Sciencemadness Discussion Board

My vacuum pump

Vosoryx - 21-11-2017 at 22:44

Just finished making an aspirator vacuum pump, and thought I could put it up here for suggestions/criticism and as a source if anyone else wants to build one.

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The aspirator and the pump were both bought online. (Ebay) the shipping was fast, and in both cases free.
The aspirator is from Deschem, and the pump is a 100 PSI (6.8 ATM) 12VDC at 3 amps max draw.
It is powered from a supply I found at the local thrift store in the electronics section, exactly 12VDC 3 amp. The connections from the motor were soldered onto the stripped ends of the power supply. I didn't put a switch in line.
In order to get from the water pump to the aspirator, you can see quite a few converters were used. These were all very cheap for me, having most of the scrap lying around. Once on the aspirator, the vacuum must go through a valve. I installed this after various problems with water sucking into the vacuum hose - Deschem's one way valve on the aspirator sucks. (Puns!)
It should only ever be open when the pump is on, and I need the vacuum applied. Otherwise, the vacuum tube fills with water, ruining the vacuum or potentially interfering with experiments.
It is all mounted inside a plastic bucket I found in a scrap pile on the side of the road. As you can see, the bucked wasn't quite wide enough, so I had to drill two holes in it to get the output hose through. I actually like this though, as I can remove the hose if I need to. The hose loops around in the water in the bucket, and is sucked up by the pipe on the right, feeding into the pump. I also crimped a piece of door screen to the bottom of the pipe leading into the pump, just to act as a filter to get rid of some of the potential solid unwanted bits in the water that might influence the performance of the pump.
I ran I test on it involving vacuum filtration, which worked very well. (I simply created a suspension involving cornstarch and water and filtered it and dried it on the pump on my glass frit.)
It worked quite well, and I am pleased to use it in the future. It is not even close to being as strong a pull as even an expensive shop vac, but it can be run continuously, unlike simple vac cleaners. I also haven't tried it with ice water, just tap water.

I know the pictures suck, they are taken in my bathroom, not my lab.

Thoughts? Opinions?

XeonTheMGPony - 22-11-2017 at 12:42

Well for doing stuff that will gas off, put a lid on with a fan to vent out side you'd have a solid unit!

zed - 22-11-2017 at 14:27

Well, I never would have thought of doing it that way.

Thank you!

aga - 22-11-2017 at 14:53

Superb !

Great to see people Doing things in amateur chemistry.

I'm slightly confused tho.

Is it a venturi type aspirator that works by water flowing through it, augmented by having a water pump to suck water through it faster ?

XeonTheMGPony - 22-11-2017 at 15:26

Pump > Aspirator > Bucket

you're converting pressure to velocity, and that high speed jet stream of water that draws in the gasses to pull vacuum.

[Edited on 22-11-2017 by XeonTheMGPony]

Vosoryx - 22-11-2017 at 16:33

Quote: Originally posted by XeonTheMGPony  
Well for doing stuff that will gas off, put a lid on with a fan to vent out side you'd have a solid unit!


Thought about that, but due to the 3 meter tube and the fact that I wouldn't have it cycle if it were something that could damage the pump I decided against it. The length enables me to put it outside my lab for long refluxes and distillation, which I would do anyway due to the noise.
I couldn't really think of any applications where that would be practical - acids i wouldn't recirc, neither bases or organic solvents for fear of damaging the pump/aspirator/tubing/connectors. What does that reasonably leave?

Quote: Originally posted by aga  
...Is it a venturi type aspirator that works by water flowing through it, augmented by having a water pump to suck water through it faster ?


Yes, it is a venturi aspirator. I'm not sure what you mean by "augmented by having a water pump" - How else is the water going to pump through the aspirator?
Some people attach these directly to their faucet, but i'm not because the water pressure at my house is... Barely existent. Higher pressure means a better vacuum.
The water, as Xeon said, goes up into the pump from the water bucket on the right, through the pump and into the aspirator, then back into the bucket on the left.

Bert - 22-11-2017 at 18:55

Bernoulli effect/Venturi effect... patata, potato.

