I agree, the calibration seems sketchy, but we don’t care about absolute temps, just what works for our products in our lab. Repeatability >> Accuracy. That being said, I would love to actually check the calibration on my cascade ovens, but havent found a great way to do it. Anybody squeeze a thermocouple in there while maintaining vacuum?
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yes i know you sell cascade. I know there is a possibility for heat loss when opening the oven door. Using a piece of copper on the tray your trying to capture the recording will help retain the temp long enough to capture a close enough temp i feel. Like i said…i wish i could get all scientific with everything. Im just doing this for personal head stash. I only smoke concentrates so i try to make them as good as i can possibly. Hopefully more people will chime in, and help me improve my tech. I just answered in this thread as i know this is pretty beginner stuff and the really smart people here have better questions to answer.
Sorry i dont own cascade ovens. Amazon has AI ovens on there site, which allowed me to take advantage of their financing so i was able to afford them. Otherwise…most ovens and this equipment is outta my reach as im in a non complaint state, with limited funds. You can read on Icmag where i actually got a leaky oven from AI but they picked it up and replaced it very fast. So, my experience with AI isnt all peaches and cream. This is just what i have. Wish i could afford more sometime! 
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Dont be too discouraged, if it holds enough vac (look into elevation above sea level adjustments) and a somewhat even temp, you are good to go. The final product is all that matters.
Love it. World needs more people like you!
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I’m liking the copper idea for trying to measure the actual temp inside the oven. What about throwing a thermocouple with the meter and everything in there so you can see it? Might be worth sacrificing a cheap temp meter. Exploding batteries might be a problem.
Kind of along those lines, anyone add thermal mass inside the oven to keep a more steady temp? I know more shelves helps with this. What about a sheet of metal, or even glass or stone?
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I do up to 102° flip every 12 hours. I always do this from a pour and never put the scrape with it. Since the scrape has been heavily agitated uit tends to want to cause nucleation sites. So we take that to the side adhd agitate it more into our honeycomb. We this always acheive under 100ppm down to 2.6ppm. While keeping a stable flavorful shatter.
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Currently using AI ovens. 3.2cf have been my favorite overall.
I recommend staging your oven in increments of -5. (Ex: -5, -10, -15) pull vac slowly while doing this. I let it sit on each increment for at least 5min. For the final stages I will pull a slow vac from -25 till I reach -27inhg. I will let this stage sit for 10-15min before pulling the final stage. I let that stage for another 10-15min with vac valve wide open. I flip every 24hrs and keep doing this for 5-7 days. Have had great results and consistently sitting under 20ppm Butane. Hope this helps!
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I start my oven at 100°F. Pull vac in increments and watch for action on the slab. As it stays active I slow the pull. It usually takes 45 min to 75 minutes depending on slab thickness to keep the surface active until I reach full vac. Leave it for 3 hours and then I put it into my 2nd day oven at 95°. From there I flip 1 time a day for 2 days and hold vac. 4th day I pull it out and put it in 85° finish oven. I let it rest over night and it comes out low ppm every time with great TERP content.
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How do you calibrate your vacuum oven?
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Set the oven to 10 degrees over operating temperature (~120) and let it sit empty for 3-6 hours under vac
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The KF-25 flange on the back of the oven is for this purpose exactly. Check out this helpful resource for all things vacuum-feedthroughs:
http://www.ldsvacuumshopper.com/powerfeedthru.html
I would recommend a type J thermocouple. Them you can use an external monitor like this:
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Wow! Thanks for all the great info!
Some new questions/observations:
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I’m surprised that most people seem to be pulling nearly full vacuum. I would think that some of the terps would boil off at that point!
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When introducing atmosphere into the oven, do I need to do that very slowly? or can I just open the valve?
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I’m starting with a 0.9 AI oven until I got a process down. Can I really fill up each shelf with a slab?
1.) Of course some terps our lost in the process. Unless you have a cold trap.
2.) I open the valve at steady pace. “Slow is smooth, smooth is fast”.
3.) Making your PTFE sheets or parchment just a bit smaller than the shelf makes it easier to work with imo.
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https://future4200.com/t/oven-tek-sop-criticisms-welcome/127/8
Hey Sidco,
I noticed you said you were a consultant for Cascade. I have been working with Cascade, Dan and Mary, for awhile now and love all of the equipment. I have a few questions for you, that I posed to Mary this morning as well:
On the Cascade website, https://cascadebotanical.com/resources/ask-cascade/, they have a FAQ page that talks about oven SOP. In their SOP, it says to keep the pumps running during the entire purge process, and that the total purge time is 8 - 12 hours. They talk about the theory of locking off vac just traps the solvent within the oven and it will settle back into the product.
In my experience, and based on the Oven tek criticism welcome thread as well, I have always needed a 3-5 day purge, and do not run my pumps the entire time. Why is cascade saying that, with their equipment, I can achieve a totally purged product within 12 hours. Mary stated it was due to Cascade using larger valves and connections, larger pumps, etc. They also recommend keeping the vac pumping the entire time… Wouldn’t this off-gas the THC with a large pump?
