Sciencemadness Discussion Board - Advice on Pond Pump for aspirator setup?

Advice on Pond Pump for aspirator setup?

iodide - 8-7-2005 at 15:11

There are several, well-priced pond/aquarium pumps on ebay, offering in excess of 400 gallons per hour ("GPH"

. Lacking a conversion ratio, I am at a loss as to how to determine what GPH rating would be best suited to allow for a relatively strong vacuum in connection with a nalgene aspirator.

Do any of you know - either from experience or through the use of a formula - what would be an appropriate rating?

chemoleo - 8-7-2005 at 17:01

The transfer rate per hour does not necessarily relate to the ability to create a vacuum, at all.
Take a fan for instance. Great ability to move air, but impotent on creating a vacuum. Admittedly an aqu. pump is likely to have a diff. design, nonetheless it isnt designed for vacuum, so I wouldnt place much trust into it.

A peristaltic pump is likely to be more effiicient, and relatively easily to make at home.

Oxydro - 8-7-2005 at 19:46

I think he means, use the pump to force water through an aspirator to create the vacuum that way.

So, basically, the question is, how many gallons an hour at what pressure does it take to drive an aspirator effectively.

And the answer is, I don't know. But I think I figured out the question anyway.

Ah.... the pump on this page takes 1 gpm (60gph) to operate. but this is at 35 psi, which iirc translates to >80 feet of head for a fountain, so not what the typical pump is designed to handle.

Big Dick pumps

Lambda - 8-7-2005 at 19:52

Sorry about this, but these pumps are good

How natural penis enlargement programs work:
http://www.veseliba.info/enlargement/page-penis-pump.html

I found this link on the same page to be of a more chemistry addaptive nature:
http://www.veseliba.info/enlargement/go.php?http://www.1-in-...

Refrigerator motor vacuum pumps (good vacuum, but susceptible to corrosive gasses)

Concerning Homemade Vacuum Pumps:
http://www.sas.org/E-Bulletin/2003-08-01/labNotesAS/body.htm...

A Homemade Vacuum Bagging System:
http://www.badger.rchomepage.com/vacbag.html

These are good, they can take nearly everything that is corrosive (vacuum depends on water temperature)

Water jet vacuum pump or aspirator (two designs):
http://www.frogfot.com/misc/waterjetvac.html

[Edited on 10-7-2005 by Lambda]

Not sure I understand, Oxydro...

iodide - 8-7-2005 at 21:52

"Ah.... the pump on this page takes 1 gpm (60gph) to operate. but this is at 35 psi, which iirc translates to >80 feet of head for a fountain, so not what the typical pump is designed to handle."

So, if the pumps on ebay are rated at a couple hundred gph, this should be an excellent match for a water aspirator as it will create an excellent vacuum, right?

unionised - 9-7-2005 at 02:37

You need to know the maximum back pressure that the pump will handle. Since the aspirator needs about 80 feet and the best I have seen for garden water pumps is about 10 feet it won't work.

Oxydro - 9-7-2005 at 08:01

Now, the funny thing is, I just basically made a wild-ass guess on the 80ft. I knew there were about 30-odd ft to 1 bar (14.7psi) so I figured I'd be in the right ballpark.

Now, time to calculate:

A ft^3 of water is 62.5lbs. A ft^2 is 12*12=144 in^2.

so feet/psi = 144/62.5=2.30.

35*2.30 = 80.64. ft of head-equivalent needed by the aspirator for full vaccuum.

I am good. Scratch an "o", I am God.

LMAO

What you need is a pump designed for household water supply. Either that or attach a bunch of the pond pumps in series

.

Or, I suppose if you can't afford this, you could stoop to a lower level and run them off the tap like everyone else does

Blind Angel - 9-7-2005 at 09:19

Oxydro: I'm here to convert you to metric system.

Repent yourself demon, the old english system time is resolve, doom is near for those who still use it. Embrace the path of light, meter and grams. Forget your old sinfull way of calculation in variable base, turn yourself to the decimal system.

P.S.: I found an old pump for astmatic in my wardrobe (like the one used in hospital) i'll have to check how much it can suck though but it seem to work, slowly but surely.

12AX7 - 9-7-2005 at 12:57

I said it before on the same subject...

Screw the French.

Tim

Oxydro - 10-7-2005 at 00:49

12AX7:
I do [screw the French].

(my girlfriend is Acadian)

He [Blind Angel] probably does too.

(he's a Quebecer)

As for metric, I quote myself:

Quote:

I think that Imperial should definitely be eliminated. But that's hypocritical - I use it myself far too often. I am trying to improve though

unionised - 10-7-2005 at 06:55

Ho Hum, It seems that in a desperate attemt to be xenophobic you kind of missed the point that you need 2 numbers (at least) to specify a pump.

Rather more tellingly, not one of you used the correct units for pressure (Pa) or flow rate (M^3/s).

Scientific Units

gorilla - 15-7-2005 at 15:11

This is called 'Science Madness': we should all be scientific units, right?

