Working principle
1. Room temperature and high temperature test
At the standard laboratory temperature, the sample of known height is compressed to the specified height according to the compression ratio requirement. Under the specified temperature condition, the sample is compressed for a period of time, and then the compression is removed under the standard temperature condition. The sample is in the free state, and the specified time is returned to measure the height of the sample.
2. Low temperature test
At the standard test temperature, the sample of known height is compressed to the specified height according to the compression ratio, and compressed for a period of time at the specified low temperature test temperature. Then, the compression is removed at the same low temperature, and the sample is recovered in the free state. The height of the sample is measured at intervals at low temperature, and a logarithmic curve of the sample height and time is obtained. The compressive permanent deformation characteristics of the sample are evaluated.