Sciencemadness Discussion Board - aspirator vacuum question

aspirator vacuum question

Db33 - 25-11-2016 at 19:57

Reduction-in-a-Vacuum-no-notes1.jpg - 616kB

i want to do vacuum distillations, but ive been told a rotary vane type pump wouldnt work because of solvent vapors would corrode and ruin it. So that leaves aspirtator. I dont have a running faucet to connect to so i need to make one myself.

Now my question is, can i just buy something like this? this looks like it would work for vacuum distillations if i keep it stocked with ice cold water, right? or is this not what i need? thanks.

elementcollector1 - 25-11-2016 at 20:25

Get a vacuum pump, they're probably much cheaper.

https://www.amazon.com/gp/product/B012CFTYX4/ref=oh_aui_deta...

^The one I bought. More than enough for most amateur uses.

Db33 - 26-11-2016 at 08:04

thats what i wanted, a simply vacuum pump. But wouldnt distilling oils and solvents ruin it? What if i change the oil every distillation? would that keep the pump good enough? Also, should i get a 1/3hp, 1/2hp, or 1hp power vacuum pump?

Dwarvensilver - 26-11-2016 at 09:59

NurdRage has a great video on YouTube about aspirator vacuum
https://www.YouTube.com/watch?v=tYLlkTDstmo
check it out it may well answer some of your questions

Cheers,

Db33 - 26-11-2016 at 11:17

Quote: Originally posted by Dwarvensilver

NurdRage has a great video on YouTube about aspirator vacuum
https://www.YouTube.com/watch?v=tYLlkTDstmo
check it out it may well answer some of your questions

Cheers,

ive actually seen that video and really loved it but i didnt understand what the red and black wires did. Do you see the diahpram pump? it has 2 wires, a red and black one. What do i do with those? He never explains. Here is a photo, what do you do with the red and black wires?

mbzdXIt_t42nRxH9EBQI6KQ.jpg - 8kB

Chlorine - 26-11-2016 at 14:00

I assume the pump is a DC diaphragm pump, if so that means the red is typically positive and the black is typically negative. Then go to the users manual and acquire the correct voltage to run the pump.

Db33 - 26-11-2016 at 14:06

it IS a DC diaphragm pump, but what do i connect the wires too? its DC12V

Chlorine - 26-11-2016 at 14:15

You can either use a 12V battery, veriac or buy a cheap power supply adapter:
https://www.amazon.com/Adapter-100-240V-Transformers-Switchi...

Db33 - 26-11-2016 at 14:45

Quote: Originally posted by Chlorine

You can either use a 12V battery, veriac or buy a cheap power supply adapter:
https://www.amazon.com/Adapter-100-240V-Transformers-Switchi...

that shows connecting red and blue wires but i assume red and black is the same? Thanks i really appreciate thats exactly what i was looking for.

Now my other question, does anyone know a good link for a good place that sells GOOD VACUUM hosing to use for the aspirator and for strong vacuum distillations/filtrations?

beerwiz - 27-11-2016 at 01:36

Quote: Originally posted by Db33

Quote: Originally posted by Chlorine

You can either use a 12V battery, veriac or buy a cheap power supply adapter:
https://www.amazon.com/Adapter-100-240V-Transformers-Switchi...

Red is positive and blue would be negative. Buy a 12v power supply with the same amperage (amps/A) as your pump. Strip the wires of the power supply connector and solder them to the 2 wires from the power supply, that's all. Check out the power supply pic.

You can get the "vacuum" hose at almost any hardware store or Home Depot/Lowes, go to the tubing/hose section and get a reinforced hose like in the picture below.

hose.jpeg - 5kB

[Edited on 27-11-2016 by beerwiz]

power supply.jpeg - 5kB

Dwarvensilver - 27-11-2016 at 09:11

Greets,

I agree with beerwiz, with the caveat that it would not hurt to have the power supply a couple hundred mA more than your requirement.

For the reinforced hose you might want to go with might be something like

https://www.amazon.com/HydroMaxx%C2%AE-Flexible-Suction-Disc...

The reinforced hose as beerwiz has pictured above, (speaking from experience) will work but may collapse with vacuum for a longer period or if your temperature is elevated as this type of reinforcement is for pressure inside to the out and as it gets warm it may collapse. The ribs in the hose pictured here are meant for pressure outside to inside support to prevent collapse up to the rating of the hose.

Cheers,

Dwarvin

Db33 - 27-11-2016 at 09:53

thats the pump i got, can anyone show me a link to where i can buy the correct ampage power supply your talking about? it says DC 12V 60W, i thought all i needed for this was something what the guy poster above, but if anyone has a link to something better please let me know.

i also dont know how to solder so i was hoping i could just get some kind of adapter where i put the red and black plugs in but really any info would help.

