I never, repeat never have any air in my system when it is in operation. Something is wrong if you are operating with air in your closed loop, especially when you are talking about recovery pumps.
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I apologize for even bringing the subject up…however, it did
spark a bit of curiosity thinking it through…and I admit to having
done a bit of research prior mentioning it.
(actually I was wondering what caused a spit butane tank I had seen)
if anyone here cares to google “nitrogen mixtures with butane”
you will find 6,450,000 hits…
“Butane works but no theory”…
seriously at many different levels…“butane extractors” have to be
the most “far out” people on the forum…
Ironically,many have made millions…
it’s the bomb.
I don’t disagree with that but the little air that is packed along with the biomass doesn’t hurt too much, particularly if one remembers to vent the recovered solvent cylinder periodically.
The system I built, a parallel version of GrayWolf’s Terpenator had seven tubes connected to two manifolds with a ton of valves and connections. I found it nary impossible to have it hold vacuum after system-wide evacuation. I soon discontinued the evacuation step.
In most scenarios, basic AC refrigerant recovery techniques is enough to safely operate a well-designed closed-loop system.
That and some understanding of physical chemistry in general, and that of phase diagrams in particular.
And above all, remember that atmosphere is 15 psi and if present in your system, will add to the total pressure, especially when pushed into a closed cylinder by a recovery pump with good seals.
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@ mitokid: 'Butane works but no theory" was a pun on another subject.
Your post is exactly what I suggested in the 20th post of this series.
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Final thought before bedtime: Every unique system design has its own set of unique “best practices” operational steps. I never did use a “helper gas” such as nitrogen to make the loop operate. To me, that just meant a more complex design and introduction of potential hazards, your “grilled chicken” analogy being one of them.
My objective was to safely achieve maximum one-person workload productivity of BHO that could go straight to distillation, none of the fancy low-temp nitrogen-push tech needed for other product classes.
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Aaahhh. I’m not a crude dude. I only make craft quality bho. We’re not having the same conversation. Operating conditions are completely different and so is desired end product quality.
You’re extremely smart and I can’t deny that. But, you’re in a completely different lane. For crude purposes nitrogen wouldn’t work, you don’t chill your solvent and that’s fine, for the lower quality product you make.
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Also, pull a vacuum on your material. Vacuum takes out air. You know how a diesel motor works, correct? TAKE THE AIR OUT OF YOUR SETUP! NO AIR IS SUPPOSED TO EVER BE IN THERE! YOU ARE FIGHTING THE WRONG FIGHT. FIX YOUR GOD DAMN LEAK.
But, you shouldn’t ever be pulling air in. That’s equipment failure. Skip past all the nonsense that nitrogen gets into my butane. We need to talk about why TF you are still defending your system having air in it. We should be talking about how to fix this so that you don’t make a diesel motor out of the useless recovery pump you have.
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This.
Preach dred.
And yeah, never had air in my system.
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I like your style.
I ran into issues during the humid summer months, techs were not pulling a full vac in between runs and residual atmosphere was collecting, condensing, and then freezing in my chilled coils, resulting in some scary ass clogs that caused my prv’s to blow.
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To some extent we are and I entered the thread sharing my experiences with accumulation of air in the recovery tank. After all, air is 70% nitrogen. Commenting on these Forum threads isn’t always the easiest since the topics are somewhat fluid, compounded by general hip-shot tendencies and unwillingness to absorb a thread in full before thinking twice prior to post.
I definitely belong to that category, particularly if my wake, bake, and coffee routine has been upset.
was always just an intermediate for very high quality distillate.
Ideally, no. But it is much easier to obtain a leak-proof system preventing butane at 60 psi from escaping the system than it is to prevent ambient atmosphere molecules (a lot smaller than butane) from entering a system under vacuum.
As I have tried to explain, not defend, is that I found that the relatively small amounts of air present in the system at start (plus the air inadvertently entering the system during deep recovery), that amount of air was something I could deal with in a satisfactory manner.