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Suction or Vacuum Power- Bernoulli

Ubya - 25-11-2017 at 16:23

just today i finished my vacuum system, just like yours it uses an aspirator and a 12v diaphragm pump rated for "100psi 5L/min". i had all the parts for a few months now and never assembled it, so finally today i did it. when i tested it the vacuum wasn't really what i expected...
when i put my finger on the tube opening it barely sucks it. so i connected it to my vacuum flask and buchner funnel and tried to see if it could be usable for vacuum filtration. i was in a rush so i really just dumped some water on the filter to see if it could at least suck it reasonably fast, whitch it did ;)
(i still have to try a real filtration dough). the problem is that i don't think i could use my vacuum system for vacuum distillation (i kinda built it for that reason...). tomorrow i will try to boil water under "vacuum" and correlate the boiling temperature to the pressure in the system so i have some numbers.

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RogueRose - 8-12-2017 at 03:29

I like these setups! I'm wondering if it would be possible to use a setup like this to circulate water in the condenser as well as draw vacuum at the same time.

One thing I don't get is why they are all 12v and the 110-120 are about 5-8x as much!

I'm kind of interested in one of these
https://www.ebay.com/itm/SCHUCO-SCHUCO-VAC-130-ASPIRATOR-SUC... it's an aspirator vacuum pump. My main goal is to be able to help do vacuum filtration as well as vacuum distillation. IDK if this type would work or not.

weilawei - 8-12-2017 at 05:39

If you get yourself a chassis mount transformer like this one, you can run the pump off 120V. Programming and electronics were my first love before chemistry (~25 years doing that :cool: ). Just wire it up with some spade terminals and chop up an existing power cord to make your connection. Wire the ground to one of the bolts holding the chassis down. Should only run you about 25$ total.

[Edited on 8-12-2017 by weilawei]

Vosoryx - 8-12-2017 at 08:03

It's very possible to use the pump to circulate water, but i wouldn't advise it. Mainly because now the inside of the jacket would then be covered in water that contains whatever is dissolved in that water from the aspirator. Since the jackets are very hard to clean, i wouldn't contamimate them. It's up to you though.

NeonPulse - 10-12-2017 at 23:29

I have used a similar setup and I found that it worked best if the Venturi device is upright and the exit is directly under the water level of the reservoir. I had to adjust it to find the best vacuum. I also used a couple of metal check valves to stop the inevitable back flow when the vacuum is stopped. Also I had to replace the water pump once. After many hours of use the diaphragm crapped out and it was no longer self priming. It can pull a pretty good vacuum though. I demonstrated its use in one of my videos: a cold acetone distillation.

Ubya - 11-3-2018 at 08:57

hey it's me again, same pump as before but in a compact version, i realized that you really don't need all that water (being recirculating) and i wanted to insall this pump under my diy fume hood, so the smaller the better (i need the space for storage). the water aspirtor is vertical as suggested by NeonPulse, and the hose ends underwater because i noticed in my tests using a faucet that if the discharge tube is not filled with water there won't be any suction, i could have used a smaller diameter tube, but i hadn't any so i just submersed the end of it to. the pump works! i still need to measure exactly the vacuum pressure, it's won't be like a rotary vane vacuum pump but it's doing it's job.
the container i used is a plastic beverage container bought at IKEA for 3,50 euros, i made the holes on the top with a hot screwdriver barely big enough for the tubes to fit so the won't wobble around, same thing for the aspirator.


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oh and i will insall also another tube connected to the fume hood so any gases won't be released in the air or under my fume hood where i keep my chemicals and other stuff:P

monolithic - 11-3-2018 at 09:42

If you get a chance, could you tell us at what temperature water boils so we can get an idea of how much vacuum it's pulling?

Ubya - 11-3-2018 at 09:47

Quote: Originally posted by monolithic  
If you get a chance, could you tell us at what temperature water boils so we can get an idea of how much vacuum it's pulling?


sure, i wan't to do exactly that

Ubya - 11-3-2018 at 10:37

soo with 20 °C water in the aspirator setup i got a boiling point of 73°C, so a pressure of about 0.31 bars.
the aspirator i bought is this
https://www.ebay.com/itm/Stainless-Steel-Aspirator-Pump-Humb...

in the specs it says that it's maximum vacuum is 420mmHg or 0,56 bars so i already beat it :D
cooling the water to near 0°C will help.
any ideas on how to make an even stronger vacuum? (i will try i few things like water level, tube length etc)

SWIM - 11-3-2018 at 11:25

Cool set-up. Incredibly compact and convenient.

