Rather than 'pollute' the FAQ, I thought I'd put this question here:
A turbo pump doesn't work until its working pressure is backed off to under 0.1mbar. This we know.
My question is about 'safety' matters in terms of ensuring a turbo pump survives. If a pump is full speed in a free molecular flow regime but is exposed to the higher pressure of a viscous flow, then clearly it will suffer damage.
But if a turbo pump is turned on, from stationary, at atmospheric pressure then is there any particular consequence? I am presuming that the inductive motor parts, which are actually quite weedy but work by slowly winding the rotor up in vacuo, would simply struggle to push the rotor around. In this state, I can't really see what damage would be caused to the rotor as I presume it wouldn't spin up very quick, though I would not 'try it out' because of the excess *electrical* load that the electronics and windings might experience.
So, in summary, if you accidentally switch a turbo on at >0.1mbar, is there any real consequence?
Connecting a Pump to High Vac System
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Chris Bradley
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Carl Willis
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Chris Bradley
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Re: Connecting a Pump to High Vac System
So if you're impatient, then it sounds safe to turn it on around 1 mbar and wait until it 'catches' the right pressure as the backing pump draws the foreline down.
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Doug Coulter
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Re: Connecting a Pump to High Vac System
Carl, that's a new record for concise! I must learn that.
I have a couple of fairly new Pfeiffer turbo systems, and that is what you do -- just turn the whole mess on.
The motor just won't put out enough power to make the turbine spin up much until the roughing is mostly done with. This is by design in that brand, and the electronics are designed to limit motor power gracefully (you can even set that limit in the software in the controller if you like).
It works fantastic, as near the end of roughing, most roughing pumps get kind of slow (see their performance graphs at their low pressure limits) but as this lets the turbo start spinning up for real, they start to have a "compression ratio" at that point and even the roughing part gets sped up significantly. As nothing is ever perfectly matched, you can actually hear it in the exhaust note of the roughing pump when the turbo starts actually helping. I have set up my systems so that the roughing pump is turned on and off by sensing the turbo drive power -- it only runs when it would help, which saves power and life on that pump. This allows me (on solar power!) to leave them on overnight etc, so I spend a lot less time waiting for tanks to outgas. Even a big turbo may only draw 20-30 watts to stay running in a good vacuum, which I can tolerate here.
That number for what a turbo needs as backing "pressure" is *extremely* variable depending on whether you have a straight turbo, or a compound (usually a turbo-drag). In the latter case, it can tolerate 10 millibars and still make ultimate vacuum, or very nearly! This is covered in the tech notes in the Lesker catalog fairly well.
I therefore propose a little clarification when we talk of these, say straight or compound turbo?
Because the numbers really are way-way different for those. A compound turbo can be backed by a diaphragm pump, that looks like what you'd see in an aquarium store, a straight turbo needs "real" roughing. You almost cannot buy a straight turbo new these days, but a lot are on the surplus market.
Basically, the compound type costs so little extra to make and it is so much better (and saves on system costs as you no longer need such a good roughing pump), no one bothers with the straight ones anymore unless they need an exact replacement for an existing system.
I have a couple of fairly new Pfeiffer turbo systems, and that is what you do -- just turn the whole mess on.
The motor just won't put out enough power to make the turbine spin up much until the roughing is mostly done with. This is by design in that brand, and the electronics are designed to limit motor power gracefully (you can even set that limit in the software in the controller if you like).
It works fantastic, as near the end of roughing, most roughing pumps get kind of slow (see their performance graphs at their low pressure limits) but as this lets the turbo start spinning up for real, they start to have a "compression ratio" at that point and even the roughing part gets sped up significantly. As nothing is ever perfectly matched, you can actually hear it in the exhaust note of the roughing pump when the turbo starts actually helping. I have set up my systems so that the roughing pump is turned on and off by sensing the turbo drive power -- it only runs when it would help, which saves power and life on that pump. This allows me (on solar power!) to leave them on overnight etc, so I spend a lot less time waiting for tanks to outgas. Even a big turbo may only draw 20-30 watts to stay running in a good vacuum, which I can tolerate here.
That number for what a turbo needs as backing "pressure" is *extremely* variable depending on whether you have a straight turbo, or a compound (usually a turbo-drag). In the latter case, it can tolerate 10 millibars and still make ultimate vacuum, or very nearly! This is covered in the tech notes in the Lesker catalog fairly well.
I therefore propose a little clarification when we talk of these, say straight or compound turbo?
Because the numbers really are way-way different for those. A compound turbo can be backed by a diaphragm pump, that looks like what you'd see in an aquarium store, a straight turbo needs "real" roughing. You almost cannot buy a straight turbo new these days, but a lot are on the surplus market.
Basically, the compound type costs so little extra to make and it is so much better (and saves on system costs as you no longer need such a good roughing pump), no one bothers with the straight ones anymore unless they need an exact replacement for an existing system.
Why guess when you can know? Measure!
