The lid of a pressure cooker is a safety component and should be inspected before every use. Check three things: the channel in the pressure regulator valve should appear open when held up to the light; the safety valve should move freely when pressed by hand; and the gasket groove should be free of residue. Do not immerse the lid in water; remove and wash the gasket separately, then dry the groove.
What speeds up cooking in a pressure cooker is the pressure that builds inside the sealed vessel. All the parts that control this pressure are in the lid: the groove that holds the gasket, the pressure regulator valve that releases steam in a controlled way, and the safety valve that engages if pressure rises unexpectedly. The body only holds the water and food; the lid is a safety component. That is why maintaining a pressure cooker means almost entirely maintaining its lid, and inspection should happen before cooking, not after a problem occurs.
Inspection takes a few seconds and requires no tools. Turn the lid over and hold the opening where the pressure regulator valve sits up to the light; if you can see through it, the channel is clear. If not, there is residue inside, so remove the valve and rinse the channel under running water. Then press the safety valve or safety pin by hand; if the part moves freely and returns to its place, it is in good condition. A safety component that is stuck, gummy, or no longer moves on its spring makes the cooker unsafe to use and must be replaced before cooking.
The third place to check is the gasket groove, and it is the most often missed. This narrow channel around the edge of the lid is where overflowing foam and oil collect most readily; residue left there can keep the gasket from seating properly and let steam escape around the edge. Users often mistake this for an old gasket and buy a new one. But removing the gasket and washing the groove resolves the problem. Wash the gasket separately as well; if it returns to its original shape right away after being stretched and released by hand, it has retained its flexibility.
There are two rules for washing. Do not immerse the lid in water or put it in the dishwasher; water left in the locking mechanism or valve seats can leave rust and mineral scale, and dishwasher detergent can stiffen the gasket. Rinse the lid under running water, wash the valves and gasket separately, and dry everything completely before putting it back together. A gasket that has not dried can stick to the groove and fail to seat properly the next time it is used. Store the lid and the cooker body separately, without closing the lid over the body.
A clear boundary is set: do not disassemble any of the valves or tamper with their interiors. The pressure regulator valve is adjusted to open at a specific pressure; if its spring is stretched or its interior is forced, it becomes a part whose opening point is no longer predictable. Cleaning is limited to the outside surface and the channel. A worn gasket, a sticking safety valve, or a warped lid rim should only be replaced with a replacement part made by that cooker’s manufacturer.