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trippleblack
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is it pointless to bleed the autoclave of air pockets
#28380261 - 06/30/23 02:37 PM (1 year, 6 months ago) |
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Question..
is it pointless to bleed the autoclave of air pockets if the bags or containers within the cooker has water?
I can save 45+ minutes by closing the pressure valve instantly instead of letting steam build up, releasing, and waiting for another build up.
it's standard practice to let pressure build up in pressure cooker/ autoclave until steam vent continuously for 5 mins, then we should shut valve and let pressure build up, then at 15 psi open valve and vent for another 3 - 5 minutes, then shut it again.
This is suppose to prevent sterilization fails from dry air pockets inside the pressure cooker -since the steam can't penetrate dry pockets.
most of us are using these autoclaves to sterilize containers already filled with water; like grain bags, grain jars, or wet substrate.
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bodhisatta 
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Re: is it pointless to bleed the autoclave of air pockets (moved) [Re: trippleblack] 1
#28382140 - 07/02/23 06:54 AM (1 year, 6 months ago) |
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This thread was moved from Advanced Mycology.
Reason: This is the basics
And you will get failed sterilization if you don't vent.
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Stipe-n Cap
The Pride of Cucamonga


Registered: 08/04/12
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Re: is it pointless to bleed the autoclave of air pockets [Re: trippleblack] 2
#28382165 - 07/02/23 07:17 AM (1 year, 6 months ago) |
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Stop trying to "save time", there's no shortcuts with sterility assurance.
Every vessel is filled with gas. Whether it be your pressure cooker, grain jar, or spawn bag all of these vessels are filled both with the material intended for sterilization and trapped gas. When you place the lid on any pc you are now encapsulating that gas.
Venting is required to purge this trapped gas from the unit/vessels while simultaneously replacing it with steam. If you fail to purge the pc/autoclave you're pressurizing the mixed trapped gases which will result in a lower temperature than if you allowed the steam to occupy the vessel alone, via the vent.
Daltons law covers this phenomenon:
Quote:
According to Dalton's law of partial pressures, the total pressure by a mixture of gases is equal to the sum of the partial pressures of each of the constituent gases. The partial pressure is defined as the pressure each gas would exert if it alone occupied the volume of the mixture at the same temperature.
https://www.shroomery.org/forums/showflat.php/Number/27970850#27970850
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SirPsycho
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Re: is it pointless to bleed the autoclave of air pockets [Re: Stipe-n Cap] 2
#28382173 - 07/02/23 07:24 AM (1 year, 6 months ago) |
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Wait... You want to bring it up to pressure, then vent and bring back up to pressure? Pretty sure the manual on mine says to not remove the weight until back down to atmospheric pressure.
Also, saving 45 mins on the most important step of a 2 month process seems just a touch pointless.
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Pandaskis
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Re: is it pointless to bleed the autoclave of air pockets [Re: SirPsycho]
#28382179 - 07/02/23 07:31 AM (1 year, 6 months ago) |
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The TCs really jumped on his ass for this one LOL
Edited by Pandaskis (07/02/23 07:34 AM)
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Stipe-n Cap
The Pride of Cucamonga