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Chris Bradley
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Re: Connecting a Pump to High Vac System
I seem to recall reading that Varian once made a turbo[like]pump that worked pumping straight from-and-into atmosphere. Not sure how true that is but I can't see any real reason why you can't have a mix of free molecular flow-type rotors at the top, and viscous axial compressors at the bottom.
Doug, what is the difference, compound/straight?
Doug, what is the difference, compound/straight?
Re: Connecting a Pump to High Vac System
There's no real damage done to a turbo turning it on at atmospheric pressure. Most system controllers have a "low speed" mode, which is intended for use when a system is leaky or has high foreline pressures.
The contamination issue is a greater concern for applications where a very very clean vacuum... no HC's or water is required. It takes a while to get the rotors scuffed free of their contamination. Flushing with a measured "ballasting" dry gas is one recommended method to clean up.
Dave Cooper
The contamination issue is a greater concern for applications where a very very clean vacuum... no HC's or water is required. It takes a while to get the rotors scuffed free of their contamination. Flushing with a measured "ballasting" dry gas is one recommended method to clean up.
Dave Cooper
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Carl Willis
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Re: Connecting a Pump to High Vac System
I recommend reading your pump's manual.
Starting at high pressure accidentally will not kill the pump. Whether or not it makes sense to do this is another issue.
On many pumps, if you start up at high pressure, the controller will shut down automatically as it senses the load at low RPMs and so there is no point in trying to get a head start just to be expeditious.
On other pumps, coolant must be supplied to the motor and / or bearings if the pump is going to be started up or run at a high load.
The real reason to have isolation around the turbo (or diff pump) is for when you are returning the chamber to air. You can leave the high vacuum pump running, do your business in the chamber, and then rough it down and return it to the high vacuum pump at once. Otherwise, you have to go through the slow process of venting the turbo / allowing the diff pump to cool down (the only exceptions to the slowness are on giant pumps that have emergency cooling or braking systems). For small systems isolation of the pump matters less or not at all. On big systems it's often worth the added complexity and cost.
-Carl
Starting at high pressure accidentally will not kill the pump. Whether or not it makes sense to do this is another issue.
On many pumps, if you start up at high pressure, the controller will shut down automatically as it senses the load at low RPMs and so there is no point in trying to get a head start just to be expeditious.
On other pumps, coolant must be supplied to the motor and / or bearings if the pump is going to be started up or run at a high load.
The real reason to have isolation around the turbo (or diff pump) is for when you are returning the chamber to air. You can leave the high vacuum pump running, do your business in the chamber, and then rough it down and return it to the high vacuum pump at once. Otherwise, you have to go through the slow process of venting the turbo / allowing the diff pump to cool down (the only exceptions to the slowness are on giant pumps that have emergency cooling or braking systems). For small systems isolation of the pump matters less or not at all. On big systems it's often worth the added complexity and cost.
-Carl
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Chris Bradley
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Re: Connecting a Pump to High Vac System
Carl Willis wrote:
> I recommend reading your pump's manual.
Manuals... Indeed, a rare treat with ebay purchases! Well worth reading if you get one: Probability of getting one..?
> I recommend reading your pump's manual.
Manuals... Indeed, a rare treat with ebay purchases! Well worth reading if you get one: Probability of getting one..?
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Carl Willis
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Re: Connecting a Pump to High Vac System
Did you try getting a manual and have trouble? What pump are you thinking about running in the manner you described?
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Chris Bradley
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Re: Connecting a Pump to High Vac System
Yes.
I'm looking at acquiring a Balzers/Pfeiffer as the controllers and pumps seem more commonly available than other. I came across a website [http://www.ptb-sales.com/manuals/balzers/] which has quite a few, but is not comprehensive and I found no other sites as openly helpful. If you have links, please say them.
Anyhow, the instructions aren't that helpful. They seem to rather presume you have an integrated system and it simply says 'turn everything on and the turbo will start automatically'. I am rather presuming that this is an instruction set for a well-installed system and not for some dodgy-bodge job by an amatuer (with some dodgy-bodged parts from ebay) where not everything might be connected in the system.
Have I done enough prior searching to satisfy you, Carl, or perhaps I shoud've done a two year night-school on vacuum technologies before justifiably asking the questions? (Not sure if that is an over-reaction, I can't read your in-between-the-lines words these days.)
I'm looking at acquiring a Balzers/Pfeiffer as the controllers and pumps seem more commonly available than other. I came across a website [http://www.ptb-sales.com/manuals/balzers/] which has quite a few, but is not comprehensive and I found no other sites as openly helpful. If you have links, please say them.
Anyhow, the instructions aren't that helpful. They seem to rather presume you have an integrated system and it simply says 'turn everything on and the turbo will start automatically'. I am rather presuming that this is an instruction set for a well-installed system and not for some dodgy-bodge job by an amatuer (with some dodgy-bodged parts from ebay) where not everything might be connected in the system.
