Turbomolecular Madness - A Nerve-Wracking Experience
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- Опубліковано 18 лис 2023
- In today's video, I'll be evacuating my vacuum chamber using my massive Pfeiffer TPH2101. The TPH2101 is a turbomolecular pump with a pumping speed of 1400 L/s. To do this, I had to fabricate a reducing flange first. The pumping speed is simply impressive.
Wissel Vakuum: wissel-vakuum.de/
Join my Patreon and support my projects! Your contribution means the world to me and helps bring my ideas to life. I truly appreciate your support! / advancedtinkering - Наука та технологія
props to the owner of mr vacuum for allowing you to do that.
Yes, definitely!
😂
For real. Coolest thing I've ever seen.
Allowing? The correct sentence would more be; "props to the owner of mr vacuum for giving you the pump and controller to play with".
@@dtiydrbro ur not smart
Lets appreciate that engineering by Pfeiffer Vaccum for a second. These turbomolecular pumps had a long productive live, are full of residue and wear&tear, have been decomissioned (probably because of that), not serviced in over a decade, dis- and reassembled by a (knowledgable) amateur.... and STILL run that well. That's how amazingly well the people at Pfeiffer designed and built them. I'm awestruck by that quality.
Nice to see in a world of planned obsolescence trash.
So much stuff like this gets such little use by universities and such and then just gets replaced because thats the name of the game. Gotta spend it all. Pokémon Labs. A subsidiary of government grant grinders in partnership with University La Ductrine; specializing in varying degrees and angles of sadist action. A fine faction to be part of.
Speaking of none sense and waste …..
When My older brother was at one of the top dental schools in the United States Inc. they were learning to work with gold and do crowns and castings and such. …,, well apparently the whole lot of them lack any sort of frugality/common sense/or that ability to always see opportunity.
I say this in relation to the fact that if it was for one person, my brothers friend; all the dimwits gold would have just been thrown in the garbage ….yeah. Soo when you work with the gold you end up with “flashing” and such. Excess gold. Well apparently they were taught this was garbage i guess? Since they were all just throwing it in then garbage with the used plaster molds and whatever. ……(i wonder how many throw away all the gold crowns they remove from people? Im guessing many do. Clueless people dentists and doctors. No business sense) ..
So his friend collected all the gold whenever an opportunity came up and for fun he made himself and entire gold “grille” for his upper and lower teeth.
Guess how much gold he got out of the trash?? Well over 10k.
And get this …
My mind instantly is running and im like uummmm sooo like is this the norm around there? Ever quarter (or semester? Whatever they’re on ) for everyone to toss their gold in the garbage. ??
“Yeah….”
😵💫
I tried to figure out how i was going to insert myself into doing free janitorial work but my brother didnt see too interested.
He was focused on worthless school.
He graduated number 1. 4.00 gpa. Every quarter.
Guess it worked out for him. He just is finishing a 8 million dollar new house in idaho. ………( its really cool …..it has solid copper gutters. ….:. Annnd it also doesnt even have a den. Or office in it for him…… did i mention his wife?? Did i mention his office isnt in idaho? Did i mention he flys home every week and sleeps in his office on a cot??……. Hmmm. His wife just had ….nevermind.
Last thing. When i met his wife before they were engaged.
Back when my brother and i were living together in the ghetto in chula vista California doing door to door sales she came down to visit ….
Thats when i learned something very unique about her….
She …..
Didnt……Know how….
To jump……
Yes. Jump. It sounds like bs. And a lie.
Nope. It was real. She thought you jumped using only your feet. Like flipper on a pinball machine launching you off the ground with hard flick of the heel toe ankle action.
Logically she saw this as the reason basketball players could jump so high. Big feet. Duh.
So rather than pointing this out to others like myself as amusement as my brother had just done i taught he how to jump….
Seriously. 🥴
And when she did achieve that first flight …soaring a quarter inch into the air..when she touched down …🎉she went ballistic.
Thats when my brother apparently knew she was the one i guess because a week later we were driving back to Seattle…….
And that was the last time my brother and i got to hangout. I had just moved down a month or two before.
Anyways he went one way and i went the polar opposite ..
I better stop. Ok bye.
Glad i got that therapy session
Thanks for listening
Ps your right about Pfieffer, really awesome precision quality creations.
And anything that is able to be serviced these days and kept alive is so important.
I have a love for vintage. Antique items of all kinds. They’re so high quality. The stuff from before ww2. Especially from the 1920’s or older.
The technology is pretty incredible. Stuff that far surpasses present day.
All sorts of electronics that utilize mercury and vacuum tubes that few even comprehend anymore.
Theres all sorts of stuff that would be claimed pseudo science by the closed mind dead clueless modern man.
