What faults may be caused by improper sample processing in high and low temperature alternating and humid heat tests?

Improper sample processing is one of the core causes of test failures, data distortion, and even equipment damage in high and low temperature alternating and humid heat tests. Specifically, it can be divided into the following categories based on the processing steps:

1、 Improper sample preparation

Inadequate pre-treatment, cleaning, sealing, and other steps before the sample enters the test chamber can directly lead to logical deviations in the test or internal damage to the equipment. Common faults include:

Residual contaminants/moisture on the surface of the sample: causing corrosion, contamination, or data deviation

If there are residual oil stains, dust, and chemical reagents on the surface of the sample, in a humid and hot environment, the pollutants will combine with water vapor to form corrosive liquids, which on the one hand leads to "non test purpose corrosion" of the sample itself and interferes with the judgment of test results; On the other hand, corrosive liquid may drop on the tank, air duct or sensor surface of the test chamber, causing corrosion of the tank, sensor sensitivity decline, or even blocking the spray port of the humidity generator, leading to the failure of the humidity system.

If the sample is not dried in advance, rapid evaporation/condensation of moisture may occur due to temperature fluctuations after being placed in the box, causing the actual humidity inside the box to far exceed the set value, resulting in "humidity loss of control". At the same time, the sample may crack or delaminate internally due to moisture expansion/freezing.

Improper sealing/packaging of samples: causing "internal failure" or "equipment short circuit"

2、 Improper placement and fixation of samples

The placement, spacing, and fixing method of samples in the test chamber directly affect the "environmental uniformity" of the equipment. Improper handling can lead to abnormal equipment operation or physical damage to the samples

Sample placement too dense/covering key components: causing "temperature and humidity uniformity exceeding the standard"

Sample not firmly fixed: causing 'physical collision failure'

In the high and low temperature alternating test, drastic temperature changes can cause the sample to experience "thermal expansion and contraction". If it is not fixed with a special fixture or if it is loose:

The sample may shift, tilt, or even collide with the air duct blades and sensor probes inside the box: in mild cases, it may cause damage to the sensor, and in severe cases, it may cause deformation of the air duct blades, resulting in ineffective airflow circulation and inability to maintain the set temperature and humidity of the equipment;

If the sample is an assembled part and not firmly fixed, it will cause uneven stress at the joint due to thermal expansion and contraction, resulting in "loosening and detachment for non test purposes". It is impossible to determine whether the fault is caused by "test environment" or "improper fixing", and the test is invalid.

3、 Improper sample loading and pretreatment

The test chamber has a rated "load rate", and some samples require "environmental balancing" in advance. Improper handling can lead to equipment overload or sample structure damage:

Sample load exceeding the standard: causing "overload of refrigeration/heating system"

If the sample volume is too large, the weight is too heavy, or the sample has a "large heat capacity", it will cause the cooling/heating system load of the test chamber to far exceed the rated value:

High temperature stage: The heater needs to continuously output high heat to make the sample temperature reach the set value, which may cause the heater to burn out and the temperature controller to trip;

Low temperature stage: The refrigeration system needs to continue working to reduce the sample temperature, which may trigger the "compressor overheat protection" due to overload and even cause compressor damage;

Wet and hot stage: High load can cause difficulty in evenly spreading water vapor inside the box, and the humidity generator needs to work frequently, which may lead to dry burning of the humidifier water tank or component aging of the humidity control system due to "continuous high load".

Sample not pre treated: causing 'internal stress failure'

Some samples need to be "pre treated" before the experiment. If they are directly placed in the test chamber:

If there is a significant difference between the internal temperature of the sample and the temperature inside the box, severe internal stress will be generated due to "thermal shock", leading to direct cracking and breakage of the sample. The failure is not the result of long-term exposure to the test environment, but rather an acute failure caused by a lack of pre-treatment;

For hygroscopic samples, failure to balance the moisture absorption in a standard environment in advance can result in abnormal moisture absorption/release rates during testing, severe fluctuations in humidity inside the box, and equipment failure to maintain the set humidity, leading to a 'humidity alarm'.

Summary: The core impact chain of improper sample processing

Improper handling → Abnormal sample status/interference with equipment operation → Distortion of test data/equipment failure → Test interruption or invalid results.

Therefore, before the experiment, it is necessary to develop an "exclusive treatment plan" based on the characteristics of the sample, and strictly match the rated load and environmental requirements of the equipment to avoid such failures.