Have I done enough prior searching to satisfy you, Carl, or perhaps I shoud've done a two year night-school on vacuum technologies before justifiably asking the questions? (Not sure if that is an over-reaction, I can't read your in-between-the-lines words these days.)
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Richard Hull
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Re: Connecting a Pump to High Vac System
I find it stunning that a simple mechanical pump down is just not done out of hand prior to turning on a turbo. It is all too easy to do. You'll not come on line any sooner.
The sluggard turbo is not going to do anything real until the mechanical pump has done its job.
More much ado about truly nothing.
If I were ever to put my large Temescal turbo online here, in my system, I would be very paranoid. They aren't cheap and a mistake is a pump life ender. With a diff pump slip up, you just have a nasty clean up job on your hands. (zero dollars to fix).
Richard Hull
The sluggard turbo is not going to do anything real until the mechanical pump has done its job.
More much ado about truly nothing.
If I were ever to put my large Temescal turbo online here, in my system, I would be very paranoid. They aren't cheap and a mistake is a pump life ender. With a diff pump slip up, you just have a nasty clean up job on your hands. (zero dollars to fix).
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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Doug Coulter
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Re: Connecting a Pump to High Vac System
Richard,
It's just the default in both my Pfeiffer integrated systems, and having tried it both ways, it is a little faster, nothing to write home about -- takes a 6 minute process to about 4 min in the big tank. Doing it that way means the turbo starts helping as soon as it actually can, rather than at some imaginary number you think you have to reach first, and which is different for every turbo design anyway. There's no hard and fast number you can tell people on that one, it differs with turbo design details, relative sizes of the pumps to each other and the tank etc. It's different for my two systems, one a 65l/sec turbo, one 512L/s. So they just take care of that for you. It makes more difference on my small pump/tank system because the roughing pump on that one is so lame -- only gets to a couple mbar by itself anyway, and is tiny, so it needs all the help it can get from the turbo.
Yes, running a turbo can be scary, I've almost lost one due to inrush accident. You do run screens over the intake so if something should shatter in the tank (had that happen) it can't eat big pieces and die from that. The owners manual equivalent of an MSDS is fairly scary -- one of those rotors can store enough mechanical energy to be fairly dangerous -- even shear off all the mounting bolts and throw the thing, according to them.
Worst I've had so far was a small inrush (a couple cu in at stp before I stopped it, operator error) and the thing made the gawdawefullest noise I've ever heard as all the rotor tips were hypersonic in the new pressure for a little while, then it recovered as it pumped the gas while slowing down fast. The whole apparatus jumped a bit, and it's never been quite as perfect since, but still way good.
I would slightly dispute the diff pump zero dollar accident cost if you were running really good diff pump oil and it either went into the mech pump or mech pump oil got into it. Oil ain't free!
It's just the default in both my Pfeiffer integrated systems, and having tried it both ways, it is a little faster, nothing to write home about -- takes a 6 minute process to about 4 min in the big tank. Doing it that way means the turbo starts helping as soon as it actually can, rather than at some imaginary number you think you have to reach first, and which is different for every turbo design anyway. There's no hard and fast number you can tell people on that one, it differs with turbo design details, relative sizes of the pumps to each other and the tank etc. It's different for my two systems, one a 65l/sec turbo, one 512L/s. So they just take care of that for you. It makes more difference on my small pump/tank system because the roughing pump on that one is so lame -- only gets to a couple mbar by itself anyway, and is tiny, so it needs all the help it can get from the turbo.
Yes, running a turbo can be scary, I've almost lost one due to inrush accident. You do run screens over the intake so if something should shatter in the tank (had that happen) it can't eat big pieces and die from that. The owners manual equivalent of an MSDS is fairly scary -- one of those rotors can store enough mechanical energy to be fairly dangerous -- even shear off all the mounting bolts and throw the thing, according to them.
Worst I've had so far was a small inrush (a couple cu in at stp before I stopped it, operator error) and the thing made the gawdawefullest noise I've ever heard as all the rotor tips were hypersonic in the new pressure for a little while, then it recovered as it pumped the gas while slowing down fast. The whole apparatus jumped a bit, and it's never been quite as perfect since, but still way good.
I would slightly dispute the diff pump zero dollar accident cost if you were running really good diff pump oil and it either went into the mech pump or mech pump oil got into it. Oil ain't free!
Why guess when you can know? Measure!
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Richard Hull
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Re: Connecting a Pump to High Vac System
Compare 50ml of KJLC704 oil (~$5.00) to a $3000.00 turbo. It is effectively zero dollars.
Oh! By the way... We are forced to purchase our first fill for the pump in a 500CC bottle and suffer the $84.00 price. That was up front money to just use the pump on day one!
After that, I can blow up my diff in 9 more stupid accidents, complete system teardowns and associated cleanings without spending another dollar. I clean and reuse all my copper gaskets as I do not crush them out of existence on first use. I can get about 3 re-applications on the same gasket.