If anyone is interested i can show you the newspaper articles from when a funny thing happened 100 years ago.. all this stuff cern is supposedly just learning like the”god particle” and the rest of it….
Literally , i kid you not, all discovered and more 100years ago. ….its like history is on repeat or something.
And i mean it please ask if interested. Its important to be aware of our true history as much as we can.
Buy some old issue of Science and Invention. Its really awesome.
I have one right here from 1921 and it goes into detail talking about human cloning and using cows as surrogates for carrying whatever animals or human they are cloning. Cover story is bout Dicyanin lenses and how theyre used in astro spectrography as well as for giving people the ability to see the human aura.
Turns out pre ww2 this was common knowledge. Dozen books written on it as well the many other types of dye discovered that allowed for sensitizing the human eyes to even more wavelengths. For instance layering with a carmine filter/lens would allow one to see another layer of the auric field i believe?
Whats insane is if you do search about this youll get sites like snopes “debunking” it and saying its” pseudo science “. Debunking and pseudo science… two weaponized tools of ignorance.
By the way i own three different sets of Dicyanin goggles and theyre truly amazing.
They forced me …quite literally …
To see the world in a different way. (I used to think auras were bs. So far from it and i was happy to learn this too. The world is a lot more interesting than i once believed….
In fact the world as we’ve known it is about to change. …ill leave it at that. )
PLEASE add a screen in front of the turbine... you don't want to ever know the horror of something flaking or popping off in the chamber, and going though the vanes..... Nobody should have to have that happen.
Hats off to your welding, and the help you got from Mr. Vacuum! Nice job there !
The scary sounds are normal with mag lev bearing pumps. It is due to the pump passing through mechanical resonance bands as the pump controller tries to actively cancel destructive resonances in the lower audio range. ❤
Aha, so that is the reason they have a cost a of a small countrys GDP.
It's important to go under or over the resonance bands...
My guy, those welds are impressive!. seriously, most people wouldn't even be able to run a TIG without going through a whole box of tungsten tips first try. meanwhile you're over here stacking dimes.
Also, ramp up vibrations are spooky. I used to have to use a large bench grinder at work, had a 10 inch aluminum oxide wheel on that thing. When you turn it on, the thing near shakes every bolt out between 40 and 60% speed but runs smooth as butter otherwise.
Thank you a lot! But to be fair, the pulse mode of the welder makes a huge different. Without it my welds did look worse.
@@AdvancedTinkering That's fair, but still you need a steady hand to tig weld even with that.
Vacuum flange adapters that size are *expensive*. You got a bargain, sir! This is a brave hobby for the financially constrained.
Wow, huge props to Wissel Vakuum for supporting you with that adapter. That big a stainless steel flange has to be crazy-expensive, so it’s a lot of dollar/euro value, plus the owner himself helped you make it. It’s great PR for him, but he’s also very generous, much respect!
Servus, ich war mal Techniker bei Pfeiffer Vacuum und habe die TPH 2101 repariert und gewartet. Die Vibrationen bei ca. 10% oder auch zwischen 50-60 Hz sind normal. Das sind Resonanzen, die vom Magnetlager der Pumpe kommen und sind in jeder TMP vorhanden. Auch in den neuen Versionen. Man kann sie aber mittlerweile gut Wegwuchten.
Zusätzlich kann es sein, dass dein Aufbau (der nicht sonderlich stabil aussieht) mit der Magnetlagerresonaz zusammen sich hochschaukelt. Bei Fragen zur Wartung oder anderen Dingen gerne melden. Ich kenne die Dinger In- und Auswendig.
Hi!
Vielen Dank für den Kommentar und die Info zu den Vibrationen! Das ist schonmal beruhigend zu wissen. Ja, der Stand ist eigentlich viel zu flexibel für die Kammer und die Pumpe zusammen. Ich hoffe irgendwann ein neues Gerüst aus Stahl bauen zu können und im Boden verankern zu können.
Wenn du die Zeit hast und es dich interessiert, würde ich mich sehr freuen, wenn du dir das Video anschaust, in dem ich eine der Pumpen zerlegt habe (zwei Videos vor diesem). Als Pfeiffer Techniker bekommt man sicher Schnappatmung wenn man mir dabei zusehen muss, aber mich würde sehr interessieren, an welchen Stellen ich ganz groben Mist gebaut habe und wie es richtig wäre. Und ob meine Theorie dazu, wie das "Ölsystem" funktioniert, richtig ist. Und welchen Zweck der O-Ring am Zentierring der Statoren erfüllt.
I love your set-up 😍 but you definitely should add a grid before the pump to avoid any damages on the blades if something fly in
During my time as an Instrument Systems Specialist I calibrated instruments on an electron beam welding system and the chamber was big enough to fit a full size 3/4 ton utility van. It used two large turbomolecular pumps along with a pair of even bigger roughing pumps to evacuate the chamber and took well over an hour to get to the lowest possible pressure. I love science, thanks for another fun video.