I am currently using TVO-5 Double ups, and each two ovens has one Agilent idp7 (the complete package “pro” setup). Would I be safer to use a smaller pump if I want to keep it running during the entire purge?
I appreciate any help. Thanks for this community, I am loving it!
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Thanks for being patient @bookem - http://www.tokecity.com/forums/archive/index.php/t-52833.html
https://www.icmag.com/ic/showpost.php?p=5870695&postcount=79
A RGA was used a few years ago to see when and what outgasses in Cascade ovens. Project was pretty much a failure due to cost but did lend some SOP insights and with it an interesting conversation about running at 115f for a few hours vs ~90f for 50+ hours. I came to this conclusion: Reduce time and variables with increased heat. And some tools are damn inaccurate.
- At sea level 100f is a good starting place, 115f on the high side. Pair a suitable oil-free pump with your chamber(s).
- Spread / pour your slabs as thin as possible. Increase surface area, reduce purge time.
- Vac slowly, to keep as much of your product on the shelf as possible (No muffin!). Uniform heating is key to consistency.
- Keep the pumps running. You might notice if you put product in a sealed & vacuumed chamber, it will appear to leak, that is really a result of outgassing - those gasses are expected to move out.
- Backfill (when/how varies) with inert gas for best results. Don’t make the oven fight your product and your 35% humidity.
- Flip 1 time, after ~8 hours. Using the RGA we noticed ~80% of the solvent was gone at this point and purge complete with another ~4 hours on side 2. Every time you open the door you alter oven and product temp, humidity, and thus consistency. Record current humidity every time you do a flip and it will be clear where the change in consistency comes from. A 12hr/6hr cycle is not a horrible place to start.
As far as outgassing THC, look-see here - There is a sweet spot @ ~100f and 750-100 micron where the purge should take water and butane with a furry but not long enough to seriously hit THC on a measurable scale. IMO a longer purge time with lower temp gives more opportunity for terpenes and other goodies to break down and outgas but I don’t have any hard evidence. Give that sweet slab a quick and efficient purge to remove the unwanted solvents at the target temp and vac instead of trying to slow melt it all away over 5 days. Though the end result is often very similar and equally as yummy, you save time and $ using proper purge tek.
!
To test your SOP - break a piece off after the first flip and another from your end product. Send both to lab for residual solvent testing. Determine if adding 5 degrees or another hour will complete the purge vs an extra flip.
As for your Agilent IDP7 (<3 that pump) note in the manual ultimate pressure varies if you are using 60Hz or 50Hz power. This means no matter a 1L vs 5L vs 10L chamber the ultimate pressure will be 2.0e-2 or 3.0e-2 Torr, lets assume 60Hz. (math magic 2x10 = 20.0, move . over 2 places =) .2 torr or 200 micron. So looking at the charts above that puts THC boiling at ~70-75f - Note that some folks are purging at 110f with larger pumps (for days at a time) knowingly degrading THC and still have a balling product. One thing to take into consideration is as the water and solvents are outgassing the pump is working to keep up, thus working much harder to achieve that THC boiling point. You are safe to use the IDP7 on one or both of your chambers at the same time.
whew - criticisms welcome.
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same goes for our tek!Not entirely so. Vacuum is vacuum. We blow past the difference in pressures based on altitude in a millisecond in the vacuum oven.
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These types of charts make me wonder why people need to pull at nearly full vacuum during the purge. It seems like you shouldn’t need to pull super deep vacuums to get rid of the solvents.
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For every 1000 Feet above sea level, the maximum possible vacuum is reduced by approximately one in-
Hg, right?
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This wall of words brought to you courtesy of my Favorite Agilent Sales Engineer. Enjoy:
The web site for Anver is about vacuum handling; using vacuum to lift objects. This does not mean that ultimate pressure is compromised by the altitude at which the pump is operated. A pump capable of attaining 1 mTorr at sea level will still be able to attain 1 mTorr in Colorado.
What the Anver site is talking about is all about differential pressure, which does become less as the altitude increases.
Thank of it this way…. Let’s say that a suction cup can remove 80% of the air beneath it. Does a suction cup work in outer space? No. Why? Because the pressure is virtually equal on both sides of the cup.
As you descend to Earth, the differential pressure will gradually increase until you reach seal level, where the delta P will be based on 14.7 PSI on the outside of the cup, and 14.7*.2, or 2.94 PSI on the inside. This leaves a delta P of 11.76 PSI. If the suction cup covers 10 square inches, you have a “lifting force” of 117.6 lbs for each suction cup. At sea level.
Move the action to Denver. According to the Anver chart, at 5000 feet, the air pressure is 12.22 PSI. The same suction cup now has only 12.22 on the outside, and 12.22*.2, or 2.44 PSI on the inside. This leaves a delta P of 9.776 PSI, so the same 10 square inch suction cup will have only 97.76 PSI of lifting force.
TL.DR: Altitude will not effect ultimate pressure of a vacuum pump/Vac oven system.
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