With a turbo, you would need $30,000 worth of up front spending to not suffer out of pocket new costs in 9 destructive events.
Turbos are massive dollar losses in waiting to all but the hyper vigilant. You can't perpetually expect to get a fully functional turbo with controller and cabling that will bolt right onto your present system off e-bay on the cheap following an accident.
I can have my exact, same diff pump back on line the same day at no additional out of pocket expense.
Again, I have a 10" throat turbo that works perfectly with all cabling and controller in storage here and refuse to use it until the right project comes along that might demand its use. The fusor is not one of those projects. I also have a 3.5" and a 5" diff pump on hand, but they are water cooled and over kill on a fusor as well. If you have a 2.5" air cooled diff pump on hand that is the one you need.
Turbo's are for people who are in and out of their systems constantly. This vastly hazards the continued existence of same due to far more operational related errors in the probability mix per unit operating time.
All things have their place and their price points. Most applicants here are very poor neophytes and vacuum based "babes in the woods".
Richard Hull
Oh! By the way... We are forced to purchase our first fill for the pump in a 500CC bottle and suffer the $84.00 price. That was up front money to just use the pump on day one!
After that, I can blow up my diff in 9 more stupid accidents, complete system teardowns and associated cleanings without spending another dollar. I clean and reuse all my copper gaskets as I do not crush them out of existence on first use. I can get about 3 re-applications on the same gasket.
With a turbo, you would need $30,000 worth of up front spending to not suffer out of pocket new costs in 9 destructive events.
Turbos are massive dollar losses in waiting to all but the hyper vigilant. You can't perpetually expect to get a fully functional turbo with controller and cabling that will bolt right onto your present system off e-bay on the cheap following an accident.
I can have my exact, same diff pump back on line the same day at no additional out of pocket expense.
Again, I have a 10" throat turbo that works perfectly with all cabling and controller in storage here and refuse to use it until the right project comes along that might demand its use. The fusor is not one of those projects. I also have a 3.5" and a 5" diff pump on hand, but they are water cooled and over kill on a fusor as well. If you have a 2.5" air cooled diff pump on hand that is the one you need.
Turbo's are for people who are in and out of their systems constantly. This vastly hazards the continued existence of same due to far more operational related errors in the probability mix per unit operating time.
All things have their place and their price points. Most applicants here are very poor neophytes and vacuum based "babes in the woods".
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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Chris Bradley
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Re: Connecting a Pump to High Vac System
Richard Hull wrote:
> I find it stunning that a simple mechanical pump down is just not done out of hand prior to turning on a turbo. It is all too easy to do. You'll not come on line any sooner.
> The sluggard turbo is not going to do anything real until the mechanical pump has done its job.
> More much ado about truly nothing.
Speaking for myself, this stuff is relevant and germane. As you say, why bother? But discussing the full enevelope of what is and what is not permissible and possible gives [in any situation] a deeper understanding. If we operate within the confines of manuals and procedures all the time that are given by others and we never seek to ask or wonder whether some other modus operandi might work, or why it might not, or why it might be damaging or unsafe, then we are just thoughtless automatons repeating something to a pattern. Some gain amusement and value from doing exactly that, but my own interests don't lie in doing anything in 'the standard' way; I want to learn *why* it is done in the standard way [which often involves asking "why not do it ..this.. way?"] and then to thereafter stretch the envelope by doing something *not* done. This is a trivial example of that tenet, but is served by it.
Doug's comments regarding the higher start-up pressures and greater flexibility for some turbo designs is particularly interesting, from an understanding of what might be practically built up into a working system.
> I find it stunning that a simple mechanical pump down is just not done out of hand prior to turning on a turbo. It is all too easy to do. You'll not come on line any sooner.
> The sluggard turbo is not going to do anything real until the mechanical pump has done its job.
> More much ado about truly nothing.
Speaking for myself, this stuff is relevant and germane. As you say, why bother? But discussing the full enevelope of what is and what is not permissible and possible gives [in any situation] a deeper understanding. If we operate within the confines of manuals and procedures all the time that are given by others and we never seek to ask or wonder whether some other modus operandi might work, or why it might not, or why it might be damaging or unsafe, then we are just thoughtless automatons repeating something to a pattern. Some gain amusement and value from doing exactly that, but my own interests don't lie in doing anything in 'the standard' way; I want to learn *why* it is done in the standard way [which often involves asking "why not do it ..this.. way?"] and then to thereafter stretch the envelope by doing something *not* done. This is a trivial example of that tenet, but is served by it.
Doug's comments regarding the higher start-up pressures and greater flexibility for some turbo designs is particularly interesting, from an understanding of what might be practically built up into a working system.
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Carl Willis
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Re: Connecting a Pump to High Vac System
If I have a piece of equipment that costs more than my car, and I want to use it properly, I read the manual.
Chris's original question about killing a turbo by turning it on accidentally at high pressure has a simple answer: no, you won't kill it.
