The standard cooking pressure of 15 psi gauge was determined by the United States Department of Agriculture in 1917. At this pressure, water boils at 121 °C (250 °F) (described in vapour pressure of water article).
How are pressure cooking times affected by “high altitudes”? Isn’t atmospheric pressure already 15 psi?
The pressure cooker adds pressure above the current atmospheric pressure. Since there is a pressure difference in the atmosphere between one altitude and another, the pressure cooker’s pressure will vary accordingly.
At sea level, the atmospheric pressure averages 14.7 psi – add 15 psi of pressure generated by the pressure cooker and the food in the cooker is cooking at 29.7 psi of absolute pressure.
Moving up in the atmosphere, or going to higher altitude, the atmospheric pressure decreases. So in Denver Colorado (about 5,000 feet) the atmospheric pressure averages only 12.2 psi- add 15 psi of pressure generated by the cooker and there the food is cooking at just 27.2 psi of absolute pressure -almost 3 psi less pressure than pressure cooking at sea level!
No matter where you are, a pressure cooker will always add pressure to the current atmospheric pressure.
The same 15 psi pressure cooker will cook 15 psi in San Francisco, California (sea level) but only 12.5 psi in Denver, Colorado (5,000 feet). Now, “standard pressure cooker” has become “non-standard” in Denver. This means that the recipes will need the same timing adjustments used for non-standard pressure cookers (see pie chart, above).
What are “standard” and “non-standard” pressure cookers?
To facilitate the writing of pressure cooker cookbooks and sharing recipes, there is an un-official standard. This standard includes the maximum operating pressure for American Pressure Cookers (15 psi) and the maximum operating pressure for most modern European Cookers (which is about 13 psi for spring-valve type cookers).
Any pressure cooker that does not fall within this range – or used in a high-altitude situation (see below) – is “non-standard.”
There is no international pressure cooker organization that sets a global standard. Pressure cooker UL Rating, which is an American Appliance Testing standard, only states that a domestic pressure cooker “operate at a nominal pressure of 15 psi (103 kPa) or less.” While in Europe the CE rating, the equivalent to the American certification, state that a “simple pressure vessel” can be above .5 bar (7.2 psi) and below 50 bar (720 PSI) . American manufactured pressure cookers adhere to a standard for pressure canners set by USDA in 1917 – 15 psi.
While some European pressure cookers are sold world-wide many of these manufacturers make a separate model specifically for the American market that reaches 15 psi. Some European manufacturers are switching to a single model distributed world-wide that reaches 15 psi. At the writing of this article, American pressure cooker manufacturers only sell their pressure cookers in the United States.
The Science Behind Pressure Cookers
FAQ
How hot is a pressure cooker at 12 psi?
What is the temperature of a pressure cooker at 20 psi?
What is 15 pounds of pressure in a pressure cooker?
Pressure Inside The Pressure Cooker
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Cooking Temperature
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0 pounds (psi)
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100ºC (212ºF)
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5 pounds (psi)
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104ºC (220ºF)
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10 pounds (psi)
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113ºC (235ºF)
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15 pounds (psi)
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121ºC (250ºF)
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How do I keep my pressure cooker at 15 psi?
Can a pressure cooker cook at 15 psi?
Most pressure cookers cannot cook higher than 250 degrees Fahrenheit, making 15 PSI the maximum that they can reach. As soon as your pressure cooker hits 15 PSI, you want to turn it down to stop the pressure from building. Most recipes will call for the pressure cooker to reach 15 PSI, but it also depends on the recipe and what you’re cooking.
How hot does a pressure cooker get?
A pressure cooker maxes out its temperature once it reaches 250.1 degrees Fahrenheit. The device traps hot steam inside, which helps to cook the food faster. The temperature of pressure is much lower than in other cooking methods. How Hot Is a Pressure Cooker at 11 Psi?
Can a pressure cooker cook at 250 degrees Fahrenheit?
However, with a pressure cooker, it can reach 250 degrees Fahrenheit when at its highest pressure setting of 15 psi, which also aids in reduced cooking time. Pressure cooking is fast, easy, economical and convenient. It also doesn’t take as long to master as other methods of cooking.
What does PSI mean in a pressure cooker?
It directly corresponds to the rise in temperature. This heat gets transferred to the food. Most pressure cookers like the Crock-Pot Express are designed to reach 15 psi (pounds per inch), which is the unit for measuring the amount of pressure inside the pot.