Pressure canning equipment needs to be checked yearly to be sure it is proper operation condition. Canners with dial gauges can get out of adjustment and no longer give an accurate reading of the pressure inside of the canner. This happens as the gauge gets old; with heavy use the gauge which results in expansion and contraction of the metals parts causing them to become brittle.
Turn off heat. Allow canner to cool until gauge reaches "0". Before opening lid, tough safety vent to be sure no pressure (live steam) escapes. Remove lid.
A gauge which is inaccurate by 1 pound, high or low, should be replaced. For every 1 pound of pressure the gauge is "off", it will be off by 2-3 F. If the maximum temperature thermometer reads 2 F high or low (at the corresponding pressure), replace the gauge.
