Originally Posted by Aurora
The purpose of a pressure cooker is to increase the pressure inside the pressure vessel to increase the boiling point of the liquid. At 15 psi, the pressure is equal to approximately 2 atmospheres. The boiling point of water at 2 atmospheres is approximately 248 degrees F. or 120 degrees C.
The metal of the pressure vessel could be as high as 248 degrees F.
You will NEVER be able to get that high a cooking temperature in just an ordinary pot of boiling water. Plus, as the water begins to heat up to the boiling point, air has to escape through the vent pipe, alllowing the pressure to build up to 15 psi. 248 degrees is extremely hot!!! This is the exact same process used in hospitals and dental facilities to sterilize the tools used during operations and dental work.
Yes, most pressure cookers have you either cool them at once in the sink with cold water running over half the top or you'd let the pressure drop of it's own accord. With mine, you just and slightly lift & tilt the jiggler on the vent pipe to the side, and the pressure is released.
And the rubber gasket DOES help keep the pressure inside from being lost during the cooking cycle. Think of it as a big plane that's pressurized in the air. If a door seal is broken, pressure will begin to escape.
One word of caution though; Not telling any of you how to cook, but 248 degrees of steam is dangerously hot!!!! If you should ever accidentally scald yourself with it, then you're on the way to the hospital for emergency medical treatment in the ER. Someone I know was scalded by one of these! Please be careful when using these sophisticated cooking devices.
And BTW, I DID forget to mention that I've also done a pot roast in mine. It came out very good and tasty!