Safety features of Pressure cookers

Early pressure cookers equipped with only a primary safety valve were at risk of explosion if poorly maintained, allowing food residues to contaminate the release valve. Modern pressure cookers typically have two or three redundant safety valves, as well as some additional safety features, such as an interlock lid that prevents the user opening the lid while internal pressure exceeds atmospheric pressure. If any of the safety mechanisms are not in place correctly, the pressure cooker will not reach pressure. Pressure cookers should be operated only after reading the instruction manual, as each model differs slightly on the implementation of the safety mechanisms and should be regularly maintained in accordance with the manufacturer's instructions.

For first generation pressure cookers with weighted valve or "jiggler", the primary safety valve or regulator usually takes the form of a weighted stopper, commonly called "the rocker," or "vent weight". This weighted stopper is lifted by the steam pressure, allowing excess pressure to be relieved. There is a backup pressure release mechanism that may employ any of several different techniques to release pressure quickly if the primary pressure release mechanism fails (for example, if food jams the steam discharge path). One such method is in the form of a hole in the lid blocked by a plug of low melting point alloy; another is a rubber grommet with a metal insert at the center. At a sufficiently high pressure, the grommet will distort and the insert will blow out of its mounting hole, relieving the pressure. If the pressure continues to increase, the grommet itself will blow out to release pressure.

For second generation pressure cookers with selectable pressure and, often hidden, spring valve operation, a common safety feature is the design of the gasket, which expands and releases excess pressure downward between the lid and the pot.