<Noxz>
doh, kid sold the edwards pump (that could do sub 1mtorr)
<Noxz>
he still has the other one that can do 2 - 1 mtorr though
<Noxz>
but dang, he should have messaged me and been like: no longer available
<Noxz>
I should have nabbed it back then
<Noxz>
was like 4 or 5 days after I first msged him
<Noxz>
what a punk
<Noxz>
lol
<Noxz>
he only got back to the country 3 days ago
<Noxz>
ughf
<Noxz>
he mentioned he had someone around the shop to help him ship it, but still, I was going tow ait fo rhim to come back, plus it gave me more time to think about things
<Noxz>
oh, also had a 1:1 with my boss and no word about slacking off, so I figured I still had a job and could buy such a toy
<Noxz>
but damn
<Noxz>
wow, the edwards pump is like 3x as fast
<Noxz>
I'm working out equations for using a capilary as a bleed valve
<Noxz>
for vacuum controller
<Noxz>
so, for his OTHER pump, that can do 4.8m^3/h (pretend it can do that at any range I want to do)... if I want 50torr .. a 1mm diameter tube would need to be 9.3cm in length
<Noxz>
neat
<Noxz>
9.8cm length gives 10torr
<Noxz>
10.01cm = 1torr
<Noxz>
neat way to tune a bleed port
<Noxz>
and of course you can coil this tube, slightly
<Noxz>
10cm of a single coil = 3.18cm diameter.. so a bit small and easier to deal with, though 10cm isn't too long
<Noxz>
I'm still mad on this punk.. like half considering looking elsewhere for a turbo pump.. the only thing is it's hard to actually find stuff with verified pressures second hand..
<Noxz>
price for the dual vane pump alone is worth it for my chemistry experiments.. but the turbo pump enables me to do a bit more
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<sync_>
Noxz: I would not worry about pressures too much, unless the pumps have been crashed they will work file
<sync_>
~fine
<Noxz>
sync_, I want to use the dual vane pump, the roughing pump, for chemistry distillations
<Noxz>
so, if I want to distill some water over, doing it at 1 mtorr doesnt make much sense
<Noxz>
but 50torr is slightly better
<sync_>
then just get a cheapshit rotary
<Noxz>
but, also, from a few pages I've read, you want to slowly bleed in UHV with, say, dry Nitrogen or Argon when venting
<Noxz>
even if venting to atmospheric, dont just open up a valve and let it all pressurize
<Noxz>
I currently get 50torr with my diaphragm pumps, but I want to get to below 10torr, and yeah, I could go with cheapshit rotary, the alternative pump he has us $400 or so, not sure what you consider cheap
<Noxz>
but, if I want to make my own SEM, or mass spectrometer, I cant really have much in there
<Noxz>
maybe 1-2mtorr is good enough for SEM
<Noxz>
but not for mass spec
<Noxz>
(from what I'vr read)
<Noxz>
and higher vacuum will also allow me to do vapor deposition from metals and whatnot slightly better
<Noxz>
like Lithium Flruoide
<sync_>
you should get a second pump, you don't want to use the one with all the crap in the oil for any serious work
<Noxz>
wont the turbomolecular pump take care of any oil backsplash?
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<Noxz>
I kind of know what youa re saying, but at the same time I think you may be missing the point of doing more than just vacuum distillations
<sync_>
no, the oil will still go through the turbo, not much but it will
<sync_>
but it is more that you don't want all the crap to end up in the high pressure side of your turbo
<sync_>
and you don't need a turbopump just for distillation
<Noxz>
for distillations I would setup a catch
<Noxz>
no, I would have valves setup for what I need
<sync_>
a catch won't help you much
<Noxz>
a line for to the fumehood/shlenk manifold for distillations, and another to, say, the SEM
<sync_>
everything will end up in the oil, eventually
<Noxz>
well, sure, that's why you change the oil after a while
<Noxz>
it's made for that maintenance
<sync_>
do whatever you want, but this is not good vacuum practice
<sync_>
just get a second pump
<Noxz>
second pump for what again? distillations?
<sync_>
as a forepump for a turbo
<sync_>
or whatever way around
<Noxz>
you are saying the dual vane pump wont be good as a roughing pump?
<Noxz>
due to the oil?
<pie_>
idk about introductory texts but there are some vacuum tech handbooks on libgen
<pie_>
(that i havent read)
<Noxz>
I am sort of at the point where it's: just pay the man for something that works
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<sync_>
no Noxz, I'm just saying, get two pumps for two very different requirements
<sync_>
one for clean vacuum work and one for dirty work
<Noxz>
hrrmm, right
<Noxz>
I guess it comes down to filtering out what works and what doesnt on ebay
<Noxz>
and knowing this dual vane can get below 1 torr (1-2mtorr at that) is what is catching my eye
<sync_>
they all can do that
<Noxz>
well, I am coming from the land of ~50torr PTFE diaphragm pumps, so it's a little shocking in some regard
<sync_>
if a rotary ends up over 10^-3mbar it is worn
<sync_>
but rotaries are not hard to rebuild tho
<Noxz>
I watched a few videos on it
<Noxz>
seemed rather easy
<Noxz>
I'd rather not rebuild something I just bought though
<Noxz>
ie, knowing it is verrified working at correct vacuum is a sellin gpoint
<Noxz>
on ebay decent looking dual vane pumps dont even show up till around the $300 mark, and even then most of them cant say: working well.. most say lacking instrumentation to fully test
<sync_>
idk, I don't think I paid more than 50€ for any of my pumps
<sync_>
and only one was broken, the vanes were stuck
<Noxz>
just cleaned and reoiled?
