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:
Wow! Thanks for all the great info!
Some new questions/observations:
Iām 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!
When introducing atmosphere into the oven, do I need to do that very slowly? or can I just open the valve?
Iām 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. āSlow is smooth, smooth is fastā.
3.) Making your PTFE sheets or parchment just a bit smaller than the shelf makes it easier to work with imo.
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 timeā¦ Wouldnāt 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 āproā 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!
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.
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 donāt 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.
Altitude alters operating procedure for chefs while they bake 
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.
These types of charts make me wonder why people need to pull at nearly full vacuum during the purge. It seems like you shouldnāt need to pull super deep vacuums to get rid of the solvents.
For every 1000 Feet above sea level, the maximum possible vacuum is reduced by approximately one in-
Hg, right?
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 wayā¦. Letās 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 ālifting forceā 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.
Maybe he can explain how altitude doesnāt effect
BOYLEāS LAW
Which states that the volume and pressure of a gas will change in inverse proportion to one another. i.e. if the pressure in a system decreases (higher vacuum) then the volume the gas occupies will increase proportionally according to the following formula:
P1 V1 = P2 V2
The product of the initial pressure and volume equals the product of the final pressure and volume. When using the above formula in calculations the values must be in absolute terms ("Hg absolute or Torr).
Example 1: Convert 20 SCFM of air to ACFM at a vacuum level of 25 "Hg at sea level.
Solution: First convert 25 "Hg gauge to "Hg absolute:
P2 = 29.92 - 25 = 4.92 "HgA or 125 Torr
Use above formula to convert:
29.92 x 20 SCFM = 4.92 x V2 ACFM
V2 = (29.92/4.92) x 20 = 121.6 ACFM
And when we change altitudeā¦
Performance curves for vacuum pumps are always derived relative to atmospheric pressure at sea level. When a vacuum pump operates at altitudes higher than sea level, the atmospheric pressure decreases. The important thing to remember when you encounter applications at altitude is to measure the vacuum level relative to barometric pressure. Refer to the example below to see how this affects the calculation of vacuum level. As a quick rule of thumb, you can assume that for each increase of 1,000 feet of elevation, the barometric pressure will decrease by 1 "Hg.
Example: The installation site is located in Denver, CO (elevation 5280 ft). A capacity of 750 ACFM at 20 "Hg gauge is required for the application. What is the equivalent vacuum level at sea level?
Solution: The following formula helps to calculate the equivalent vacuum level:
Pref = P1 x (29.92/P2) which
Pref = corrected vacuum level
P2 = barometric pressure at altitude
= 25.3 "HgA (chart)
P1 = P2 - required vacuum level at altitude
= 25.3 "HgA - 20 "Hg = 5.3 "HgA
Pref = 5.3 "Hg x (29.92/25.3) = 6.3 "HgA or 23.4 "HgV
Therefore, select the pump with a minimum capacity of 750 ACFM at 23.4 "HgV.
I live at 6000 ft altitude and can only get my extractor down to -21 to -22 and my ovens down to about -24 (Different pumps). Its a bit of a bitch but with a bit of tinkering it all works out.
What kind of valve are you using?
I actually tried this technique today on a strain ive been having issues with crazy muffins, and really hard to get it flat. I went up in increments of 10 for 30 mins and wow. This seriously solved an issue with this strain. Thanks i think ill be using this going forward!
No problem man glad it helped. Not sure if i mentioned it but i will usually run mid 90ās for stable resins and low 90ās for less stable resins.
I have to say thank you to everyone for participating in this thread. Love the info I got back from you guys.
I am just curious if it is possible to make a crumble or wax with a similar technique as specified above. If so, what is the delta?
I can only work with liquids, so does solvent matter?
Iāve tried purging above 95f and might just be my oven but the wax turns very sticky and oily at that temp and never is it shatter. But as soon as I donāt apply heat and do a long purge at about 70-80% total vacuum I start at 20% vacuum never trying to pull a muffin . Very hour or two depending on how slab looks I add more vacuum until gets to about 70-80% I leave it for 24-48 hours after that do a flip and same thing again another 24-48 hr. And ends up with some awesome stable shatter. All strain dependent some very stable shatters can purge up to 110 before seeing it have any difference . IMO you need to leave for a long time for the terps to actually evaporate out of the slab. If your goal is to keep terpenes you need to make diamonds. My goal is to have stable hard shatter with good color not the most terpenes cuz then it canāt be shatter. Not saying shatter canāt have flavor but it isnāt going to have the most flavor out there as say some sauce thereās a reason there like water and the thc is hard. Maybe has to do since I am in very hot San Diego weather maybe itās always pre heating my slabs to not need so much heat in oven like 85* is already to hot and slab will be ready in 24 hours but pure goey stuff can barely remove from paper on most strains. If the value of your wax drops if itās perfect stable shatter to some oily stuff it is well worth buying as much ovens as you need when each one holds over 1lb of wax . Also spread thin if you spread thick you will need more heat and therefore never get stable shatter in my experience. I have found anywhere from 25-40 grams pure suare foot is a great place to start. If your strain can handle heat pour thicker use more heat . If it canāt pour thinner and use lots less heat.
Etoh shatterā¦
Cold wash -60 or colder
Max 110 degree scrub with hardwood carbon
Filter through silica
Evaporator Max 110f till resin crawls the flask
Pour slabs thin but cover the sheet
Oven at 95 let slabs sit a few minutes to heat
Pull vac to 20hg to contain muffin (strain dependant)
Then pull lower vac until ethanol aggressivly purges
Around 28.5 to 29 works pretty well in our ovens.
Leave slab untouched for 24 hours
Flip slabs and purge again for 12 hours
Depending on the strain and freshnessā¦you should have some tasty hard shatter!
This is our standard starting points
If im doing a vac purge at room temp is there any way i could over purge the oil? Like if i vacced it too many times or let it sit under vac for a week?
@sidco hey guys I use 6 of your cvo-5 with the agilent idp-15ās and Iām located in denver. I can reach 25.1 in. hg in the ovens if I leave the vacuum pump valve open. I feel like this is more vacuum then i need, Iām doing all live product and want to retain all the terps I can.
I tend to shoot for a lower temp during the purge process and jus go slow and watching my reaction until Iām around maybe 24.5 in. hg at the most. Iām always shutting my valve back off because if left opened itād be to much I feel. My coworker feels like we should leave valve open and just let it crank so that it gets everything, but I feel like weād lose terps and convert thca to thc even. What are your thoughts?
I talked to agilent they said we could leave the pumps open and running 24/7 so they can handle it with the max traps. Do you tell customers to leave them running and open continually? I feel like for shatter where we are losing the terps anyway we could leave it up and running and get a faster purge but for terpy product its to much vac, Any input is appreciated!!
