Pressure canners are a common tool used for processing canned goods. Modern pressure canners are lightweight, thin walled kettles with many of them having turn-on lids. They have a jar rack, gasket, dial or weighted gauge, an automatic vent or cover lock, a vent port to be closed with a counterweight or weighted gauge, and a safety fuse. *Note: only purchase pressure canners that have the Underwriter’s Laboratory (UL) approval to ensure their safety.
Pressure Canning Models
Weighted-gauge models control their set pressure automatically and precisely. They control their pressure by exhausting tiny amounts of air and steam each time their gauge rocks or jiggles during processing. The sound of the weight moving during processing indicates that the canner is maintaining the set pressure. Weighted-gauge models are unable to automatically adjust pressure settings to accommodate higher altitude; the user must change the pressure according to their elevation.
How to Use a Pressure Canner
Step 1) Put 2-3 inches of hot water in the canner. If the recipe includes a food that calls for more water make sure it is a USDA approved recipe. Using a jar lifter, place filled jars on the rack. To properly use a jar lifter make sure that it is securely positioned below the screw band of the lid. Keep the jar upright at all times. Fasten canner lid securely.
Step 2) Leave weight off the vent port or open petcock, depending on your model of pressure canner. Heat at the highest setting until steam flows freely from the vent port or open petcock. While maintaining the high heat setting, let the steam flow continuously for 10 minutes. Once vented for 10 minutes, place the weight on the vent port or close the petcock. The canner will pressurize in the next 3-5 minutes.
Step 3) Start the timing process when the pressure reading on the dial gauge indicates that the recommended pressure has been reached. This can be indicated by the dial, when the weighted gauge begins to jiggle or rock, or as the canner manufacturer describes.
Step 4) Regulate heat under the canner to maintain a steady pressure at or slightly above the correct gauge pressure. Check your manufacturer’s directions for how your canner indicates it is maintaining the desired pressure. *Note: if at any point your pressure goes below the recommended reading, bring the canner back up to the appropriate pressure and begin the timing of the process over from the beginning. This is important to ensure proper food processing and safety.
Step 5) When the timed process is completed, turn off the heat, remove the canner from the heat, and let the canner depressurize. It is important not to force-cool the canner– forced cooling could result in unsafe food or spoilage. If you have an older model that does not have a dial gauge, make sure to time the depressurization. Standard-size heavy-walled canners require approximately 30 minutes when loaded with pints to depressurize, and 45 minutes when filled with quart-sized jars. Newer thin-walled canners cool quicker and are equipped with vent locks. These canners are depressurized when their vent lock piston drops to a normal position.
Step 6) After the canner is depressurized, remove the weight from the vent port or open the petcock. Wait 10 minutes, unfasten the lid, and remove it carefully. Lift the lid away from you so that the steam does not burn your face or hands.
Step 7) Use a jar lifter to remove the jars from the canner. Place them on a towel, making sure to leave one inch spaces between the jars during cooling. Let the jars sit undisturbed to cool at room temperature for 12-24 hours.
Pressure Canner Maintenance
Check dial gauges for accuracy at your county Cooperative Extension office before use each year- gauges that read high cause under-processing of food and low readings cause over-processing. Replace gauges that differ by more than 2 pounds.
Clean lid gaskets carefully and according to the manufacturer’s directions. If gaskets get dried out or nicked they can allow steam leaks during pressurization of the canner. Make sure to keep gaskets clean between uses. Older pressure canners may require a light coat of vegetable oil once per year; newer models are pre-lubricated and do not require oiling. If you’re unsure whether your gaskets need oiling check your canner’s instructions.
If new gauges or other parts are required for your canner make sure to give your canner model number and describe the parts that you need. Many replacement parts can be found at stores offering canning equipment or from the canner manufacturers.
Troubleshooting Your Pressure Canner
Pressure canners are effective canners because they can reach high temperatures for the appropriate amount of time to be able to destroy microorganisms; pressure itself does not destroy harmful microorganisms. At sea level, a canner operated at a gauge pressure of 10.5 lbs maintains an internal temperature of 240°F.
If your pressure canner is not maintaining a temperature of 240°F check these two instances:
- If you are at a higher altitude than sea level make sure you have adjusted the pressure on the gauge to the appropriate setting.
- Make sure not to have too much air trapped in the canner. Too much air trapped can lead to lower temperatures. To be safe, all types of pressure canners should be vented for 10 minutes before they are pressurized.