Since restarting the Deuteron accelerator project I've notice my turbo is a lot louder - the whine can be heard much farther away and is certainly louder. Since I obtained a free identical non-working turbo in a deal for an extra controller I decided that finding the oil port/access for this pump would be fairly safe - so I disassembled that pump to both determine what caused it to be junked by the original owner (turns out both bearings seized - i guess due to lack of oil - looked rather dry) but also to learn where and how to add bearing oil to this style of pump (aside: someone gave me turbo pump oil - a lot.) Well, for this turbo it is ridiculously easy to access the oil reservoir and it contains a small felt that the lower shaft fits into.
So I removed my turbo from the system and opened the base access plate. Looking at the oil felt/reservoir that the lower shaft reaches the felt looked brand new as did the visible shaft. But I didn't see any sign of free oil - so I assume it was fairly dry (on my pump on the lower side near the base there is a small screw that references oil but it does not appear to have any easy access for the oil to enter.) So, bottom line - the turbo does appear to require/take oil but how it is delivered to that side port is something I do not see.
However - since the main reservoir is accessible and appears dry and further, as I mentioned previously, the turbo "whine" has gotten significantly louder when running at speed I decided to add some oil. Not knowing how much is safe to add I just wagged it on the low side, and reassembled the pump and re-installed it into my system.
The good news is that the turbo is almost completely silent now - a rather extreme improvement compared to its previous operation - the decrease is much greater than I ever expected. That does appear to indicate that the bearings appeared to need oil. The down side of this process is that the oil needs to out gas as does the pump (less so but it was exposed to moist air - I have dry processed air that is used to purge the system normally but that isn't possible with the pump off the system and the pump was exposed far longer than I liked.) So I expect it will need to be run in for a while to get back to the 10^-6 torr range and out gas any moister exposure that might have gotten into the replacement turbo oil.
Currently, it has taken over half an hour to get to 2.0 x 10^-5 torr which is rather slow for my system. I guess I should have heated the oil and out gassed it under vacuum before using it ... live and learn!
Turbo Pump Whine Fix
-
Dennis P Brown
- Posts: 3189
- Joined: Sun May 20, 2012 10:46 am
- Real name: Dennis Brown
Turbo Pump Whine Fix
Last edited by Dennis P Brown on Thu Apr 17, 2014 5:52 am, edited 1 time in total.
-
Jerry Biehler
- Posts: 975
- Joined: Tue Nov 24, 2009 3:08 am
- Real name:
- Location: Beaverton, OR
Re: Turbo Pump Whine Fix
I would stop using the pump immediately and get the right oil cartridge for the pump before you toast the bearings. I am guessing this is a pfeiffer pump?
Oils are not something to mess with, especially at the speeds that turbos. I dont know what kind of oil you put in, there are lots of different pumps and different oils for them, but if you put diff pump oil in there I can almost guarantee you would have killed the pump. Assuming a modern silicone diff pump fluid, then is has zero lubricative properties for metal-on-metal situations.
The bearings are on the roughing side of the pump so they are not exposed to high vacuum. Outgassing of the oil will not cause high pressure in the chamber. Wrong viscosity will cause the pump to run slow (If too thick) and that will slow down your pumping.
I am dead serious, do NOT run this pump if you value it.
Oils are not something to mess with, especially at the speeds that turbos. I dont know what kind of oil you put in, there are lots of different pumps and different oils for them, but if you put diff pump oil in there I can almost guarantee you would have killed the pump. Assuming a modern silicone diff pump fluid, then is has zero lubricative properties for metal-on-metal situations.
The bearings are on the roughing side of the pump so they are not exposed to high vacuum. Outgassing of the oil will not cause high pressure in the chamber. Wrong viscosity will cause the pump to run slow (If too thick) and that will slow down your pumping.
I am dead serious, do NOT run this pump if you value it.
-
Dennis P Brown
- Posts: 3189
- Joined: Sun May 20, 2012 10:46 am
- Real name: Dennis Brown
Re: Turbo Pump Whine Fix
Thanks for the warning - and yes, I know silicone based oil cannot be used in a turbo. Since I didn't say never use DP silicone based oil in my post that was a major error that could cause a disaster for anyone reading my post - good catch.
However, I did use turbo pump oil (and I believe it is Pfeiffer oil, as is my turbo.) So, the viscosity should be correct and sufficient. The issue, I believe, is that the container has been open previously and I suspect that water vapor has contaminated the oil to some extent.
