Introduction to the outer volume of the climate and environment test chamber

The working chamber volume of the climate environment test chamber should be at least 3 to 5 times the outer contour volume of the subject product. There are several reasons for making such a provision:

1] The accuracy indicators of environmental parameters in the working chamber of the climate box [such as temperature, humidity, salt spray sedimentation rate, etc.] are all detected under no load. Once the test piece is placed, it will have an impact on the uniformity of the environmental parameters in the working chamber of the test box. The greater the space the test piece occupies, the more serious this impact will be. The actual test data show that the temperature difference between the windward surface and the leeward surface in the flow field can reach 3 to 8℃, and in severe cases it can be as large as above 10℃. Therefore, the requirements of a] and b) must be met as much as possible to ensure the uniformity of the environmental parameters around the subject's products.

2] After the test piece is placed into the box, the smooth passage is occupied. The narrowing of the passage will lead to an increase in the airflow flow rate. Accelerate heat exchange between the air flow and the test piece. This is inconsistent with the reproduction of environmental conditions, because in the relevant standards, the air flow rate around the test samples in the test chamber should not exceed 1.7 m/s, in order to prevent the test samples and the surrounding atmosphere from producing inconsistent heat conduction. When no load is available, the average wind speed in the test chamber is 0.6~0.8m/s, not exceeding 1m/s. When meeting the space and area ratio specified in the two points a) and b) requirements, the wind speed of the flow field may increase (50~100)%, and the average wind speed is (1~1.7)m/s. Meet the requirements specified in the standards. If the volume or windward section area of ​​the test piece is increased without limitation during the test, the airflow wind speed during the actual test will increase to exceed the wind speed specified in the test standards, and the effectiveness of the test results will be doubted.

3] According to the principle of heat conduction, the temperature of the air flow near the box wall is usually 2 to 3℃ different from the center of the flow field. It may also reach 5℃ when the upper and lower limits of high and low temperatures. The temperature of the box wall is different from the temperature of the flow field near the box wall (depending on the structure and material of the box wall). The larger the difference between the test temperature and the external atmospheric environment, the greater the temperature difference. Therefore, the space within the distance from the box wall (100-150 mm) is an unusable space.

MoreMaterial testing machineAll information is available at Jinan Hengsi Shanda Instrument Co., Ltd.