Even after replacing the diffusion pump oil? @MagisterChemist
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Yes, if it burns, it will deposit burnt char onto the surface of the steel, much like you might observe on the steel pans you cook with. Unfortunately the design of the diffusion pump is such that you can’t easily access the char to scrub it, and solvents have little effect. Once it’s been charred, the diffusion pump will never perform as well again.
I tried many methods to clean it but unfortunately it really requires abbrasion to remove, and there’s no good way of doing that at least on the model I used.
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The process that you are describing is not so much a char but the effects of oxygen interacting with oil at high temps- the pump oil undergoes a process called “polymerization”
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Yes, that’s correct. Char’s just a qualitative description. Same thing with the cooking oil actually (and seasoning cast iron pans!)
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You aren’t burning the oil. You ate fracking it. And soaking it with molecules. Hot oil fracks and turns to a lesser quality oil when air is there. It’s not burning it.
That’s not burned char from oil. The burned char from the miscellaneous compounds that that were in the pile while other gases or major air leaks came on and torched those compounds. Diffusion oil is inert oil typically. Or extreemely high temperature ultra, high vacuum refined oils. They are made at higher vacuum and temps than what the diffusion pumps offers. Those marking tour talking about are from unprofessional and improperly maintenance on a diffusion of contamination that was burning inside like distillation compounds from a reaction etc…
Edwards themselves told me this would happen even with just air and oil, no distillation taking place. Without evidence, your words will fall on deaf ears.
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You spoke with a sales rep who clearly misguided you.
What’s burning is the crap loading up the pump and burning inside the heater cavity. Not the oil. Air fracks the oil.
Make sure you validate those crazy things Edwards sales reps tell you or pay better attention to what they are saying. You’re giving incorrect info as falsified facts and you don’t even know it. Don’t hate me. Hate the facts, you aren’t burning the oil. You are burning the stuff that’s getting sucked into it.
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Please post sources
There are no manuals ever that say inert diffusion oils or highly engineered silicone style oils are going to burn and leave char on the inside of a diffusion pump. You have to understand the physics behind diffusion pumps. They opperate on oils that are distilled at a much higher temps than the diffusion pups sits at. And higher vacuum. They don’t react. That’s the whole point of how they work.
Do you understand how diffusion pumps work. Please tell us all.
So now you apparently have insight into who I have had conversations with. Yet this is one more assertion without evidence. Thus, like the others, we should set it aside.
I also love the hypocrisy here.
Summit: I sell vacuum pumps, therefore I know what I’m talking about.
Also Summit: that person was just a vacuum pump salesman, therefore they don’t know what they were talking about.
It was not a sales rep, by the way.
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Here I’ll explain how diffusion pumps work so you actually understand.
Under vacuum mechanical pumps with moving parts are grabbing molecules but suffer because they can no longer grab molecules around 1 micron.
Inside of a diffusion pump you have a lower heater, a jet stack either two to three stage. And a ejection port as well as inlet. Within the theoretical aspect of how the pump works under vacuum imagine empty space with very little molecules present.
The pump has a roughing pump that sucks up the excited pressure of molecules rushing out of the diffuser exit port.
What is happening is a inert - pay attention to that word - a inert oil or a highly refined higher temperature oil resistant to bonding to molecules and repels under opperation…is heated and creates a “smoke” or a cloud. This center jet stack is basically absorbing the cloud of difusion thats being shot up in a 'smoke like pattern". The jet then rushes out as a cloud of diffusion oil in the cloudy mist against the cooler wall. Where the oil is a couple hundred of degrees Celsius the wall is about 18-20c. So it’s sorta like a cold trap.
The hot mist shoots out the jet stack and captures miscellaneous molecules floating around in this evacuated chamber. And then as they become dense and condense on the cooler wall the oil that has captured the molecules now runs down the inside wall of the diffusion pump and hits the hot oil. This immediately excites the molecules and ejects it from the ejection port.
See none of this would work if the inert oils reacted and burned. Because the oil cannot burn it is the reason why diffusion pumps work. They are inherently able to opperate for weeks to months at a time because they excite and make molecules jump out from the oil and “burn off” the contamination within the diffusion oil so it can vaporize and eject.
Again. The chared contaminated particles that entered and burned into the walls. Has nothing. Again nothing to do with the inert oils.
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Yes. Edwards engineers are in checkslovakia. They don’t rely speak English. If you called anyone at edwards they we’re remote techs and salesmen. Edwards is a subsidy owned by atlas copco. Also a sales company. You probably never spoke to a Edwards engineer and maybe not when a engineer at all. But you can still talk about diffusion pumps like you know what your talking about with this whole burning oil thing.
Wow, you can watch a YouTube video!
What you fail to understand is that those oils are inert when below the specified pressure of air. They are not inert when under full atmosphere. This is why every diffusion pump manual takes great care to specify that the diffusion pump must not turned on until the backing vacuum has reduced pressure below the specified level, and then no air can be admitted until the diffusion pump has been cooled back down.
Or else what?
Or else, per this manual, thermal breakdown of the oil will occur.
Thermal break down is fracking the oil. It’s not at all…repeat…not at all burning. Your talking about fracking the oil. It doesn’t char or burn.
The actual reason why the diffusion Should be evacuated is because air will splash forcing some of the silcone oil into the backing pump with isn’t good for vac
You can accellerate like a oxidizer, the molecules that havent been ejected from the system worth introduction of oxygen and that can burn in itself on place using the hot oil as a heater basically. But still those contaminates are what are burning.
When you frack a oil it means the oil basically splits on two or three shorter chain molecules and they no longer opperate like it’s original oil. It’s not burning it’s more like a long chain oil created a chemical reaction that’s violent with air and the molecule splits up into a similar but less efficient oil in the diffusion pump but it’s still not burning or Charing.
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The oil boils off.
I spent minimum of a half hour talking to the lead engineer at pope scientific about exactly how diffusion pumps operate and why.
It burns. It boils off and burns. It does not get sucked into the roughing pump.