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Ghatti
Totally not a Federal Agent

Registered: 06/23/14
Posts: 1,733
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Re: Contamination Questions [Re: Ghatti]
#20608951 - 09/23/14 10:24 PM (10 years, 3 months ago) |
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Have I not been sterilizing my jars? I was under the impression that as long as it was "wet" heat was what mattered and that the water under 15psi would be just about as hot as the steam itself.
Since water under pressure has a much higher boiling point right?
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Sanguin3
Optimist

Registered: 10/19/13
Posts: 2,273
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Re: Contamination Questions *DELETED* [Re: Ghatti]
#20608991 - 09/23/14 10:32 PM (10 years, 3 months ago) |
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Post deleted by Sanguin3
Reason for deletion: .
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Kizzle
Misanthrope


Registered: 08/30/11
Posts: 9,870
Last seen: 2 months, 7 days
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Re: Contamination Questions [Re: Sanguin3]
#20609065 - 09/23/14 10:45 PM (10 years, 3 months ago) |
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The water and the steam will be at the temperature. Water can splash into short jars like half-pints if they're not elevated a bit.
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bodhisatta 
Smurf real estate agent


Registered: 04/30/13
Posts: 61,915
Loc: Milky way
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Re: Contamination Questions [Re: Kizzle] 1
#20612552 - 09/24/14 04:54 PM (10 years, 3 months ago) |
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same temperature in equilibrium. at 15psi the steam and water are about 250F IIRC.
You would think steam would actually transfer heat less since water is more dense right? wrong.
When steam hit's the surface of the thing it's heating up (your glass jar) it condenses they call this "latent heat" so the steam gives up it's energy to the vessel being heated as it condenses on the surface on that vessel. steam is very energetic since it's hard to break hydrogen bonds in water so steam is full of energy it wants to lose to turn back into water. it loses that energy into the glass.
when water is touching your jar the only heat transfer is through convection and conduction which are much slower than the latent heat transfer via steam condensate.
hopefully that made some sense. there's some hefty physics behind why steam does that.
I found an awesome graphic for it
http://www.tlv.com/global/TI/steam-theory/overall-heat-transfer-coefficient.html
click play it shows how steam produces latent heat transfer.
the boil kettle for beer at the place I work operates at 100psi so the steam is 340F or thereabout. We could use water jacketed kettles at 100psi and get the water to 340F to but the heat transfer through stainless is about 20% higher with steam.
Edited by Trusted cuItivator (09/24/14 05:01 PM)
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Ghatti
Totally not a Federal Agent

Registered: 06/23/14
Posts: 1,733
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Re: Contamination Questions [Re: bodhisatta]
#20612718 - 09/24/14 05:25 PM (10 years, 3 months ago) |
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Wow thanks for the science type answer. Good stuff.
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Kizzle
Misanthrope


Registered: 08/30/11
Posts: 9,870
Last seen: 2 months, 7 days
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Re: Contamination Questions [Re: bodhisatta]
#20613626 - 09/24/14 07:55 PM (10 years, 3 months ago) |
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Quote:
bodhisatta said: same temperature in equilibrium. at 15psi the steam and water are about 250F IIRC.
You would think steam would actually transfer heat less since water is more dense right? wrong.
When steam hit's the surface of the thing it's heating up (your glass jar) it condenses they call this "latent heat" so the steam gives up it's energy to the vessel being heated as it condenses on the surface on that vessel. steam is very energetic since it's hard to break hydrogen bonds in water so steam is full of energy it wants to lose to turn back into water. it loses that energy into the glass.
when water is touching your jar the only heat transfer is through convection and conduction which are much slower than the latent heat transfer via steam condensate.
hopefully that made some sense. there's some hefty physics behind why steam does that.
I found an awesome graphic for it
http://www.tlv.com/global/TI/steam-theory/overall-heat-transfer-coefficient.html
click play it shows how steam produces latent heat transfer.
the boil kettle for beer at the place I work operates at 100psi so the steam is 340F or thereabout. We could use water jacketed kettles at 100psi and get the water to 340F to but the heat transfer through stainless is about 20% higher with steam.
If the water is boiling there should be steam in the water as well shouldn't there?
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Sockadin



Registered: 01/03/10
Posts: 7,266
Last seen: 1 month, 21 days
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Re: Contamination Questions [Re: Kizzle]
#20614001 - 09/24/14 09:00 PM (10 years, 3 months ago) |
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Water under 15PSI gets to 250 F before it starts to boil. Steam is much less so we have to boil longer.
OP looks like a contaminated syringe is your culprit. I would still do no lss than 90 mins if you are PCing.
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bodhisatta 
Smurf real estate agent


Registered: 04/30/13
Posts: 61,915
Loc: Milky way
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Re: Contamination Questions [Re: Sockadin]
#20614237 - 09/24/14 09:40 PM (10 years, 3 months ago) |
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Quote:
If the water is boiling there should be steam in the water as well shouldn't there?
steam doesn't dissolve in water but steam exists in equilibrium(in a closed vessel) with the water. Theres steam condensing on the surface of the water just as fast as water turning into steam. Depending on the pressure this exists at a higher or lower temperature. if you add more heat there will be a shift in equilibrium making more steam.
To be noted though super heated steam is what they call saturated. which means the steam is above the heat of vaporization so the steam can lose temperature and still remain steam before condensing. which also helps with heat transfer. that's where I get fuzzy on the steam physics.
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Sockadin



Registered: 01/03/10
Posts: 7,266
Last seen: 1 month, 21 days
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Re: Contamination Questions [Re: bodhisatta]
#20616149 - 09/25/14 09:40 AM (10 years, 3 months ago) |
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Yeah I just reread what I posted the other day. It didn't make sense to me either. Hard posting from your phone sometimes. But yeah what Muda said makes more sense.
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