The small pump I have does expose the high vac side to the oil when the blades are not running (I disassembled one and know this does occurs in my pump and that for most turbo's, you are correct and that isn't the case (pun, there?)) The trouble is, since mine does expose the oil to the lower turbine blades/main shaft the issue of back streaming will be an problem unless the oil is extremely clean (no water vapor exposure.) Out gassing from the oil does appear to be causing issues - I really should have heated the oil and put it under high vacuum for a few minutes before using it.
Again, thanks for the warning and flagging that DP oil statement since I did not mentioned never to use silicone based DP oil but did say using DP oil is possible. I would say that while the Youtube someone posted here (on how to replace bearings in turbo pumps) does indicate not to use silicone based DP oil they do recommend using DP oil - I now suspect that (like you said) that this is just a bad idea regardless and I should not have said that in my post and have edited that out.
Post edit: after reading the Pfeiffer manual (google does work!) on adding oil to the pump turns out I didn't add too much after all. But I did get excess oil in the housing by my fill method (and yes, the oil is exposed to the vacuum.) Since I did use the correct oil and since I am certain it has excess water vapor exposure, my choice is a bake out or cleaning (and then re-oil the bearings with properly out gassed oil.) I'll try a bake out first and if that does not work a cleaning of the pump.
For the bake out, I'll keep it under 50 C (so this isn't a bake out but more of a warming) for sure and only heat the upper section to further protect the bearings (turbo will be off); Pfeiffer does say a bake out is safe for that pump but give zero parameters in their manual - great. My fore pump has an anti-back flow section so I assume that will be sufficient to allow a bake out under vacuum for the turbo (a micron or so.) Not holding my breath this will improve too much on the vacuum - I guess cleaning may be the next step. Turns out someone I know thinks they have the Freon liquid cleaner ... . Cross that bridge when/if I reach it.
However, I did use turbo pump oil (and I believe it is Pfeiffer oil, as is my turbo.) So, the viscosity should be correct and sufficient. The issue, I believe, is that the container has been open previously and I suspect that water vapor has contaminated the oil to some extent.
The small pump I have does expose the high vac side to the oil when the blades are not running (I disassembled one and know this does occurs in my pump and that for most turbo's, you are correct and that isn't the case (pun, there?)) The trouble is, since mine does expose the oil to the lower turbine blades/main shaft the issue of back streaming will be an problem unless the oil is extremely clean (no water vapor exposure.) Out gassing from the oil does appear to be causing issues - I really should have heated the oil and put it under high vacuum for a few minutes before using it.
Again, thanks for the warning and flagging that DP oil statement since I did not mentioned never to use silicone based DP oil but did say using DP oil is possible. I would say that while the Youtube someone posted here (on how to replace bearings in turbo pumps) does indicate not to use silicone based DP oil they do recommend using DP oil - I now suspect that (like you said) that this is just a bad idea regardless and I should not have said that in my post and have edited that out.
Post edit: after reading the Pfeiffer manual (google does work!) on adding oil to the pump turns out I didn't add too much after all. But I did get excess oil in the housing by my fill method (and yes, the oil is exposed to the vacuum.) Since I did use the correct oil and since I am certain it has excess water vapor exposure, my choice is a bake out or cleaning (and then re-oil the bearings with properly out gassed oil.) I'll try a bake out first and if that does not work a cleaning of the pump.
For the bake out, I'll keep it under 50 C (so this isn't a bake out but more of a warming) for sure and only heat the upper section to further protect the bearings (turbo will be off); Pfeiffer does say a bake out is safe for that pump but give zero parameters in their manual - great. My fore pump has an anti-back flow section so I assume that will be sufficient to allow a bake out under vacuum for the turbo (a micron or so.) Not holding my breath this will improve too much on the vacuum - I guess cleaning may be the next step. Turns out someone I know thinks they have the Freon liquid cleaner ... . Cross that bridge when/if I reach it.
-
Dennis P Brown
- Posts: 3189
- Joined: Sun May 20, 2012 10:46 am
- Real name: Dennis Brown
Re: Turbo Pump Whine Fix
A bit of good news so far - after the warm out (my so-called bake out) for two hours or so at a few microns, I let the turbo cool off and then started it up. Within two minutes I was at 2.0 x 10^-5 torr just like before I serviced the turbo with "new" oil (in that, at least, the turbo is acting normal again.)