I think aspirators of that design are generally able to make pretty high vacuum with enough pressure and flow.
Often the limiting factor is water temperature when you get down under 40 Torr , but at higher pressures the water temperature isn't as much of an issue as long as it's not too warm.


With a small reservoir it sounds like things would get pretty frothy in there when it's running.

This could mean sucking bubbles into the pump, which could be a problem.

Maybe if you put something like a few layers of screen or plastic pot-scrubber pads in the space between the input and output pipes it would help lessen any trouble with air bubbles getting in the pump. (If that is a problem...I'm just supposing here.)

They make little things that go on aspirator outlets that are kinda like little funnels packed with screen which help slow down the output velocity and cut down on splashing.

One of those might help, but I'll be damned if I can remember what they call those things.

Hey, you could maybe kill two birds with one stone by putting a mesh bag full of crushed ice in the center of the container.
Cool the water and keep bubbles out of the pump.


Ubya - 11-3-2018 at 15:48

Quote: Originally posted by SWIM  



With a small reservoir it sounds like things would get pretty frothy in there when it's running.

This could mean sucking bubbles into the pump, which could be a problem.

Maybe if you put something like a few layers of screen or plastic pot-scrubber pads in the space between the input and output pipes it would help lessen any trouble with air bubbles getting in the pump. (If that is a problem...I'm just supposing here.)



yes, i noticed bubbles being sucked, and i thought it could be a problem, indeed it is. i will try to reduce them with a screen separator of some kind as you suggest.
thank you for the tips:cool:

VSEPR_VOID - 11-3-2018 at 16:54

I wonder how small you could make this thing. Also if you cool the water or add a salt, forgive my memory, then you will achieve a higher vacuum. Nerd Rage said something along these lines.

Sulaiman - 12-3-2018 at 02:38

When recirculating water through the pump and aspirator I would expect the water to heat up significantly,
does it ?

For vacuum filtration I highly recommend a cheaper, quieter and easier approach http://www.ebay.co.uk/itm/DC-12V-24V-80Kpa-Micro-Piston-Vacu...

Ubya - 12-3-2018 at 03:21

Quote: Originally posted by Sulaiman  
When recirculating water through the pump and aspirator I would expect the water to heat up significantly,
does it ?


the water is never in contact with the motor, so i don't think it would heat up, anyway i'll test the water temperature after running the pump for a while

Sulaiman - 12-3-2018 at 04:05

I meant direct mechanical heating of the water,
e.g. 60 W motor/pump x 50% efficient = 30 W power into the water,
with brief operation and a large metal reservoir you may not notice the effect
but prolonged operation with a small plastic reservoir may be problematic.

Ubya - 13-3-2018 at 02:47

Quote: Originally posted by Sulaiman  
I meant direct mechanical heating of the water,
e.g. 60 W motor/pump x 50% efficient = 30 W power into the water,
with brief operation and a large metal reservoir you may not notice the effect
but prolonged operation with a small plastic reservoir may be problematic.


you where right, after 4 minutes of running the water temperature went from 16.1 °C to 17.2 °C, i didn't measure the volume of water but surely for prolonged use it needs cooling.


SWIM, i got it working using a cleaning sponge :D
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NeonPulse - 19-3-2018 at 03:56

Recently I came across a load of old glass for cheap and this was in the bundle. I’m sure it’s made of polycarbonate plastic and it works very well. Unfortunately though there’s no anti suck back device on its inlet. It may be vintage and I can’t find anything on its manufacturer. Most of the other glass was vintage too and used to Belong to an analyst. There was a lot of volumetric pipettes and burettes in the bundle as well as a large chromatography column. Just wondering if anyone has heard of this manufacturer. Pics enclosed.

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18thTimeLucky - 19-3-2018 at 08:49

Sorry if this is a stupid question, but I live in the UK and eBay will only show me water aspirator pumps being sold from the US, costing £30 each. I clicked on the link Ubya gave above for the water aspirator pump they bought (https://www.ebay.com/itm/Stainless-Steel-Aspirator-Pump-Humb...) and there are loads of different chinese ones costing below £10 suddenly. I am guessing this is the american eBay site (as all prices are given in dollars), but all these say they are selling to the UK too, and it suggests them to me on the sidebar of the UK eBay site now that I have viewed a few through the US site...

