Application comparison of various testing methods in high and low temperature test chambers-Chemical Instrument Network

High and low temperature test chamberThe test methods are divided into non heat dissipation test samples and heat dissipation test samples (commonly known as whether the tested sample has heat generation or not in the industry). The following is a comparison of the application of various test methods:

1. Non heat dissipating test samples and heat dissipating test samples: During the conditional test period, when the temperature of the test sample reaches a stable level and is measured under free air conditions (i.e. without forced air circulation), if the temperature of the hottest spot on the surface of the test sample is higher than the surrounding atmospheric temperature by more than 5 degrees, it is considered to be heat dissipating. Otherwise, it is considered a non heat dissipating test sample. All storage tests and tests without power or load during the test period are non heat dissipating test samples, and the low-temperature test method is used for the test.

2. Non heat dissipation test sample: Temperature gradient test in a temperature mutation test chamber (the former is a temperature rapid change test chamber and the latter is a high and low temperature test chamber).

Temperature mutation test Aa: First adjust the temperature of the test chamber to the specified test temperature, and then place the test sample at room temperature. This test method is applicable when the known temperature mutation does not cause any operation on the test sample.

Temperature gradient test Ab: First, place the test sample with room temperature into a test chamber at the same room temperature, and then turn on the cold source to gradually cool the temperature inside the chamber to the specified test temperature. If the test sample is too large or heavy, or due to complex functional test wiring, it cannot be placed in a low-temperature chamber without frosting during the mutation test, test Ab should also be used.

3. Heat dissipation test samples with and without forced air test: The industry's method for ensuring uniform fluctuations is to use the air circulation mode, where the motor drives the fan to generate air circulation and form the wind speed direction. The test without forced air circulation is a test that simulates the influence of free air conditions and is more suitable for testing heat dissipation test samples. The test with forced air circulation is used when it is difficult or impossible to guarantee the specified test conditions without using forced air circulation. There are two methods of forced air in the test method Ad: A and B. Method A is used for test chambers that are large enough to meet the test requirements without forced air circulation, but when the specified low temperature cannot be maintained without forced air circulation inside the chamber, that is, the cooling or heating requirements of the high and low temperature test chambers are met. When forcing air circulation.