"No prior experience welding"
Proceeds to absolutely *stack dimes* like he's been welding custom exhaust systems right out of the womb.
Haha, to be honest, the pulse setting on the welder makes it much easier.
I have a small TMP that is sketchy to use. A blade broke off it at work, so they threw it away by letting me take it home. Fortunatley, it was an ebay special because we were not treating it well (the reason the pump didn't tear itself apart was because we were evacuating a sticky process, and the side wall was so sticky that the blade stuck to the wall instead of falling into the rest of the blades).
I fixed most of the balance problems by cutting out completely the missing blade as well as the blade on the opposite side, but even though it is only a ISO-100 pump the startup is still loud enough that hearing protection is needed until it gets up to speed.
What I need to do is build up an air bearing type thing so I can properly balance it.
Very nice video!
Resonances and vibrations of TMPs always sound really scary to be next to.
But they can be beasts. We have a dozen or so pumps of similar size running in our labs that are close to 50000 hours operation without a single one showing issues or failing.
If you have the adapters for it, hooking up the small Turbovac50 as backing for the TPH2101 might be interesting to see if you can down even further.
Absolutely! During those resonances, my heart rate definitely went up.
It's fascinating how long these machines can run without any issues.
Actually, I have the necessary adapters to connect the Turbovac50 as backing for the TPH2101. That sounds like a fantastic idea! ;)
@@AdvancedTinkering Another comment to the spikes in the pressure readout: the gauges sometimes switch between emission currents (if they have a filament) or readout full scales when they get to lower pressures, which can cause jumps like that.
Yes, as the pressure gets lower most controllers will step down the filament current. On glass gauges you could see the change in brightness, where I work we got rid of our last system with a clear glass gauges several years ago, now everything is a black box connected to a computer...
@@AdvancedTinkering I wouldn't recommend it. The load on the 50 could be so high that it overheat, of if a slight puff of air is compressed by the big on the output from it can be so high that the small one can be totally destroyed. And you won't get any lower anyway since you are way past the vacuum regime of that to work, that only work at rough vacuum.
I was standing right next to a Leybold D2500 TMP, about 15 hp, when it went from 39000 to 0 rpm in about 1/2 second. I'll never forget that sound. One blade tip rubbed and welded to the housing, broke off and wiped the rest of the blades out. We also had an uncontained burst with an experimental Becker pump, it was like a bomb went off. We use those on fast axial CO2 lasers. Every pump we used ran through a few harmonic areas on spool up.
Holy shit!
We had that happen to a jet engine! The N1 and N2 shafts were out of alignment and able to rub and weld. The pilot had to change his pants when it went from 105% RPM to 0% in about half a second! Didn't frag the engine though.
in our mass spectrometer we had 4 turbopumps and two rotary vane pumps resulting in a ion trap pressure of 1.4*10E-9 mbar
If you'll be moving around anything with more mass it's probably worth the cost to get a lift of some sort. I use an engine hoist to move around machine tools and it folds up into a small size when not in use.
You can traverse the vibration regions, whatever the reason for them, more quickly by having the pump under less load as it's spinning up--you could use the turbovac50 to bring the chamber below 1e-2 mbar and then start the tph2101. Also the pressure in your chamber seems a bit high--you might consider just pumping on it for a few days to see if that boils off whatever's causing the problem. Vacuum chambers that have been worked on and not pumped in a while often have anomalously high loads of miscellaneous outgassing.
Alternately, there might be a leak, of course, but you're well equipped to find and fix that. If it's such a large leak as to bring the chamber to a few e-6 mbar under that big pump, it's admitting air at ~1e-3 mbar L/s so helium will penetrate at ~1e-2 mbar L/s, so if you use the helium leak detector on it bear in mind what a full scale detection looks like. One more coarse-grained trick for such large leaks is to just spray any gas other than air--it will read differently on the ion gauge, so you will see a jump in the signal if you put eg argon or helium or even to some extent nitrogen near the outside of the leak.
Congratulations! It was really cool of Mr Vacuum to let you do that.
I have a couple of different medium-sized turbos, and they both have a very distinctive spin-up sound before they go quiet, right in the initial stage of startup. It's a little scary since it sounds like it isn't balanced for a moment, but it quickly accelerates past that point. You have such an amazing setup, having so many generous donors and friends who will help out sure is nice.
10% load means ~3000 RPM, which equals to around 50 Hz. This frequency is the same as the grid frequency you supply your power with.
maybe this is the reason for the resonance of the motor at around 10% load.
As you mentioned already in the video, it must be an electrical resonance, because after power off, the resonance disappears. So a purely mechanical resonance is not an option.
is there a way to look at the voltages of the motor / the input power to see some sort of phase alignment?