<Noxz>
or needed new vanes
<sync_>
no, it was completely rusted to fuck inside, I could have rebuilt it, but I just threw it out
<sync_>
not worth my time
<Noxz>
right, that is exactly my point
<Noxz>
I see a few on marketplace for around $400 tested that can get to 25mtorr or less, which is plenty for any of my needs
<Noxz>
so, if I want to go with his pack, jsut for verified turbo and all connections and such, great
<Noxz>
then if I need another pump just for chem alter on, it would't cost me too too much
<Noxz>
he's also throwing in some decent guages
<Noxz>
maybe a roughing pump with an oil filter would be better, especially if for a mass spec, so the turbo doesnt have to deal with anything coming up
<SpeedEvil>
Second hand vacuum pumps are really pretty good. But probably you don't get to the good stuff quite at $300
<Noxz>
they have another one without pulling 25mtorr for $325 USD
<Noxz>
without oil filter
<Noxz>
not quite sure how I feel about 1.6 m^3/hr though
<SpeedEvil>
I was almost at the point of considering ordering a 10kW vacuum pump as it was cheap.
<SpeedEvil>
The primary issue was it was too heavy.
<sync_>
Noxz: easy, more flow more better
<Noxz>
the one from the kid is rated at 3-4x as much, which was stil 1/3 of the rv12
<Noxz>
also... turbo+controller on ebay is not less than $1k
<Noxz>
so his setup, with gauges, for $1300 or so (+ mroe fo rthe vane pump) seems not too bad, with all the extras and knowledge and junk
<Noxz>
maybe use theat 'roughing' pump for chem, and that oil filtered one I linked as the real roughing pump, for a cleaner setup
<sync_>
I don't think I have paid more than 200€ for a turbopump
<Noxz>
how many do you have???
<sync_>
I think 7 or so
<Noxz>
and again, I am not really in the mood for 'parts' stuff, or not verrified to work
<sync_>
#yolo
<Noxz>
well... you wanna sell me a pump+controller? ;)
<sync_>
sure, if you pay for shipping to overseas
<sync_>
but controllers are not really the issue
<Noxz>
maybe I can get the kid down some price since he let that edwards pump go, and I'll pickup that oil filter one, which has the right connectors for with the roughing pump
<Noxz>
end up with 3 pumps in the end, another gauge would be nice, looks like another $100 or so for the same thing
<sync_>
I would not worry so much
<Noxz>
I'm not exactly worried
<sync_>
seems like you are
<Noxz>
I dont want bunk stuff
<Noxz>
I dont like to waste time and money, but I dont have the lab setup just yet
<Noxz>
I really like things that were fully tested
<sync_>
that counts as worrying
<Noxz>
does it? hrm, I need to work on not worrying
<Noxz>
2am, time to chill out in a warm bed, methinks
<Noxz>
the idea of having an oil filter is certianlky interesting.. I am told that oil fumes up a room rather quickly
<Noxz>
the chem one (no filter) would exhaust to inside the fumehood
<Noxz>
so there's that
<Noxz>
k, bed time
<sync_>
even with an oil filter you will get mist at the exhaust, it is quite annoying, yes but nothing unbearable
<superkuh>
I have an exhaust tube going out the window (cut the corner off a 2x4 and slid it under the bottom window) I use for my pumps. A lot just precipitates on the tube but it still does the job.
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<Noxz>
lol, the punk replied back: yeah the edwards sold, but I still have the other one
<Noxz>
going to ask for a full list of the whole turbo setup components, just so I am on the same page
<Noxz>
superkuh, what kind of setup do you have? curious what everyone is actually making
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<Noxz>
half looking at a new Across pump, actually
<Noxz>
15m^3/h is basically onpar with what that edwards would have been, and 15mtorr is plenty
<Noxz>
turbo should be able to handle that
<Noxz>
a pfieffer doc says the exhaust pressure must be between 0.1-20 mbar, which is 15mtorr max,, I wonder how much fudge room you have there
<sync_>
well, the drag will increase so the efficiency goes down, the ultimate pressure goes up and your motor will burn
<sync_>
and the less pressure you have there the better
<Noxz>
hrm.. right.. but how much fudge room do I have? ;)
<Noxz>
would 15mtorr be too high? (for a pfieffer tmh 260)
<Noxz>
hrm, maybe their docs state 10mbar.. which is 7.5mtorr.. so half of what that across does
<Noxz>
I think I need to go outside with the dog, too nice not to
<sync_>
you should not be using a turbo above 10^-1 mbar on the exhaust side, they work fine with higher backpressures but the ultimate pressure will go up significantly
<sync_>
I chain two turbos to cut down on the load