Chris's extrapolation from this about turning a turbo on at high pressure if you're impatient just doesn't follow. At all. Most of these pumps (and I have no choice but to defer to the specific pump's manual for details) won't abide that condition, either because of an overload trip or an overtemperature trip. Again, you won't kill the pump! But this is not a recipe to save effort or simplify your job. It's a recipe to have to reboot your pump a bunch of times, possibly apply water cooling during spin up, or get shut down for longer because of an overtemp trip.
The whole episode here is just illustrative of a certain tendency to extrapolate information from a response that just isn't implied. And it annoys me that this happens. Chris, when and if you do get a turbo and get to know it, I'm confident (in spite of your comments here) that you will have no problem treating it right and finding the right balance between expediency and good operating practices. I'm also confident that you will locate its manual.
-Carl
Chris's original question about killing a turbo by turning it on accidentally at high pressure has a simple answer: no, you won't kill it.
Chris's extrapolation from this about turning a turbo on at high pressure if you're impatient just doesn't follow. At all. Most of these pumps (and I have no choice but to defer to the specific pump's manual for details) won't abide that condition, either because of an overload trip or an overtemperature trip. Again, you won't kill the pump! But this is not a recipe to save effort or simplify your job. It's a recipe to have to reboot your pump a bunch of times, possibly apply water cooling during spin up, or get shut down for longer because of an overtemp trip.
The whole episode here is just illustrative of a certain tendency to extrapolate information from a response that just isn't implied. And it annoys me that this happens. Chris, when and if you do get a turbo and get to know it, I'm confident (in spite of your comments here) that you will have no problem treating it right and finding the right balance between expediency and good operating practices. I'm also confident that you will locate its manual.
-Carl
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Chris Bradley
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Re: Connecting a Pump to High Vac System
Carl Willis wrote:
> Chris, when and if you do get a turbo and get to know it, I'm confident (in spite of your comments here) that you will have no problem treating it right and finding the right balance between expediency and good operating practices. I'm also confident that you will locate its manual.
I hope you are right, Carl... I have been busy on ebay today. My bidding plans went a little wrong, though. Well, wrong in a good way.
I was focussed on a TPH050 that was listed (to go with a controller I've bought from the US). The guy had two others that I though I might as well put a little bid on, just in case. Looks like I had no real bidding competition today!:
I should soon be the recipient of;
A TPH050 pump, cable and TCP040 contrller
A varian turbo V60, cable and controller
An Alcatel 20/40 pump
A TPH062 pump with some marginally stiff bearings.
I plan on dismantling the TPH062 for the learning exercise. If all looks OK maybe I will clean the bearings and spray some dry PTFE lubricant on them. Who knows, maybe I can fix it?
I am told the other items are all functional. We'll see...
Ebay is great. This lot might be junk, or it might be gold, but seeing as all 4 turbos and 2 controllers cost a total of GBP247, I figure I might be able to recover most of the cash just on the cables and controllers alone, in the worst case scenario.
The upshot of this is that I have been looking all day for manuals and, more importantly, wiring diagrams so I don't mess things up. I now have the connection circuits for the TCP040, courtesy of Thomas Dressel (many thanks!) but would still like to ask if anyone has information on the other items.
[[If anyone happens to either come across, or knows where to get, a suitable cable and controller for the Alcatel then please let me know. I might either buy those off you, or sell the pump to you. Also to note, I may have a spare system I can sell, once I have tested them both and find I have a surplus, which may be useful for a fellow "isolated" UK hobbyist. Keep an eye on the trading post... ]]
As I mentioned before, I have rarely seen diffusion pumps in UK ebay, which would be the preferred option for simplicity and robustness, yet turbos seem more plentiful. But could I really turn down the chance of some turbo systems for maybe even less than I would expect to pay for a dirty old diff stack?
> Chris, when and if you do get a turbo and get to know it, I'm confident (in spite of your comments here) that you will have no problem treating it right and finding the right balance between expediency and good operating practices. I'm also confident that you will locate its manual.
I hope you are right, Carl... I have been busy on ebay today. My bidding plans went a little wrong, though. Well, wrong in a good way.
I was focussed on a TPH050 that was listed (to go with a controller I've bought from the US). The guy had two others that I though I might as well put a little bid on, just in case. Looks like I had no real bidding competition today!:
I should soon be the recipient of;
A TPH050 pump, cable and TCP040 contrller
A varian turbo V60, cable and controller
An Alcatel 20/40 pump
A TPH062 pump with some marginally stiff bearings.
I plan on dismantling the TPH062 for the learning exercise. If all looks OK maybe I will clean the bearings and spray some dry PTFE lubricant on them. Who knows, maybe I can fix it?
I am told the other items are all functional. We'll see...
Ebay is great. This lot might be junk, or it might be gold, but seeing as all 4 turbos and 2 controllers cost a total of GBP247, I figure I might be able to recover most of the cash just on the cables and controllers alone, in the worst case scenario.
