Canning at High Altitude
Using the process time for canning food at sea level may result in spoilage if you live at altitudes of 1,000 feet or more. Water boils at lower temperatures as altitude increases. Increasing the process time or canner pressure compensates for lower boiling temperatures. Therefore, select the proper time and pressure for the altitude where you are canning.
Canning food altitude.
The following table can be used for pressure and temperature conversion for canners that use the metric system.
|Boiling water temperature and associated pressure|
|° F||° C||Pounds per square inch (psi)||Atmosphere (atm)||Bar|
A weighted gauge comes in three pressure settings: 5, 10 and 15 lbs. After the canner is being vented, the pressure inside is 14.69 psi and the temperature at 212° F, 100° C.
- Adding a 5 lb weighted gauge increases pressure to 14.69 + 5 = 19.69 lb of pressure which corresponds to about 227° F, 108.5° C.
- Adding a 10 lb weighted gauge increases pressure to 14.69 + 10 = 24.69 lb of pressure which corresponds to about 240° F, 116° C.
- Adding a 15 lb weighted gauge increases pressure to: 14.69 + 15 = 29.69 psi. This corresponds to 250° F, 121° C.
Recipes usually list processing times and pressures for altitudes of 0-1000 feet for dial type and weighted gauge pressure canners. If you are canning at higher altitudes, follow the USDA altitude adjustments listed below.
|Canning Pressure (in pounds) at Different Altitudes|
|Altitude (feet)||Dial Gauge Pressure Canner||Weighted Gauge Pressure Canner|
NOTE make sure you know the type of your pressure canner.
If your recipe calls for 15 lbs. pressure at the sea level increase the pressure 1 lb. for each 2000 feet altitude. Thus at an altitude of 4000 feet, process food at 17 lbs. of pressure instead of 15 lbs. pressure. If you canner will not allow you to increase the pressure over 15 lbs., increase processing time 20% for each 1,000 ft. rise in altitude.