Pressure canning. How critical is altitude?

SKR8PN

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Do any of you ever factor in your altitude when your pressure canning? Reason I am asking is........The Wife was canning some chicken today with our Presto 23 qt canners. Those canners come with a heavy weight, and you have to keep the pressure where it needs to be by playing with the heat. I purchased a couple of the "adjustable" weights because you can set them for 5, 10 or 15 lbs and not have to monitor it as closely. Wife forgot to set the weights for 10lbs of pressure and the canners went to 14-15 lbs(twice!) before she finally realized her mistake. She managed to remove the one ring from each weight without having to remove the weight completely off the canner, which would have dropped the pressure. She NEVER let the pressure get BELOW the 10lbs required.
ANYWAY....she got all flustered and called Presto. When The Wife explained to the lady what had happened, she asked what our altitude was !?!? We are only 1200 ft above sea level, but she tried to tell the wife that IF we were using the adjustable weights, we should have been processing at 15 lbs, NOT the 10 lbs called for in the Ball Canning book. Her reasoning was, the adjustable weights won't maintain the 10 lbs, even though we explained we still use the gauge to double check the pressure. She was adamant that we should have been doing 15lbs instead of 10lbs with these weights and at our altitude. BUT, in the next breath, she said that IF we use the original weigh that came with the canner, we didn't need to worry about adjusting for altitude unless we were 2000 ft or higher. She was VERY confusing and didn't make any sense to me....... 10 lbs is 10 lbs no matter WHAT weight your using.
I told The Wife that I would ask the experts here and get another opinion or three.
 
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We are at 6400 ft. Wife says she has to keep it at 15lbs because of the altitude. She's been very successful at canning.
 

Ldychef2k

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Sometimes when I am canning, I get distracted and the pressure gets up to 15 and can stay there a while. I have some siphoning (loss of liquid) but have not noticed any other problems. An expert may speak to this better than I, but I believe the internal temperature will still get to the right level to kill the germs. I believe that the main issue is losing water and how it affects the seal. If the liquid that siphons has fat in it, the seal may not hold.
 

farmerlor

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I was told that you canned at 1 pound over recommended pressure for every 1000 feet. Critical? I have no clue because that's what I've always done. The only time I ever lose any contents in the jar is if I've filled them too full in the first place. I almost never have a jar not seal but then I'm a freak when it comes to cleaning the rims of my jars.
Another thing I've just discovered (not to hijack the thread or anything) is that I don't have to pre-heat/boil/sterilize the flats. I just clean the rims of the jars meticulously per usual, stick the flats and rings on and process. STILL haven't had a jar fail on me.
 
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farmerlor said:
I was told that you canned at 1 pound over recommended pressure for every 1000 feet. Critical? I have no clue because that's what I've always done. The only time I ever lose any contents in the jar is if I've filled them too full in the first place. I almost never have a jar not seal but then I'm a freak when it comes to cleaning the rims of my jars.
Another thing I've just discovered (not to hijack the thread or anything) is that I don't have to pre-heat/boil/sterilize the flats. I just clean the rims of the jars meticulously per usual, stick the flats and rings on and process. STILL haven't had a jar fail on me.
Super Freak.
 

SKR8PN

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We don't sterilize the flats, but we do keep them in hot water to help soften the seals. Seems to make them seal better. We also keep the tops of the jars as clean as we can. The Wife wipes them down just before she installs the flat and the rings. My job is "Chief Jar Filler" and I also am "The guy who carries the full jars out and sets them the canner" and "He who removes the HOT jars when the time is up"
I also tote the cooled jars down to the pantry. :gig
 
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