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Re: The importance of venting a pressure cooker [Re: The Dalcassian]
    #26279506 -

What would be the best venting procedure for a PC with a steam-1-2 dial, like in the pic? ['2' sets the valve for high pressure (~13-15 psi depending on model), the '1' is for ~10 psi, and the 'steam' setting is used to equalize.]



Initially I used 'steam' to vent (mimicking the procedure described here) but then it occurred to me that '1' and '2' produce a steam cone just as nice. So why spend the 10 min venting time on 'steam' when you could be at 15 psi, right? Just starting with '2' and waiting for 10 minutes of forceful steam before reducing the heat appears to be best, or am I missing something?


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My LAGM2020 grow log


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Re: The importance of venting a pressure cooker [Re: curious.psychonaut]
    #26457776 -

curious.psychonaut said:
What would be the best venting procedure for a PC with a steam-1-2 dial, like in the pic? ['2' sets the valve for high pressure (~13-15 psi depending on model), the '1' is for ~10 psi, and the 'steam' setting is used to equalize.]



Initially I used 'steam' to vent (mimicking the procedure described here) but then it occurred to me that '1' and '2' produce a steam cone just as nice. So why spend the 10 min venting time on 'steam' when you could be at 15 psi, right? Just starting with '2' and waiting for 10 minutes of forceful steam before reducing the heat appears to be best, or am I missing something?


It makes sense that removing air that is more pressurized will be faster at removing air from a vessel vs removing air that is less pressurized.

But I’m guessing there’s more to it...

P.S. as for the original post, when venting the PC we’re not just venting the air above the water, we’re also venting air dissolved in the water. Once properly vented all that should b in the cooker, ideally, is water (liquid and gas) and whatever you’re cooking.😳

Thanks bod, I’ll be venting religiously from now on...


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Looking to learn all about it

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: bodhisatta]
    #26862396 -

Thank Bod,
Here it is seven years after this was posted and it's still as golden as the day you posted it. Cheers and thank you

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: bodhisatta]
    #26937206 -

SO i have a n00b question. I have a insta-pot 7-1 pressure cooker/sterilizer. Now I have been reading a lot of stuff on here and have come to the conclusion that my pressure cooker doesn't reach a high enough psi to properly sterilize my Whole oats. Is that true? do i need to go buy an All american pressure cooker? Can i really do it without? Please help. This will be my first batch EVER. I have already inoculated the first batch that i ordered pre sterilized from amazon. I am sure I will have more questions but this is it for now. THANKS FOR WHOEVER HELPS

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: bodhisatta]
    #27255436 -

I get that it's important but Im not fully understanding the how to do the venting. I'm using a 30$ farberware pressure cooker from walmart

my methid was to let water in it boil, riser in place, load it up, reduce heat some, lid on, wait for steam then put the stopper on, wait for the stopper to jiggle and for it to look inflated then tilt/lift the stopper for about 1 minute to let the air bubble out reduce heat, let it go
this pressure cooker has no guage, I feel a little blind at this
When running oat jars, like I am right now, I prefer to let it go for 2 hours, but sometimes it boils all the water off around 90 min in, and I'll just stop the heat when that happens.


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yeah keep telling yourself that's voluntary

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: bodhisatta]
    #27446274 -

I was surprised by the need to vent. However, Bod is right.

I have a Kuhn Rikon pressure cooker. There is no way to vent this PC as per manufacturer instructions. I am considering two options: (1) set the heat so high that it releases a lot of steam for 10 minutes, (2) wedge something in the valve to hold it open for 10 minutes.

I did my first grain to grain transfer not knowing this, and was surprised to see contaminants. I am no longer surprised!


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Just starting on Golden Oyster on coffee grounds. Where will this go?

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: SheepShrooms] * 1
    #27446399 -

Buy a pressure cooker that can be vented, make sure it can reach the appropriate temperature/pressure or forget about it.

Use the right tool for the right job.

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: Stipe-n Cap]
    #27446496 -

Don't worry, it vents. It's just automatic like the pop up valve on a presto.

It would appear that it is designed to vent when the lid is first put on until it builds enough pressure to finally push the "knob" up and seal. This "should" be sufficient. Edit: from the manual:

Quote:
As food begins to boil, any air present in the pressure cooker firstly escapes
through the valve. The valve cap will then move up. Now, the pressure indicator
stem rises with increasing pressure inside the pressure cooker. Please observe:
after a short while the first red (pressure indication) line will become visible indicating that cooking level 1 has been reached.



They wouldn't sell a cooker that doesn't vent. The presto works the exact same way with the pop up valve it just has an additional weight.

from my own test of unvented PC:

214f at 15 psi from 57f starting temp with no venting (actually minor venting from leaking lid.) No bueno.


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- Sandbag Tek - How To Sterilize Spawn Bags - All About Static Pressure / Pressure Drop for DIY Flow Hoods - Sandman's LC Tek-

Marijuanaut escapes earth to cultivate - Grow-room is church temple of the new stoner breed

Edited by sandman420 (08/28/21 05:33 PM)

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: bodhisatta]
    #27921298 -

Hi, I've been trying to get better at achieving good spawn, and only now am I paying attention to venting, it never seemed important enough. After reading this thread, I think I understand the need of venting with each PC cycle.

Nonetheless, after re-reading the quote boxes in the OP, questions start arising in my head. Aren't the jars where we sterilize our dryish grains big potential air pockets inside our PCs? Is it not easy that our unscrewed lids and foil (is that still good?) become too restrictive to allow equalization of the pressure and steam inside, and expelling of all air? That wouldn't happen at normal pressure, during venting, right? Shouldn't we be taking measures to allow wet steam to have plain access the grain "chamber", even if it took changing grain preps, at the risk of having oven conditions created inside the jars?

