In order to obtain reproducibility, temperature test must be designed: the high and low temperature test chamber at a point on a test sample of the highest or lowest temperature is the same, with the independent laboratory test, the test sample with respect to the temperature reached relatively stable for the short time required for the duration of the trial design, should consider the following precautions:
1, the test velocity of the air surrounding the sample:
High and low temperature test samples of air and heat exchange between the efficiency depends on the air speed, high and low temperature test, hoping to accurately simulate the actual environment of the air speed, but due to limited knowledge to grasp the actual situation and the difficulty of confirmation chamber the air velocity, this simulation is usually impossible, therefore, generally to press the "worst case" to be tested to cover all possibilities, the test specimen is non-heat, high air velocity results in a higher the / low temperature test of the test sample to a low temperature, therefore, recommended for such a test chamber using a high air velocity (measured at the load is preferably not less than 2M / S), heat test sample test, if the the test sample is higher than the temperature of the hot ambient air temperature, the higher air velocity reduces the temperature of the point, so in most cases, as much as possible, in the absence of such tests should be forced air circulation (i.e. free air conditions) chamber is carried out when the heating or cooling chamber can only be achieved by circulating air to the occasion, can be used as an alternative method of forced air method.
2 Conditions:
In order to obtain reproducible, high and low temperature throughout the test period provisions must be well chamber air temperature - time course, in the real environment do accurately simulate the case can simulate this situation is to specifically design temperature - time course, should be noted that the temperature - time process diagrams in the following details and test A and test B are different:
a, the beginning of a narrow temperature range (25 ° ± 3 °);
b, the temperature during the establishment of a pilot chamber air temperature rate of change;
c, test duration is the air from the chamber, the moment when the temperature reaches a predetermined value.