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volleyshroom
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Converting Pressure Chamber into Steam Autoclave
#28361263 - 06/15/23 05:20 PM (7 months, 9 days ago) |
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Hey everyone, I've been running a Presto 23 quart canner for awhile. I've reached a point where I need more sterilization capacity and I know that I'd like to stick with a pressurized sterilizer. I have a couple pressure chambers - a 45 gallon and 20 gallon - that were used as steam autoclaves decades ago but more recently have been set up for resin casting work, pressurized to 15 psi with an air compressor. I need some help and suggestions for getting them set up for substrate sterilization. Here's a photo of the larger unit and a diagram applicable to both:
I'm leaning towards building a separate steam generator to hook up to the tanks. Such a project would mean taking a second, smaller pressure tank, installing a vent, a heating element in the bottom with PID controller, and an exhaust pipe for the steam to connect to the larger tank. Here are my questions and thoughts: - Can I use a large pressure cooker/canner as the tank for a steam generator? A 41 quart All-American unit may be large enough to hold adequate water for a 2.5 hour run. How much water do you think I'll need per run for the 45 gallon chamber? - Would it be possible to go with a smaller steam generator tank and add a float valve to the system? Is it possible to add water to the system while it's under pressure? - Should I use my 20 gallon chamber as the tank for the steam generator? It will certainly be large enough, I'll just need to consult with someone to help install the components through the double walled design. - I'll reorient the 45 gallon tank vertically to make it easier to pack with substrate. I considered adding a heating element directly into the bottom of the tank but that would take up some of the sterilization space. Going with the separate steam generator and modular design seems advantageous. - Are there other options out there for a steam generator that can operate under pressure? Any ideas, suggestions, or references to similar projects or those with expertise in this area are greatly appreciated.
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SHROOMSISAY01
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Re: Converting Pressure Chamber into Steam Autoclave [Re: volleyshroom]
#28369984 - 06/22/23 10:58 AM (7 months, 3 days ago) |
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Is the picture with all the arrows the way it is set up now or what you plan on doing with it?
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volleyshroom
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Re: Converting Pressure Chamber into Steam Autoclave [Re: SHROOMSISAY01]
#28370562 - 06/22/23 07:07 PM (7 months, 2 days ago) |
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The diagram shows the schematic of the double walled pressure chambers that I'm intending to use. Right now I'm trying to find some information on whether or not it'd be wise to add a port through both walls of the smaller chamber in order to add a heating element to the bottom.
Edited by volleyshroom (06/23/23 09:57 AM)
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SHROOMSISAY01
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Re: Converting Pressure Chamber into Steam Autoclave [Re: volleyshroom] 1
#28370833 - 06/23/23 01:21 AM (7 months, 2 days ago) |
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Be very careful you are potentially building a bomb, not a steamer.
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volleyshroom
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Re: Converting Pressure Chamber into Steam Autoclave [Re: SHROOMSISAY01]
#28371166 - 06/23/23 09:52 AM (7 months, 2 days ago) |
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Thanks. Unfortunately most of the threads I've come across on here are filled with hobbyists doing just that by attempting to pressurize 55 gallon barrels. These pressure chambers were originally produced for use as steam autoclaves and are equipped with pressure release safety valves at 15 PSI, so where safety is concerned, that's a good start.
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EdgarPoe
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Re: Converting Pressure Chamber into Steam Autoclave [Re: volleyshroom]
#28372493 - 06/24/23 10:01 AM (7 months, 1 day ago) |
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I don't currently have any kind of steamer setup yet, but I'm looking into designing and building one myself. I like the way the schematic looks, but like SHROOMSISAY01 mentioned, it could easily go south.
You mentioned that the tanks are equipped with safety pressure relief valves at 15 psi. You also mentioned that the tanks are decades old. This may be a given, but I would consider testing those valves to ensure that they still work (if you haven't done so already) before getting too deep into the build. Pressure can fluctuate greatly depending on several different factors.
I would also consider installing an emergency relief valve that's manually operated from the outside and rated for at least 20 psi. That way you have a second option that you have control over to prevent an explosion should the internal safety valves fail.
Aside from all of that, your design looks very nice. I like the idea.