Maybe the controller has some old caps that are not up to the task, and some extra ripple is passing thru.
Mechanical resonance is still possible an issue. If you turn it off the rpm starts changing and changing rpm will cancel out vibration.
but highly unlikely. The change in RPM is very slow because of the low friction of the rotor. When he turns the power of the motor off, the vibrations instantly stop, the rotor spins on freely with roughly the same RPM@@SaviorTheBurn
@@matze1508 I doubt a vacuum makes it low friction. Im sure pieces are pulling together tightly.
the rolling friction in the bearings doenst increase that much while under vacuum. @@SaviorTheBurn
I used to work on large vacuum systems, the scariest noise after a strip down was a nut or bolt loose in the chamber just before the TMP came apart. It did happen even though we used to treat the system like surgeons and check everything we had used to make sure nothing was left in the patient!
I'm sure surgeons do the same thing lol
I have the same turbo pumps on my vacuum system and they make the same noises. I think 10% is where it lifts off the physical bearing. If coatings build up on the blades it will get even worse. I noticed your first pump had some coatings on the blades. I have disassembled and reassembled my pumps several times.
I work with these pumps in a CR doing r&d in semiconductor technology.
It's awesome you have these beast. But may I ask... what the hell are you doing at home with these?! :D
I've never felt particularly anxious bringing up my turbo, but watching this I was stacking sandbags in front of my monitor 😂
My understanding is that it's normal for turbo pumps to accelerate through a resonance band during spin-up, I know that mine does. Some fancy pump controllers make an effort to brake through this band on shut-down to minimize the time spent at resonance and avoid wear. I also believe Edwards talks about this in the manual for my pump in the section about venting during shut-down to brake the pump more quickly.
Take that with a grain of salt, of course, I'm strictly a hobbyist.
Awesome video once again, cheers,
Thanks! Yes, I think you can see that I was pretty nervous 😅
Thanks for the information.
Looking forward to a new video from you!
We recently bought a used GC-MS. When we started to pump down, the noise was similar. Not so happy faces. Turns out the seller's technician forgot to plug a blind into the purge port of the turbomolecular pump. It happily drew vane pump oil into the whole system.
I was so happy it came with a 3 months warranty. Now it is running nicely.
Very nicely done, really enjoyed the spin up footage I’m stoked that you even got the internal footage lol cuz getting to see and hear the resonation was really cool, glad ya did that!
I have worked with these exact pumps, and yes, the vibration at low rpm is normal, just need to be clamped securely. Not sure what you meant by connecting the two turbos together to the big pump, but to make sure, you should never connect a turbo to a turbo, the pressure on the exhaust should not be less then 10e-3mbar, for only one simple reason, the oil will boil, leading to problems with bearings. The difference in base pressure is not so important, the turbovac 50 can get in 10e-9mbar region without problems, but the big one cant. The major use of such big pumps is fighting with high gas loads, for evaporation, sputtering etc... Keep up with turbo madness, this is just wonderful to see...
Thank you for that information! That's good to know.
Mh... that's unfortunate. I wanted to test what happens if I cascade the turbomolecular pumps. Considering the very low vapor pressure of the oil I would not have thought that a significant amount will vaporize.
Yes, the size of the pump has nothing to do with the reached pressure (as long as there is no leak). The only value important for that should be the compression ratio as far as I know.
I'm glad you liked the video! :)
You absolutely can stack TMPs (and in fact there are scientific apparatus that utilise such "compression turbos"). In principle you will shorten pump life on hybrid pumps, but in practise I've seen 10+ years of operation in this configuration. If you use full maglevs, I've seen 15 plus years of service.
These cascaded TMP systems are done to get sufficient compression ratios for hydrogen and helium for solenoidal ion sources and atom beam microscopes.
For some more context, these are systems that run in the 10^-10, 10^-11, and even 10^-12 mbar range.
@@mattgbarr Stacking oil lubricated TMPs is a big no-no, unless you have money, then its ok :) Of course maglev pumps can be stacked, but then again, thats for specific needs, and given the fact how much maglev pumps cost... I wouldnt do it anyway. For systems that require pressures lower then 10e-9, other types of pumps are used... Devil is in the details., money is also a big problem...
Well, of course you always have NEGs and TSPs and ion pumps. None of which serve you anything worthwhile whilst working with helium.
It's pretty much stacked TMPs or bust. Whilst a no-no in principle, it's extremely common to do so and can give you a very long service life if you use good quality units.
Love this video and all the comments! I will be needing a similar set-up for MBE experiments.
I suggest the vibrations are the resonance frequency of your adapter.
I would make some vertical WEBS to seam weld onto both of the flanges and onto the adapter tube.
