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Pressure Cooker Questions


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#1 Oldpunk

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Posted 02 April 2021 - 10:22 AM

Hey everybody.
I decided to step up my game and get a pressure cooker. I'm moving into my 1st clone attempts and have some agar on the way....so I figured it's time.
I've never used one before. And I have a couple questions that hopefully you all can give me some advice.

1. My PC instructions said always use 3 qt of water. No matter how many jars. My first test run I only used 1 qt (just enough to cover the bottom spacer plate) I was using 1/4 pint shorty jars for liquid culture mix and 3 qt would have fully submerged them. Does the water amount matter really?

2. My test run seemed to hover at 13psi . I know the magic number always says 15. It was cooking at pretty low heat, but seemed to be boiling like crazy. Do I just turn the burner up until I hit 15? Or is the pressure regulator flopper doohicky supposed to be heavier?

3. When you guys wrap jar lids and scalpels and other tools in foil and PC to sterilize. How do you? You know like how long, how much water in it, where do you set the tools and such so they not in the water?
I was thinking of making a little rack by bending up some hardware cloth. Any qualms about using galvanized metal?

I know these are probably common knowledge questions once a person has some experience. So please excuse my totally uneducated newbie-ness.

Oh. One more. Shit I forgot.
Shouldn't have had that early morning doobie-ness.

Oh wait. There it is.
4. Have any of you tried out single burner hot plates with your PC? Mines a 16qt job so the hot plate would have to be 10-12" probably. Just in case I ever build that secret mushroom lab.

I always wanted an underground secret grow room. Turns out it's a lot more work than a guy has time for. But if I ever do I'm gonna call it my Bong Shelter.
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#2 jrh

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Posted 02 April 2021 - 10:54 AM

1. How much water you use varies directly with how long your cook time is, which usually varies with how "thick" what you're cooking is. Water itself has a heat capacity of 1, so to a first approximation, a jar of water will heat up at the same rate as the inside of the pressure cooker itself. Air is a really good insulator, so the center of a jar (or bag) of grain will heat up much more slowly than the pressure cooker, so will require a longer cook time to make sure the center is sterilized. 30 mins @ 15 psi should be good for tools, jars of water, and anything thin. I normally do 30 mins for agar, liquid culture, water (it's good to have sterilized water on hand), 2 hrs for jars of grain, 3 hours for mycobags.

 

2. I use an electric high pressure canner that's supposed to figure out all that stuff. I believe with normal PC you let things heat up, then you vent for awhile, then you let it fully pressurize and turn down the heat some, but someone else will have to answer that. I believe you have different weights for different pressures, but again, I don't have the same setup. What you DON'T do is just crank the heat -- that will only cause you to boil away your water faster and running out of water in your PC is bad.

 

3. You can put tools in a jar or polypropylene plastic container (often referred to as PP5). Anything with a lid will need to have the lid loose or a little "vent" hole so the change in pressure doesn't cause it to pop as it heats up (like in a microwave). People use jar rings to make platforms to set stuff on. I'm not sure about your galvanized metal, but at high pressure and temperature, things will oxidize faster than they will just sitting around the garage.

 

4. I dunno.



#3 Arathu

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Posted 02 April 2021 - 11:06 AM

1. My PC instructions said always use 3 qt of water. No matter how many jars. My first test run I only used 1 qt (just enough to cover the bottom spacer plate) I was using 1/4 pint shorty jars for liquid culture mix and 3 qt would have fully submerged them. Does the water amount matter really?

 

The fine balance between NOT running it out of water (DOING SO WILL CAUSE DAMAGE AND IS POSSIBLY DANGEROUS) during a sterilization run. You are right that submerging your jars or other substrate containers that will withstand a sterilization run is not what you want to do BUT you must ensure that you do not run the PC out of water or dry EVER. Trial and error will be your friend. Look inside and see if it has water fill lines marked in it. Obviously when cool and not pressurized......just sayin....

2. My test run seemed to hover at 13psi . I know the magic number always says 15. It was cooking at pretty low heat, but seemed to be boiling like crazy. Do I just turn the burner up until I hit 15? Or is the pressure regulator flopper doohicky supposed to be heavier?

