LuckyWinner
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What Pump to Use for your Water Aspirator?
got a high quality plastic water aspirator but can only boil water at 39C at 30C water temp.
cooling the water does not do much.
the aspirator is inside a bucket and gets fed by a fuel pump 60PSI 12V , good quality, not from china.
tried a direct connection to a high pressure water faucet and did not get any better of a vacuum...
question... what pump do I need to use for my water aspirator to pull a 20mmhg vacuum or better.
the instructions on my aspirator say a <16mbar vacuum is possible.
tell me pls flow rate/psi/... anything , cant find anything online...
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Sulaiman
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There have been a few discussions on this topic,
the SM search engine is poor,
e.g. In your Google search field enter this text
site:sciencemadness.org water aspirator pump
CAUTION : Hobby Chemist, not Professional or even Amateur
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Swinfi2
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I'm thinking of doing this as it sucks to have the aspirator backflow every time someone flushes the toilet... I was going to get a 100psi pump like
(can't remember who) one of the chem youtubers said.
I'm thinking of putting MEG (mono ethylene glycol) through it as it seems to have a good vapour pressure but I'm not sure it's the best, maybe
something higher boiling?
I think to get the really low vacuum you need a good combination of factors and to be extra careful for leaks.
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LuckyWinner
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chem youtubers name is NurdRage, I saw the video and already read a lot of threats here but
there is no clear conclusions.
anyone have real life experience with a good pump to use?
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Waffles SS
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NurdeRage used: DC 12V 115Psi High Pressure Diaphragm Water Pump 5Lpm
And i used:DC 12V 160Psi High Pressure Diaphragm Water Pump 100W 8L/min (more powerful pump than Nurdrage pump)
By Kartell Aspirator i got 30mmhg pressure.
But there is cheaper and better option:
https://www.youtube.com/watch?v=2nQBoQ3HucM
Plastic part made by 3dprinter and i connect it to my aspirator.
I think using mixture of MEG and water has better effect on pressure.
[Edited on 21-2-2019 by Waffles SS]
Chemistry = Chem + is + Try
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LuckyWinner
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thanks but I need around 20mmHg or better.
can you tell me what specs are needed to get this 20mmHg with 30C celsius water?
and what is your water temp for your 30mmHg?
[Edited on 21-2-2019 by LuckyWinner]
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Waffles SS
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If you cool your water to around 10c then you will get less than 20mmhg according to kartell datasheet.(your water pressure should be 0.65atm at last)
 
Also i have another complete chineese circulating vacuum pump that reach 10mmhg if i cool water around 8c.
Dont forget to find your city elevation (height from sea) to calculate correct vacuum pressure.
[Edited on 21-2-2019 by Waffles SS]
Chemistry = Chem + is + Try
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LuckyWinner
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thanks
but waffen SS, can you tell me if a higher psi and flow rate will equal in a higher vacuum or is there a limit?
what water temperature do you have with your 160PSI pump at 30mmHg?
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zed
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Geeze. The aspirator utilizes the venturi effect. The water rushing through the aspirator entraps air, pulling it into itself and "flushing" it
away. Thereby the pump creates a relative vacuum.
Because the flowing water itself, begins to boil at a modest level of vacuum, it loses its mojo... And its further ability
to increase the vacuum.
That being said; a high volume, of fast moving chilled water, passing though the aspirator, should maximize aspirator performance. And, ease of
hook-up, to standard plumbing, would be a plus.
As such, I am considering ditching the exotic water pump I have been using, and going with something more standard. Standard to the USA, that is.
Harbor Freight sells a 12 volt DC transfer pump, also available in 120 AC. Might do the trick. Since it is right down the road from me, if I don't
like it, I can just take it back. No questions asked. About 50 bucks, with a coupon 20-25% less.
Hooks up to standard garden hose. I think.
The link doesn't work well, but it will take you close.
https://www.harborfreight.com/12-volt-dc-transfer-pump
https://www.youtube.com/watch?v=3NOggDRivK8
The pump Nurdrage uses, will pump about a gallon of water per minute.
The Harbor Freight pump, will pump approximately 4-5 gallons per minute.
I can simply attach a length of Garden hose to the output, and slip the aspirator pump, onto the hose.
I have tried making regular plumbing connections, but there is no world wide standard. I spent an afternoon at a well stocked plumbing section,
trying to find threaded connectors. Nope! No way.
My imported stuff just doesn't fit together, and it doesn't fit together with anything I can buy.....Incompatible dimensions and Thread types.
Wishing to avoid a Rube Goldberg type set-up, I tried machining new treads into my Stainless steel aspirator pump, and it destroyed my tap. Grrrr.
Time to build the machine with alternate parts! Life is too short.
https://wonderopolis.org/wonder/what-is-a-rube-goldberg-mach...
[Edited on 22-2-2019 by zed]
[Edited on 22-2-2019 by zed]
[Edited on 22-2-2019 by zed]
[Edited on 22-2-2019 by zed]
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morganbw
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Dang @zed, it would have been easier for my simple mind to know what you have and what you are thinking of.
Anyway, glad you have a plan.
edit: dang-it, you edited and gave more info during the time I was hitting the enter button. No worries sir.
[Edited on 2/22/2019 by morganbw]
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zed
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Gotta do that. This engine doesn't seem to allow leaving during mid-composition, and returning with a link.
You click to elsewhere, without posting, and your work is erased.
So.... I often make a vapid posting, then edit-in the vital stuff.
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morganbw
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I actually bought a pump similar to NurdRages pump.
Mine has Asian DNA.
