low-temperature equipment such as compressors and cooling water. Therefore, after the temperature overshoot, only natural cooling occurs, which causes temperature overshoot. Some equipment due to this reason, the temperature can reach more than 10 ℃. If the test article is at the limit temperature, it is undoubted that such a test will generate a lot of waste.
3.3. Probe Placement of Environmental Chamber
The cause of the temperature overshoot is also the placement of the probe and the direction of the agitation wind. It has been proved by experiments that placing the probe at the position of the air outlet is a better method. In addition, for windless environmental chamber, the probe is best placed at the geometric center point of the interior volume of the environmental chamber.
However, if the reaction speed of the probe and the accuracy of the meter are not enough, the temperature will be overshooted. This is due to the control principle. Because the probe is located at the air outlet. Therefore, the temperature during heating is higher than the temperature of other parts of the environmental chamber.
Therefore, when the sensing temperature of the probe does not reach the set value, the heating part of the environmental chamber will be heated at full power. After reaching the temperature, the heating part stops the full power heating and becomes intermittent heating. And the temperature of each point in the test chamber is gradually leveled under the stirring of the stirring wind.
4. DGBell Environmental Chamber
DGBell environmental chambers’ temperature overshoot is ≤ ± 2°C. Besides, it is equipped with Tecumseh (France)-fully air-cooled double-fall cooling compressor or Bock (Germany) semi-enclosed air-cooled refrigeration. So whether your product is temperature sensitive or otherwise, you can safely choose DGBell equipment for testing!
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