The relevant standard outlines the procedure for recovering the test sample after the completion of a programmable high and low temperature damp heat test. This recovery process should be conducted under either standard atmospheric conditions (as specified in section 5.3 of GB/T2421-1999) or under controlled recovery conditions, depending on the requirements of the specific test.
According to GB/T2423.4-2008, if controlled recovery is necessary, the test sample can either be moved to another chamber or remain in the same programmable high and low temperature damp heat test chamber for recovery. In the first scenario, the transfer time should be minimized and must not exceed 10 minutes to avoid unnecessary exposure to environmental changes.
In the second case, the relative humidity should be reduced to (75 ± 2)% within one hour, followed by a temperature adjustment to match the laboratory temperature with a tolerance of ±1 K, which should take an additional hour. For larger test samples, extended transfer times may be permitted, as outlined in the relevant standards.
The recovery time, typically ranging from 1 to 2 hours, is calculated from the moment the specified recovery conditions are met. If the test sample has a large thermal time constant, it may require a longer recovery period to ensure full temperature stabilization, as mentioned in Chapter 4 of GB/T2421-1999.
Additionally, the standards should specify whether any special procedures are needed to remove moisture from the surface of the test sample, as this can affect the accuracy of post-test evaluations.
After the recovery phase, the test sample should undergo a visual inspection and be tested according to the applicable specifications. Measurements should be taken immediately after the recovery period, with the most humidity-sensitive parameters measured first. Unless otherwise stated, all measurements should be completed within 30 minutes to ensure consistency and reliability of results.
This structured recovery process ensures that the test sample returns to stable conditions before final evaluation, maintaining the integrity of the testing procedure.
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