How Does a Pressure Cooker Work?

Table of contents for Pressure Cooker 101

  1. How Does a Pressure Cooker Work?
This entry is part of a series, Pressure Cooking 101»

“Pressure makes diamonds.” – General George S. Patton, (1885-1945)

Pressure cooking principles are quite simple and the chances are good that you already know the basic physics behind how they work.

It’s a Sealed System

A pressure cooker is a sealed pot, plain and simple. When the water inside a pressure cooker is boiled, steam builds and creates pressure. It is this higher pressure (typically 15 psi or pounds per square inch) which allows the food to cook quickly. Here’s why:

  • Water normally boils at 212ºF and no matter how much heat you add to it, it will never get any hotter.
  • Steam trapped inside the pot under pressure allows the temperature to rise beyond what it could reach normally in a traditional uncovered pot.
  • At 15psi the temperature inside the pressure cooker is near 250ºF an increase of 38ºF compared to normal boiling water.
pressure cooker diagram

Pressure cooker diagram (Source: Promotion)

Increased Pressure and Temperature

Higher temperatures and higher pressures inside a pressure cooker cook foods much faster than conventional methods and since the food is being cooked with steam, everything from delicate seafood to various cuts of meats are cooked efficiently.

Pressure Cooker Temperature Graph

Control and Safety

The pressure level inside the pot is controlled by the heat level you adjust on your stove-top.  By keeping the pressure cooker at “pressure” for different amounts of time all foods no matter how tender or tough can be cooked to perfection.

What about safety? Modern pressure cookers are designed with built in safety features to vent overpressure and lock the lid closed until it is safe to open.  Modern pressure cookers are 100% goof proof and easy to use.

Resources:

Smith, Vickie. Miss Vickie’s Big Book of Pressure Cooker Recipes. New Jersey: John Wiley & Sons, Inc., 2008.
“Pressure Cooking”. The Nibble: Great Food Finds <
http://www.thenibble.com/zone/kitchen/appliances/pressure-cook.asp>
“What are the effects of Pressure on Steam Temperature?”. Broadely-James Corp <
http://www.broadleyjames.com/FAQ-text/102-faq.html


Thanks for reading.

"I was 32 when I started cooking; up until then, I just ate." ~Julia Child  
Why learn pressure cooking?
It's 7 pm. The end of the work day stomach rumbles...

In one hand, a take out menu. In the other hand, the refrigerator door...its contents staring back almost as blankly as we are towards them. We want a homemade meal, but also want something quick and simple to make.
1. Simple and quick recipes requiring basic skills to become proficient in the kitchen.
2. Quality ingredients, not necessarily 100% organic, but meals without artificials and chemistry class additives.
3. To understand more of the story of our food and take small steps towards self-reliance.

It's true, there are many benefits to pressure cooking: the time savings, the taste, a small step towards self-reliance, sustainability... but the real benefit is in what we learn as we redefine our relationship with food. Good food can be fast. Good food can be easy.

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{ 5 comments… read them below or add one }

weight September 27, 2010 at 6:09 pm

yeah my dad will like this

tsanko October 18, 2010 at 10:05 am

Wonderful ..thanks a lot for posting a good informitive blog

gloria December 27, 2012 at 2:42 pm

I have a Patton tank pressure cooker,and need to find a gasket and a manual. Help! Thanks
us pat.#3632014

joe February 19, 2015 at 2:05 pm

Your incorrect why a pressure cooker…cooks faster. Under pressure yes you gain 38 degrees. However that not the magic. Phase Change is the magic. Water to become steam takes on and holds 500 cals of energy per gram of water. 500 cals that huge. ice to water takes on only 50 cal per gram. A steam burn at 212 F degree has more energy. Look up PHASE CHANGE OF WATER. It really is amazing.

Brenda November 28, 2016 at 4:50 pm

While starting to use a pressure cooker , after we put the items for cooking. The lid became locked not able to open or lock for cooking ???

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