First ever Turbo experience

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
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Richard Hull
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First ever Turbo experience

Post by Richard Hull » Wed Oct 09, 2019 11:12 pm

Being a perpetual curmudgeon and Luddite, I must admit to total ignorance beyond what I have read here on the care and feeding of a turbo pump.

The story:

My long time friend from the 70's and well known East Coast glass blower and maker of rare gas filled tubes, Bill Connery, had one of the finest vacuum setups for such endeavors one might ask for. Bill has been to virtually every hamfest since the 70's up and down the East coast and was known to thousands of people. He attended every HEAS big event and every New York Teslathon from their inception in the late 80's. People would instantly mob his table, (I was one of them), not even allowing him to complete his setup. We were all after his rare gas tubes, and other completely neat and rare materials he seemed to always have on hand for sale.

Sadly, Bill was diagnosed with untreatable, spreading cancer in 2015. Although his voice was reduced to a whisper, he continued to be seen at every hamfest and HEAS event. Realizing he was near the end, in 2017 he dismantled his vacuum system and brought his Turbo pump to HEAS 2017 and sold it to me, specifically. (I bought my diff pump used on fusor IV from Bill in 2000). Bill was last seen by me at HEAS 2018. He passed away July 4th of this year. He was one of my tutors in vacuum and a hero.

Note: Bill bought this brand new off the showroom floor, $$$$, and put all the 2500 hours on it. He noted that he ran it very intermittently and only when he made tubes or needed it for a project under vacuum.
I will, likewise, rarely run it with the fusor, maybe two of three times per year. My diff pump took it like a champ all these years. If I run it in the winter in a lab at 30 deg F. will it suffer any restraint regarding startup?

HELP!

We have some of the finest users of turbos under our roof here. I need a spoon feeding on the operation of this pump as I hope to use it as I construct fusor V. I do not wish to ruin it through stupidity of a novice operator/user. I have images below. You can glean the model from them. I have many questions.

The top inlet flange is a standard 4.5 conflat. I have a zero length mating flange to 2.75 CF so that is taken care of.
Assuming I am all hooked up and you folks have helped me and it is ready to rock and roll. What are the three buttons and in what order would be proper to start up? (I think I know but humor me)
Does this thing need water cooling? Notice that Bill seems to have gotten along with just the Pfeiffer/Balzers fan on the side.
There are two KF16 ports. the large piped one at the bottom is certainly the foreline hookup. The tiny piped one mid body...Is this for a vacuum gauge? Looks like Bill just blanked it off
There is a heater at the throat or inlet. Is this required and is started by the "heater button" on the controller? Do I heat the throat first in the startup?

Thanks in advance for helping this old luddite out. Make me smart and turbo wise.

Richard Hull
Attachments
Turbo (1).JPG
Blessedly, absolutely complete with factory cabling...no problem here
Turbo (3).JPG
less than 2500 hours...Three buttons...In what order do I use to start up the pump
Turbo (4).JPG
Hose barbs - Cooling? Bill did not say he water cooled this puppy. Do I?
Turbo (6).JPG
Heater marked 35 watt 220 volts at throat...Why is this here and do I need it?
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: First ever Turbo experience

Post by Jerry Biehler » Thu Oct 10, 2019 12:37 am

Manual is here, its kind of awful, I use a similar vintage pump in my SEM.

viewtopic.php?t=8021

Pumping unit turns on a relay that can control the fore pump and the turbo I believe. Heater is for baking out, rarely used.

First thing I would do is change the oil, it uses the standard Pfeiffer TL011 oil which is available from Duniway somewhat cheaper than other places.