The upshot of this is that I have been looking all day for manuals and, more importantly, wiring diagrams so I don't mess things up. I now have the connection circuits for the TCP040, courtesy of Thomas Dressel (many thanks!) but would still like to ask if anyone has information on the other items.
[[If anyone happens to either come across, or knows where to get, a suitable cable and controller for the Alcatel then please let me know. I might either buy those off you, or sell the pump to you. Also to note, I may have a spare system I can sell, once I have tested them both and find I have a surplus, which may be useful for a fellow "isolated" UK hobbyist. Keep an eye on the trading post... ]]
As I mentioned before, I have rarely seen diffusion pumps in UK ebay, which would be the preferred option for simplicity and robustness, yet turbos seem more plentiful. But could I really turn down the chance of some turbo systems for maybe even less than I would expect to pay for a dirty old diff stack?
Re: Connecting a Pump to High Vac System
I'll be interested in anything surplus you have, Chris.
We use a lot of Alcatels at work, I think we only use the others for replacement on old units. I'll see what I can dig up.
EDIT: Maybe we still use Pfeiffers on the bigger machines.
We use a lot of Alcatels at work, I think we only use the others for replacement on old units. I'll see what I can dig up.
EDIT: Maybe we still use Pfeiffers on the bigger machines.
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Chris Bradley
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Re: Connecting a Pump to High Vac System
Sounds good. Particularly any handbooks indication of circuitry - were I to find some 'spare time' later next year I'd be inclined even to have a go at bulding my own controller for the Alcatel, for the educational potential. But I'd need to know what the connections, are and to know it doesn't have a mag bearing to worry about.
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John Futter
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Re: Connecting a Pump to High Vac System
Chris Brian Et Al
most turbos that appear on Epay are the older turbomolecular type, they are not turbo drag type that can stand much poorer vacuums on their backing side. At work we buy off Epay to keep costs down and have had very little luck with modern drag type pumps, one even had a sticker on it when it arrived from Pfeiffer service saying it was unrepairable --this was not stated in the auction or visible in the pictures --all it said was that it spun freely --this was not quite the truth giving the rotor a flick it would almost do a turn before stopping.
Its now on our "Sacrifices to the Gods of High Vacuum" shelf. a waste of US$700
From our point of view the best pumps are the Leybold TMP series ie 50 , 150 ,360, 450, 1000 L/S units.
2 bad TMP50's out of ten but 9 bad controllers out of 10
1 bad TMP150 out of 5
1 bad TMP350 out of 4
0 bad TMP1000 out of 2
0 bad TMP450 out of 1
The following where bought new with new controllers
Elsewhere in the place we have had Micro Seiki turbos all replaced with Pfeiffers due to their high pitch scream that became an OSH issue--still running.
Most varian turbos have been replaced a least once--Noisy --bearing failure and about half the varian controllers have emitted smoke and have had to be replaced @ US$7000 each, the turbos are replaced / factory exchange at half new price approx US$10,000 each.
One exchange Varian V550 @ and one new Varian controller to suit is more than we have paid total for all the Leybold pumps and controllers.
Some of the Non Epay TMP350's at work have now been spinning for more than 23 years and are cycled up to air and back to high vac 4 out of 5 days a week 50 weeks a year.
All the above mentioned Leybold Turbos stall at about 5 by ten to the minus 1 millibar and do not pump properly until they are backed at better than 7 by ten to the minus 2 millibar
Hopefully this helps fusoneers to make some choices ---it could be that you are not lucky with every purchase!!!!
PS the bad TMP350 is what is going on my fusor build, it works but is noisy ( not as bad as the Micro Siekis) and is not allowed in our lab through OSH / possible hearing damage issues.
most turbos that appear on Epay are the older turbomolecular type, they are not turbo drag type that can stand much poorer vacuums on their backing side. At work we buy off Epay to keep costs down and have had very little luck with modern drag type pumps, one even had a sticker on it when it arrived from Pfeiffer service saying it was unrepairable --this was not stated in the auction or visible in the pictures --all it said was that it spun freely --this was not quite the truth giving the rotor a flick it would almost do a turn before stopping.
Its now on our "Sacrifices to the Gods of High Vacuum" shelf. a waste of US$700
From our point of view the best pumps are the Leybold TMP series ie 50 , 150 ,360, 450, 1000 L/S units.
2 bad TMP50's out of ten but 9 bad controllers out of 10
1 bad TMP150 out of 5
1 bad TMP350 out of 4
0 bad TMP1000 out of 2
0 bad TMP450 out of 1
The following where bought new with new controllers
Elsewhere in the place we have had Micro Seiki turbos all replaced with Pfeiffers due to their high pitch scream that became an OSH issue--still running.
Most varian turbos have been replaced a least once--Noisy --bearing failure and about half the varian controllers have emitted smoke and have had to be replaced @ US$7000 each, the turbos are replaced / factory exchange at half new price approx US$10,000 each.