I had asked my college science technicians to place an order for me this week for a needlessly more expensive water aspirator pump so if someone could just very quickly confirm I am not a moron here before I throw around limited money, that would be very appreciated. If I can buy one of these chinese metal water aspirator pumps from here in the UK, I want to cancel that science technician order as soon as possible...

[Edited on 19-3-2018 by 18thTimeLucky?]

Ubya - 19-3-2018 at 11:39

18thTimeLucky? i'm from italy and i never use ebay.it, it doesn't show listings from everywhere and most of the times shipping costs are excessive, i shop from ebay.com (and sometimes from ebay.co.uk), there are more and cheaper listings from china with free shipping (most of the time) so i think it's better. anyway i bought that pump for about 10$ (i don't remember exactly) and free shipping to italy, so i can recommend to buy that pump from ebay, shipping time is about 1 month so if you are impatient order it from your technitian, if you don't mind the waiting go for it, i never had any problems (i bought stuff on ebay from chinese sellers many many times)

18thTimeLucky - 19-3-2018 at 13:42

Thanks for quickly reply Ubya. I will have to keep that in mind when looking at eBay. I don't mind waiting a month - I have plenty of time but not much money - so if I still can, I will cancel my order with my college science technicians tomorrow and buy a similar water aspirator pump to you (they are 3x cheaper!).

DavidJR - 19-3-2018 at 23:15

Try deschem on aliexpress. I got my aspirator from them along with a lot of glassware. Very fast shipping.

18thTimeLucky - 20-3-2018 at 12:14

I managed to cancel buying the water aspirator pump from the list of equipment I asked them. I wish I could order chemicals through my college, would be so convenient...
I think I might try deschem then if you recommend them DavidJR.

It seems many people go for a similar 100Psi 12V DC water pump to couple with their water aspirator pump (I am guess this is because Nurd Rage recommended that design). Ubya, or anybody else, you seem to use a water pump like this, how do you power yours? (Nurd Rage does not mention how he does in his video) Do you just use a AC/DC 12V phone charger or similar? I have one laying around but it gives out 1.5A and I don't know if this would be enough if the water pump is 60W, I am not particularly brilliant at electronics.

This is a water pump I am interested in for reference: https://www.ebay.co.uk/itm/Hot-DC-12V-115Psi-High-Pressure-D...

Thanks in advance.

EDIT: Link was not working.
EDIT: A smily emoji keeps ruining my link! I will give a different link.

[Edited on 20-3-2018 by 18thTimeLucky?]

[Edited on 20-3-2018 by 18thTimeLucky?]

DavidJR - 20-3-2018 at 13:00

That's the exact listing I bought.

P=IV
=> 60W=I * 12V
=> I = 60/12 A
=> I = 5 A

So you'll need a supply capable of at least 5 amps. These pumps will run at lower current but the results will be less than satisfying...

Here's a link to the aspirator from deschem: https://www.aliexpress.com/store/product/Laboratory-Aspirato...

They also have a copper version for a slightly increased price.

18thTimeLucky - 20-3-2018 at 14:00

Thank you, I apoligise for the spoonfeeding, making you do such a simple calculation - I expected it to be way more complicated than that. Thanks for the link, although deschem's eBay account seems to be selling atleast the stainless steel one cheaper for some reason so I think I will get it from eBay.

Seems like I now have a shopping list of:

https://www.ebay.com/itm/Stainless-Steel-Aspirator-Pump-Humb...

https://www.ebay.co.uk/itm/Hot-DC-12V-115Psi-High-Pressure-D...

https://www.ebay.co.uk/itm/AC-Converter-Adapter-DC-12V-5A-Im...

Hopefully this will pull a decent vacuum.
Again, thanks for the help Ubya and DavidJR, much appreciated.

Ubya - 20-3-2018 at 16:21

Quote: Originally posted by 18thTimeLucky?  


It seems many people go for a similar 100Psi 12V DC water pump to couple with their water aspirator pump (I am guess this is because Nurd Rage recommended that design). Ubya, or anybody else, you seem to use a water pump like this, how do you power yours? (Nurd Rage does not mention how he does in his video) Do you just use a AC/DC 12V phone charger or similar? I have one laying around but it gives out 1.5A and I don't know if this would be enough if the water pump is 60W, I am not particularly brilliant at electronics.

