Sciencemadness Discussion Board

water aspirator problem

exodia - 9-1-2017 at 13:29

Hi there, recently I bought a water aspirator to set up my vacuum, this one:
http://www.ebay.com/itm/Laboratory-Aspirator-Pump-Humboldt-V...

I¨ve just tried to set it up and doesn´t work, I´m nor teally sure why.

hooked it to my crappy cheapy (but enough for this and to feed my condenser, which is all I need now) aquarium mini pump

the pump rate is 1000 l per hour (at least it claims that)
max Height 1.5 meters

at first I though the pump was too weak, so I hooked it to my garden hose full blast, and still nothing.

just to see if the aspirator was working at all I sucked and aspirated myself (all brand new never used equipment, not even the fritted phunnel I was checking it with) and it worked

it was terrible (I suppose because my lungs can´t do anymore than that) but that´s proof it sort of works

so I don´t know what to try next.

PS: the suction port had a bit of plastic inside (allegedly the "anti-suckback" is easily removed, I left it of, put it in turned 180degree to see if it was faulty or made any difference) and nothing.

[Edited on 9-1-2017 by exodia]

[Edited on 9-1-2017 by exodia]

Maroboduus - 9-1-2017 at 15:03

The pump IS too weak. It doesn't supply the kind of pressure an aspirator needs by a long shot. Aspirators generally need around 7.5 to 9 PSI to work. At least all the ones I've found the specs for require that much pressure or more.

It should work on the hose, unless the hose is too weak too. 2 GPM at around 9 PSI is plenty for most of these aspirators, and most garden hoses will do that and much more.

These aspirators are so simple in construction that I have a hard time even imagining what the problem could be, but we have had reports here in the last year on that exact same model of aspirator doing just what you're reporting.

Try measuring the rate of flow out of the bottom of the aspirator. If you have a way to do it, try measuring the pressure in the water line just before the aspirator while the aspirator is running. This may tell us something helpful, but as I recall in the last incident reported with this model of Humboldt aspirator not working right the hose output and pressure were fine and the thing STILL didn't work.

I am beginning to suspect that there are quality control problems with that aspirator, and more than a few of them don't perform up to spec. It doesn't seem to be a very good aspirator anyway. 420 mm is pretty poor vacuum, really only suitable for filtering. (My Nalgene aspirator draws well over 700 mm of vacuum, and many other models on Amazon claim similar performance).

I see that the rating on that product is 2 stars, and it only has 1 rating. That could actually be one of the other members here who posted about that aspirator not working.

JJay - 9-1-2017 at 19:56

I'm not the one who posted on it previously, and I didn't review it either, but I have the same aspirator, and I can report that it does work with a garden hose or with a household sink with sufficient pressure and flow.

I remember having the same problem when I first purchased it, and I tried the same thing with the anti-suckback, which certainly does need to be in the right orientation. Sufficient pressure and flow was the issue; it requires a high-velocity stream to produce a good vacuum. You want to have well in excess of 15 PSI for a good vacuum with *any* water aspirator.



[Edited on 10-1-2017 by JJay]

Maroboduus - 9-1-2017 at 21:19

Quote: Originally posted by JJay  

You want to have well in excess of 15 PSI for a good vacuum with *any* water aspirator.



[Edited on 10-1-2017 by JJay]


It certainly is a pity that so many aspirator manufacturers publish specifications that contradict this statement.

Just for clarification; you do mean under operation at the appropriate flow rate as opposed to static pressure, right? Most 15PSI rated dynamic pumps will produce nowhere near that pressure with any reasonable flow rate, and even a faucet with a 15 PSI static pressure won't necessarily produce this at a decent flow rate in some cases.

exodia - 10-1-2017 at 06:26

thank you for the quick responses, at least I know it works so I´m less dissapointed, now I just need to get it going.

Unfortunately I dont have a manometer or any other way to measure the pressure, I did measure the litres per minute I can achieve.

my crappy water pump gets to 3 lpm (when connected, the aspirator outlet ejects water at 1,2 lpm)

my garden hose/outside sink at full throttle goes up to 8 lpm (outlet of the aspirator giving 3,8 lpm, wich is consistent to the previous 1,2, so around half the flow rate)

I´m not sure how much pressure can my hose build up but this aspirators are made for sinks, so I´d suppose my 8 lpm should be enough

JJay - 10-1-2017 at 06:47

Quote: Originally posted by Maroboduus  
Quote: Originally posted by JJay  

You want to have well in excess of 15 PSI for a good vacuum with *any* water aspirator.



[Edited on 10-1-2017 by JJay]


It certainly is a pity that so many aspirator manufacturers publish specifications that contradict this statement.

Just for clarification; you do mean under operation at the appropriate flow rate as opposed to static pressure, right? Most 15PSI rated dynamic pumps will produce nowhere near that pressure with any reasonable flow rate, and even a faucet with a 15 PSI static pressure won't necessarily produce this at a decent flow rate in some cases.


I mean with the water flowing... most residential faucets are 30-40 PSI.

Fulmen - 10-1-2017 at 07:32

Quote: Originally posted by exodia  
Unfortunately I dont have a manometer or any other way to measure the pressure

Sure you do, it's called a long hose. Just measure the height the pump can lift.

exodia - 10-1-2017 at 11:11

Thank you fumen, I knew I could do this to determine the pres sure (sort of) the only thing I cannot find is the equation to give the pressure units in relation to the heigth reached.
If you could tell me or point me in the direction of those equations I'll greatly apreciate it (im a bit more rusty theory wise than experimental wise.. and thats something I'm trying to improve)
I've been away from chemistry for a while and I'm craving for a bit of notebook scribbling.