-------------------- "The world was made for the dead." -Flannery O'Connor, "The Violent Bear It Away"
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SHROOMSISAY01
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Re: Converting Pressure Chamber into Steam Autoclave [Re: EdgarPoe]
#28372674 - 06/24/23 12:24 PM (7 months, 1 day ago) |
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Here are the problems I see if you put your element in the vessel and pressurize you will not know if you are losing water and you could actually keep burning up elements. But you will lose less water because it will be sealed. I would hook up a low water cut-off so the water will stop heating and sound an alarm if it gets too low (I have a diagram for this). The only other way I see would be to have another container to heat your water but it would also need to be able to handle 15 psi because it would also need to be pressurized. I love trying to figure stuff like this out so if you need help let me know here or PM me.
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volleyshroom
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Re: Converting Pressure Chamber into Steam Autoclave [Re: EdgarPoe]
#28373777 - 06/25/23 07:19 AM (7 months, 8 hours ago) |
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Thanks for the reply, safety is my first and main concern in designing the pressure chamber. I'll definitely be testing the valves - they work under air pressure but will need to be tested under steam pressure. I would like to put a pressure relief valve inline between the eventual steam generator and the larger tank.
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volleyshroom
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Re: Converting Pressure Chamber into Steam Autoclave [Re: SHROOMSISAY01]
#28373789 - 06/25/23 07:31 AM (7 months, 8 hours ago) |
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To clarify, I'm thinking about adding a heating element to the bottom of the smaller 20 gallon pressure chamber, filling that chamber with water, and connecting it to the larger 45 gallon chamber. That way the steam generator chamber capacity will well exceed the amount of water necessary for a run. Both chambers will then be at ubiquitous pressure throughout and can be kept at 15 PSI with a pid controller. Let's talk more over PM and see if we can come up with a workable design.
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deadmandave
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Re: Converting Pressure Chamber into Steam Autoclave [Re: volleyshroom]
#28373890 - 06/25/23 09:16 AM (7 months, 6 hours ago) |
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This is cool. Do you know how big of an element would be needed to reach and maintain 15psi?
Is there another pressure regulator on the waste line that isn't included in the drawing?
Are you using this for grains? If you're just doing bulk sub a 55 gallon steamer would be simpler and safer imo.
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SHROOMSISAY01
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Re: Converting Pressure Chamber into Steam Autoclave [Re: volleyshroom]
#28374036 - 06/25/23 11:51 AM (7 months, 3 hours ago) |
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Quote:
deadmandave said: This is cool. Do you know how big of an element would be needed to reach and maintain 15psi?
Is there another pressure regulator on the waste line that isn't included in the drawing?
Are you using this for grains? If you're just doing bulk sub a 55 gallon steamer would be simpler and safer imo.
I would probably go with a 5500-watt element just so it would get to temp quickly. Once it is at 250F (15 psi) then the PID will control it by giving it the proper power. The proper PID and SSR are important if the PID says you need 80% power to maintain the temp then the SSR will switch on and off 80 times a minute. 60% would be 60 times a minute and so on. This is just an example there is a lot more going on but it gives you the idea of what is actually happening and how it can keep it at a certain temp. A temperature controller on the other turns on at a certain temp and off at a certain temp so you have a fairly large fluctuation of the temp.
Quote:
volleyshroom said: To clarify, I'm thinking about adding a heating element to the bottom of the smaller 20 gallon pressure chamber, filling that chamber with water, and connecting it to the larger 45 gallon chamber. That way the steam generator chamber capacity will well exceed the amount of water necessary for a run. Both chambers will then be at ubiquitous pressure throughout and can be kept at 15 PSI with a pid controller. Let's talk more over PM and see if we can come up with a workable design.
Yea, that makes sense. I don't know how comfortable you are with building the PID. I build them and 3D print custom controller boxes with timers. If you are interested let me know. If you are going to build it yourself I have diagrams to help...
https://www.shroomery.org/forums/showprofile.php?User=398452
Here are my old-style PID controller boxes the ones I build now are actually nicer and stout. The current design mounts on a wall I am working on a desktop model...

The reason I have a separate timer instead of having the timer built into the PID is I hate having to go into a menu and set the PID each time. The separate timer is quick and easy.
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