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Old 07-21-2006, 04:24 PM   #1
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Test Pressure Cooker Gauge

Hello,

I have recently purchased a 22 quart Presto Pressure Cooker. It's a very cool old-school looking model with a separate pressure gauge on top. The instructions indicate that the pressure gague should be tested by my local county extension office before use.

I'm located in Los Angeles county - in the pasadena area. I found the UCDavis Cooperative Extension web site:
http://celosangeles.ucdavis.edu/nutrition/index.html

I called number listed under "Food Preservation Education" (323) 260-2267 and I was told they no longer test pressure cooker gauges - they could not provide me with any information on who could test the gague - they suggested contacting the manufacturer.

I tried calling the Presto's service department - they could only tell me to contact my local extension. Presto said I could mail the gague to them for testing, but that it may again become inaccurate if mishandled during return shipping.

I'm hoping someone here can provide me with some new ideas on who to contact to get my gauge tested. Are there other companies/organizations that I may find locally that can test this (plumber? fire department? scuba tank filler?) I'm grasping at straws here!!! Help!

I've also considered using the pressure cooker without testing the gauge - what's the worst that could happen?

Thanks!,
Fritz

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Old 07-21-2006, 04:29 PM   #2
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I am sure someone will come along with a suggestion for you. I unfortunately do not know the answer to your main question.

For an answer to "What is the worst that could happen" though, from my understanding what could happen is the pot could explode spewing above boiling temp liquid and food all over. It would basically become a bomb. Be very careful!
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Old 07-21-2006, 04:53 PM   #3
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I have two pressure cookers, both made by Kuhn Rikon in Switzerland, and they're fantastic! Madhur Jeffrey swears by them in her wonderful Indian cookbooks, and they make great stews of all sorts.

However, you must know that pressure cookers can be very dangerous if the pressure is allowed to build too high, so the gauge and the valves that release pressure must work properly. I'm not sure if a pressure cooker can actually explode, or whether that's urban myth, but I wouldn't want to find out. I would NOT trust an old gauge to work properly, and I probably wouldn't want to use an old pressure cooker that relied on such a gauge unless it had other safety devices built in.

Modern pressure cookers like those from Kuhn Rikon have triple safety devices. They don't use a dial-type gauge like the older units, but instead have a spring-loaded valve with an indicator that rises above the lid as the pressure builds up. There are marks on the indicator to show whether the pressure is high or low (the only two settings usually used for most recipes). If the pressure pushes the indicator too high, it lets steam escape so that the pressure never exceeds the danger point. Pressing the indicator down also releases pressure, which is absolutely essential before opening the unit (the failure to release the pressure may be the source of many of the explosion stories -- if the pressure isn't released before opening the lid, steam and superheated food would fly all over the place, and the lid would hit the ceiling -- or your head).

The second safety device is a pair of valves in the lid, under the rubber ring that seals the lid (BTW, the ring MUST be in good shape for the unit to operate properly and safely). If the first device fails to open, these valves are pushed open by the pressure, allowing steam to escape from under the rim of the lid.

The third safety device is an emergency valve in the lid that will blow open if all the others fail.

One word of caution -- despite all of these devices, never leave a pressure cooker on the stove unattended. They're very safe if used properly. If you don't know what your doing, get "Pressure Cooking for Dummies" or any of Lorna Sass's great books on pressure cooking.
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Old 07-21-2006, 06:04 PM   #4
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I have an old pressure cooker that was handed down by my grandparents to me. It uses the little device that rattles atop a steam nozzle. This one is unique in that the "dancer" as I call it, has three different sized openings to set over the steam nozzle. One is marked 5 lbs., with the second labeled 10 lbs., and finally, the last lis labeled 15lbs. I once defeated the saftey of using the "dancer" weight as I couldn't find it. I instead used a weight for another pressure cooker. (this was done in my younger, more foolish years). The result was that the little plastic safety release bubble shot upward like a bullet and steam and liquid spray got my ceiling all messy. I had to do a lot of scrubbing. But the safety device did its job, preventing the internal pressure of the pot from loading the pan metal beyond its limit. I replaced the safety device, found the correct wieght, and have been using the pressure cooker successfully for years. It works very well for me.

The lesson learned? Follow the directions and never substitute or defeat the safety devices built into the pot.

As for removing the lid before the pressure escapes, well here's the physics.

Force of pressure F is defined by the equation: force F = Pressure per square inch PSI multiplied by the area in square inches, or F = PSI X Area.

So, if your pressure cooker lid has an area of 80 square inches, and the internal pressure reaches 15 lbs., then the generated force upon the lid = 80 multiplied by 15, or 1200 lbs. This amount of force, if released sudenly, by opening the lid before allowing the pressure to escape, would probably blow the lid right out of your hands. The sudden depressurization would cause the scalding contents to explode outward from the pot in all directions. You would most certainly be injured by the hot contents, and possibly killed by the fast-moving lid.

Even if you let almost all of the pressure escape, let's say that ony two lbs. of pressure remained, you would still have 160 lbs. of force to control when you opened the lid.

