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Many users think that the constant temperature and humidity test box can put as many samples into the test box as there is space in the box.
In fact, this is wrong, because according to the standard requirements, the studio volume of the constant temperature and humidity test box should be at least the outer volume of the sample to be tested.
3 to 5 times, so that good test results can be achieved
.
The reasons are as follows: 1.
According to the principle of heat conduction, the temperature of the airflow near the box wall is usually 2 ~ 3°C different from the temperature of the center of the flow field, and it may reach 5°C at the top and bottom of the high and low temperature
.
The temperature of the box wall is different from the temperature of the flow field near the box wall by 2 to 3°C (depending on the structure and material of the box wall).
The space within the distance of the box wall (100 ~ 150mm) is unusable space
.
2.
The accuracy indicators of the environmental parameters in the working chamber of the constant temperature and humidity test box are all the results of testing under no-load conditions.
Once the product to be tested is placed, it will have an impact on the uniformity of the environmental parameters in the working chamber of the test chamber.
The larger the space occupied, the greater the impact
.
The measured test data show that the temperature difference between the windward side and the leeward side in the flow field can reach 3 to 8°C, and in severe cases, it can be as large as 10°C or more
.
Therefore, it is necessary to meet the requirements specified in the standard as much as possible to ensure the uniformity of the environmental parameters around the tested product
.
3.
After the product to be tested is placed in the box, the smooth channel is squeezed, and the narrowing of the channel will lead to an increase in the flow rate of the airflow and accelerate the heat exchange between the airflow and the product to be tested
.
This is inconsistent with the reproduction of the environmental conditions, because the relevant standards stipulate that the air flow rate around the test sample in the constant temperature and humidity test chamber should not exceed 1.
7m/s for the temperature environment test, so as to prevent the test sample and the surrounding atmosphere.
Unreal heat conduction occurs, and the average wind speed in the test box is 0.
6 ~ 0.
8m/s at no load, not exceeding 1m/s
.
When the space and area ratios specified in the above requirements are met, the wind speed of the flow field may increase by (50~100) %, and the average high wind speed is (1~1.
7) m/s, which meets the requirements of the standard
.
If the volume or windward cross-sectional area of the product to be tested is increased without restriction during the test, the airflow speed will increase to exceed the high wind speed specified in the test standard during the actual test, and the validity of the test results will be questioned
.
In fact, this is wrong, because according to the standard requirements, the studio volume of the constant temperature and humidity test box should be at least the outer volume of the sample to be tested.
3 to 5 times, so that good test results can be achieved
.
The reasons are as follows: 1.
According to the principle of heat conduction, the temperature of the airflow near the box wall is usually 2 ~ 3°C different from the temperature of the center of the flow field, and it may reach 5°C at the top and bottom of the high and low temperature
.
The temperature of the box wall is different from the temperature of the flow field near the box wall by 2 to 3°C (depending on the structure and material of the box wall).
The space within the distance of the box wall (100 ~ 150mm) is unusable space
.
2.
The accuracy indicators of the environmental parameters in the working chamber of the constant temperature and humidity test box are all the results of testing under no-load conditions.
Once the product to be tested is placed, it will have an impact on the uniformity of the environmental parameters in the working chamber of the test chamber.
The larger the space occupied, the greater the impact
.
The measured test data show that the temperature difference between the windward side and the leeward side in the flow field can reach 3 to 8°C, and in severe cases, it can be as large as 10°C or more
.
Therefore, it is necessary to meet the requirements specified in the standard as much as possible to ensure the uniformity of the environmental parameters around the tested product
.
3.
After the product to be tested is placed in the box, the smooth channel is squeezed, and the narrowing of the channel will lead to an increase in the flow rate of the airflow and accelerate the heat exchange between the airflow and the product to be tested
.
This is inconsistent with the reproduction of the environmental conditions, because the relevant standards stipulate that the air flow rate around the test sample in the constant temperature and humidity test chamber should not exceed 1.
7m/s for the temperature environment test, so as to prevent the test sample and the surrounding atmosphere.
Unreal heat conduction occurs, and the average wind speed in the test box is 0.
6 ~ 0.
8m/s at no load, not exceeding 1m/s
.
When the space and area ratios specified in the above requirements are met, the wind speed of the flow field may increase by (50~100) %, and the average high wind speed is (1~1.
7) m/s, which meets the requirements of the standard
.
If the volume or windward cross-sectional area of the product to be tested is increased without restriction during the test, the airflow speed will increase to exceed the high wind speed specified in the test standard during the actual test, and the validity of the test results will be questioned
.