Much info is canning related which doesn't really apply (right?), as we start with jars full of air and humid cereal, not immersed vegetables...

Edited by SarahP (08/27/22 03:59 PM)

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: SarahP]
    #27921380 -

Water molecules are very small, such that high pressure gas phase water should have no problems getting into the jars and displacing the air pockets within, regardless of unmodded lids and tinfoil (assuming you leave the lids loose).


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🅃 🄴 🄰 🄼    🄲 🄻 🄸 🄽 🄶 🅆 🅁 🄰 🄿

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: KROM]
    #27921437 -

Yeah, I understand that's the reasoning behind what we do, when we insert jars like that in a PC.

But does it really? (Does anyone have real evidence of that?)

During venting there's no pressure to force the air out from the jars, and as pressure starts to build up faster outside than inside, wouldn't the foil stick, pressed to the lid&glass and practically seal the jars? Or maybe pressure would press the lids down?


My wheat is very much dry after each PC cycle, does't look wetter than when I loaded it. It surely does't look like it was just sterilized under wet steam. And I'm thinking I was surprised when recently I was reading that people got roasted cereal inside jars, when trying to PC it at really high pressure/temperature. That's compatible with oven conditions, right? My common sense intuition says that cereal subject to hot vaporized water shouldn't roast...

Edited by SarahP (08/27/22 05:23 PM)

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: SarahP]
    #27921444 -

I am unfamiliar with the roasted grains you’re referencing, so I cannot comment. The only times I’ve heard of grains getting roasted was when the PC ran dry. I assume there is not a noticeable change to the moisture content inside the jar because hot gas phase water escapes the jars as the pressure in the pc decreases. If it doesn’t cool down enough to condense in the jar, I assume it doesn’t collect inside the jars to any appreciable extent. I don’t have proof, though, so I could be full of shit.

Edit : to respond to your edited points. Pressure does not have a specific direction. Pressure is the sum of the forces of the collisions between (in this case) gas phase water molecules with the walls of the vessel(s). As such, it does not just push the lids downward. Also, high pressure systems will spontaneously move down pressure gradients to low pressure systems. As such, the pressure gradient between the high pressure system in the PC outside the jars and the low pressure system(s) inside the jars provides a thermodynamic driving force to push high pressure gas phase water into the jars to displace the air pockets, until a dynamic equilibrium between the systems is attained.


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🅃 🄴 🄰 🄼    🄲 🄻 🄸 🄽 🄶 🅆 🅁 🄰 🄿

Edited by KROM (08/27/22 05:42 PM)

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: SarahP] * 2
    #27921471 -

This science is well understood, adding grains to the equation serves only to increase the complexity of the load, not the mechanism.

I suggest that you read more on the topic of steam sterilization and the operation of autoclaves before spamming the thread with questions.

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: KROM]
    #27921476 -

I think it was in this thread

Josex said:
(...)

Last time I had an LC not recovering at all was very recently. I like to sterilize jars at 15-17 psi max but I got distracted and when I came back the dial was nearing 30psi.

The grain came out a lot browner than usual but I noc'd it up anyways and nothing happened for a good 2 weeks until the colony started to colonize like a couple kernels in some of the jars but never got passed that. Opened a jar and put some kernels in my mouth... they were perfectly hydrated but they tasted burnt.

This organism never ceases to surprise me, it seems to have a delicate palate too lol


Maybe "roasted" is exaggerated. But still.

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: Stipe-n Cap]
    #27921488 -

Are you sure my questions aren't pertinent?

Are the conditions inside "our" sterilizing jars the same you find in all those science reports about sterilization? Because we're trying to sterilize the grains in the center, right?

The quote boxes in the OP got me thinking. Can you point me to some links, please?

Edited by SarahP (08/27/22 05:57 PM)

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: SarahP]
    #27921502 -

This might do it, check gravity displacement autoclave.


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🅃 🄴 🄰 🄼    🄲 🄻 🄸 🄽 🄶 🅆 🅁 🄰 🄿

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: SarahP] * 1
    #27921504 -

Listen man, every noob comes around questioning the status quo wothout first taking the time to familiarize themselves with the process, mechanisms, modalities, etc, etc.

I have basically all of the pertinent information regarding sterilization practices, assurance levels, autoclave function, validation, etc in my sig. Many links, much reading.

Endospore experiment.

Yeah maybe your questions are valid, but one askes questions after taking the time to familiarize themselves, thwn should any questions remain....otherwise your questions simply generate more questions and ultimately confusion.

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: KROM]
    #27921509 -

Thank you for your explanation.

But if I got that right, that only happens under pressure, right? Then, does it still make sense to vent before each cycle?

I'm sorry if I sound provocative. English is not my native language, I don't mean to affront anyone, or to soil other peoples shinny threads. I've been around just as a watcher for a couple of years, maybe I just should keep that way...

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: Stipe-n Cap]
    #27921516 -

I have already read your Endospore thread, like less than a moth ago. And Josex's. It felt like a revelation. Thanks for your work.

I guess you're assuming things about me, just because you never "saw" me around.

Edited by SarahP (08/27/22 06:16 PM)

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Re: The Importance of Venting a Pressure Cooker or Autoclave [Re: SarahP]
    #27921522 -

Order these 170-240f temp indicator strips & these 250-320f temp indicator strips, place one of each in a jar of hydrated grain, run through a PC cycle, check the strips to see what temp was achieved in the center of the grain jar.

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