Home | Community | Message Board

NorthSpore.com BOOMR Bag!
This site includes paid links. Please support our sponsors.


Welcome to the Shroomery Message Board! You are experiencing a small sample of what the site has to offer. Please login or register to post messages and view our exclusive members-only content. You'll gain access to additional forums, file attachments, board customizations, encrypted private messages, and much more!

Shop: Kraken Kratom Red Vein Kratom   Left Coast Kratom Kratom Powder For Sale

Jump to first unread post Pages: 1
Some of these posts are very old and might contain outdated information. You may wish to search for newer posts instead.
InvisibleGhatti
Totally not a Federal Agent
 User Gallery
Registered: 06/23/14
Posts: 1,733
Vacuum in a pc
    #21751144 - 06/02/15 12:35 AM (8 years, 7 months ago)

Will someone help me understand why a jar would form a vacuum in a PC? Take regular canning for instance: you put veggies or a liquid in a jar with a set amount of air in it and you screw the lid down tight. As the air and liquid in the jar heat up they undoubtedly expand but apparently not enough to explode the jar. Or does it expand if the pressure in the PC is the same as the jar (1atm)? Once the contents of the jar begin to cool it forms a vacuum why?

As the air cools it contracts and negative pressure occurs but this doesn't make sense to me since the amount of air in the jar itself hasn't changed, only expanded and contracted. The volume hasn't changed at all so I don't get it.

Someone break it down Barney style for me?


Extras: Filter Print Post Top
InvisibleballsalsaMDiscord
Universally Loathed and Reviled
Male User Gallery


Registered: 03/11/15
Posts: 20,856
Loc: Foreign Lands
Re: Vacuum in a pc [Re: Ghatti]
    #21751155 - 06/02/15 12:38 AM (8 years, 7 months ago)

solids and gasses can be compressed. so thier volume can actually change based on pressure.  only liquids can't be compressed


--------------------


Like cannabis topics? Read my cannabis blog here


Extras: Filter Print Post Top
Invisiblermshroom
The PNW
 User Gallery


Registered: 04/16/15
Posts: 118
Re: Vacuum in a pc [Re: ballsalsa]
    #21751299 - 06/02/15 01:53 AM (8 years, 7 months ago)

During this heating process air is driven out of the jar and as it cools a vacuum seal is formed. This vacuum seal prevents air from getting back into the product which would bring with it contaminating micro-organisms.

On a molecular level, Atoms are forced out, but none can enter. Thus you get the effect of when you suck on a cup and it sticks to you lips when you don't let anymore air back in.:stoned:

Thank you chemistry lol


--------------------


Extras: Filter Print Post Top
InvisibleGhatti
Totally not a Federal Agent
 User Gallery
Registered: 06/23/14
Posts: 1,733
Re: Vacuum in a pc [Re: rmshroom]
    #21751638 - 06/02/15 07:32 AM (8 years, 7 months ago)

How is air forced out if the jar is sealed?


Extras: Filter Print Post Top
OfflineCliftonGK1
Sasquatch
Male


Registered: 03/27/13
Posts: 327
Loc: A place
Last seen: 5 hours, 29 minutes
Re: Vacuum in a pc [Re: Ghatti]
    #21751735 - 06/02/15 08:16 AM (8 years, 7 months ago)

Quote:

Ghatti said:
How is air forced out if the jar is sealed?





If you're fixing the lid rings down tight when you're canning foods, whether by immersion or pressure methods, you're doing it wrong.
The seal on the lid of a canning jar is meant to be slightly loose when you load your containment vessel.  The ring holds the lid lightly in place to keep things from seeping in, but the pressure build up from the heating can burp air out from the seal.  As the jars cool after removal from the canning vessel, the cooling creates the vacuum which seals the jar against further contamination.  That's why you don't keep any jars where the lid doesn't pop down:  They're not properly sealed.


--------------------


Extras: Filter Print Post Top
InvisibleGhatti
Totally not a Federal Agent
 User Gallery
Registered: 06/23/14
Posts: 1,733
Re: Vacuum in a pc [Re: CliftonGK1]
    #21751816 - 06/02/15 08:57 AM (8 years, 7 months ago)

Ahh ty. I always thought those canning folk screwed the lid tight as all the canning instructions I've ever seen says to screw the ring on hand tight, didn't know pressure could still get out.


