A pressure canner is the only safe method for canning low acid foods—red meats, seafood, poultry, and low acid vegetables. Ensuring your pressure canner is working properly and in good condition is critical to producing unquestionably safe products every year.
Dial Gauges Must be Tested Annually for Accuracy
Most of today’s pressure canners have either a dial gauge or weighted gauge for indicating and regulating the pressure. There is one exception; the All American brand has both a dial and weighted gauge. For canners having a dial gauge, safe canning beings with getting the gauge checked for accuracy yearly or before the start of the canning season. A dial gauge has movable parts which can go out of calibration. Gauges that read high cause under-processing and may result in unsafe food. Clostridium botulinum bacteria are the main reason why low-acid foods must be processed with the correct pressure and time to be safe. Gauges with low readings may cause over-processing which is not a food safety issue, but rather a food quality issue. Pressure adjustments can be made if the gauge reads 2 pounds high or low. Gauges testing more than 2 pounds of difference, should be replaced. The dial gauge should also be checked if any of the following conditions exist: cover has been submerged in water or dropped, gauge lens is broken or has fallen out, parts are rusty, pointer is not on “0”, or for any reason you believe the gauge may not be accurate. The dial should be replaced if it is cracked, rusted, or the glass is missing. Gauges on new canners and replacement gauges should be tested before use.
Weighted gauges do not require testing for accuracy because they cannot go out of calibration.
Dial Gauge Testing Services
There are several services that provide dial gauge testing.
Local County Extension Office – Many County Extension Offices have the equipment and trained personal for testing the National (National Pressure Cooker Company), Magic Seal (sold by Montgomery Ward), Maid of Honor (sold by Sears, Roebuck and Company), or Presto® brands. Check with you local office for availability or to find out about testing events in your area. AnswerLine (800-262-3804 or 515-296-5883) can help residents of Iowa and Minnesota find a location for testing in your area.
Presto – National Presto Industries will test dial gauges at no charge provided it is one of the following brands: National (National Pressure Cooker Company), Magic Seal (sold by Montgomery Ward), Maid of Honor (sold by Sears, Roebuck and Company), or Presto®. Check out the Care and Maintenance Guide at Go.Presto.com for information on how to send a gauge for testing.
Hardware Stores – some hardware stores also offer this service. Call before you go.
All-American – For testing of All-American dial pressure gauges, contact Wisconsin Aluminum Foundry, 920-682-8627. The weight is more accurate than the gauge and customers should use the weights to attain the correct pressure. If the weight begins to rock at the desired pressure and the gauge is off by more than 2 psi the company recommends replacing the gauge. The gauge is primarily used as a reference to know when the unit is at 0 psi and can safely be removed and the canner opened.
Canner Manufacturers – For pressure canner brands not aforementioned, contact the manufacturer of the unit.
After testing is complete, you will get a Canner Dial Gauge Testing Report or similar. It is a good idea to keep the reports for reference.
In addition to getting dial gauges checked, there are a number of other items to check out to make sure that the canner is in good working order for canning season. If any of the following do not check out, they should be replaced or cleaned as needed.
Annual Pressure Canner Checklist
|Jars must be off the bottom of the canner during processing to reduce stress on the glass. Rack
should be free of rust and strong enough to support weight of jars.
|The intense heat of pressure canning may cause the gasket to shrink or crack allowing air and
steam to escape under or around the lid. Under normal conditions, the gasket should be replaced
every three years or sooner if steam or water is coming out around the lid or if a hissing sound is
detected. Wash the gasket to remove any food deposits or grease that may have accumulated on
the gasket. Also wash the gasket trough before replacing the gasket.
|The pressure plug should be replaced at the same time that the gasket is replaced. Many gasket
replacements come with the pressure plug as well.
|Corrosion of any sort, water deposits, food debris, etc., in the vent pipe can cause a build-up of
pressure inside the canner that is not registered on the dial or it can prevent the weight from jiggling.
Use a pipe cleaner to brush along the sides and clean away any deposit that my be there.
|Most weighted gauge canners use a three-piece system–a center piece that fits onto the vent
pipe and two rings that slip over the center. Each piece measurers 5 pounds of pressure. If 15
pounds of pressure are needed, all three pieces are used together. For 10 pounds of pressure,
use the center piece and one ring. For 5 pounds of pressure, only the center piece is needed.
Another type of weighted gauge is a round disc that is turned to the appropriate poundage needed
and placed on the canner.
|The manual that came with the canner is invaluable for learning more about the canner, model
number, etc. If the manual has become lost, the Pick Your Own website has a listing of canner
manuals to download. If the canner is several years old, there is a good chance that the
processing information in the manual is out of date. Should this be the case, replace the manual
with the USDA Complete Guide to Home Canning (2015) (purchase or download).
Replacement parts are available at some hardware stores or stores that also sell food preservation equipment. Parts may are also be purchased directly from some of the manufacturers. The Pressure Cooker Outlet has replacement parts for many makes and models of canners. Parts can also be found at Amazon.com. Be sure to know the canner model number and part number of the needed item (may be found in the canner manual). The model number can be found on the bottom of the canner, the handle, or the lid.
Start the canning season off right. Get the gauge tested and make sure that your canner meets all check marks.
- Care and Maintenance Guide, National Presto Industries
- Pressure Canner Dial Gauge Testing, PennState University Extension
- Testing Dial Pressure Canner Gauges, University of Minnesota Extension
- Testing Dial Pressure Canner Gauges, South Dakota State University Extension
- Pressure Canner Manuals, PickYourOwn.org
- So Easy to Preserve, University of Georgia Cooperative Extension
- USDA Complete Guide to Home Canning, USDA National Institute of Food and Agriculture
- Pressure Canner Checklist, PennState Extension