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Re: First ever Turbo experience

Post by Andrew Seltzman » Thu Oct 10, 2019 2:03 am

Welcome to the world of turbos, if all goes well you'll never want to go back to a diffusion pump again. If all doesn't go well I encourage you go get another turbo. A turbo pump is a fine addition to a fusor, hopefully it will give you many years of quality vacuum without any oil back streaming of a diffusion pump or need for a foreline trap. A roughing trap for the mechanical pump is a good idea to prevent contamination of the turbo. If you ever need / want to buy another turbo, stick with the pfeiffer line, they are quality pumps. A good upgrade is a TMH-071P, they are relatively plentiful on ebay for about $900 and typically include their own attached 24V input controller:
https://www.ebay.com/itm/GOOD-PFEIFFER- ... SwmU1ciAQ4
These are a turbomolecular / molecular drag hybrid and some can tolerate a backing pressure up to 15 Torr. A small 4 stage diaphragm pump typically pulls down to 500mTorr to 1Torr and can back these replacing an oil sealed backing pump. You'll never go back to an oil based backing pump once you have tried a "dry" turbo station; they are virtually service free, never leak oil and really easy to use. Your pump will require a 2 stage oil sealed roughing pump.

There are a few main ways to kill a turbo, most of the are ways to "crash" the turbo by having the rotor and stator blades touch and break.
After a crash the pump looks something like this: https://www.reddit.com/r/engineering/co ... 30000_rpm/
The typical ways to crash the pump are:

Drop something in it while it's running
There is very little clearance between the rotor and stator blades, even a very small object (screw, grid wire fragment) can destroy the pump. Don't position it directly beneath the vacuum chamber. Optionally you can attach a "splinter guard" a fine mesh screen within the inlet of the turbo. It reduces pumping speed somewhat, but a fusor is not a heavy gas load so I think it's well worth the protection.

Rapidly vent to atmosphere while it's running at full speed
Excessive stress on the rotor blades may cause them to touch the stator blades and crash the turbo. If you want to SLOWLY vent while the turbo is spinning down after it is turned off to speed up the shutdown, there are specially designed vent valves that slowly admit air in a safe manner.

Sudden impact, rotation, motion while it's running
Also might cause a crash or damage to the top bearing. The top bearing is a permanent magnetic levitation bearing so no lubricant is required, if the pump is moved or rotated the torque on the rotor will push it to one side. There is a ceramic safety bearing, but it's only there for protection not designed to be spun up; it wares down a little every time it is touched when the rotor is spinning.

In addition most controller manuals warn about disconnecting the cable while the pump is running
Unplug the controller-pump cable while the controller is powered or the turbo is still spinning
The controllers send power to hall effect sensors in the pump, these may be damages, particularly on the older pumps like you have if they are disconnected under power. The rotor will also generate back-emf while spinning; best to wait until the rotor stops before unplugging it.

If you draw a plasma discharge into the inlet of the turbo, you can also damage the electronics, especially the hall effect sensors in the motor. Craig Wallace's fusor killed a turbo of the same model as yours this way. This is another reason to use a mesh screen splinter guard over the turbo inlet.
Andrew Seltzman
www.rtftechnologies.org

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Re: First ever Turbo experience

Post by John Futter » Thu Oct 10, 2019 3:05 am

Richard
The little KF16 amidships is for flushing nasties away usually dry nitrogen or dry air into here slowly to flush volatiles -you will not need this so blank it off.
This port is also used on SEMs to bring the pump to a quick halt for sample exchange sort of a Jacobs brake using the bottom of the rotor stack as a compression brake

For the first few minutes start the turbo then stop it a few seconds later restart go double the number of seconds before stopping continue this for as long as you have patience. This ensures that the oil /grease in the bearings is redistributed properly. Any turbo that has been in storage for more than a couple of months will thank you for this treatment

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Bob Reite
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Re: First ever Turbo experience

Post by Bob Reite » Thu Oct 10, 2019 4:10 am

In addition to what the turbo experts have said, they do not like sitting in storage for a long time. As a minimum, run your system every three months. Once a month for an hour or so is even better. As I recall, Pfeiffer states that if it sat idle for more than a year it should go back to the factory for bearing cleaning and oil replacement.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.

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Re: First ever Turbo experience

Post by Richard Hull » Thu Oct 10, 2019 6:49 am

Thanks for the info guys. .... and the manual

What about those hose barbs???
Will the side fan be adequate for 1-2 hour runs????
The three buttons???? no one said a word about start up.....is the stanndby the on-off? Then hit the spin-up button and once at speed, to shut down hit the standby button again? the heater button is for bake out.

I will spin up the pump in short, even increasing bursts as recommended to distribute the oil before full speed. I will not have to worry about debris as the 2.75 CF on top will hook to an S hooked super fine welded flex hose that was used on fusor IV...working like a sink trap....It will mess up the conductance a bit, but hey, the chamber is a cross!