 

On most units the weight IS what will set the working pressure. If you were holding steady at 13 psi with vigorous "boiling" happening then my bet is that your unit is rated at 12 psi. I would DEFINITELY NOT get a heavier weight than the manufacturer included with the PC. If you want, list manufacturer and model number and I will go and check it out. After I've reached vigorous venting on the PC I put my weights on and then carefully adjust the flame/heat until the weight just barely rocks and vents at 15psi. This keeps the pressure/temperature where I need it to be and maximizes the length of time I can run the PC without running it dry. You will get the hang of it. Make notes.......

3. When you guys wrap jar lids and scalpels and other tools in foil and PC to sterilize. How do you? You know like how long, how much water in it, where do you set the tools and such so they not in the water?
I was thinking of making a little rack by bending up some hardware cloth. Any qualms about using galvanized metal?

 

I have done scalpels and other instruments wrapped in foil inside quart jars with a very loose lid and foil over the top, also I've used sterilization envelopes and Tyvek envelopes as well. Anything that will not fit in a jar I usually sit on top of the first layer of jars specifically so they are not immersed in the water. It can be challenging to do and will take some creativity and experience. Stainless steel trays and sterilization containers are also available.....

 

4. Have any of you tried out single burner hot plates with your PC? Mines a 16qt job so the hot plate would have to be 10-12" probably. Just in case I ever build that secret mushroom lab.

 

Personally I do not use a hot plate for sterilization runs because my PC's are large and the hot plate doesn't seem to have enough wattage, or supporting mass, to do the job. Mine are done on a gas range which makes HPOO, or any other "stinky" substrate for that matter, a subject of domestic harmony......i.e. "You are NOT cooking shit on the stove in my kitchen you asshole!!!"........ "I don't care what it's for....!"  My wood substrates are BARELY acceptable. I resurrected a really nice stainless steel gas grill for usage outside in the warmer months. 

 

 

Good questions.....hopefully others will also elaborate.....

 

A


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#4 Mycol

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Posted 02 April 2021 - 11:42 AM

Arathu and jrh have pretty much said everything I would tell you .

Can you post a pic of your setup and weight ? Click “more reply options” on the bottom right to do that .

I second the don’t run out of water .

You’re weight is usually more accurate than the gauge , mine reads 13 when my weight starts doing its thing .

#5 Oldpunk

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Posted 02 April 2021 - 12:43 PM

So I picked up a Presto 16qt liquid capacity model 0175510. I live in a small town and it was the only one available locally

20210402_122804~2.jpg 20210402_122937~2.jpg

My pressure gauge also read 13 when it started dancing. I ran some karo/water for 30 min and maybe one fifth of the quart of water evaporated. With longer cooks and bigger jars I will use more water.

#6 bezevo

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Posted 02 April 2021 - 01:06 PM

i bought two   large commercial hot plates to use with my AA PC, i Also got them  to avoid using  kitchen and upsetting

.............THE PANTS  .............

These hot plates had  many reviews from people using them for 20 quart  and 25 quart  AA  PCs  for  canning . i need to run a few tests jars 

i have 2 vintage All American PC .One is 15 qrt  it was  $11 and other  $20 , 18 quart . Thrift store bargains  . i bought few new parts  from AA direct for $36 to up date the used PCs.  i bought two over pressure plugs , one pressure gauge and one replacement baka-light T-handle . i  tested both of the refurbished  PC's  with TEMP Test strips and a  little glass tester  tube tester  for PC so i feel  there safe .i did cpl test runs  they held at 15 PSI  and the  two test devices  said it reached desired temp and pressure

ill  look for  hot plate   specs  ect .

 

BEZ


Edited by bezevo, 02 April 2021 - 01:10 PM.

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#7 rockyfungus

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Posted 02 April 2021 - 03:29 PM

I’ll have to check my pressure cooker when I head home. It’s some presto...