Registered: 08/04/12
Posts: 8,269
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Re: is it pointless to bleed the autoclave of air pockets [Re: SirPsycho]
#28382181 - 07/02/23 07:32 AM (1 year, 6 months ago) |
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Yeah, that's what the manual says for All American bench sterilizers. It's called pulse evacuating, or something. I personally don't vent that way because I never use the basket. I remove the vent tube as well, the tube gets in the way and is only practical when used alongside the internal basket. Fuck the basket.
OP, just keep your valve open while allowing the steam to realease as the unit temperature climbs. Start your timer for purge once steam begins to hiss from the valve. I don't trust pulse evacuating with bags, it might be ok but feels like a poor choice.
I vent 75x for 30 mins, everything under that for 15.
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AyePlus
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Re: is it pointless to bleed the autoclave of air pockets [Re: Stipe-n Cap]
#28382293 - 07/02/23 09:08 AM (1 year, 6 months ago) |
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I sometime pulse evacuate @ 5-7psi for bags, it does shave ~30 minutes off
Close as soon as it starts hissing, Bring to 5, open and drop to 2-3psi then close and repeat i let it bleed for about 2 minutes in total,
Only worth doing if youβre on a tight schedule imo, i have my cookers on timers and sometimes you have to have it dialed before getting into another project..
Iβve had a few friends who lost whole runs to bacillus because of not venting long enough, seems to be prevalent in the local wheat source (bar ale)
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trippleblack
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Re: is it pointless to bleed the autoclave of air pockets [Re: Stipe-n Cap]
#28382390 - 07/02/23 10:22 AM (1 year, 6 months ago) |
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Quote:
Stipe-n Cap said: Stop trying to "save time", there's no shortcuts with sterility assurance.
Every vessel is filled with gas, whether it be your pressure cooker, grain jar, or spawn bag all of these vessels are filled both with the material intended for sterilization and trapped gas. When you place the lid on any pc you are now encapsulating that gas.
Venting is required to purge this trapped gas from the unit/vessels while simultaneously replacing it with steam, if you fail to purge the pc/autoclave you're pressurizing the mixed trapped gases which will result in a lower temperature than if you allowed the steam to occupy the vessel alone, via the vent.
Daltons law covers this phenomenon:
Quote:
According to Dalton's law of partial pressures, the total pressure by a mixture of gases is equal to the sum of the partial pressures of each of the constituent gases. The partial pressure is defined as the pressure each gas would exert if it alone occupied the volume of the mixture at the same temperature.
https://www.shroomery.org/forums/showflat.php/Number/27970850#27970850
i know this is basic stuff.. but i just did it, without understanding it's grave importance or the detailed reason behind it.
Daltons Law..
thanks. this is what i was looking for. I never not vented of course, but was pondering over the possibility. That thread is absolutely amazing, i missed it.
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Stipe-n Cap
The Pride of Cucamonga


Registered: 08/04/12
Posts: 8,269
Loc: Canada
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Re: is it pointless to bleed the autoclave of air pockets [Re: trippleblack]
#28382396 - 07/02/23 10:25 AM (1 year, 6 months ago) |
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One of my biggest mistakes as a new grower was to attempt shaving time off the process by not venting. The resulting plague of bacteria was biblical, but that blunder taught me a lot.
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bodhisatta 
Smurf real estate agent


Registered: 04/30/13
Posts: 61,916
Loc: Milky way
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Re: is it pointless to bleed the autoclave of air pockets [Re: Stipe-n Cap] 1
#28382412 - 07/02/23 10:43 AM (1 year, 6 months ago) |
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Quote:
Stipe-n Cap said: Yeah, that's what the manual says for All American bench sterilizers. It's called pulse evacuating, or something. I personally don't vent that way because I never use the basket. I remove the vent tube as well, the tube gets in the way and is only practical when used alongside the internal basket. Fuck the basket.
OP, just keep your valve open while allowing the steam to realease as the unit temperature climbs. Start your timer for purge once steam begins to hiss from the valve. I don't trust pulse evacuating with bags, it might be ok but feels like a poor choice.
I vent 75x for 30 mins, everything under that for 15.
I called AA and spoke with an engineer and explained what mushrooms growers are trying to do and he agreed removing the tube and basket was appropriate.
https://www.shroomery.org/forums/showflat.php/Number/24180711/vc/1#24180711
Also here's my supplemental reading material on the matter
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Stipe-n Cap
The Pride of Cucamonga


Registered: 08/04/12
Posts: 8,269
Loc: Canada
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Re: is it pointless to bleed the autoclave of air pockets [Re: bodhisatta]
#28382424 - 07/02/23 10:52 AM (1 year, 6 months ago) |
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Sweet
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