Scientific units means SI. Look it up. Don't post crap.

A typical aspirator requires 12 Litres / minute at 150 KPa. Work it out. That's around 3 gallons per minute at 1.5 bar. Most pond pumps won't generate the pressure.

unionised - 17-7-2005 at 01:36

Litres/ minute isn't an SI unit, on the other hand, it's a bit more practical than cubic metres/ second. (Equivalent to 60 tons of water/minute)

bio2 - 23-7-2005 at 16:21

........what GPH rating would be best suited to allow for a relatively strong vacuum in connection with a nalgene aspirator.........

Nalgene has the specs on their website for this polypropylene aspirator which works very well.

I don't think you will find a pond pump up to the job. I use a 1/4hp pump rated at thier specs near shutoff on the pump curve. Pulls 12mm with cold water no problem. This aspirator takes less pressure than any other I've seen. The capacity is a little low but sufficient for a 6-10 liter setup just takes a while to pull down.

demax - 30-7-2005 at 19:31

Hey Bio2,

just had a look see at the nalgene page and cant find the graph referred to.

Demax is wanting to put together an efficient hydro aspiration system and would love some ideas on putting together a simple rig. UTSE but sought of get the impression that some are going about this the hard way.

Demax has some of his own ideas about this but if peeps are having good results then would love the hear about them.

take it to,

demax

arche - 30-7-2005 at 22:20

See how this works for you.

Attachment: aspirator.html (4kB)
This file has been downloaded 1063 times

bio2 - 30-7-2005 at 22:31

I think I used 25 or 30PSI at their flow rate to size the pump. Pump only draws 2.3amps@120v and is a water pump used for house pressure from a storage tank. Since the flow is very little to maximize efficiency and minimize the NOISE choose the pressure to be near the pumps shut off head. Plumbed to a 3gallon cooler it does a good job and only needs a trickle of fresh water if you will be running it for a long time.

Nalgenes 7.5PSI statement is mainly for filtering use, not to attain the maximum stated vacuum. Take out the shitty flapper check valve as it will surely fail and only after you start to rely on it.

6140 Vacuum Pump, Aspirator

Materials:
polypropylene
polyethylene tubing

Attaches to faucet for maximum free air pumping capacity of 11.5 liters per minute at a water flow rate of 6.5 liters per minute. Operates efficiently with water pressures as low as 7.5 psig (.517 bar) for minimum water consumption. Ultimate vacuum: 28-1/2 in. (723.9 mm) Hg. Supplied with integral check valve, 3/8-in. NPT connecting thread, and 4-3/4-in. length of tubing for insertion in discharge end.

demax - 31-7-2005 at 19:21

Thanks for the replies. I have a couple of questions though?

If one is using a 1/3 or even 1/2 horsepower pump is this not going to be to strong for the aspirator, that is is the engine going to be overworked because it is beng asked to pump to much water through something as small as the aspirator?

The system designed by polythenesam looks quite nice and simple to construct any thoughts on how much vacuum something like this would pull. Motor only looks to be small from memory.

These 30-40 psi pumps would pull how much vacuum? Looking for something real low ;-)

take it to,

demax

[Edited on 1-8-2005 by demax]

demax - 4-8-2005 at 01:57

Demax has found two pumps for his aspirator rig and is hoping someone can judge their worth. The specs for pump:

A) Motor Output: .77HP or .58 KW
Motor Input: 1.1256 HP or .84 KW
Max Total Head: 28 M or 91.8 ft

B) Motor Output: .71 Hp 0r .53 KW
Motor Input: .99 Hp 0r .74 KW
Max Total Head: 37 M 0r 121.3 ft

Calculation of the Psi:

A) 91.8 x .4335 = 39.79 psi

B) 121.3 x .4335 = 52.58 psi

Are these pumps to powerful for an aspirator setup. The seem to sort of fall within the specs as provided by Arche. My preference is for Pump B simply because it is quieter than pump A but will be guided by others.

Thanks

take it to,

demax

[Edited on 4-8-2005 by demax]

[Edited on 4-8-2005 by demax]

Tacho - 4-8-2005 at 03:39

0,71HP?

I used a 0,25HP pump and used 2 aspirators in parallel, because there was too much pressure. 37 meters head is like having a reservoir at the top of a 13 floors building. Any leak in your pipework will squirsh water to the next block. Your tubes will have to be very tightly fit.

If I had to buy another pump, I would buy one fully built in plastic. I had problems with rust that made my pump get stuck a few times.