Thank you for your responses

Maroboduus - 10-1-2017 at 12:15

Quote: Originally posted by JJay  
Quote: Originally posted by Maroboduus  
Quote: Originally posted by JJay  

You want to have well in excess of 15 PSI for a good vacuum with *any* water aspirator.



[Edited on 10-1-2017 by JJay]


It certainly is a pity that so many aspirator manufacturers publish specifications that contradict this statement.

Just for clarification; you do mean under operation at the appropriate flow rate as opposed to static pressure, right? Most 15PSI rated dynamic pumps will produce nowhere near that pressure with any reasonable flow rate, and even a faucet with a 15 PSI static pressure won't necessarily produce this at a decent flow rate in some cases.


I mean with the water flowing... most residential faucets are 30-40 PSI.


That's static pressure. I don't think you have *any* idea what you're talking about.

But fortunately for me, I really don't care anymore. So yes, YOU'RE right and the manufacturers of these devices are wrong. Congratulations!

I also wish you luck with that empty van that watches you from the street while it changes colors from grey to white. That sounds really disturbing.

















JJay - 10-1-2017 at 12:31

I know that's static pressure. Try to follow the flow of conversation.

Fulmen - 10-1-2017 at 12:41

In metric units it's simple: 1bar equals 10meters. That's 15PSI for every 30feet, or 1/2psi per feet.

Maroboduus - 11-1-2017 at 12:21

Quote: Originally posted by JJay  
I know that's static pressure. Try to follow the flow of conversation.


Your lack of communication skills seems to be as great as your lack of knowledge about aspirators. Which is obviously considerable by *any* standard.

There is no other obvious explanation for your quoting the standard static pressure in household plumbing since it was in no way germane to the discussion. No, the only possible explanation is that you lack *any* ability to "follow the flow of conversation". And by that I mean *any* conversation.

I strongly recommend that you Take *any* English courses that you can avail yourself of, and see if you can develop *any* further ability along these lines. Even learning basic punctuation would be helpful to *any* person in your situation.

Glad to hear that one of those two empty vehicles that were watching you has gone away. Pity it wasn't the one with the power to change colors.

JJay - 11-1-2017 at 12:40

Quote: Originally posted by Maroboduus  
Quote: Originally posted by JJay  
I know that's static pressure. Try to follow the flow of conversation.


Your lack of communication skills seems to be as great as your lack of knowledge about aspirators. Which is obviously considerable by *any* standard.

There is no other obvious explanation for your quoting the standard static pressure in household plumbing since it was in no way germane to the discussion. No, the only possible explanation is that you lack *any* ability to "follow the flow of conversation". And by that I mean *any* conversation.

I strongly recommend that you Take *any* English courses that you can avail yourself of, and see if you can develop *any* further ability along these lines. Even learning basic punctuation would be helpful to *any* person in your situation.

Glad to hear that one of those two empty vehicles that were watching you has gone away. Pity it wasn't the one with the power to change colors.



You, sir, are an obvious troll. Kindly do not bother me again.

Maroboduus - 11-1-2017 at 15:29

Quote: Originally posted by JJay  
Quote: Originally posted by Maroboduus  
Quote: Originally posted by JJay  
I know that's static pressure. Try to follow the flow of conversation.


Your lack of communication skills seems to be as great as your lack of knowledge about aspirators. Which is obviously considerable by *any* standard.

There is no other obvious explanation for your quoting the standard static pressure in household plumbing since it was in no way germane to the discussion. No, the only possible explanation is that you lack *any* ability to "follow the flow of conversation". And by that I mean *any* conversation.

I strongly recommend that you Take *any* English courses that you can avail yourself of, and see if you can develop *any* further ability along these lines. Even learning basic punctuation would be helpful to *any* person in your situation.

Glad to hear that one of those two empty vehicles that were watching you has gone away. Pity it wasn't the one with the power to change colors.



You, sir, are an obvious troll. Kindly do not bother me again.


Name calling isn't going to help your situation; just confirm to *any*one reading this that Your manners are every bit as faulty as your other faculties appear to be. And based on your posts here, that's pretty bad by *any* standard.

Your assertion that my posts here are for the purpose of "bothering you' shows you to either be a liar, or seriously ill. The extreme paranoia you show elsewhere on this board would tend to indicate the latter to *any* disinterested observer.

Perhaps you believe that I posted on this thread before you did as part of an insidious plan to 'bother you'. Or even that I changed the specifications of various aspirator manufacturer's products in order to 'bother you'. These are delusions.

People who labor under the handicaps you evidently suffer from CAN get help. It only requires your admitting to yourself that you have a problem, and going to a competent professional.

Whether you do or don't decide to get *any* of the help you appear to need, I would appreciate it if you desisted from *any*attempts at 'bothering' me by accusing me of 'bothering you'.

I would also appreciate it if you made at least a token effort to grow up and desist from *any* name calling. This would also be in your own self-interest for *any* number of reasons.

Texium - 11-1-2017 at 16:33

JJay, Maroboduus.

Both of you are intelligent, respectable members of this forum. It pains me to see you arguing with each other like this. Let's try to get along being as I already have enough crap to clean up from actual trolls, kewls, and meth cooks, and I don't need to add flame wars between legitimate members to that list. I'm locking the thread since the question appears to have been answered sufficiently. Please do not resume this argument anywhere else.