It would be one thing if he was like “hey I just let my diffusion pump run without backing vacuum for 30 minutes – here’s before and after pictures, no char”. Then I would say the three manuals are wrong. But when it’s just his bare assertions and nothing else, yes, i’m going to go with the book. Especially when he says that it’s physically impossible for a diffusion pump to function if the fluids can react with oxygen; but diffusion pumps are sometimes run with hydrocarbons, and those most certainly do burn.
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I mean come on everyone. Read the warnings here about using hydrocarbons as diffusion fluid. Then tell me more about how the laws of physics prevent a burnable substance from being effective in a diffusion pump.
https://www.tungsten.com/tips/differences-in-diffusion-pump-fluid/
The truth is that nothing in the world is inert, even helium! Something can only be inert in reference to a specific context. PTFE is considered utterly inert, but it is not inert above 300C, because oxygen will burn it. Gasoline would not typically be considered an inert substance, but in an atmosphere of 100% nitrogen, it is inert. In an atmosphere of fluorine, almost nothing is inert. Inside of a fluorite shell, fluorine itself is inert.
The question, then, is not whether the diffusion fluid is inert. The question is in what context, in terms of temperature, atmosphere, pressure, time, is it inert?
For a diffusion pump to work, the fluid must be inert, in the context of a running diffusion pump. In a running diffusion pump, vacuum is very deep, many fluids are inert. Even very oxidizable hydrocarbons will function, because in a deep vacuum, they are inert. But you would be well advised, if using these hydrocarbons, to cool the pump down before breaking the vacuum and admitting oxygen. When you admit oxygen, the context has changed. What was previously inert can no longer be considered so.
So there is no contradiction whatsoever in saying on one hand, the diffusion pump fluid is inert enough to serve it’s purpose. And on the other hand, saying the diffusion pump fluid is susceptible to oxidation. For they refer to two different contexts, and each is true in it’s context. The laws of physics, as always, continue to hold true.
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Why are you grasping at straws. The debate is over.
Diffusion oil now adays in cannabis and for the sake of argument isn’t burning or Charing. It’s the crap us distillers are getting into it and Charing the insides that way, if it’s happening.
Move along. I think everyone got thier dose of education. Next time you get diffusion pump oil to char on it’s own let us know.
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This topic is temporarily closed for at least 4 hours due to a large number of community flags.
The roughing pump is what is keeping the oil from igniting, it allows the oil to boil at a slightly lower temp, just like a distillation of cannabinoids. The silicone oil isn’t subject to as much oxidation as a comparable hydrocarbon oil. As an experiment I encourage you to heat up a small test tube of dow 702, it will burn plain as day.
here is the flash point:
Table III: Ignition Temperatures of Dow Corning 705 Diffusion Pump Fluid vs.
Hydrocarbon Diffusion Pump Fluid
Spontaneous
Ignition
Partial Fluid Volume Fluid Temperature,
Fluid Pressure, torr Vapor, percent °C (°F)
Dow Corning 705
Diffusion Pump Fluid … 23 3 475 (890)
37 4.9 464 (870)
72 9.5 440 (824)
Hydrocarbon
diffusion pump fluid … 8.1 1.1 300 (572)
21 2.7 325 (619
read up on the specs here
https://www.capvac.com/files/downloads/MSDS/DC704702705_Specs.pdf
now not all oils are created equal, and not all users will use the same diffusion pump oil. Some oils will not tolerate the 02 and will infact burn when the pump is improperly vented to the atmosphere.There are lots of cases like this
I also invite you to read this manual, on page 22 there are instructions how to start the pump, it literally has a big warning that says the oil may catch on fire if the pump is exposed to atmospheric conditions. Oils may polymerize as well at they get older, this can make a coating on the inside of the pump.
This seems to be the gerneral consensus among the people who make these products, its not what it is, just what you fill it with.
my .02
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Like I said, you both have good points and you are correct…you will destroy the diff fluid if you heat it under atmospheric conditions…I hope nobody is arguing that fact. Methyl/phenyl siloxanes are oxidation resistant…not oxidation proof. The 705 fluids will give you the best performance and reliability, but if get contaminated…all bets are off. I always pull vacuum on the backside of the diff pump and make sure it does get below 0.100 torr before I turn on the heater element. I am not sure of the argument here…I always teach people (operators) to follow that start-up procedure…its a no-brainer. Sometimes during debates, heated or civil, it can be a learning experience for all, so don’t delete anything…the manuals don’t lie, so you never can be wrong following that. But sometimes it has to be tweaked a little in the real world…outside the engineering bubbles.
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Soxhlet…100% correct. Hydrocarbon diff pump fluids are a thing of the pass, just like the mercury units of days gone by. The mercury pumps were bullet-proof, well if you don’t mind mercury poisoning and the environment. The 705 fluids work the best, but like I said in an earlier post, they are not oxidation proof and will fall apart chemically in a heated oxygen rich environment. I have seen operators forget to turn off the heaters overnight and it did not catch fire…maybe just luck, but it did not ignite. We did have to do a shutdown, drain the crappy fluid and refill the unit. Worked fine after that mess, but I am sure it did do wonders for the unit.
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Thank you for backing me up here. My point is nothing other than this plain indisputable fact, that if you run the diffusion pump open to air the oil will burn. It may not explosively detonate like the hydrocarbon version would, but it will burn.
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at least it would smoke real good!
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I want my time back.
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LOOOOOL SAAAME that was just ridiculous
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I would hit up next level lab’s he ran short path for years and now been rocking whip film . He has the knowledge and is head of the game a great person hit up has alot of tip’s and tricks .
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Are you using a 50/60 diffusion? Do you kike it, ive been wanting to get a diffusion pump for 1 of mt 5L just to get a basic understanding of howbto use them. I believe a varient is what beaker and wrench use on there wfe
I have used that type. Yeah, they work great.
Ive just never tried one before and i figured the turbo ‘s from the wipers would be to much. Seems like there easy to operate i just need to do some more reading before i feel comfortable and spend the money dont want to end up buying a paperweight i never use
I would check out next level lab’s he has alot year’s tip and tricks. Check him out on Instagram he is Rocking whip film .
One question, what do you run in short path for distillation if you have a wipe film in place?
Short path can fraqtionate better than wiped film so if you are hunting minor cannabinoids or want to make sure they stay out of your main body then spd works better
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I was having vac troubles at the time. Not something that continued over time. The facility demanded production and that’s all we had that functioned.