Before using your pressure canner, have your dial gauge tested for accuracy. Testing will ensure your pressure canner reaches the appropriate pressure needed to process low-acid foods, such as vegetables and meats, safely. Over time, a pressure canner's dial gauge will become inaccurate, resulting in either reading too high or too low. If the pressure gauge reads too high, it will lead to under-processing resulting in unsafe foods. This is because the high temperature needed to destroy harmful microorganisms, such as the botulism toxin, can only be reached under pressure. If the dial gauge reads too low, your product will lose quality due to over-processing, and foods may become mushy.
If the dial gauge reads up to two pounds high or low, slight pressure adjustments can be made without replacing the dial gauge. However, if it differs by more than two pounds, the gauge must be replaced.
The only way to know if your pressure gauge is accurate is to have it tested. University of Illinois Extension is holding Pressure Canner Testing Clinics beginning this May and will run through July. These events will be held at the local Extension offices, with several dates to choose from. Bring in your pressure canner lid with the gauge attached. Staff will inspect the lid, gasket, and gauge for accuracy and provide you with an assessment. We do not test weighted gauge pressure canners. However, if you’d like it to be inspected, we can do that.
Please Note: We test gauges for National, Magic Seal, Maid of Honor, and Presto brand canners. We do not test weighted gauge pressure canners. However, we can inspect the gaskets and lid of these canners. The All-American pressure canner is a weighted gauge canner with a reference gauge; therefore, we do not test the gauges on an All-American canner.