Steam Pressure Canner Stainless Steel Pressure Canner
How Altitude affects Processing Times - Steam Pressure Canner Altitude Adjustment

Altitude in feet

Weighted Gauge Pressure

Dial Gauge Pressure

0 to 1,000 10 lbs. 10 lbs.
1,001 to 2,000 15 lbs. 11 lbs.
2,001 to 4,000 15 lbs. 12 lbs.
4,001 to 6,000 15 lbs. 13 lbs.
6,001 to 8,000 15 lbs. 14 lbs.
8,001 to 10,000 15 lbs. 15 lbs.

Because water at higher altitudes boils at lower temperatures, the pressure must be increased to raise the temperature to the required 240 degrees F. That is why the higher pressures are needed.