How to judge the shrinkage of the filter bag of bag filter?

Each type of bag filter material has its own special molecular composition, and the operating temperature is also very different. When the operating temperature limit of the filter material is exceeded, the filter bag will shrink and become unable to filter, or even be unable to extract the bag cage. A brief introduction to the shrinkage phenomena of filter bags is as follows:
(1) The bag cage in the dust collector is higher than the filter bag, and sometimes it is above the blow pipe, indicating that the filter bag has shrunk.
(2) The bag cage in the filter bag cannot be pulled out (except for deformation of the filter bag), indicating that the filter bag has shrunk.
(3) The bottom of the filter bag is broken by the bag cage, indicating that the filter bag has shrunk.
(4) The color of the filter bag becomes darker (except for corrosion).