If it can get below 5 x 10 ^-6 torr within a half hour, than I will say it is ok. If not, I guess I'll remove it and clean it ... . In any case, I will take the turbo oil I have and vacuum distillate it tomorrow when I have some time. Than reseal it and keep it on hand.
One thing that came out of this is that after disassembling the other identical but none-working turbo I have (a TP-040), I discovered that both its bearings and rotor blades are fine except one blade tip is missing but I think I can address that issue.) I am at a lost for the damage it does have (the lower shaft is badly damaged below were it just passes the lower bearing) but I guess I need to find replacement for the missing spring (a small one is missing that goes on that lower shaft) and put it together again. I guess I will get to see if it will spin up ok or is badly out-of-balance. Strange how/why it was damaged.
Also, I am heating/purging my air drier while the turbo evacuates my accelerator system. Might as well do some house cleaning chores while I'm waiting!
Update: first off, as I mentioned the system jumped to 2 x 10 ^-5 torr in no time but then struggled to reach 1.1 x 10 ^-5 torr and reached this only after an hour - then for another hour held this without any further improvement. So, I may need to clean the pump after all. I will see if it further improves this weekend; maybe a higher temp bake (again, really warm) out under vacuum may further improve this value. Worth trying before attempting a removal and cleaning.
In related news, the turbo oil started to boil at 192 C and 200 microns. Not sure if that is acceptable or questionable for that oil - I'm not convinced that is acceptable. The bearing and its oil are exposed to the lower section of the turbo blades and will create a back pressure depending on the oils vapor pressure. Maybe I will test some DP oil (non-silicone, of course) and see if that boils under those same conditions (190 C @ 200 microns.) Might be an interesting test ... .
If it can get below 5 x 10 ^-6 torr within a half hour, than I will say it is ok. If not, I guess I'll remove it and clean it ... . In any case, I will take the turbo oil I have and vacuum distillate it tomorrow when I have some time. Than reseal it and keep it on hand.
One thing that came out of this is that after disassembling the other identical but none-working turbo I have (a TP-040), I discovered that both its bearings and rotor blades are fine except one blade tip is missing but I think I can address that issue.) I am at a lost for the damage it does have (the lower shaft is badly damaged below were it just passes the lower bearing) but I guess I need to find replacement for the missing spring (a small one is missing that goes on that lower shaft) and put it together again. I guess I will get to see if it will spin up ok or is badly out-of-balance. Strange how/why it was damaged.
Also, I am heating/purging my air drier while the turbo evacuates my accelerator system. Might as well do some house cleaning chores while I'm waiting!
Update: first off, as I mentioned the system jumped to 2 x 10 ^-5 torr in no time but then struggled to reach 1.1 x 10 ^-5 torr and reached this only after an hour - then for another hour held this without any further improvement. So, I may need to clean the pump after all. I will see if it further improves this weekend; maybe a higher temp bake (again, really warm) out under vacuum may further improve this value. Worth trying before attempting a removal and cleaning.
In related news, the turbo oil started to boil at 192 C and 200 microns. Not sure if that is acceptable or questionable for that oil - I'm not convinced that is acceptable. The bearing and its oil are exposed to the lower section of the turbo blades and will create a back pressure depending on the oils vapor pressure. Maybe I will test some DP oil (non-silicone, of course) and see if that boils under those same conditions (190 C @ 200 microns.) Might be an interesting test ... .
-
Dennis P Brown
- Posts: 3189
- Joined: Sun May 20, 2012 10:46 am
- Real name: Dennis Brown
Re: Turbo Pump Whine Fix
The so-called bake out (really just a low temp warm out or should I say warm over (?); i.e. under 50C) has improved my systems overall out gassing performance a good bit. Instead of the 1 - 2 micron/sec pressure rise (slows down dramatically as it approaches hundred micron but overnight got to ten torr or so) the pressure rise now is just a micron every few seconds at the bottom of the scale (and the overnight max is about 400 microns.)