It simply provided me with an overall increase in operational simplicity.
I deemed that the lessons I learned from my experiences with the system I designed were valuable enough to share in this thread.
I do know about the glow plug part. While some hydrocarbon/air mixtures can ignite in the absence of a hot point, the pressures typically needed far exceeds that of the pressure a typical refrigerant recovery pump (I used the oil-less CMEP) can attain.
I agree with you on this, butane extracts makes far better distillate than ethanol extracts.
Debatable. Neither one of these should happen and they are both equally as easy to prevent.
Thank you for reminding me. Haha I need more of both
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haven’t noticed that one. will have to pay more attention…
how many did you get through 
seems like this one might have relevance to the argon vs nitrogen crowd.
https://pubs.acs.org/doi/abs/10.1021/je00058a015
I haven’t made it past the paywall yet, but there does seem to be a difference…
https://sci-hubtw.hkvisa.net/10.1021/je00058a015
edit: past the paywall and still befuddled… oh well. maybe someone with more physical chemistry than myself can give us the take home? Time for me to get to work…
Air in your system….maybe your not pulling a full vac on one of your columns?
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believe it or not! that is the one I read…answer 1.
I thought the pressures were all too high to be relevent here…
but if you note my comment on someone doing an experiment of
mixing/over pressuring butane liquid with N2 at -50 C and letting things come to equilibrium
room temp in a Parr style reactor…thus measuring the absolute pressure the system might obtain. (split tank observation)…only…
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Butane dissolves quite a bit of water but once saturated with water, a heavier aqueous layer will form in the tank.
That layer can be expelled from a recovery cylinder by setting it upside down and opening the gas port of the cylinder.
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There’s a big difference between air and N2 in your closed loop. That 20+% of O2 gives the air a lot of punch and it certainly isn’t inert; it’s an oxidizer. If your closed loop system allows atmosphere in, it ain’t closed. Close it.
Whenever a liquid is stored in a sealed system there needs to be head space in the cylinder to permit enough room for thermal expansion of the liquid without rupturing the container. That head space can be occupied with any vapor and can be pressurized to the extent allowed by the characteristics of the vapor.
C3 & C4 hydrocarbons are filled as liquids. Let’s talk about a blend of butane and propane that has a vapor pressure of exactly100 psig, (lower than 108 if pure propane). As soon as the liquid fill starts, the blend boils and generates vapor at 100 psi. As the cylinder gets filled, the rising liquid compresses the vapor to a higher pressure and it drops back to liquid phase until the pressure of the vapor pushing down reaches the vapor pressure of the liquid pushing up @ 100 psi. Cool, we all get this.
If you add 200 psi nitrogen into the head space in the full cylinder, the vapor phase blend will liquefy to the point where it’s diluted pressure reaches equilibrium with the liquid below. Because the liquid has a 100 psi vapor pressure, the volume of the 200 psi nitrogen in the head space can hold 50% of the solvent, balanced with 50% nitrogen. The % level of the solvent blend in the vapor will increase as the pressure in the head space decreases. When enough liquid is removed to double the volume of the head space, the pressure of the vapor will be halved to 100 psi and the nitrogen will no longer have any effect on the liquid below. The N2 will not push the liquid out of the tank - the 100 psi of the liquid will and the liquid solvent will maintain the head space at 100 psi.
Here’s where the problem with air in the system comes into play. The LEL and UEL if propane in air is 2.1% & 9.5%, respectively. There may well be enough air / atmosphere in the system to get the solvent in the air in the head space within that range. If it does, the vapor in the head space is explosive. All it needs is a source of ignition.
That’s why you need to make sure your systems have no air in them. Even a pinhole leak can bring air into your system. If your system leaks, fix it. Vacuum your system every time it’s open to atmosphere.
While you’re at it, replace those shitty cheap valves that come on refrigerant recovery cylinders because they have cheap rubber gaskets and seals in them and they are not designed to be exposed to flammable solvents.
Be safe out there.
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