Old aluminum pressure vessels were made differently
than those today using modern manufacturing methods.
Tiny, virtually invisible cracks weaken the pot cause
a drop in pressure which is unacceptable in a canner,
as well as potentially dangerous in either a pressure
canner or cooker. These old vessels do not have
any of the safely features avalable in today's modern
pressure cookers which may offer as many as 6 safety
systems to prevent excessive heat and pressure from
causing the pot the to explode.
There is no way to know if these second hand, used
and vintage cookers are in proper working order
without having them tested. Pressure testing can check the accuracy of the gauge
as well as detecting any leaks that indicate the vessel
is not capable of holding pressure. The weighted pressure regulators
on the old style pressure cookers do not need to be checked. Keep the
clean and rust free.
Most problems with pressure canners is a
gauge that is not working properly or needs to be calibrated.
If the gauge is out
of calibration, it will need to be replaced, or in some cases it may be sent back to the manufacturer for
re-calibration. Check with your manufacturer to see if they offer this
service and the cost. Even newer canners should be tested to ensure the safety
of the food being processed. Dial gauges should be tested annually or more often if used frequently.
local Cooperative Extension may perform this test for you or provide information
on how to get this done. In some cases the manufacturer
may be able to test their various models, or even cookers
made be other manufacturers. Contact manufacturers
directly and inquire if testing services are available
and be prepared to pay a modest fee for this service,
as well as shipping costs both ways. Often, especially
in the case of large, old-fashioned canners, the costs
of shipping out weigh the actual value of the vessel.
If you cannot get it tested nearby, write to see if the manufacturer can do
it. The manufacturer's name and address will be pressed into the canner or on a
plate attached to it. Also check here in the replacement
parts page for up to date addresses. Ask for shipping instructions. Pack it like fine crystal
and label the package "fragile." If you do not have an instruction book for your
canner, write for one.
Some canners have a gasket. These gaskets are made of rubber or
rubber-like compounds to keep steam from leaking out around the cover. You can
remove and replace most gaskets as needed. Some only need to be turned to ensure
a tight seal. Replace a worn, stretched or hardened gasket with a new one. Refer
to the canner instructions for directions. Leakage makes it difficult to reach
the right pressure and may cause the canner to boil dry.