1, the volume of choice
When the test product (components, components, parts or parts) is placed in environment chamber to test, in order to ensure that the surrounding atmosphere of the tested product can meet the environmental test conditions stipulated in the test specification, the working size of the climate box and the tested product Between the dimensions should follow the following requirements:
a.The volume of the tested product (W × D × H) shall not exceed 20% of the effective working space of the test chamber (20% recommended). It is recommended that no more than 10% of the products recommended for heat in the test.
b.The ratio of the windward cross-sectional area of the tested product to the total area of the working chamber on the section is not greater than (35 to 50)% (35% recommended).
2, the climate chamber working inner environment
Parameters (such as temperature, humidity, salt fog sedimentation rate, etc.) are the accuracy of the indicators in the no-load test results, once placed into the test piece, the working chamber of the chamber within the environmental parameters of the uniformity will have an impact, The greater the space occupied by the test piece, the more serious the impact. Measured test data show that the flow field in the wind and leeward surface temperature difference can reach 3 ~ 8 ℃, severe can be as large as 10 ℃ or more. Therefore, we must try to meet a、b the two requirements to ensure that the parameters of the surrounding environment parameters of the uniformity
3, the choice of humidity range
Domestic and foreign environmental test chamber gives the humidity indicators are mostly 20 ~ 98% RH or 30 ~ 98% RH, if the wet test chamber without dehumidification system, the humidity range of 60 ~ 98%, this type of test chamber can only be high Wet test, but its price is much lower. It is worth noting that the corresponding temperature range should be indicated after the humidity index, or the minimum dew point temperature should be given. Because the relative humidity is directly related to the temperature, for the same absolute moisture content, the higher the temperature, the relative humidity is smaller.
5, the choice of temperature rate
Ordinary high and low temperature test chamber without cooling rate of the index, from the ambient temperature to the nominal minimum temperature of the time is generally 90 ~ 120min. High and low temperature alternating test chamber, high and low temperature alternating hot and humid test chamber have the requirements of temperature change, the temperature rate of the general requirements of 1 ℃ / min, in the speed range of this adjustable. And the rapid temperature change test chamber temperature faster, heating, cooling rate can reach 3 ℃ / min ~ 15 ℃ / min, in some temperature heating, cooling rate can even reach 30 ℃ / min or more
6, the accuracy of humidity control
Most of the humidity measurement in the environmental test chamber is the dry and wet ball method, the environmental testing equipment manufacturing standard GB10586 requirements, the relative humidity deviation should be ± 23% RH. In order to meet the requirements of humidity control accuracy, humidity control box temperature control accuracy is higher, the temperature fluctuation is generally less than ± 0.2 ℃. Otherwise it is difficult to achieve the humidity control accuracy requirements.