So, I guess the turbo wasn't exactly purged before the warm over since that was the only section I "baked out ... I mean warmed over. Considering this baseline pressure was what I often achieved before I even serviced my turbo - I'm glade I did the warm out. Still, the turbo refuses to get pass 1.0 x 10^-5 torr (within an hour - I'm not gonna wait longer than that because my goal is low 10^-6 torr and not getting to the top of that range in an hour really makes that goal difficult - especially since previously that was easy for my system.) So I am considering a more deep cleaning of the turbo (the bearing felt should be purged) may be in order; not exactly a difficult task since the felt is mounted and easily removed. But re-oiling may be an issue since that might put me back at square one. Of course, as noted, I did purge my reserve turbo oil (boiled under vacuum @ 192 C) and let it stay under vacuum (hot but not at the boiling temp) for a few hours so it should behave better under high vac ... I hope. If not ...well, will see first. I will try running my diffusion pump oil under vacuum/high temp and see where and if it boils (my vacuum furnace tops out at 195 C. By the way, the DP oil is bis(2-ethylhexyl) phthlate which the person who rebuilt turbo's indicated can be used. This may be incorrect so I'll avoid trying this but the heating test is just too much fun not to check.)
I have just cleaned the fore line trap on the system's two-stage pump. This has also improved my roughing vacuum by a not insignificant level; instead of 10-15 microns the pump would normally achieve the system now gets to 2-3 microns. Aside: I use a surplus Baratron gauge so those numbers are neither absolute nor calibrated and need to be taken with a gain of salt; however, as for the relative before/after measurement the change is accurate. That was a rather significant improvement even though the organic fluid I used to clean the fore line trap (after I removed from the unit from my system!) came out rather clean ... . also, I baked the trap out before re-installing it back into the trap housing. Then with my system closed off from the fore line trap, I pumped the trap out for a while before opening the valve to my system. Trying to following good vacuum practice helps prevents other issues from developing. Always fun when you fix a problem only to create a worse one ... sounds a little too familiar to me ... .)
Aside: the system pressure is now 9.5 x 10 ^-6 torr after the trap purge (an improvement) after fifteen minutes of running. Considering it was bottoming out at 1x10^-5 torr after half an hour that is an interesting result just from the fore line trap change. Still, I doubt it will allow me to get where I want with the system but will give it another hour or so. This shows that system warm over is making some improvements to my high vac system. That is encouraging. I often forget about the fore line trap - I guess that isn't a good idea.
So, I guess the turbo wasn't exactly purged before the warm over since that was the only section I "baked out ... I mean warmed over. Considering this baseline pressure was what I often achieved before I even serviced my turbo - I'm glade I did the warm out. Still, the turbo refuses to get pass 1.0 x 10^-5 torr (within an hour - I'm not gonna wait longer than that because my goal is low 10^-6 torr and not getting to the top of that range in an hour really makes that goal difficult - especially since previously that was easy for my system.) So I am considering a more deep cleaning of the turbo (the bearing felt should be purged) may be in order; not exactly a difficult task since the felt is mounted and easily removed. But re-oiling may be an issue since that might put me back at square one. Of course, as noted, I did purge my reserve turbo oil (boiled under vacuum @ 192 C) and let it stay under vacuum (hot but not at the boiling temp) for a few hours so it should behave better under high vac ... I hope. If not ...well, will see first. I will try running my diffusion pump oil under vacuum/high temp and see where and if it boils (my vacuum furnace tops out at 195 C. By the way, the DP oil is bis(2-ethylhexyl) phthlate which the person who rebuilt turbo's indicated can be used. This may be incorrect so I'll avoid trying this but the heating test is just too much fun not to check.)
I have just cleaned the fore line trap on the system's two-stage pump. This has also improved my roughing vacuum by a not insignificant level; instead of 10-15 microns the pump would normally achieve the system now gets to 2-3 microns. Aside: I use a surplus Baratron gauge so those numbers are neither absolute nor calibrated and need to be taken with a gain of salt; however, as for the relative before/after measurement the change is accurate. That was a rather significant improvement even though the organic fluid I used to clean the fore line trap (after I removed from the unit from my system!) came out rather clean ... . also, I baked the trap out before re-installing it back into the trap housing. Then with my system closed off from the fore line trap, I pumped the trap out for a while before opening the valve to my system. Trying to following good vacuum practice helps prevents other issues from developing. Always fun when you fix a problem only to create a worse one ... sounds a little too familiar to me ... .)
Aside: the system pressure is now 9.5 x 10 ^-6 torr after the trap purge (an improvement) after fifteen minutes of running. Considering it was bottoming out at 1x10^-5 torr after half an hour that is an interesting result just from the fore line trap change. Still, I doubt it will allow me to get where I want with the system but will give it another hour or so. This shows that system warm over is making some improvements to my high vac system. That is encouraging. I often forget about the fore line trap - I guess that isn't a good idea.