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Idkleine
Stranger


Registered: 02/23/14
Posts: 81
Last seen: 2 years, 9 months
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Pressure cooker vacuum
#21644072 - 05/06/15 01:03 PM (9 years, 14 days ago) |
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The literature GGMM and others mention multiple times that you can have problems with contams getting inside if your pressure cooker does not form a vacuum when it cools. I am using several older All Americans. The gauges only read pressure and not vacuum. So.. how can I tell if It is forming a vacuum or not? So far I have assumed that it is not, and try to take all the necessary precautions, Trash bagging the top of it as soon as its cool enough to touch, and opening it in wind of the the flow hood after spraying isopropanol around the lid and seal area. I'm just curious about the vacuum thing. Thx
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nasyn
Stranger


Registered: 03/27/14
Posts: 86
Last seen: 2 years, 7 months
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Re: Pressure cooker vacuum [Re: Idkleine]
#21644141 - 05/06/15 01:24 PM (9 years, 14 days ago) |
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Honestly, it depends on what you're pressure cooking. If it's jars that have their own filter - you don't have to worry about it that much.. just wipe things with iso before putting them in front of the hood/in your SAB.
I would really only worry about this if you're PC'ing unsealed spawn bags or something that would get contams if left out in the open air.
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gray

Registered: 03/07/15
Posts: 127
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Re: Pressure cooker vacuum [Re: nasyn]
#21644168 - 05/06/15 01:35 PM (9 years, 14 days ago) |
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I took a tip from RR and put small pieces of tyvek over the parts of PC that suck in air on the lid, after I've turned it off. The theory being that as the PC sucks in air it's filtered through the tyvek.
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Juiceh
Dabbing All Day



Registered: 09/25/12
Posts: 3,208
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Re: Pressure cooker vacuum [Re: gray]
#21644579 - 05/06/15 03:39 PM (9 years, 14 days ago) |
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My AA921 is only a couple years old. My AA930 is not even a year old. They both pull vacuum on cool down. Take a close look at your gauge. When the needle is at zero there should be a small peg under the needle that the needle hangs just above. The needle will come down further and rest on that peg on cool down when it pulls vacuum.
If you are using jars with SFD lids and the lids are on tight you should be able to release vacuum and open the cooker in open air without pulling contams into the jars, I have been just leaving them overnight lately. With unsealed bags, even with tyvek sleeves I think its best to let the cooker cool overnight and equalize the vacuum before opening in front of the flow hood.
Here is a video of vacuum slowly being released in front of a flow hood with an AA921. You can see that the needle is below zero and resting on the peg, then it comes back up to zero as vacuum is released. This is how I open my cooker when I am going to pour agar. If I don't pull the weight off right when pressure hits zero it will pull vacuum.
Edited by Juiceh (05/06/15 09:46 PM)
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