One exchange Varian V550 @ and one new Varian controller to suit is more than we have paid total for all the Leybold pumps and controllers.
Some of the Non Epay TMP350's at work have now been spinning for more than 23 years and are cycled up to air and back to high vac 4 out of 5 days a week 50 weeks a year.
All the above mentioned Leybold Turbos stall at about 5 by ten to the minus 1 millibar and do not pump properly until they are backed at better than 7 by ten to the minus 2 millibar
Hopefully this helps fusoneers to make some choices ---it could be that you are not lucky with every purchase!!!!
PS the bad TMP350 is what is going on my fusor build, it works but is noisy ( not as bad as the Micro Siekis) and is not allowed in our lab through OSH / possible hearing damage issues.
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Chris Bradley
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Re: Connecting a Pump to High Vac System
That's a very useful set of statistics, John, perhaps unique! How many others buy so many pumps off ebay that the data begins to look almost 'statistically significant'. Thanks for you time preparing the data. Very informative.
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Tyler Christensen
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Re: Connecting a Pump to High Vac System
I bled my system to about 250torr during my earlier days when I had a poor valve system with diffusion on using DC-704 oil and there was no damage, zero oxidation and I'm still using the same oil charge. It just made a little hissing noise. That stuff seems just about bullet proof.
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Doug Coulter
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Re: Connecting a Pump to High Vac System
I would say this,
Certain things are never sold cheap unless they have failed. OK, the word never is too strong, but clearly in the ballpark.
We have used ebay extensively, gone to university auctions and so on. If a piece of rare, complex equipment is usable, even if obsolete -- it doesn't show up there in the first place. If by some miracle something good does show up in an auction, it goes very fast for a price to take your breath away -- those guys who sell reconditioned surplus for 1/2 the new prices and more are there to bid against you.
About the only way we find stuff of this category that works is at liquidation sales, where the owner just went out of business or something similar, and even then the good stuff is picked over before we get to it. Small sales don't tend to bring out the pro bidders.
I have ranted several times about "just buying the magic without understanding" and this is peripherally related to that -- now we're just trying to buy it cheap, instead.
You might be surprised what price you'd be quoted if you went straight to a manufacturer and went through the paperwork with the help of a rep -- RFQ, all that kind of thing. It's not like they are selling more of anything than they can make in this economy. Be a good horse trader, and you do pretty well.
I would up paying about $3.5k for a complete turbo pumping station (65l/s). I had to add a mass spectrometer, numerous fittings, valves(!), flanges, fancy quick access doors, and chamber to get the bill up to my $8k budget for that system.
Now, looking at losses on ebay, and hamfests (where you're out the cost of the drive no matter what)
I don't think those numbers are all that bad -- I was up and running RIGHT NOW, not two years of scrounging later, having paid for 3 things for each thing that actually worked and was useful (not the same thing) -- which is a fair to middling record for scrounging. Two years of my hobby time may not be worth as much as my professional time, but....it's worth something for sure. Certainly it is to anyone mortal who can't get those years back to play in.
I know this will cause a few old scroungers to turn up their noses. So be it. We scrounge too, and get lucky and brag about it as well. But lets not leave out the reality that there are some scrounges that looked awful good on ebay or auction or hamfest that just didn't pan out, and not only did they cost money, they cost time and effort.
Do you want to do fusion, or be a pro scrounger -- there's room for all, but.....???
Keep your eyes on the prize!
There are far more interesting and worthwhile accomplishments to be had then merely bragging rights on how you copied someone else's science on the cheap (and sins of omission about how it wasn't truly even that cheap). How about getting on with creating NEW science?
Certain things are never sold cheap unless they have failed. OK, the word never is too strong, but clearly in the ballpark.
We have used ebay extensively, gone to university auctions and so on. If a piece of rare, complex equipment is usable, even if obsolete -- it doesn't show up there in the first place. If by some miracle something good does show up in an auction, it goes very fast for a price to take your breath away -- those guys who sell reconditioned surplus for 1/2 the new prices and more are there to bid against you.
About the only way we find stuff of this category that works is at liquidation sales, where the owner just went out of business or something similar, and even then the good stuff is picked over before we get to it. Small sales don't tend to bring out the pro bidders.
I have ranted several times about "just buying the magic without understanding" and this is peripherally related to that -- now we're just trying to buy it cheap, instead.
You might be surprised what price you'd be quoted if you went straight to a manufacturer and went through the paperwork with the help of a rep -- RFQ, all that kind of thing. It's not like they are selling more of anything than they can make in this economy. Be a good horse trader, and you do pretty well.
I would up paying about $3.5k for a complete turbo pumping station (65l/s). I had to add a mass spectrometer, numerous fittings, valves(!), flanges, fancy quick access doors, and chamber to get the bill up to my $8k budget for that system.