This is a water pump I am interested in for reference: https://www.ebay.co.uk/itm/Hot-DC-12V-115Psi-High-Pressure-D...



i use a 15v 60w laptop charger to power the pump, but soon i want to upgrade it to a 120W 12V LED power supply i found one on ebay for cheap , i could use the extra 60w for other things i might need in my DIY fumehood


[Edited on 21-3-2018 by Ubya]

NeonPulse - 6-5-2018 at 19:20

Just finished my new vacuum pump yesterday and testing it this morning. It is powerful. Maybe the pressure pump is a bit of overkill but in combination with the tap I can easily control the pressure delivery. I’m yet to test it with a water distillation to get a gauge of what vacuum it can attain but I’m sure it will reach the optimum vacuum that the aspirator can reach. I found the small caravan water pumps do work but the diaphragm shits out after a few hours run time. This pump is also quieter. The pump I have now cost me 30$ second hand and the plumbing fittings all up cost me 10$ since I had some of them already the aspirator was 15$ from Deschem so it’s well under 100$ to make it and it will prove to be very useful for some distillations where I don’t want to subject my rotary vane pump to like acidic and solvent laden solutions. The reservoir is sufficient enough to ass ice bricks and such to keep it cool too.

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Panache - 13-5-2018 at 00:15

Quote: Originally posted by NeonPulse  
Maybe the pressure pump is a bit of overkill but in combination with the tap I can easily control the pressure delivery.


Thats like saying by building a blast wall we are controlling the explosion, you'd be far better off controlling the pumps motor as soon enough the back pressure is going to affect your mechanical seal, or worse your motor.
But technically i guess you're correct and if works and only see's intermittent use then fine and its looks kind of sculptural with that bend in the hose...

wg48 - 13-5-2018 at 00:57

Quote: Originally posted by Panache  
Quote: Originally posted by NeonPulse  
Maybe the pressure pump is a bit of overkill but in combination with the tap I can easily control the pressure delivery.


Thats like saying by building a blast wall we are controlling the explosion, you'd be far better off controlling the pumps motor as soon enough the back pressure is going to affect your mechanical seal, or worse your motor.
But technically i guess you're correct and if works and only see's intermittent use then fine and its looks kind of sculptural with that bend in the hose...


The motor looks like an induction type so it will not be easy to control it.

A bypass would be simpler i.e. put the tap between the output and input.

Panache - 13-5-2018 at 01:26

Quote: Originally posted by wg48  
Quote: Originally posted by Panache  
Quote: Originally posted by NeonPulse  
Maybe the pressure pump is a bit of overkill but in combination with the tap I can easily control the pressure delivery.


Thats like saying by building a blast wall we are controlling the explosion, you'd be far better off controlling the pumps motor as soon enough the back pressure is going to affect your mechanical seal, or worse your motor.
But technically i guess you're correct and if works and only see's intermittent use then fine and its looks kind of sculptural with that bend in the hose...


The motor looks like an induction type so it will not be easy to control it.

A bypass would be simpler i.e. put the tap between the output and input.


i concur, i wasn't really thinking about what i was saying at that point i just wanted to use that blast screen to control the explosion bit.....

[Edited on 13-5-2018 by Panache]

What is the attraction to re-circulating vacuum pumps ?

Sulaiman - 13-5-2018 at 02:58

So far I have been using a cheap small 12 Vdc motor vacuum pump like this https://www.ebay.co.uk/itm/DC-12V-24V-80Kpa-Micro-Piston-Vac...
for 'vacuum' filtration and reduced pressure distillation.
Admittedly over four years of use/abuse it's performance has dropped a little, but it works just fine.

What is the benefit of a recirculating water pump driven vacuum aspirator ?
Surely the water needs de-gassing and cooling ?
Why is all the extra effort and cost beneficial ?

P.S. I have a dual-stage rotary but it never gets used for chemistry,
mainly due to fear of damaging it.
(and the vacuum would boil most common liquids at room temperature)

XeonTheMGPony - 13-5-2018 at 04:28

Quote: Originally posted by Sulaiman  
So far I have been using a cheap small 12 Vdc motor vacuum pump like this https://www.ebay.co.uk/itm/DC-12V-24V-80Kpa-Micro-Piston-Vac...
for 'vacuum' filtration and reduced pressure distillation.
Admittedly over four years of use/abuse it's performance has dropped a little, but it works just fine.

