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rezasmith
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Registered: 01/27/20
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Question about Pressure cooker 1
#26674683 - 05/16/20 11:41 AM (3 years, 8 months ago) |
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So it's pretty hard to find big pressure cookers where i live and i don't have access to amazon ebay etc either so i finally found a 16 L pressure cooker and on the lid it says min pressure 0.55bar(8psi) and max 1.10bar (16psi)
and the regulator has a system that when you bend it , it will take alot longer to whistle again so my question is this : do you think when i bend the regulator it actually reaches 16 psi? cause other wise that min/max thing doesn't make sense to me

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meanoldman
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Re: Question about Pressure cooker [Re: rezasmith]
#26674699 - 05/16/20 11:48 AM (3 years, 8 months ago) |
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Without a gauge, you won't really know the pressure. If it's whistling through the vent, then you cam the lever over and it takes a while to start whistling again, one could assume you raised the pressure relief threshold.
The difference between 8psi and 15psi is like 15*F
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rezasmith
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Re: Question about Pressure cooker [Re: meanoldman]
#26674716 - 05/16/20 11:56 AM (3 years, 8 months ago) |
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Quote:
meanoldman said: Without a gauge, you won't really know the pressure. If it's whistling through the vent, then you cam the lever over and it takes a while to start whistling again, one could assume you raised the pressure relief threshold.
The difference between 8psi and 15psi is like 15*F
I mean it's true that the difference in temp is low but the 15psi is alot more reliable to kill contam at the certain time Is there anyway to test the pressure? like cooking a food or something? i don't know how else i can make sure it actually reaches 15psi other than a gauge
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A.k.a
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Re: Question about Pressure cooker [Re: rezasmith]
#26674917 - 05/16/20 01:47 PM (3 years, 8 months ago) |
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I’d just cook a couple quarts of grain for 90 or 120 minutes and see if it goes bad.
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LAGM2020     
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Moower
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Re: Question about Pressure cooker [Re: A.k.a]
#26675138 - 05/16/20 03:31 PM (3 years, 8 months ago) |
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OK. I actually studied the matter for like a week some other time.
The difference between 0.55 bar and 1.10 bar may seem like small one in regards to temperature (113C vs 122C). After all it's ONLY 9C! 7,4%. How much of a difference could that make? Turns out that it makes enormous difference.
Generally sterilization is made at 121C, and if we want to change that temperature we have to also change the time.
F0 value is used to determine the exposure time of material for sterilization at a particular temperature. F0 value is the time in minutes for the specified temperature that gives the same thermal lethality as the 121C in one minute.
It explains that temperature is not as important factor in thermal sterilization as one might think, but lethality is very important. Time of sterilization can be changed according to the lethality of the temperature.
F0=dt / 10^((T-121)/10)
Where: T-temperature of sterilization dt - 60s (1min)
Thus by sterilizing at 113C compared to recommended 121C we can put this into the equation:
F0 = 1 / 10^((113-121)/10) F0 = 1 / 10^(-0.8) F0 = 6.31
To achieve same level of sterilization at 113C as at 121C, You'd have to sterilize for 6.3x longer. And suddenly the difference is enormous.
Getting back to the question. Make sure that those are really 2 different setting and that 1.1 bar isn't rating for 2nd safety valve. If 1.1bar is in fact the accurate pressure for the knob folded down, then on the other hand you can Pressure cook for 80% of the original time 
*All calculations based on the level of the sea.
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