Now, looking at losses on ebay, and hamfests (where you're out the cost of the drive no matter what)
I don't think those numbers are all that bad -- I was up and running RIGHT NOW, not two years of scrounging later, having paid for 3 things for each thing that actually worked and was useful (not the same thing) -- which is a fair to middling record for scrounging. Two years of my hobby time may not be worth as much as my professional time, but....it's worth something for sure. Certainly it is to anyone mortal who can't get those years back to play in.
I know this will cause a few old scroungers to turn up their noses. So be it. We scrounge too, and get lucky and brag about it as well. But lets not leave out the reality that there are some scrounges that looked awful good on ebay or auction or hamfest that just didn't pan out, and not only did they cost money, they cost time and effort.
Do you want to do fusion, or be a pro scrounger -- there's room for all, but.....???
Keep your eyes on the prize!
There are far more interesting and worthwhile accomplishments to be had then merely bragging rights on how you copied someone else's science on the cheap (and sins of omission about how it wasn't truly even that cheap). How about getting on with creating NEW science?
Why guess when you can know? Measure!
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Chris Bradley
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Re: Connecting a Pump to High Vac System
Your words are all too true - indeed, I fully recognise that I might be about to receive 247 quid's worth of hi tech scrap. But I now know a much greater amount about turbomolecular and drag pumps that I never knew two weeks ago. Needs must. And immersing oneself in trying to get some bits of kit working is the best way of learning, I say. Nothing can top it.
There is a little story I thought of when I read your post: Two financial chaps are strolling along Wall St and one points to something on the floor. "That's a $100 bill!". "No it's a fake" says the other "if it were real then someone would've picked it up long ago".
I quite like the pro-scrounging bit, I think! But as you say, if you've got the cash you can do cleverer things with it - one company I called up asking on availability of repair kits was telling me that many customers who sent their pumps back to the manufs now end up just getting a new one back. As you suggest, there are deals out there right now and he offered me a sub GBP2000 new pump as we spoke (the new type that just run off an input voltage with the controllers built in).
Such experiences as these enrich even the professional engineer in a way that neither books, nor lectures, nor journals and nor, even, experience doing other people's jobs can. Doing one's own project and improvising with a limited set of unpredictable bits and making something out of it all - I'll take that person on my team any day, the clean-handed PhD can go work on someone else's project.
There is a little story I thought of when I read your post: Two financial chaps are strolling along Wall St and one points to something on the floor. "That's a $100 bill!". "No it's a fake" says the other "if it were real then someone would've picked it up long ago".
I quite like the pro-scrounging bit, I think! But as you say, if you've got the cash you can do cleverer things with it - one company I called up asking on availability of repair kits was telling me that many customers who sent their pumps back to the manufs now end up just getting a new one back. As you suggest, there are deals out there right now and he offered me a sub GBP2000 new pump as we spoke (the new type that just run off an input voltage with the controllers built in).
Such experiences as these enrich even the professional engineer in a way that neither books, nor lectures, nor journals and nor, even, experience doing other people's jobs can. Doing one's own project and improvising with a limited set of unpredictable bits and making something out of it all - I'll take that person on my team any day, the clean-handed PhD can go work on someone else's project.
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Chris Bradley
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Re: Connecting a Pump to High Vac System
Doug Coulter wrote:
> We scrounge too, and get lucky and brag about it as well. But lets not leave out the reality that there are some scrounges that looked awful good on ebay or auction or hamfest that just didn't pan out, and not only did they cost money, they cost time and effort.
Well, just for the bragging; the items were being sold by a very hospitable semi-retired mass spectrometer engineer clearing his workshop and quite happy that these were going to support a privateer project.
A nice chap at Alcatel has advised me that their unit, which I paid the princely sum of 18 pounds for, is a turbo-drag hybrid pump. Nice! It appears to be essentially unused. He offered me some controller bits for it (a bare controller board) at very reasonable prices, though he's looking for some electrical diagrams for me and I am inclined to try to make a fully-variable speed controller so that I can have better control over pumping speeds and pressure regulation.
> Do you want to do fusion, or be a pro scrounger
Successful scrounging feels real good!! Maybe room for both?
> We scrounge too, and get lucky and brag about it as well. But lets not leave out the reality that there are some scrounges that looked awful good on ebay or auction or hamfest that just didn't pan out, and not only did they cost money, they cost time and effort.
Well, just for the bragging; the items were being sold by a very hospitable semi-retired mass spectrometer engineer clearing his workshop and quite happy that these were going to support a privateer project.
A nice chap at Alcatel has advised me that their unit, which I paid the princely sum of 18 pounds for, is a turbo-drag hybrid pump. Nice! It appears to be essentially unused. He offered me some controller bits for it (a bare controller board) at very reasonable prices, though he's looking for some electrical diagrams for me and I am inclined to try to make a fully-variable speed controller so that I can have better control over pumping speeds and pressure regulation.
> Do you want to do fusion, or be a pro scrounger
Successful scrounging feels real good!! Maybe room for both?