Let me quote HRH_Prince_Charles that made excellent posts about aspirators and pumps in the homebrew aspirator thread.:

"The thing that governs the limiting pressure of the water-jet pump is the velocity of the water jet"

"The typical pumping speed of a lab. water-jet pump is 67 ml/s or 0.15 cfm"

"That 1/4 hp pump sounds almost perfect Tacho. I've looked everywhere, and the best I could get was a 370 W model. It does give 25 L/min at 15 m head, so I could run a pair of water jet pumps. "

"A typical water-jet pump only requires around 30 W of power to run! (calculate from pressure drop x flowrate). However, a typical pump is only 20% efficient at driving the water - the other 80% goes into heating the water in the pump. So, to get 30 W of water power for the water jet, you need a pump of

100/20 x 30 W = 150 W (0.2 HP)"

"Note also that the maximum head for a pump is at zero flowrate. In use, the head will be lower. My pump is 35 m max. head but only 15 m head at 25 L/min. "

You should read that thread carefully again before buying a pump.

bio2 - 4-8-2005 at 22:47

Demax;

These pumps for most aspirators are definetly overkill. The cost to run and the noise would be much more than a 1/4 or 1/3 HP which is plenty depending on the aspirators specs.

There is a large difference in aspirators and for best operation the pump should be matched. For most any normal lab use the smaller flow, lower water pressure types are fine.

.....Motor Input: 1.1256 HP or .84 KW...

During a 10 or 12 hour distillation you will be sorry you have this monster neverminding the electricity cost. I run mine even a couple days on the dessicator at times and have it under the house about 10 feet away.

.....Max Total Head: 28 M or 91.8 ft......

As was mentioned this is at shutoff! The pressure at the required flow is all that is meaningful. The reason I mentioned to choose one near shutoff is because a centrifugal pump draws the least current at the 0 flow condition and for the pressure needed with an aspirator which has very little relative flow compared to what these types of pumps are designed for the operation point will be near the shutoff anyway.

The Nalgene plastic one works great at 25PSI 1.5 GPM and some larger metal ones require 60PSI and a lot more flow. Do NOT get a metal aspirator they corrode quiclkly. I had a nickel plated one that lasted maybe 6 hours pumping formic acid fumes!

An all plastic head, magnetic drive pump is the best choice. March and Little Giant companies are two that are very popular.

demax - 8-5-2007 at 03:01

Ok i am confused by all this talk of psi etc when it comes to selecting a pump for a water aspirator.

This aside i have a Nalgene aspirator that claims it will acheive its maximum free air pumping capacity at a water flow rate of 6.5 L per minute.

Thus if 6.5 L per minute is flowing through this device it will be operating at its or near full potential?

Today i found a fountain/pond pump that at 1 meter of head will pump water at 16 L per minute.

I plan on placing the aspirator about 75 cms vertically above this pump and oh about 50cms horizontally out from the pump.

This pump has a power output of 240V.

Do you guys think a unit like this will be strong enough?

Thanks

Eclectic - 8-5-2007 at 06:14

No, it won't have enough pressure to drive the aspirator. You need a soda fountain type pump that can produce 35-80 psi of pressure (at least 25 meters head) at 1.5-3 gallons per minute. (6-12 L/min).

PainKilla - 8-5-2007 at 06:39

Shurflo pumps work great, and are available cheaply on ebay.

http://motors.search.ebay.com/shurflo_W0QQfromZR40QQpqryZshu...

The 30psi works wonderfully, though I prefer traditional vacuum pumps (rotary vane-oil etc... they cost about the same, and create much better vacuums).

[Edited on 8-5-2007 by PainKilla]

aspirator.JPG - 57kB

bio2 - 8-5-2007 at 08:11

These Sureflow rubber impeller type pressure pumps are not intended for continuos duty of hour after hour and under the best of conditions the flexible impeller won't last long even not
taking into account the effect of various solvent vapors.

These pumps are also positive displacement hence the pressure
switch mounted to the head. Also they are noisy as hell!

The primary use of this type of pump is water transfer and
bath/shower intermittent use.

PainKilla - 8-5-2007 at 11:03

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]

bio2 - 8-5-2007 at 12:38

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 .

Boomer - 9-5-2007 at 07:43

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.

elementcollector1 - 16-5-2015 at 13:14

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?

Magpie - 16-5-2015 at 14:41

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.

blogfast25 - 16-5-2015 at 14:57

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.

elementcollector1 - 17-5-2015 at 06:59

Heh. I meant by forcing the water through an aspirator, but that works too.
Hey, I'll take a caravan!

blogfast25 - 17-5-2015 at 08:57

Quote: Originally posted by elementcollector1

Heh. I meant by forcing the water through an aspirator, but that works too.

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]

macckone - 17-5-2015 at 09:26

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.

smaerd - 17-5-2015 at 09:32

Macckone - Have you measured what kind of vacuum you can pull with that thing? Thats a really affordable option.

blogfast25 - 17-5-2015 at 10:34

Quote: Originally posted by macckone

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.

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]

smaerd - 17-5-2015 at 11:19

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.

macckone - 17-5-2015 at 12:56

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.

elementcollector1 - 17-5-2015 at 19:26

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?

beerwiz - 17-5-2015 at 23:01

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?

macckone - 18-5-2015 at 07:03

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.

blogfast25 - 18-5-2015 at 08:03

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.

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]

Dr.Bob - 18-5-2015 at 09:23

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?

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.

macckone - 18-5-2015 at 20:36

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.

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.