[Edited on 27-11-2016 by Db33]

this is an old dell laptop adapter i have, if i stripped this and connected the wires would this work??

[Edited on 27-11-2016 by Db33]

elementcollector1 - 27-11-2016 at 10:07

When I bought one of these for an aspirator a while back, I rigged a laptop battery charger to power it. Provides 12V at 5A (60W, just as needed), so it works out great.

Unfortunately, the pump itself was too weak to sustain a good vacuum when hooked up to the aspirator. You're going to want something like a pump rated for 400 GPH, because the faster the water goes through the pump, the more chance you'll have of drawing a vacuum.

Db33 - 27-11-2016 at 10:23

Quote: Originally posted by elementcollector1

When I bought one of these for an aspirator a while back, I rigged a laptop battery charger to power it. Provides 12V at 5A (60W, just as needed), so it works out great.

Unfortunately, the pump itself was too weak to sustain a good vacuum when hooked up to the aspirator. You're going to want something like a pump rated for 400 GPH, because the faster the water goes through the pump, the more chance you'll have of drawing a vacuum.

any link to something u would recommend? this is so complicated maybe i should just a vacuum pump and just change the oil every time, then i wouldnt have to worry about this. but yeah, i already bought the aspirator and now i dunno what to do.

beerwiz - 29-11-2016 at 12:11

That adapter is no good! You need one that is 12V x 5A (amps). You can twist the wires together and cover them with black electrical tape instead of soldering but the connection will be flimsier.

Db33 - 29-11-2016 at 13:07

Quote: Originally posted by beerwiz

That adapter is no good! You need one that is 12V x 5A (amps). You can twist the wires together and cover them with black electrical tape instead of soldering but the connection will be flimsier.

what does 5A mean, and how do i know thats what the diaphragm requires?

http://www.ebay.com/itm/12V-5A-60W-AC-to-DC-Adapter-Power-Supply-for-5050-Flexible-LED-Light-Strip-3528-/371241294072?hash=item566fb498f8:g:vPQAAOSw2s 1UwKpI

this one says its 60W and 5A , the diaphragm says its also 60W so is this the correct adapter? and i just strip the wire and connect the black and red wires and then use electrical tape?

[Edited on 29-11-2016 by Db33]

XeonTheMGPony - 29-11-2016 at 17:17

Watts = Volts Times Amps

Think of the volts like water pressure, and amps is like the flow! You need the pressure to push the volume through the device.

12V * 5A = 60W, Good design is all ways going to an adapter that can supply more, ie you need 5A aim for a 7Amp adapter n such.

careysub - 29-11-2016 at 20:20

I have seen the Savant Gel Pump recommended on this site also.

It is an oil-less, Teflon coated pump designed to handle acid vapors. They show up on eBay for $100-150 with shipping. They pull 7mm, which is better than the ~30mm of an aspirator, and have a pump rate of about 1.4 CFM.

Db33 - 29-11-2016 at 20:49

Quote: Originally posted by careysub

I have seen the Savant Gel Pump recommended on this site also.

It is an oil-less, Teflon coated pump designed to handle acid vapors. They show up on eBay for $100-150 with shipping. They pull 7mm, which is better than the ~30mm of an aspirator, and have a pump rate of about 1.4 CFM.

you got a link? also what is a good CFM for a vacuum pump? alot of pumps ive seen have between 3-7 what is the best?

Cezium - 29-11-2016 at 22:35

Actually you can use dell's adapter, but put 12V (car taillight ~20W) light bulb in series, this will ghetto step-down the voltage. It will also lower wattage a bit, to around 45W.

XeonTheMGPony - 30-11-2016 at 07:00

Quote: Originally posted by Db33

Quote: Originally posted by careysub

you got a link? also what is a good CFM for a vacuum pump? alot of pumps ive seen have between 3-7 what is the best?

Best volume depends on how much of a wet substance you want to boil with the vacuum alone! to fast and you freeze it to little you wait for ever. For most lab scale things 2L pump is plenty, my little pos 1.2L one does every thing I need it to do.

For the vacuum desiccation/drier system I am building I will aim for a 6Lpm pump as the faster pull down will be required

So what is best? That depends on you! if it doesn't matter just get the most common one at the cheapest quality price.

EDIT: If there are any HVAC/ refrigeration repair places near you, Ask if they have an old fridge compressor or buy one from them that still works.