1 web between each clamp.
It's possible that this stiffening might simply alter the resonance frequency and move it up quite a lot.
So it may then need more webs or else a new set of webs centrally mounted horizontally between the vertical webs.
First thing to try might be a few extra clamps?
Well done on the welding! I can weld with sticks but have never tried TIG. Very nice of the company to allow in their workshop.
Thank you! The pulse setting makes it easier.
Yes, definitely very nice of them!
That's a sick setup man! Damn! I love it. Congratulations on putting it all together. Very expensive hobby indeed. You do the things I love to see. Thanks again for making your videos.
Having been in a passenger aircraft whose auxillary turbine in the tail no longer worked, slowly externally starting a jet engine has a similar resonance that goes away at full speed. This is normal.
My best guess as an engineer: Run through the band of resonance as fast as possible. I heard of a hydroelectric plant that had an accident because it stayed in the unsafe operating area of resonance too long. Also use a sandbag ring or lead shot bag or something to damp it out and reduce the hazard.
The vacuum created is awesome, by definition of the word awesome. The welds are way better than I have ever been able to do and before multiple sclerosis took over my nervous system I had been an auto mechanic welding professionally.
Subscribed. As a Graduate Engineer I spent 2 years in a Semiconductor factory process line working around various vacumn pumps, implanters etc
1:28
That 4 jaw chuck and it’s key are worth the price of admission.
It exudes confidence and strength.
Great video. Thanks
Wow! You are a natural at welding😮
This is some of the coolest content on youtube, love it man!
Thank you!
Looks like you got yourself a turbo-spectacular machine :)
That spin up began like the machine in the movie Contact.. I think your outro assessment is correct. Let the fun begin!
very nice pump👍
Amazing machine!
It really is!
But also intimidating!
Just stumbled on to this channel, Instant sub. Amazing, Educational, And funny too. Thanks so much :)
Thank you! I appreciate it!
My Balzer vacuum evaporator used a Pfeiffer turbomolecular pump. I had to replace the pump at one time and since I lived and worked within 10 miles of the Pfeiffer factory near Wetzlar I got a tour of the factory, as well as a new pump. Compared to oil-diffusion or ion-getter pumps they are certainly simple and reliable. One of our electron microscopes also had a TM pump. I was a bit leery about vibration, but it was not a problem. You probably will want to put a screen in front of that pump.
Pushing past the critical speed is nerve wracking for sure. Possibly while moving the initial bit of air molecules may cause inter-stage surging… try using an ammmeter on the pump to watch how much work it does. Also, if you don’t torque the clamps evenly, you could warp the bell housing on the pump. Might be the source of the vibrations…
I tried my best to tighten the screws evenly. But thank you for the advice! However, I don't believe that was the reason for the vibrations. They should be continuous if that were the case, not suddenly stopping. Also, when the pump is turned off and slows down, the vibrations don't occur at 10% speed (only at 50%, which leads me to believe that range is resonance). So, it must be related to the electronics.
@@AdvancedTinkering maybe it's a resonance between the motor coils and the esc electronics. Sort of like engine knock, as in there's a certain speed where it's not timing the phase change correctly to the coil current, and there's some sort of flyback?
@@AdvancedTinkering If you let it ramp up while the chamber is at high vacuum I suspect that you might not get any vibration, since I am guessing that it is occurring at the point where the motor is having to put in the most torque. It's still a little concerning when you first hear it since failures in the motor could cause it to push the rotor into the crash bearings, which could possible sound like that at low speeds. I wonder if it could be good practice to start a questionable pump under a high vacuum so you can know immediately if you hear any vibrations that it is likely a problem.
In industrial equipment SEMs and similar (not things made in the university physics lab) the turbo pump current was our main parameter the vac control system uses to generate faults. RPM and to a lesser extent vacuum rate also played a role but you capture some aspect of those in the turbo pump current draw.
imagine doing Schlenk chemistry with this beast
Yes, in my opinion Schlenk line would implode… as we talked lastly in comments - we can now try who was right ;)
@@mgrzegthe most force a vacuum can put on anything is 1 bar, changing a bit depending on the weather
Extreme overkill unless you were building large arrays of stuff that off gassed a lot.❤
This is equally fascinating and terrifying.
That's a heck of a machine.
good job!
Aaaaand now I have to go and watch video of sevicing the turbomolecular pump. That's yet another knowledge that I will never need in my life :-D
You never know when being able to disassemble a turbomolecular pump might save your life ;)
Your artifact at the 10-6 region can be 1-pinholes in welds (virtual leaks) 2- compounds boiling off and burping (fingerprints , vacuum grease etc) 3-actual very small leaks 4- permeation through o-rings or pin holes.
Excellent video! The harmonic and resonant vibrations which occur at those speeds are very hard to understand. Your pumps sound pretty good to me!
