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PainKilla
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I have used the pump for many hours in total (including multiple hour evacuations), pumping things from solvents to the insidious fumes of DMS and
H2SO4. The pump runs smoothly and consistently, so I cannot share your concerns.
Also, I don't know what you consider noisy; the pump I have is quite a bit softer on the ears than my rotary-vane vacuum pump, which isn't something
I'd call loud to begin with. Maybe I am just deaf?
[Edited on 8-5-2007 by PainKilla]
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bio2
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Must be the SureFlow brand is better built than the Jabsco
of the same type which I am familiar with.
The Jabscos sound as if they will fly apart when cycled on the pressure switch.
The impellers are neoprene I believe which can't handle
hydrocarbon fumes very well .
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Boomer
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These pumps are used in the *tens of thousands* as boost pumps for carbonated drinks (small outlets though). While normally for intermittent use, some
hudred to perhaps a thousand hours for a few bucks is not too bad.
If you need vacuum two hours per experiment, that's *years* even if you distill under vacuum twice per week.
And he probably meant it as a water pump for the ass pirator, not for the vacuum itself.
BTW many pumps of higher power level have a screw to adjjust 'shunt' flow (bypassing the load). You can adjust pressure independant from flowrate. If
they don't have it, use a bypass and close it up untill the pressure in *the other string* is just right.
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elementcollector1
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I recently bought this pump for use in producing vacuum, only to find that it doesn't work at all. Is there something I'm doing wrong, or is this thing simply not
good enough?
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Magpie
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That's a water pump meant for pumping liquids. It is not a vacuum pump. However it does indicate that it is capable of lifting water a certain
(undefined) distance.
The single most important condition for a successful synthesis is good mixing - Nicodem
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blogfast25
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Quote: Originally posted by Magpie  | | That's a water pump meant for pumping liquids. It is not a vacuum pump. However it does indicate that it is capable of lifting water a certain
(undefined) distance. |
You're not much of a sales guy, are you? I'd have sold him a caravan by now!
Sorry, EC1, couldn't resist that one. 
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elementcollector1
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Heh. I meant by forcing the water through an aspirator, but that works too.
Hey, I'll take a caravan! 
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blogfast25
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You don't think it might have been simpler to get a cheap vacuum pump? 
Water aspirators are ok but the vacuum is quite limited.
[Edited on 17-5-2015 by blogfast25]
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macckone
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This is the pump I use.
http://www.amazon.com/gp/product/B006M6MU90/
use a cold trap for organic vapors.
Acids can cause corrosion but sodium carbonate will keep the pH acceptable.
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smaerd
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Macckone - Have you measured what kind of vacuum you can pull with that thing? Thats a really affordable option.
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blogfast25
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That's not really a vacuum pump either.
I use one of these to feed condensers (cooling water), having no running water in my shedlab.
[Edited on 17-5-2015 by blogfast25]
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smaerd
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No it's not a vacuum pump but its a water pump and like the thread title suggests when coupled with an aspirator it can function as a vacuum pump.
Seeing as how it can dump a tenth of a gallon a second, it's probably right for the job. I'm just suspicious because it's so cheap and back when I was
researching this I gave up when I found that most of the pumps were around 200$+ so I bought a diagphragm pump instead.
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macckone
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The vacuum is pretty low when using ice and sodium carbonate but varies depending on the aspirator. I don't have a gauge that goes that low. But I
would guess I get below 7 kpa easily with ice water. It isn't enough for true vacuum work but is more than sufficient for most vacuum distillations.
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elementcollector1
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Hmm. Maybe I'll save up some money for that pump, then.
I've been trying to see if I can implement a needle valve to keep the vacuum in, and only use the aspirator periodically. However, the vacuum gauge
I've been using seems to have sprung a leak... Is there any convenient way to check for a vacuum present in a closed system without a gauge?
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beerwiz
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A) Can someone summarize which aspirator and which water pump you need to get down to 10 mmHG (10 Torr) or even lower? A water pump is convenient
because it won't consume 100's of Liters of water per hour like it would at the faucet.
B) Can you achieve 10 Torr vacuum pressure using tap water flow? What if the pressure is too low? How do you measure the pressure at the faucet?
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macckone
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10 mmHg is too low for water even with ice. However, that is achievable using a two stage system using steam or air as the lower pressure stage.
Hypothetically you could even use ambient air pressure as it will be at least 10 psi above the water aspirator pressure.
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blogfast25
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| Quote: Originally posted by macckone | | 10 mmHg is too low for water even with ice. However, that is achievable using a two stage system using steam or air as the lower pressure stage.
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Sure but it's little academic, no? What would a decent '10 mm Hg' vacuum pump cost?
I do wish we wouldn't mix up our measuring units when it comes to pressure: Torr, mm Hg, Pa, psi, bar, atm, 'over pressure', 'under pressure', grrr!
What's wrong with good old Pa? Absolute pressure in Pascal?
[Edited on 18-5-2015 by blogfast25]
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Dr.Bob
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| Quote: Originally posted by elementcollector1 | | I've been trying to see if I can implement a needle valve to keep the vacuum in, and only use the aspirator periodically. However, the vacuum gauge
I've been using seems to have sprung a leak... Is there any convenient way to check for a vacuum present in a closed system without a gauge?
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It is nearly impossible to keep any real vacuum in a "sealed" system at a consistent low pressure without keeping the vacuum source connected at all
times. I used to think the same think, pull a vacuum and then hold it in a system with a stopcock. But pretty much all systems leak, and most
chemicals and even solids outgas constantly at temperatures about LN2, so if you have any chemicals (any materials with mass: solid, liquid or gas) in
a system (Short of a glove box), they will contain some dissolved gases, as well as constantly wanting to evaporate due to the vacuum, so to get any
reliable vacuum, you need the vacuum "pump" to be constant, and then if you want a "weaker" vacuum, you simply bleed air (or an inert gas) into the
system between the experiment and and the vacuum pump.
The only place that I know where keeping a vacuum is easy is space, so the space station would be a great place to do a distillation. But even there,
they constantly loose air due to leaks, so they must keep bringing air there along with food and water.
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macckone
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| Quote: Originally posted by blogfast25 | | Quote: Originally posted by macckone | | 10 mmHg is too low for water even with ice. However, that is achievable using a two stage system using steam or air as the lower pressure stage.
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Sure but it's little academic, no? What would a decent '10 mm Hg' vacuum pump cost?
I do wish we wouldn't mix up our measuring units when it comes to pressure: Torr, mm Hg, Pa, psi, bar, atm, 'over pressure', 'under pressure', grrr!
What's wrong with good old Pa? Absolute pressure in Pascal?
[Edited on 18-5-2015 by blogfast25] |
A pump $200. One that can handle acids and organic will be more.
As for mixing unit, what would America be if we started using that french stuff?
To be fair science literature still doesn't use Pascal consistently.
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