Examination of technical indicators of temperature shock test chamber

Wind Speed Requirements

Temperature change test standards, including various types of temperature testing, specify wind speed limits within the test chamber. Most of these standards require a wind speed of less than or equal to 2 m/s. This is to prevent excessive airflow from affecting the test product, which could lead to unrealistic heat transfer that doesn’t reflect real-world conditions. A controlled wind speed helps ensure rapid and uniform temperature distribution inside the chamber. However, if the wind speed is too high, it may cause uneven heat exchange between the surface and the back of the test item, preventing proper internal heat conduction and leading to inaccurate test results.

Absolute Humidity Requirements

MIL-STD-810F does not impose specific humidity requirements, as it assumes the use of general-purpose materials where humidity has minimal impact on temperature shock testing. However, the standard highlights that porous materials, such as fiber-based products, are prone to moisture absorption. During low-temperature cycles, this moisture can expand and potentially damage the material. Therefore, it is recommended to control humidity levels in the test chamber. Typically, the absolute humidity should be kept below or equal to 20 g/m³ to avoid unwanted effects during testing.

Recovery Time for Air Temperature in Temperature Shock Chambers

Standards like GJB150.5 (equivalent to MIL-STD-810 C/D) and GB2423.22 (similar to IEC60068-2-14) specify that the air temperature recovery time should be less than or equal to the time it takes for the product to reach thermal stability. In contrast, MIL-STD-810F sets a stricter limit of no more than 5 minutes. The purpose of this requirement is to ensure that the test chamber has sufficient thermal capacity to provide true and sudden temperature shocks, simulating real environmental conditions effectively.

Difference Between Chamber Wall Temperature and Test Temperature

Several standards also set limits on the difference between the chamber wall temperature and the test temperature. This is to prevent excessive radiant heating caused by large temperature differences, which can result in uneven temperature distribution across the test item. General guidelines suggest that the difference should not exceed 3% at high temperatures and 8% at low temperatures to maintain test accuracy and reliability.

Understanding the Core Technical Indicators of a Temperature Shock Test Chamber

By understanding the key technical specifications outlined above, one can gain a deeper insight into the principles of temperature shock testing. It also aids in selecting the right equipment and helps users better understand the operation and maintenance of the test chamber. Proper attention to these parameters ensures accurate and repeatable test results, making it an essential aspect of any temperature shock testing process.

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