What causes jars to break in pressure cooker?

Overfilling jars: Overfilling the jars beyond the recommended level creates excessive pressure inside the jars, which can cause them to burst.

Improper sealing: If jars are not properly sealed or there is any leakage, air can enter the jars during the pressure cooking process, causing the pressure inside to fluctuate and potentially leading to breakage.

Thermal shock: Rapid temperature changes can cause jars to break. For example, if cold jars are placed directly into a hot pressure cooker, the sudden temperature difference can cause thermal shock and breakage.

Defects in the jars: Jars that have defects such as cracks, chips, or weak spots are more likely to break under pressure.

Malfunctioning pressure cooker: If the pressure cooker is not functioning properly or the pressure gauge is inaccurate, it can lead to excessive pressure build-up and subsequent jar breakage.

To prevent jars from breaking in a pressure cooker, it's important to follow the recommended guidelines for filling and sealing jars, heat the jars gradually to avoid thermal shock, use jars that are free of defects, and ensure that the pressure cooker is in good working condition.