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Author: Subject: Vacuum aspirator using DMSO
Keras
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[*] posted on 25-6-2019 at 00:15
Vacuum aspirator using DMSO


According to the Gaylord corp's technical bulletin, DMSO has a rt vapour pressure of circa .5 mm Hg, or around 70 Pa, vs 3.2 kPa for water.

Did anyone ever attempt to pull a vacuum using DMSO and an aspirator?

[Edited on 25-6-2019 by Keras]

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Pumukli
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[*] posted on 25-6-2019 at 02:44


I had the same (very similar) idea months ago: why not use ethylene-glycole in a recirculating aspirator system?
Glycol is fairly cheap and has much lower vapour pressure than water (at least it should have, I didn't bothered to check).

Problems I see:
- price of the working fluid (DMSO is not that cheap)
- if it absorbs water then the achievable vacuum will eventually deteriorate
- these fluids has much higher viscosity than water, it may cause problems with the pump

Anyway, my feeling is if it worked we already had seen completed projects, working units in commerce. Do you know such system? I don't. So there's obviously a stumbling block somewhere what we don't see yet.
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Keras
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[*] posted on 25-6-2019 at 03:19


I agree for the viscosity. In fact, just after the graph plotting partial pressure vs temperature, there's a viscosity graph, too. But I have no idea how viscosity units translate into the real world, i.e. what is viscous vs. what is not.
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Tsjerk
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[*] posted on 25-6-2019 at 05:31


Fractionated diesel fuel?
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walruslover69
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[*] posted on 25-6-2019 at 08:11


diesel and Kerosene would probably make good candidates due to their relatively low viscosity. I think you will definitely need a efficient solvent trap to prevent whatever you are pumping off from mixing with the working fluid. I imagine DMSO could also be very hard or incompatible with the seals on common pumps.
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Sulaiman
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[*] posted on 25-6-2019 at 09:19


Vacuum pump oil ?



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DavidJR
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[*] posted on 25-6-2019 at 10:24


DMSO sounds like a great way to end up with a big vat of contact poison
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[*] posted on 25-6-2019 at 12:46


DMSO is not that toxic, is it?

I agree kerosene could be a better idea, but it is flammable…



[Edited on 25-6-2019 by Keras]
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Metacelsus
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[*] posted on 25-6-2019 at 12:57


Quote: Originally posted by Keras  
DMSO is not that toxic, is it?


No; in fact I regularly use 10% DMSO as a cryopreservative for cells, which handle it just fine.

However, DMSO solutions, along with any solutes, are easily absorbed by skin contact. So if anything toxic is dissolved, it would be dangerous.

[Edited on 2019-6-25 by Metacelsus]




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[*] posted on 25-6-2019 at 13:46


Quote: Originally posted by walruslover69  
diesel and Kerosene would probably make good candidates due to their relatively low viscosity. I think you will definitely need a efficient solvent trap to prevent whatever you are pumping off from mixing with the working fluid. I imagine DMSO could also be very hard or incompatible with the seals on common pumps.

If you need to use a cold trap why the hassle of using a water pump? HVAC rotary vane vacuum pumps can be bought now for less than $60 on Ebay, and to use them you need a trap. The point of using a water aspirator (in my opinion) is to not have to worry about a trap, at the end if the water is too contaminated, just change it, it's not as expensive as a vacuum oil change.





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[*] posted on 25-6-2019 at 14:32


Ignoring all the hassle of using DMSO, just assuming you'd need a minimum of a couple of liters of dmso to fill the system I really can't see how it'd be less expensive than buying a vacuum pump.
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[*] posted on 25-6-2019 at 18:49


I like the vacuum pump oil suggestion, but there's always Lucas DOT 4 brake fluid too.

Vapor pressure 10 Pa, boiling point 232 C. 121 C flashpoint.


But if you're really after low pressure and damn the consequences, how a bout a garbage can full of mercury?
(hope you've got a strong floor)




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[*] posted on 25-6-2019 at 22:23


For all the emphasis I see on scimad (and elsewhere) regarding ultimate vacuum, I would hope to see even more focus on preventing and eliminating vacuum leaks.


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[*] posted on 26-6-2019 at 00:06


BTW do you have any idea of the vacuum that a common, run-of-the-mill vacuum cleaner can pull?
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[*] posted on 26-6-2019 at 00:19


Just a few inches of mercury

They move a lot of air though

[Edited on 6-26-2019 by happyfooddance]
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[*] posted on 26-6-2019 at 00:24


about 1/5 th pressure reduction, -20kPa relative to atmospheric, +80kPa absolute.
O.K. for vacuum assisted filtration but probably not much else in the lab other than its intended purpose..


A £10 dc motor vacuum pump pulls about -80 kPa (20kPa abs.)
A £40 HVAC vacuum pump can achieve about 10 Pa abs.
My £85 dual-stage rotary gets down to below 1 Pa ... if you believe the specs.
Peristaltic pumps, hand-operated (brake bleed) vacuum pumps etc. are also viable options.

If you have mercury then a Sprengel pump may be viable
(Cody's Lab has a video on YT)




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[*] posted on 26-6-2019 at 11:36


The reason I was asking is that I bought those space saving bags you can put duvets into. Once it’s done, you suck the air out using a simple vacuum cleaner and you get something not only pretty squeezed (packed up, takes less space), but also that looks as if there’s hardly any air left inside.

[Edited on 26-6-2019 by Keras]
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[*] posted on 26-6-2019 at 11:49


Quote: Originally posted by Keras  
The reason I was asking is that I bought those space saving bags you can put duvets into. Once it’s done, you suck the air out using a simple vacuum cleaner and you get something not only pretty squeezed (packed up, takes less space), but also that looks as if there’s hardly any air left inside.

[Edited on 26-6-2019 by Keras]


you could do it even by sucking air with your mouth (on a small bagbif you don't want to get light headed). 1 atm = 14 psi, so even if you can create a vacuum of half a atmosphere every squared inch of those bags feels a weight of 7 pounds, you can see why the get so flat :D





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[*] posted on 26-6-2019 at 17:31


What Ubya said.

You can pull a better vacuum with your lungs (I've been doing it with ziplocks of cheese for damn near 30 yrs).

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[*] posted on 26-6-2019 at 18:05


sucking 'cheese-air' sounds ok ... sucking 'duvet-air' sounds less appealing
(mites and their shit etc.)

one thing to be aware of with vacuum storage bags,
they are not hermetically sealed, air slowly leaks in,
then the contents try to resume their natural volume.




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[*] posted on 26-6-2019 at 18:11


Also, what Sulaiman said
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[*] posted on 27-6-2019 at 01:00


Hah. I remember bringing back munster from Alsace. It'd better be carried in a vacuum pack, because otherwise I would've been kicked out of the carriage!

Ok, thanks for all your answers! :)

[Edited on 27-6-2019 by Keras]
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