This makes me think of my best friend who worked with vacuum equipment and other lab kit for his career. He passed at 48 years old this year unexpectedly.
Well done! A lot of fun to watch. Thanks for sharing. And i foresee a rotary tig welder setup in your future : D
I completely agree with others about your welds. A nice bead. Not overly hot. You could have easily warped the flange or cracked the weld on the opposite side. I’ve seen seasoned welders destroy 316. Pulse mode or not. Excellent.
The scary noise coming out from the TMP is due to the mecanical forces induced in the rotor by the stator. Is like when you hear a big generator starting, the electromagnetic field of the inductors make shake everything. So when the motor does all the hard work of acceleration you get all those noises and vibrations, and as soon you start getting closer to the desired spining regime the motor only have apply force to keep the movement. at the desired conditions.
Thank you. In fact, not so many ppl can have a chance to wintess real work of equipment that level.
Those welds are beautiful
Thank you!
The folks over at r/welding would give you A+
Video emozionante !!! 👋👋
It's amazing how my expirience is similat to yours. But I am working as mad scientist in former USSR lab and we have like 100 or somithing old but usable turbomolecular pumps so we are not so worried with sounds its produce as you x) I'm really interested in what you doing with your vacuum chamber, what are your plans? Any experiments? Plasma coating? I'm really want to invite you to my lab, but it is probably unlikly and hard to achieve.
Someone is selling a TMN-500 right now...which is interesingly a horizontal pump with magnetic bearing...and 36 stages!
Bravo!
It's safe enough lol. Great engineering.
Now I'm no weldician but for a first weld that looked noice
This guy is great! I felt bad tho. You can definitely tell he was so worried! Lol I dont blame him tho, that's a very nerve-wracking experiment!
The vibration is probably caused by the fact you still have atmosphere at 10% so the motor is under load. There is probably an optimum that you can run the motor in different pressure gradients.
Mr vacuum thank you!
My guess would be that the vibrations is a result of a the inverter drive pushes the motor with a frequency where the windings matches in a way that the forces is not ideal and it stops when the frequency is passed that area. Some drives has curve settings that can minimize but it might not be within the motors thermal margin to accelerate faster at that speed.
I worked for a tech-firm that x-rayed power supply modules...insurance purposes.
They beat the heck outta their turbo pumps...their operating procedure called for pumping down the x-ray tube every morning, running it hard all day, then cooling it down at the end of the day with 'air flooding'.
Yup, they let the air in at night, then played with the filament in the morning before pumping it down again.
In the 4 years I was there, there were two instances where the filament had any problem that needed attention.
The technician who wrote the 'instruction manual' is now head of an entire Division...of course his instructions will never be reviewed...it would reflect poorly on the Great Man.
Apparently replacing turbo-pumps was cheaper than re-writing the instructions.
Nerve wracking. Crazy that it works after so well. As of the pressure spike, looks like calibration is required for the pressure sensors, so the two modes match well during switchover. I do know nothing about vacuum systems tho.
Man great job ! Quite scary to here them ramping up in speed... Come to the lab I work in to fix the turbo pump installed on my mass spec please ^^
Resonance was my first guess too, but now I'm guessing that at 10%, there might be more reactionary force being applied by the air in the chamber to the blades of the pump than before the chattering starts or after it stops. Maybe, before that point in the startup, the pressure in the chamber is "high", but the blades of the pump aren't going fast enough and aren't imparting enough force to shake the chamber. Afterwards, there's very little air left, so, no matter how fast the blades spin, they're imparting very little force, which means there is little reactionary force. To test that theory, you could evacuate the chamber to a mild vacuum using a standard vacuum pump, then disconnect it and start the turbomolecular pump. If the chattering doesn't happen or happens at a different point in the startup of the turbomolecular pump, then this would explain it.
Or, maybe it's caused by differences in relative pressure on one side of the chamber vs the other. Eg. there's a small enough pressure of gas in the chamber that differences in pressure don't propagate very quickly, which would cause a sort of slosh from side to side, causing one side of the pump to hit more air molecules than the other, imparting imbalanced forces on the unit and causing it to shake.
You can get that resonance from PWM type motor controls. PRF do not have the same issue and neither do analogue controls. The trick is usually to select a PWM frequency that produces resonance at low speeds so that less power is available to cause vibration if it is not possible to get out of the resonance range.
A lot of devices that spin have an RPM range that they have to pass through during which there are resonant oscillations. Once the device is spinning faster it is no longer a problem. Therefor the device usually has a warning about not loitering at certain speeds. Fancy nuclear centrifuges come to mind, there is a RPM range where they will self-destruct, which is what that Stuxnet virus exploited. I wonder if these things are similar, since you can clearly see the vibration increasing until it starts making that noise.