I taped 3 quarters to my weight to prevent that annoying rocking...This presto if not watched closely will keep going till those pressure escapes burst...

 

I start it without the weight and let it run for 7-10 mins with the steam venting. This is typical a bit lower then high on my stove. (8/10)

After it has vented, I lower the temperature to medium low (5/10), and when gauge hits about 12-13 I lower stove to (2/10) this will bring it to 15psi and tend to keep it between 15-17 psi.

Learn the sounds of the vent and you can almost do it all by ear...


Edited by rockyfungus, 02 April 2021 - 04:38 PM.

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#8 vork21

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Posted 02 April 2021 - 04:24 PM

Yes, I have used a hot plate.  You'll need at least 1500W plate, and heatup time is much slower than a range.  A single propane burner is a better option IMHO.

 

Something I've discovered is that I like to put a silicone trivet at the very bottom, I can smell the silicone when the water gets low but before the PC runs dry. 

 

When you install the guage on your Presto, position it so the black plastic plug is in the back (opposite as you have pictured).  The black plug is the safety blowout, you don't want that pointing at your face when you're checking the gauge. 



#9 Mycol

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Posted 02 April 2021 - 05:17 PM

I’ll have to check my pressure cooker when I head home. It’s some presto...
I taped 3 quarters to my weight to prevent that annoying rocking...This presto if not watched closely will keep going till those pressure escapes burst.


I just use a small magnet

#10 Auhron

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Posted 02 April 2021 - 06:11 PM

Great answers so far, I would like to expand on number 3.  one thing about building your own rack to prop things up on, if it's just going to sitting on top of the rack provided with your pressure cooker, the material (aside from oxidation issues) isn't a big deal, but if your building a taller rack to use instead of the supplied rack, ensure you are using the same material your pressure cooker is made of, this will eliminate the chance of a reaction that could result in damage to your pressure cooker.


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#11 Oldpunk

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Posted 02 April 2021 - 08:56 PM

Heard.

Thanks for the input everyone. It's not quite rocket science, but as I opened the box there was a bit of head scratching. And a little good advice is always appreciated.
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#12 sandman

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Posted 02 April 2021 - 10:01 PM

cadco/broilking csr-3t 1500w hotplate is the one you want for a hotplate. Anything less is trash and you will hate it. Even still your stove range has a 2400 watt 8" burner so compare that, nearly half power. But 1500w max power from your normal  wall plugs.

 

tape a Nickle or quarter to your weight to get it to jiggle at a higher psi or not use any water at a normal psi.

 

Scalpels and hard things are best sanitized with a alcohol wipe and flame sterilized, no real need to pc a scalpel handle it's a little silly.


Edited by sandman, 02 April 2021 - 10:03 PM.

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#13 4sporeand7flushes

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Posted 08 April 2021 - 08:40 AM

Hey everybody.
I decided to step up my game and get a pressure cooker. I'm moving into my 1st clone attempts and have some agar on the way....so I figured it's time.
I've never used one before. And I have a couple questions that hopefully you all can give me some advice.

1. My PC instructions said always use 3 qt of water. No matter how many jars. My first test run I only used 1 qt (just enough to cover the bottom spacer plate) I was using 1/4 pint shorty jars for liquid culture mix and 3 qt would have fully submerged them. Does the water amount matter really?

 

I always use 3-3.5 liters/quarts or measured with my index finger, right around the second knuckle joint or just under.  You can raise the level of the bottom trivet with lid rings or empty tuna cans with bottom and tops removed and a hole punched in the side so they won't hold water.  You'd be surprised what containers are capable of inside a PC...

2. My test run seemed to hover at 13psi . I know the magic number always says 15. It was cooking at pretty low heat, but seemed to be boiling like crazy. Do I just turn the burner up until I hit 15? Or is the pressure regulator flopper doohicky supposed to be heavier?

 

If the jiggler is jiggling (around once a minute is what you want) there isn't anything you can to to increase the temp/pressure at that point.  *cough* there are people that modify their PC weights *cough* DON"T DO THIS!  I don't think there are any real industry standards for the pressure cooker industry.  I just picked up a used 22qt Mirro with 15PSI weight and it is 20F hotter than my other PCs. which are supposed to be 15PSI as well.