What is the benefit of a recirculating water pump driven vacuum aspirator ?
Surely the water needs de-gassing and cooling ?
Why is all the extra effort and cost beneficial ?

P.S. I have a dual-stage rotary but it never gets used for chemistry,
mainly due to fear of damaging it.
(and the vacuum would boil most common liquids at room temperature)


- Allot of places you are charged for the water per gallon, So think about the amount of water needed for a long distillation! It adds up fast.

- Compounds absorbed by the water my render it illegal to discharge down the drain (re circulation nullifies this issue)

- City water pressure can fluctuate heavily unless you have a hydro static booster pump (Most good labs and medical buildings will have this equipment) House tend not to have these so your vacuum can fluctuate unpredictable.

- Water condition, some places have crap loads of salts dissolved in water (Like my place) that will corrode or plug aspirator, my water will do both, re circulation eliminates this issue by being able to use distilled, which further offers better predictable vacuum

just a few off the top of my caffeine deprived brain.

Sulaiman - 13-5-2018 at 05:12

Quote: Originally posted by XeonTheMGPony  
Quote: Originally posted by Sulaiman  
So far I have been using a cheap small 12 Vdc motor vacuum pump like this https://www.ebay.co.uk/itm/DC-12V-24V-80Kpa-Micro-Piston-Vac...
for 'vacuum' filtration and reduced pressure distillation.
Admittedly over four years of use/abuse it's performance has dropped a little, but it works just fine.

What is the benefit of a recirculating water pump driven vacuum aspirator ?
Surely the water needs de-gassing and cooling ?
Why is all the extra effort and cost beneficial ?

P.S. I have a dual-stage rotary but it never gets used for chemistry,
mainly due to fear of damaging it.
(and the vacuum would boil most common liquids at room temperature)


- Allot of places you are charged for the water per gallon, So think about the amount of water needed for a long distillation! It adds up fast.

- Compounds absorbed by the water my render it illegal to discharge down the drain (re circulation nullifies this issue)

- City water pressure can fluctuate heavily unless you have a hydro static booster pump (Most good labs and medical buildings will have this equipment) House tend not to have these so your vacuum can fluctuate unpredictable.

- Water condition, some places have crap loads of salts dissolved in water (Like my place) that will corrode or plug aspirator, my water will do both, re circulation eliminates this issue by being able to use distilled, which further offers better predictable vacuum

just a few off the top of my caffeine deprived brain.


Those all seem to be reasons to not use an aspirator ?

XeonTheMGPony - 13-5-2018 at 05:23

No, just to use a self contained system, Aspirators can with stand things that will destroy a rotary van pump, and a cryotrap for a rotary van pump is allot more costly then a simple aspirator set up.

I've been working on a multistage PELT set up for a cryo trap, trying to figure out some different topolagies and geometries for both vacuum freeze drying and for vacuum trap. you need -80 to ensure most substances are properly scrubbed from damaging the pump.

The system must be able to run for 24h as well so it is no small task! most use autocascade systems.

So either you invest a couple grand for that, or less then a hundred for aspirator in a self contained system.

monolithic - 10-6-2018 at 20:15

Quote: Originally posted by NeonPulse  
Just finished my new vacuum pump yesterday and testing it this morning. It is powerful. Maybe the pressure pump is a bit of overkill but in combination with the tap I can easily control the pressure delivery. I’m yet to test it with a water distillation to get a gauge of what vacuum it can attain but I’m sure it will reach the optimum vacuum that the aspirator can reach. I found the small caravan water pumps do work but the diaphragm shits out after a few hours run time. This pump is also quieter. The pump I have now cost me 30$ second hand and the plumbing fittings all up cost me 10$ since I had some of them already the aspirator was 15$ from Deschem so it’s well under 100$ to make it and it will prove to be very useful for some distillations where I don’t want to subject my rotary vane pump to like acidic and solvent laden solutions. The reservoir is sufficient enough to ass ice bricks and such to keep it cool too.


Did you get a chance to test your new recirculating aspirator? How much vacuum did it draw (mm Hg, boiling point of water, etc.)? Also, what are the specs of your pump?