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General and Off Topic => General Discussion => Topic started by: mj on September 22, 2016, 08:29:14 AM
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I have a pressure cooker and I want to know what weight I need to use to run it at 15 psi at an altitude of 3445 ft. above sea level, it has a vent tube with an ID of 3/16". Any science/math guys here who can help me? I think I missed that day in science class with a cold, cough cough. I am gong to guess somewhere in the 3.5 - 4 ounce range as close but I would like to have an exact weight for safety sake. thanks for the help. Regards mj.
PS: no pressure gage on my simple pot. With my my factory regulator weight of just under 3 ounces and at my altitude I am cooking at a lower heat than it would at sea level. I want to adjust (increase) the weight of my regulator weight so that at my elevation my cooker will be operating at an internal pot pressure of 15 psi and that will result in an increase in internal temperature to what I can presently achieve. Thanks.
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USDA canning --- http://nchfp.uga.edu/publications/publications_usda.html
Of coarse it helps if it's properly calibrated, they say it's susposto be done every 3 years
(http://)
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Thanks for posting. My understanding is that I need to calculate the actual weight for a new regulator weight itself for my situation if I want a pot pressure of 15 psi. A standard 15 psi regulator weight for use at sea level is typically around 3 ounces in weight, as you go up in elevation you will require the weight of the regulator to increase to compensate for the decrease in atmospheric pressure. You are usually told to cook for a longer time as the decrease in pressure results in a lower pot temperature. I want to build a new regulator weight so I can cook at 15 psi which will be a higher internal temperature than what I an achieving now. I hope this makes sense.
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https://www.sciencemadness.org/
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the consensus is that the pressure difference is about 12% so the regulator weight has to go up 12% . Done will check it out on some brown rice tomorrow and see how much more quickly it cooks. Thanks for the help.
Note: asking more questions not sure that this is the correct answer I think I have been asking the wrong questions will get back as this develops.
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(http://static.fjcdn.com/pictures/It+s+so+cool+thinking+about+re+watch+steins+gate+again_ada81f_5155583.jpg)
http://www.youtube.com/watch?v=OnwBLXuAWX4
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What's the atm at 3445 ft?
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roughly : 900hPa
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the standard you have ....does it have a psi number at all?
It may not matter anyway, if your standard is for 15 psi then the Lower temp won't matter bc at the lower atm you're boiling at a lower temp and the vapor pressure will be the same as it would be if it was boiling at sea level, at 212, but only if your standard 3 oz is for vapor pressure of 15psi....in theory. I don't have a pressure cooker but I would ask some one here who has one to see how heavy their 15 psi standard is.
And while the temp will be lower its not very much, what are you cooking? If it's for autoclaving,, it shouldn't be too much longer in time, and you could always increase temp except you would vent more vapor. I can see why you would want a heavier oz.
I'll see what I can do in a bit
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Do you know the volume ? I was wrong about the temp though, increasing temp will only increase the steams temp
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sciencemadness.org
sciencemadness.org
sciencemadness.org
Please direct your questions to the aforementioned address. Also, if you would be so smart, there is this thing called Newtonian physics (complete with calculus included for free along with the physics knowledge which is free, too); y'all should learn how it works; It can, and will, make your life much easier (and possibly save it, as well; hell, just run a few kinematic thought experiments about what happens to your body when it gets into a motorcycle wreck, and then feel free to thank me when you decide to never ever ride one of those TBI-inducing-death-trap-machines again).
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Do you know the volume ? I was wrong about the temp though, increasing temp will only increase the steams temp
PV=nRT
P=F/A
F=ma
http://www.scienceofcooking.com/science_of_pressure_cooking.htm
Enjoy, kiddos,
-Mangrove
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Also America's super outdated super screwed up system of scientifically unsound physical measurements makes us scientists stroke-out on the inside from pure nuclear hot rage at the fact that people would have the chutzpah to dare to nix metric and "American" units into one physics equation, not convert the Amercian gobblety-gook into actual SI units of measurements, and then expect their super expensive pressure cookers not to blow up in their faces when they dare to mix the sacred with the profane. This is a super-unkosher move when it comes to this sacred science of physics.
Don't mix your units up; otherwise you're results are just going to literally blow up in your face.
Keep it Kosher,
-Mangrove
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The easiest way to solve this is to start with what temp you want to have
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The easiest way to solve this is to start with what temp you want to have
For the love of Jesus Tap Dancing Christ, please please please convert it to kelvin, or at the very least, Celsius; Fahrenheit is for flunkies.
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I could be wrong but I think this is the equation for determining the pressure and temp that may be needed......however I've got to get back to my own, so I check on this later, we re going to get this :)
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I could be wrong but I think this is the equation for determining the pressure and temp that may be needed......however I've got to get back to my own, so I check on this later, we re going to get this :)
NOW we're cooking with gas ;)