Abstract: Environmental test equipment is a sophisticated, expensive equipment. Proper use and operation of thermal shock chambers not only provide an accurate basis for the inspectors, but also makes environmental testing equipment uptime and extend the life of the equipment.
Proper use of thermal shock test chamber
1、doing environmental testing, samples should be tested for the desired properties, test conditions, test procedures and test techniques to be familiar to the technical performance of test equipment used to be familiar, construction of the equipment to be understood, in particular, the operation and performance of the controller should be familiar with. Also read the test equipment operation manuals, to avoid operational errors caused by the normal operation of the test equipment is not causing damage to the test sample, the test data is incorrect.
2、a reasonable choice of test equipment. To ensure the normal test should be based on different circumstances test sample, select the appropriate test equipment, it must maintain a reasonable proportion between the effective volume of the test sample and the chamber. For test heat test sample, the volume should not exceed one-tenth of the effective volume of the chamber. For non-heat test sample volume should not exceed one-fifth of the effective volume of the chamber. For example, a 21-inch color TV doing temperature storage test, use a cubic volume of the chamber will be able to meet the requirements, and in the power of work, it can not meet the requirements, should for a greater number of chambers, Because the TV at work to diverge heat.
3、the test sample is placed correctly. Placement test sample, leave me cold shock chamber walls more than 10cm, multiple samples should be placed on the same plane. The sample is placed should not clog the outlet and return air, to the temperature and humidity sensors should also set aside a certain distance. To ensure that the correct test temperature.
4、for added environmental testing required test medium, add correctly based on test requirements. As heat chamber is a certain requirement of water, the water chamber resistivity of not less than 500 ohms. Meters, the general water resistivity 10 - 100 ohm. Meters, distilled water resistivity 100--10000 Europe. Meters, deionized water resistivity 10000-100000 Europe. meters, so hot and humid test water use distilled or deionized water, and be sure to use fresh, because the water in contact with air, are vulnerable to carbon dioxide and dust pollution, water has a variety of substances can be dissolved nature, a long time after, the resistivity to decrease. There are now a pure water, more economical, and convenient, it is equivalent to the resistivity of distilled water.
5、the use of thermal shock chambers. Thermal shock chambers with a wet ball gauze (wet bulb paper) is a set of requirements, can not substitute any gauze, because the relative humidity reading is the root of the difference between the temperature and humidity of the pitch is, strictly speaking, but also with the local prevailing atmospheric pressure, wind speed. Wet bulb temperature indication and gauze inhaled water, the situation is related to surface evaporation. These are directly related to the gauze quality is closely related to the provisions on the weather so wet ball gauze must be a dedicated sub linen "wet ball gauze." Otherwise it is difficult to ensure the accuracy of the wet bulb thermometer indication, that is correct humidity. Also wet ball gauze placed there clearly defined, gauze length: 100mm, tightly wound sensor probe, the probe away from the humidity cups 25-30mm, gauze dipped in glass, so as to ensure the accuracy of the device control correctness and humidity.
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