I plan on testing this thing with it mounted rigidly long before I trust it and build it into a fusor V edifice. Until then, the diff pump that is currently mounted and in place on the foreline will remain king of the hill. I paid Bill $75.00 for this turbo system and only $25 for the diff pump back in 2000. $200 is as high as I go for a complete functional turbo with all cabling or it will be diff pumps forever. I bought a 250ml bottle of 704 oil at this 2019 HEAS for $10.00 and have 500ml of Santovac in an unopened bottle that has been hangin' around the lab since 2003. No matter what happens, I have the vacuum system covered.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: First ever Turbo experience

Post by John Futter » Thu Oct 10, 2019 8:46 am

Richard
You will only need those hose barbs if you are wasting huge amounts of deuterium
the actual power consumed when spinning @ 10^6 is minimal so no cooling needed
but if you have a huge gas throughtput @ 10^-4 then expect the motor to heat up
in your case you will be choking the turbo back from the chamber so the actual load on the turbo will be minimal

move along nothing of interest here

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Dennis P Brown
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Re: First ever Turbo experience

Post by Dennis P Brown » Thu Oct 10, 2019 12:30 pm

I have the identical type; mine has neither a heater nor those fluid lines that yours does.

I use a small fan for cooling and that is more than enough.

For operation, I simply get the system down under 100 microns, and use the "Pumping Unit" button to allow the turbo to get to full speed. The "STAND BY" button is for maintaining a lower quality vacuum for long periods of time (to spare the bearings) - that is, when a system isn't need for high vacuum operation but needs to stay clean. I've never had use for that function in a fusor.

My unit dates to 1986 so I added turbo bearing oil to the internal "oil wick" system when I first obtained the unit. I then pumped the system a few days to out-gas stuff in that added oil (fore pump only.) Then I tested it and the unit did require an hour or so under high speed operation to finish the out-gassing process. I did bake it out then (using a heater strip I borrowed.)

Frankly, I prefer my diffusion pump far more for a fusor and no longer use my turbo (that is for only clean high vac work, anyway). But to each, their own, I guess.

I have a screen cover over mine to protect it from items that could fall in (easier to do than I ever thought) and to protect it from plasma (my unit is also grounded separately to be certain.)

To turn it off, select the "Pumping Unit" button again. The turbo will slow down and stop after a while.

Aside: I have a dry air feed located on that small (16 mm) mid-level adapter flange. AFTER I turn the unit off, I use a valve to feed dry air into the unit/vacuum system via that port. That allows the unit to quickly stop to avoid long spin times in the "unbalanced" rpm period. You'll really hear that if you listen and let it slow on its own. That puts a good bit of strain on the bearings. But most people don't use that function since dry air or other gases aren't usually available.

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Re: First ever Turbo experience

Post by Richard Hull » Thu Oct 10, 2019 5:06 pm

Thanks once again for the extra tips. No water cooling and fan only will do. Dry nitrogen is used for slow down by some, but is rather expensive. I wonder if a slow leak of air filtered through dryerite chamber might be OK?

I have read the manual which as noted leaves a bit to be desired. When I unscrew the oil plug in the bottom can I invert the pump? It looks like there is no oil in the cup just a good soaking of the wick and felt.
OR...should I unscrew from the bottom with the pump upright?

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Dennis P Brown
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Re: First ever Turbo experience

Post by Dennis P Brown » Thu Oct 10, 2019 8:04 pm

I use dry air - that is, room air filtered and sent through dryerite; however, that was only for my high vac system. Frankly, I'd think for a fusor, it wouldn't really matter all that much if one didn't use dry air at all but just filtered air. Then used their fore pump, afterwards, to pump the system down from atmospheric to below 10 microns.

My oil plug for the end of the "wick" was filled using an eyedropper while the unit was open to the air. My wick screw is on the side of my unit but I guess they differ. But upside down can't hurt the unit as long as it isn't spinning. AS for the oil, wetting the wick doesn't take very much so again, being upside down shouldn't matter. Since you will pump on it and can bake it out, once its under vacuum, that should work fine.

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