3. When you guys wrap jar lids and scalpels and other tools in foil and PC to sterilize. How do you? You know like how long, how much water in it, where do you set the tools and such so they not in the water?
I was thinking of making a little rack by bending up some hardware cloth. Any qualms about using galvanized metal?

 

I make/leave room for a jar and put them in the jar then cover with Al foil.  I also put about a 1/4 cup water in the jar because wet heat conducts and sterilizes better/faster, mostly when I'm doing LC or Agar, because it is such a short time but if I'm doing grains I don't bother with the water.

I know these are probably common knowledge questions once a person has some experience. So please excuse my totally uneducated newbie-ness.

Oh. One more. Shit I forgot.
Shouldn't have had that early morning doobie-ness.

Oh wait. There it is.
4. Have any of you tried out single burner hot plates with your PC? Mines a 16qt job so the hot plate would have to be 10-12" probably. Just in case I ever build that secret mushroom lab.

 

I've heard of people with glass-top stoves using them so they don't crack their stove.

I always wanted an underground secret grow room. Turns out it's a lot more work than a guy has time for. But if I ever do I'm gonna call it my Bong Shelter.

 



#14 4sporeand7flushes

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Posted 08 April 2021 - 09:36 AM

Great answers so far, I would like to expand on number 3.  one thing about building your own rack to prop things up on, if it's just going to sitting on top of the rack provided with your pressure cooker, the material (aside from oxidation issues) isn't a big deal, but if your building a taller rack to use instead of the supplied rack, ensure you are using the same material your pressure cooker is made of, this will eliminate the chance of a reaction that could result in damage to your pressure cooker.

 

I made these out of a leftover piece of siding - powder coat over galvanized steel and they seem to be all right and people have been using lid rings in the bottom of their PC's forever.  The PC I just bought had rust stains in it from lids - presumably, lots of scale as well, a couple rounds with some vinegar added to the water cleaned it right up and no signs of damage.  That being said, I have always wondered about the effects of adding vinegar to every load of jars that lots of people recommend when canning, to keep jars nice and clean.  Aluminum is highly reactive and vinegar is acid... just makes me wonder how much aluminum is being dissolved every round of canning when vinegar is used... I don't personally use it aside from the occasional cleaning maybe once every few years.
 

trivets.jpg



#15 FLASHINGROOSTER

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Posted 08 April 2021 - 11:55 AM

When I was trying to find a pressure cooker I came to the realization that only American made and sold pressure cookers hit a true 15 psi during operation. Places like Europe and Canada often advertise on the box that they are a 15 psi cooker, but when used the pressure never climbs above 13 psi due to venting.

 

I thought I was the only crazy bastard that super glued a stack of change to a rocker in order to bump it up to the 15 range. Good to check your pressure releif valve setting in the manual if you can, just in case it is set super low you can avoid scaring the shit out of yourself



#16 jrh

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Posted 08 April 2021 - 12:23 PM

How do you measure what temp or PSI your PC is running at?



#17 4sporeand7flushes

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Posted 08 April 2021 - 12:46 PM

How do you measure what temp or PSI your PC is running at?

 

I put a couple pieces of black electrical tape on the lid big enough for the head of my IR thermometer.  Without the tape the shiny surface only registers just over 100F.  I don't know how accurate it is but my cookers with unmodified weights read 250-254F and 264F after mods, The Mirro I just picked up is reading 274F without mods.  The first time I used this method all I wanted to do was match my little 9 liter Fresco to be the same temp as my AA, so I just kept adding wire around the pear shaped weight until I got the same reading from both.  With my IR thermo, it takes a while to get it acclimated to the temperature, I'll let it rest on the stove about 3-4 inches from the pot, facing the burner to start getting it warmed up and then hold it directly to the taped spot for about a minute.  I dunno, my thermometer is probably a piece of shit.


Edited by 4sporeand7flushes, 08 April 2021 - 12:51 PM.





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