They are similar indeed. In these turbos you can tell apart the critical speed due purely to the rotor moment of inertia from any other resonance due to the motor drive (and not rigid enough mounting) if you pay attention to the spin _down_ behaviour, where only inertial phenomena would make themselves evident.
@@SVanHutten ah, I see
Yes they are extremely similar to gas centrifuges, magnetic bearings and all. ❤
So interesting, easy to listen to. Subbed here.
Thank you! I’m glad you like the videos!
bravo. now i wonder what two would do?
deamn these welds lock good
Thanks!
we had pumps like that at the lab (physics uni)
those things are dope, if you can use them for something
The 10% speed ratteling could maybe be a failing capacitor in the driver? something to do with the magnetic bearing PI/PID loop maybe?
Realy interesting.
Awesome work! The vibration around ten percent speed could be an interaction between the control loops in the motor driver and a mechanical resonance in your setup. Since it disappears when the controller is powered down, this seems like the most likely candidate to me. Are there any specific pump mounting requirements from Pfeiffer when it comes to rigidity or vibration?
Very interesting. If I understand you correctly, you're suggesting that the resonance prompts the control electronics in the controller to counter-regulate, and these two aspects exacerbate each other?
@AdvancedTinkering in my setup in the lab I use a piezo stage which is controlled by a PID controller. Maybe the motor is controlled by PID as well? PID controllers often have resonances if combined with setups that have resonances as well. My stage, untuned, has two or one resonances at certain frequencies. You can tune these by applying a notch filter. Roughly speaking, a notch filter makes the controller not do anything at certain frequencies, which is better than doing something and creating a resonance. Making your setup more stable/less top-heavy might also work
@@AdvancedTinkering That's it. When the mechanical system has resonant modes and a method for these to couple with the electrical control system, then interactions like this can happen. It depends a lot on the details of the motor control scheme and controller bandwidths, they might use anything from open loop V/Hz control to field oriented control with nested current (torque) and voltage (speed) loops. I have a few different pumps and controllers, and there is a lot of variation here, with larger pumps generally having more advanced control schemes. This is just speculation on my part, but if you want to look further into this, it might be verifiable by looking at the motor phase currents, to see if there are any unexpected frequency components there corresponding with the mechanical resonance. This could be done with an oscilloscope and a shunt resistor, but I would be careful about introducing any components between the controller and pump, and the voltage is likely also floating relative to the oscilloscope ground. I'd prefer a contactless sensor instead, like a clamp-on oscilloscope current probe, if you have access to one. Looking at the motor phase voltage might also be useful, but probably a lot less clear since it tends to be a pulse-width modulated square wave with the output amplitude encoded in the pulse width.
Thank you for this incredibly informative comment! This is why I just love UA-cam comments! Unfortunately, I currently don't have access to an oscilloscope with a non-contact current probe, nor do I probably have the expertise to interpret the data readings accurately. However, it's definitely going on my list of things to test in the future!
Thanks for the info! Yes, the stand is way too top-heavy with the pump. Once I have more space, I'll build a new stand for my chamber that hopefully can also be bolted to the floor. Right now, I need to be able to move the chamber and save space, so it's my only option at the moment.
Still cannot believe you traded a few cases of beer for these plus the controller. 😮 That is better than you could do at a US hamfest.😂
Many centrifuges also make strong vibrations from resonances at some lower speeds than their maximum. Just got to power through it.
hell yea.. maybe some really interesting experiments coming
Sounds fine to me. Do you have an HPU001 or something to get hours and error codes to see how it has been functioning for it's life so far?
Unfortunately not, I only have a very bare bones controller without a display.
i've never seen a turbomolecular pump used upside down, i just assumed they all work "right side up"
This pump actually has to be used “upside down” or on its side due to the oiling system. In my video about the disassembly of that pump I briefly talked about that.
First off all: interesting work! At work we use smaller TPs and I just had short resonance windows with very old pumps. But our chambers are also more massive. Your TP/chamber ratio is a bit...off😅
Since you did a oil transfer between the pumps, I guess the high pressure side is oil lubricated. In this case the upside down position should not be used (check manual). Only dry lubricated pumps or such as maglev can be mounted upside down.
Your rough pump is a bit small for this huge TP. Pump down performance of the TP is restricted in this setup. Pumping down just with the ratary vane pump may cause oil contamination since there might be a non laminat flow of oil molecules to the chamber. So I suggest never running the rough pump without the TP, since it will prevent molecules getting in the chamber.
For better pressure you should think about switching to cf and do a bake out. Then X^-10mbar is no miracle. Downside ist you need to replace the gaskets every time.
Hope this didn't sound too much like bad criticism. I'll just wanted to share some (hopefully) useful informations.