This is very scary until you realize that by simply letting all steam escape, all pressure is equalized and there is no dangerous pressure to create any force on the lid. The outside and inside pressures become equal.

So yes, pressure cookers are very safe. And, if used improperly, very dangerous.

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Old 07-21-2006, 06:34 PM   #5
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And because of the high pressure, the steam and food are superheated to well above 212 degrees (100 Celsius), the normal boiling point of water.

But, even on his best day ever, I doubt that even Arnold Schwarzenegger could have gotten the lid off either of my pressure cookers without first releasing the pressure. I can barely budge it until there's no steam coming from the relief valve.
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Old 07-21-2006, 11:40 PM   #6
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Fritzy - you started where I would have suggested - with the county extension office. You might try contacting the state office - California Department of Food and Agriculture and see if maybe they can point you in the right direction. If not, my next place to contact would be the Division of Measurement Standards.

If they can't help - then maybe calling a dive shop might give you a lead on who can certify pressure guages. If that doesn't work ... look in the yellow pages for places that sell/repair industrial/medical gasses/quages.

What can happen if the guage is off? If it is reading low - you'll blow the safety seals and make a big mess trying to get it up to pressure according to the dial - or if the pressure isn't high enough to blow the safety seals the food will cook quicker than the "recipe" states. If it reads high - then just the opposite ... the food will not be done according to the time on recipe or chart.

If this is a pressure cooker/canner and you are using it for canning ... same thing goes for if it reads too low ... if it is reading high then the food will not be properly processed for safe storage according to the canning instrucions.
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Old 07-22-2006, 11:48 AM   #7
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Good point! I assume that you intend to use your 22-quart pressure cooker for canning, not for making a 500-pound batch of lamb vindaloo.

You need to be aware that the improper canning of certain food items, particularly those with low acid content, is a major cause of botulism poisoning, which is very often fatal. The jars of food must be heated to the proper temperature and keep there for sufficient time to kill the bacteria that produce the deadly toxins. That is, the bacteria don't kill you, but what they leave behind in the jar is a deadly poison. Because of this, a malfunctioning gauge or thermometer could be an invitation to disaster.


Here's what the Center for Disease Control says about preventing botulism poisoning:
Botulism can be prevented. Foodborne botulism has often been from home-canned foods with low acid content, such as asparagus, green beans, beets and corn. However, outbreaks of botulism from more unusual sources such as chopped garlic in oil, chile peppers, tomatoes, improperly handled baked potatoes wrapped in aluminum foil, and home-canned or fermented fish. Persons who do home canning should follow strict hygienic procedures to reduce contamination of foods. Oils infused with garlic or herbs should be refrigerated. Potatoes which have been baked while wrapped in aluminum foil should be kept hot until served or refrigerated. Because the botulism toxin is destroyed by high temperatures, persons who eat home-canned foods should consider boiling the food for 10 minutes before eating it to ensure safety. Instructions on safe home canning can be obtained from county extension services or from the US Department of Agriculture. Because honey can contain spores of Clostridium botulinum and this has been a source of infection for infants, children less than 12 months old should not be fed honey. Honey is safe for persons 1 year of age and older. Wound botulism can be prevented by promptly seeking medical care for infected wounds and by not using injectable street drugs.


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Old 07-22-2006, 11:55 AM   #8
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I would keep trying various phone numbers for your local county extension office. Around here, the tester makes rounds around the counties and you must call and make an appointment, then the tester is sent to your nearest operating office.
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Old 07-30-2006, 02:50 PM   #9
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Quote:
Originally Posted by fritzycat1
Hello,

I have recently purchased a 22 quart Presto Pressure Cooker. It's a very cool old-school looking model with a separate pressure gauge on top. The instructions indicate that the pressure gague should be tested by my local county extension office before use.

I'm located in Los Angeles county - in the pasadena area. I found the UCDavis Cooperative Extension web site:
http://celosangeles.ucdavis.edu/nutrition/index.html

I called number listed under "Food Preservation Education" (323) 260-2267 and I was told they no longer test pressure cooker gauges - they could not provide me with any information on who could test the gague - they suggested contacting the manufacturer.

I tried calling the Presto's service department - they could only tell me to contact my local extension. Presto said I could mail the gague to them for testing, but that it may again become inaccurate if mishandled during return shipping.

I'm hoping someone here can provide me with some new ideas on who to contact to get my gauge tested. Are there other companies/organizations that I may find locally that can test this (plumber? fire department? scuba tank filler?) I'm grasping at straws here!!! Help!

I've also considered using the pressure cooker without testing the gauge - what's the worst that could happen?

Thanks!,
Fritz
I think if it is new, the place that made it checked the guage before they boxed it. If it is not new, definitely check with your home demonstration agent or extention agent. I've canned for 50 years and have only had the one I use tested once. It was fine. Which tells me as long as the guage isn't dunked in water, dropped, or banged around, it most likely is okay. If you are in question, some old hardware stores are able to test them. Look in your phone directory for guage testing or pressure cooker parts; that will be the person who will test it for a fee. Your Extension agents will test it for free.
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