Extras: Filter Print Post Top
OfflineYaMoonSun
The Double Standard


Registered: 10/23/14
Posts: 3,967
Loc: NY
Last seen: 5 months, 10 days
Re: Vacuum in a pc [Re: Ghatti]
    #21752004 - 06/02/15 10:01 AM (8 years, 7 months ago)

I'm not entirely sure, but I'd like to imagine that the water content absorbs some of the oxygen content as it's cooling - I love how my freshly cooled liquid culture mediums sound like a Snapple after I'm done sterilizing them.


Extras: Filter Print Post Top
Invisiblermshroom
The PNW
 User Gallery


Registered: 04/16/15
Posts: 118
Re: Vacuum in a pc [Re: Ghatti]
    #21752074 - 06/02/15 10:20 AM (8 years, 7 months ago)

Quote:

Ghatti said:
How is air forced out if the jar is sealed?




Actually its forced out by the expansion of molecules. As the jar heats up the molecules bounce around looking for an escape as they gain energy. This is why you must put holes in turkey bags, They will expand and explode because the expanding molecular entropy cannot make its way out of the bag. The way the lid is formed, no matter how tight will let those molecules escape. You can put the lid on as tight as you want my friend, to a reasonable degree lol:grin:


--------------------


Extras: Filter Print Post Top
OfflineCliftonGK1
Sasquatch
Male


Registered: 03/27/13
Posts: 327
Loc: A place
Last seen: 5 hours, 29 minutes
Re: Vacuum in a pc [Re: Ghatti]
    #21752604 - 06/02/15 12:33 PM (8 years, 7 months ago)

Quote:

Ghatti said:
Ahh ty. I always thought those canning folk screwed the lid tight as all the canning instructions I've ever seen says to screw the ring on hand tight, didn't know pressure could still get out.




It's just tightened down to the point of securing it, but not to where you're smooshing that sealing compound hard against the glass.
That compound is a one-time-only thing, so you can't reuse canning lids for making food.  When it's a finger-tight seal, there's still room for air to escape.  If you watch an immersion canning rack full of jars, you'll see the bubbles escaping the lids as the jars heat up.  Once the vacuum is drawn, that lid has served its one-and-done life span.


--------------------


Extras: Filter Print Post Top
Jump to top Pages: 1

Shop: Kraken Kratom Red Vein Kratom   Left Coast Kratom Kratom Powder For Sale


Similar ThreadsPosterViewsRepliesLast post
* PC question AKA PC 1,291 5 04/08/03 11:33 PM
by AKA PC
* Is it possible to vacuum seal a glass jar?
( 1 2 all )
megaman3 4,937 26 05/14/04 03:00 PM
by megaman3
* Who uses an Alcahol soaked rag over pc in cooldown?
( 1 2 all )
Gr0wer 3,297 20 05/07/04 12:00 AM
by Ref
* The advantage of a big PC
( 1 2 3 all )
agar 6,941 58 04/21/06 08:52 PM
by Jaeger
* Birdseed, After the PC'ing avarrin 1,539 10 05/29/02 04:09 PM
by ShroomNewb
* Will rice expand in a pressure cooker? On_the_Down-Low 1,206 5 10/27/02 08:41 PM
by VSOPXO
* how long to let simmered grains drain before pc laughingbuddha 6,032 10 03/27/15 03:21 PM
by Stromrider
* PC Water Question... biglo 795 5 11/29/04 07:55 AM
by djred

Extra information
You cannot start new topics / You cannot reply to topics
HTML is disabled / BBCode is enabled
Moderator: Shroomism, george castanza, RogerRabbit, veggie, mushboy, fahtster, LogicaL Chaos, 13shrooms, Stipe-n Cap, Pastywhyte, bodhisatta, Tormato, Land Trout, A.k.a
665 topic views. 36 members, 242 guests and 34 web crawlers are browsing this forum.
[ Show Images Only | Sort by Score | Print Topic ]
Search this thread:

Copyright 1997-2024 Mind Media. Some rights reserved.

Generated in 0.025 seconds spending 0.011 seconds on 14 queries.