The process of alternating test in a constant temperature and humidity test chamber

Before the constant temperature and humidity test chamber does the alternating test, the test sample should be inspected according to the relevant standards. The following is the alternating test process of a certain product. You can refer to this process to set the relevant program for temperature exchange test.

At a temperature of 25±3℃ and a relative humidity of 45%-75%, make the test sample reach a stable temperature, and then increase the relative humidity in the working space of the constant temperature and humidity test chamber to not less than 95% within 1 hour , according to the standard, the temperature in the working space changes cyclically within 24 hours:

1. Heating stage: within 3±0.5 hours, the temperature of the working space is continuously raised to the high temperature value that needs to be tested. The heating rate should be limited to the range of the standard specification. At this stage, the relative humidity can not be lower than 90% except for 15min, the relative humidity of the rest of the time should not be less than 95%.

In order to make the test sample produce condensation, but the large-scale test sample must not produce excessive condensation (Note: Condensation on the test sample means that the surface temperature of the test sample is lower than the dew point temperature of the air in the working space).

2. Constant high temperature and high humidity stage: Maintain the temperature of the working space within the range of 40±2°C (or 55±2°C) until 12±0.5 hours from the beginning of the heating stage. At this stage, except for the beginning The relative humidity of 15min should not be lower than 90%, and the other time should be 93±3%.

3. Cooling stage: Reduce the temperature of the working space of the constant temperature and humidity test chamber from 40±2°C (or 55±2°C) to 25±3°C within 3 to 6 hours. The cooling rate should be limited to the standard time range. The cooling rate within 1.5 hours after the start of cooling is the rate at which the temperature drops from 40±2℃ or 55±2℃ to 25±3℃ within 3h±15min.

There are two ways to change the relative humidity at this stage: Change 1 should not be lower than 90% in the first 15 minutes, and not lower than 95% for the rest of the time; Change 2: Allow the relative humidity to be no lower than 85%.

4. Constant low temperature and high humidity stage: Maintain the temperature of the constant temperature and humidity test chamber at 25±3℃, and the relative humidity should not be lower than 95%, until 24 hours have passed since the beginning of the heating stage.

The above process is relatively simple. You only need to set the temperature and humidity of the constant temperature and humidity test chamber, and start the program to automatically do the alternating test. If you don't know how to operate, you can consult us.