Keep up the nice work!👍
i think all pumps have a ponit of resonance, my turbovac50 has it and the other pfeiffer do too, they all resonate at different speeds
I'm curious to know of the pressure in your vacuum line. I don't know these things, but if your other pump was still running, then it might have had time to pump down? I just bought one myself for $250 American. I'll be happy to help find that sweet spot of terrir
I've always wondered about cascading these things....
Could you do a run with the Big pump, feeding the little pump, (that's feeding the roughing pump) ?
You seem to be almost set up for it.
Would that get you though your "Noise and vibrations" stage quicker, as the big pump wouldn't really be doing much until after the little pump has cleared out the bulk of the chamber to E-4 ?
You absolutely can, in this configuration the smaller turbo is called a "compression turbo". You need to be mindful of oil changes on the outlet side of the main turbo (or run a full maglev). It's done to get high compression ratios, usually for light gases like hydrogen and helium.
To rule out the vibration coming from the mounting structure, I'd perform a frequency range test on the setup and determine it's natural frequency.
It might be that the natural frequency of the structure is the same as the pump at 10% output - which would explain why it was observed on both pumps, and that the resonance disappeared when the pump frequency increased.
Based on how much smaller your roughing pump is relative to those massive turbopumps, there may be some effects caused by a rise in foreline pressure during parts of the pumpdown.
I have seen whole movies that had less thrill, emotions, high-tech and all without special effects. :D
Run in time for new bearings can give noise or vibration at one frequency you have run them a while at a lower speed and it breaks them in?
Out of curiosity but is it possible to run one of these pumps at a far lower speed to produce a much lower vacuum?
I have seen a lot of setups use a traditional vacuum pump for the first stage of pumping. Could pumping out all that air be too much a load on the turbomolecular pump?
I am using a roughing pump to get to a lower pressure before starting the turbomolecular pump.
I can confirm that resonances in low ranges are a thing.
Lab centrifuges have resonant frequencies at around 600 - 1000 rpm.
Also, could one of those resonances (either in the low range, or at 50%) be acoustic resonance?
After reading the comments, I agree with the assessment that the issue at the 10% rotor speed is likely electrical in nature. Others have pointed out that the issue appears to coincide with line voltage 50 Hz. It could be a sort of unfortunate feedback loop in resonance with the motor controller. If you have access to a isolation transformer, that might reduce voltage surges if that is the result of the issue. Alternatively, if you have some clamp on ferrite cores, that might be worth trying out. These are mostly guesses though, do you have anyway of measuring EMC?
Regarding the vibrations of the stand, 3D printers have made great advancements in the modal analysis and tuning field. With a sensor and a stepper motor, you could figure out the resonance and make a custom damper if that is a project worth the challenge?
The noise is very likely turbulence during the most dense stage of operation.
Check the psi and see if at the time of the noise, if it is fluctuating.
This would likely be the cause as the Air leaving will have a small stage of higher pressure as the Vacuum pump can't vacate as quickly as it is ramping up.
(bouncing from a zone of high pressure to the lower one and back again until it finally moves out of the system and balances out.)
Then there will be a drop-off as the vacuum finally eases past this "cliff".
What kind of motor is driving the pump? Could the sound be resonance in the motor caused by electrical effects rather than vibration in the rotor caused by physical (mechanical) resonance?
I feel I’m missing something. What is the chamber pressure when you start the turbo? I see your little single stage vane pump there.
I've tried starting both turbomolecular pumps at the same pressure. The TPH2101 was started at 0.2 mbar and the Turbovac50 at 0.14 mbar if I remember correctly.
2:58
I don’t believe the o-ring would have popped out unless mounting ring was deflected in some way.
Perhaps you could check it’s flatness next time it is available. I am just curious.
Nice to find your channel. I appreciate thick meaty science content. You have it in spades.
Enjoy your Sunday.
Resonance frequencies are meant to be quickly surpassed or not reached. However, at the high rotational speeds of the turbopump, amplitude resonances are usually encountered. / Resonanzfrequenzen sind dazu da, schnell überfahren oder nicht erreicht zu werden. Bei den hohen Rotationsgeschwindigkeiten der Turbopumpe werden jedoch meistens welche erreicht. (Amplitudenresonanz)
It's not clear from the manual of that pump what active vibration compensation it might have, but mag-lev turbo pumps especially need a stiff chamber to mount on so that they can "push against" the chamber to compensate for internal vibrations. If your chamber or the supports are wiggly, you can create standing waves between the chamber and vibration compensation or rotor and you *can* destroy the pump from this vibration (ask me how I know). Also, claw clamps are not a safe way to connect turbo pumps because of the rotational inertia. If the bearings seize or there is some other problem with the pump, the pump will go flying off your chamber. You should use full ISO bolt rings instead.