I have had it for more than a month and I believe that if I can figure out how to plumb it that would prove some intelligence from me.
Time will tell but the outlook looks dim as of now.
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LuckyWinner
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good to hear other people break a lot of things in this hobby ^^
such a pain in the a** to get things working sometimes.
the harbor freight pump has a couple bad reviews, many people complains it gets VERY HOT
and breaks fast...
is there any data on the increased vacuum if you use a stronger PSI / gallons per hour pump?
is there a limit to the standart water aspirator, at what pump strenght?
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LuckyWinner
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some pumps have no PSI rating.
would a water submerged pond pump like this work well with a water aspirator ?
if not whats the limit in HP, W and L/min ?
167 l/min
500 W
0,67 HP
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Sulaiman
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I have no experience with aspirator vacuum pumps but -
Quote: Originally posted by LuckyWinner  | got a high quality plastic water aspirator but can only boil water at 39C at 30C water temp.
cooling the water does not do much.
.....
question... what pump do I need to use for my water aspirator to pull a 20mmhg vacuum or better.
..... |
If 30oC water gives a 39oC vacuum
then 4oC water should give about 13oC vacuum
i.e. your water for the aspirator is too hot.
With a recirculating water pump powering the aspirator,
almost all of the pump power goes to heating the recirculating water,
so not only will you have to initially cool down your water,
you will need to keep cooling it during operation.
__________________________________________________________
Like millions of UK residents I pay a fixed monthly fee for mains water,
irrespective of how much water I actually use (no water meter),
so a continuous flow of water through an aspirator (or condensers etc.) is effectively 'free' for me,
but I consider that to be wasteful / non-environmentally-friendly,
so I use electric vacuum pumps (and re-circulating condenser water)
My work-horse vacuum (reduced pressure) pump is for filtrations,
- a £12 '-80kPa' 12V piston pump. . excellent (if you have a 12Vdc supply)
My rarely used pump is a
- Chinese HVAC dual-stage rotary-vane oil-sealed vacuum pump.
I have not found this pump very useful because;
- as the most expensive single purchase for my chemistry hobby I don't want to kill it
- to protect it I would need cryogenic cooling
- at minimum pressure I would also require cryogenic coolers for the condensers
But if I add a variable air leak bubbler I can achieve usable pressures.
I suspect that if you consider all of the costs of a recirculating water aspirator
(aspirator, water pump, (water pump power supply), water reservoir, plumbing, water cooling (ice or refrigeration) etc.)
and consider that one of the main benefits of a water aspirator is lost in a recirculating system,
(the ability to handle noxious/toxic/corrosive gasses and remove them from your environment)
and the set-up and put-away times,
a cheaper single-stage rotary-vane vacuum pump may be a better choice than a recirculating aspirator ?
_____
P.S. after posting the above I re-tested one of my peristaltic pumps;
the pressure stopped dropping at about -98 kPa relative (2kPa (c15 mmHg) absolute),
(measured with a cheap Bourdon gauge near the bottom of its range, so not very accurate)
presumably because water droplets (from existing condensation in the tubing) were evaporating as fast as the pump could pump.
So if you are EXTREMELY patient, have no air leaks, and can condense anything evaporated,
then a peristaltic pump is capable of the pressures that you desire.
So, I doubt that a peristaltic pump would meet your needs.
(at least that's one option eliminated for you) 
_____
P.P.S. I am also suspicious of the longevity of a plastic nozzle with high flow rate high pressure water.
Could anyone with long term experience of using a plastic aspirator comment please ?
_____
P.P.P.S. for reduced pressure distillations (or filtrations) a vacuum pump has two requirements ;
Initial pump-down - removal of the bulk of the enclosed gas(ses)
here a high flowrate pump is appreciated
Pressure regulation - maintaining the required operating pressure
in theory the pump only has to handle intentional and un-intentional air leaks.
If air leakage is relatively low then the vacuum pump can be rested (stopped) for the majority of the operating time.
A large suck-back trap also acts as a 'vacuum reservoir' allowing even longer times between active pumping periods.
[Edited on 22-2-2019 by Sulaiman]
[Edited on 22-2-2019 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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LuckyWinner
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i cooled my water down to 5C in my water aspirator cycle bucket and strangely the water did not start boiling after 20min of running the aspirator...
there must be something wrong...
I wonder if you can get a better vacuum with 'hot' 30C water temperature if you use a stronger pump?
avoid the water cooling by shooting more water through the aspirator.
cause water heats up fast...
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zed
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Um. Well, I live in Portland, Oregon.... where we have a bountiful supply of the cleanest, most delicious water on the planet. Snow covered
mountains and volcanos, glaciers, and mighty rivers abound. Heap big medicine!
But water? Water isn't cheap! Not cheap at all! Not when you total all the numbers.
Our water bills, are tied to our sewer bills. Yup! We pay a huge fee for processing sewage water, based on home water use. They even charge us for
the run-off of rainwater from our roofs.
So, the minimal water fee is about 50bucks/month per person. While, regular cautious use, usually results in a fee of about $100/month/person. And,
extravagant use (like regularly running an aspirator directly on a faucet) would surely result in bills of multiple hundreds of extra dollars per
month.
If you aren't running a cartel drug lab, or you aren't stealing water somehow.... You have to find a way to recycle your lab water.
Trust me, I long for the luxuries of yesteryear. When I unthinkingly, wasted an extravagent quantity of water, with no financial repercussions.
Ahhhh. Ignorance really WAS bliss. Easier to plumb too!
[Edited on 27-2-2019 by zed]
[Edited on 27-2-2019 by zed]
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