How Does a Pressure Cooker Work?

By John Albers

What is a Pressure Cooker

A pressure cooker is a device which is used to cook foods faster than any other method, barring a microwave oven. A pressure cooker appears to be little more than a heavy pot with a reinforced lid. Nowadays they have pressure gauges and regulators, redundant safety seals, locking pins and steam vents. All this is necessary because a pressure cooker cooks foods faster by containing superheated steam within a pressurized chamber along with the food. The entire cooker must be designed and built to safely contain very high pressures, hence the great weight and thick metal.

What are the Dangers of Using a Pressure Cooker

In the past, when pressure cookers were relatively new, there were a large number of accidents. This was due in part to the negligence and improper use of the pressure cookers by inexperienced owners. Often they would be overfilled or too much water would be added, creating an internal pressure that was beyond the capacity of the cooker to contain. Also many of the early pressure cookers lacked the safety features that current standards require. This unfortunate confluence of circumstances has resulted in pressure cookers exploding. Flying pieces of metal have injured, crippled, and even killed anyone within the vicinity of the explosion. Superheated steam has permanently disfigured and blinded people. No such accidents have been reported within the last 25 years as a result of more exacting standards by the government, but the potential for them still exists and should be considered whenever using a pressure cooker.

How Does a Pressure Cooker Work?

A pressure cooker works under the principle that water is a more effective way to transmit heat than air is, meaning a pot of boiling water at 212 degrees can do the job of a convection oven at 400 degrees. There is no other way under normal environmental circumstances to heat water beyond 212 degrees in order to increase the speed of cooking. A pressure cooker is the solution to this problem. The food to be made is placed in the pressure cooker, along with some amount of water. The lid is securely fixed into place, usually by means of several latches or flanges. The vessel is then placed on a heat source. When the water reaches the boiling point at atmospheric pressure it begins to boil, but since the produced steam in the pressure cooker cannot escape the pressure rises, consequently raising the internal boiling point. Once the pressure increases to the designed level above air pressure a relief valve opens, releasing steam and preventing the pressure from rising any further. After a short time, you remove the cooker from the heat source and press the release valve. This safely vents all the steam so you can open the cooker and remove the food.