Pressure canner physics
I have this pressure canner at home which unfortunately does not include a thermometer. The vessel has a volume of 18 liters. The procedure that I am following is this : pouring 3 litres of water inside it with the lid slightly open and waiting for the water to boil. After it boils I wait for around 10 minutes so that any air trapped inside the canner is squeezed out. Afterwards I close the lid. Can I assume that if I reach 1 bar pressure inside the pressure canner I will have 120 degrees Celsius inside it?
PS: I live at an altitude of around 700 meters.
Best Answer
pouring 3 litres of water inside it with the lid slightly open and waiting for the water to boil.
Good. You definitely want to get everything up to local boiling. The amount of water is reasonable for many canners, but depends on the model and size.
After it boils I wait for around 10 minutes so that any air trapped inside the canner is squeezed out.
If you haven't closed the lid, this serves no purpose doesn't do anything about "squeezing out the air". However in many canning recipes there is a boil period with your jars in the water before the pressure phase. If you had room temperature food in the jar it can take a while to come up to temp. A 10 minute boil gets the food heated up so the (later) pressure cook phase doesn't have to last as long.
Afterwards I close the lid. Can I assume that if I reach 1 bar pressure inside the pressure canner I will have 120 degrees Celsius inside it?
The operating pressure indicated on a pressure cooker is the target additional pressure over your local atmospheric pressure that should be maintained during cooking. (The operating pressure may be lower than the maximum on the relief valve).
At 700m altitude, the ambient standard pressure is 930mbar (but can be lower with low pressure systems). Let's say on a rainy day that it's as low as 900mbar for you.
IF your cooker operates at a true 1 bar, then the internal pressure will be 900 + 1000 or 1900mbar (27.5 psi / 1.87 atm) absolute. Using a calculator you can find that water will be at 118.6C/245.5F when it is boiling under such pressure.
Pictures about "Pressure canner physics"
How does a pressure cooker work physics?
A pressure cooker is based on the principle that with the increase in pressure, boiling point of water increases. It works by capturing the steam which increases the pressure in the vessel. Due to increase in pressure the boiling point of water rises up.How does a pressure canner work?
Pressure canners and pressure cookers work by trapping steam and building up pressure inside a pot. The steam is trapped because the lid, which is fitted with a rubber gasket, forms an airtight seal once it's locked into position. As the contents of the pot heat up, steam gets trapped and pressure builds.How does a pressure cooker work thermodynamics?
A pressure cooker is a thermodynamic system. According to the definitions of thermodynamic systems, a sealed pressure cooker with the whistle in position is a closed system as no mass can enter or leave the pressure cooker, but heat can be transferred to it.What makes a pressure canner explode?
Pressure cookers can explode for many reasons, including being overfilled, using oil improperly, and vents being clogged. These are all preventable reasons by the user. A pressure cooker can also explode due to a malfunctioning or defective part.How does a Pressure Cooker Work? - Science for Kids | Educational Videos by Mocomi Kids
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