Fill it with a quality mineral oil for an air compressor, On the outlet bend the pipe down into a can packed with Stainless steel scrubbies (Oil trap)

This will make a fairly good vacuum pump for most purposes most will do apx 25Inches of mercury no prob and are fairly quiet, you will need some sort of chem trap and a cold trap to protect it, but the same is true for any vacuum pump other then a diaphragm type or aspirator

[Edited on 30-11-2016 by XeonTheMGPony]

zed - 30-11-2016 at 17:30

A decent car battery charger should be an adequate power supply. A five to ten dollar, garage sale item. Most of mine, have two settings. 2 Amps or 6 Amps, at 12 volts. Now, this is a mite puny, for actually starting a car directly...But, it should be plenty for powering the small motor on that water pump. Love you very long time.

Next....Learn how to solder. Solder those leads to longer wires. Then slid shrink tubing over your soldered wires, and shrink it. Then, seal over that tubing , to make it water-proof. Rosin core solder, and a cheapo soldering gun, will work fine for small jobs.

http://www.harborfreight.com/180-watt-industrial-soldering-g...

Looks like this model comes with solder and flux. Surprisingly, sometimes these dirt cheap units work well and last a long time.

[Edited on 1-12-2016 by zed]

Db33 - 30-11-2016 at 19:00

i think im just gonna say fuck all this and just get a regular vacuum pump and just change the oil after every vacuum distillation. Its too much work trying to find the right adapters and make an aspirator unit. I just want a vacuum i can switch on and off and let it go. Now i just have to decide on whether to get a single or double stage pump, and figure out what CFM is best, 3, 3.5, or the higher 5-7 yellow jackets.

careysub - 30-11-2016 at 19:20

A typical aspirator pulls 0.4 CFM (11 L/min), and its max vacuum is about 10mm with ice cold water.*

Virtually any mechanical vacuum pump will beat it handily in both capacity and max vacuum.

*Water's vapor pressure is 4.65mm at 0 C, but the water goes through the pump, gets squeezed through a nozzle, and it is in the throat where it mixes with air where the temperature matters and it will be significantly warmer than in the tank.

XeonTheMGPony - 30-11-2016 at 20:07

Quote: Originally posted by Db33

i think im just gonna say fuck all this and just get a regular vacuum pump and just change the oil after every vacuum distillation. Its too much work trying to find the right adapters and make an aspirator unit. I just want a vacuum i can switch on and off and let it go. Now i just have to decide on whether to get a single or double stage pump, and figure out what CFM is best, 3, 3.5, or the higher 5-7 yellow jackets.

Depending on what your doing that simply will not help it.

Go with a single stage at 3cfm, cheapest to replace and more then enough.

Make sure to buy a cold trap and allot of air duster! (Fill a thermose with the air duster liquid and put the cold trap in it!)

To start with use a fridge compressor, as it will be free to stupid cheap, and you'll learn how fast you'll cook it from fumes.

[Edited on 1-12-2016 by XeonTheMGPony]

Magpie - 30-11-2016 at 20:59

I bought a single stage, rotary vane, vacuum pump rated at 2.5cfm from Harbor Freight for $100.

It works fine for vacuum distillations pulling down to 1-2mmHg. So why would I need a 2-stage?

During a vacuum distillation all you need capacity for is for leaks in your system. If you seal your system right there will be very little leakage. So why would you need anything more than 2.5cfm? Probably could use a lot less.

I bought this one because it was cheap. I've had this pump for several years and have only had to change the oil twice. If I'm distilling something that is compatible with oil I don't change the oil.

Edit: I wanted to add that when distilling something really nasty, like nitric acid, I will by all means use my aspirator if at all possible.

[Edited on 1-12-2016 by Magpie]

Db33 - 1-12-2016 at 07:44

Quote: Originally posted by Magpie

I bought a single stage, rotary vane, vacuum pump rated at 2.5cfm from Harbor Freight for $100.

It works fine for vacuum distillations pulling down to 1-2mmHg. So why would I need a 2-stage?

During a vacuum distillation all you need capacity for is for leaks in your system. If you seal your system right there will be very little leakage. So why would you need anything more than 2.5cfm? Probably could use a lot less.

I bought this one because it was cheap. I've had this pump for several years and have only had to change the oil twice. If I'm distilling something that is compatible with oil I don't change the oil.

Edit: I wanted to add that when distilling something really nasty, like nitric acid, I will by all means use my aspirator if at all possible.

[Edited on 1-12-2016 by Magpie]

if distilling something like that, could i just use a vacuum pump and fresh oil and then afterwards change the oil without worrying about to much damage?

Magpie - 1-12-2016 at 11:13

I would guess that would be OK as long as this is a small quantity like 500mL.

Why can't you use a $20 aspirator. Calculate your water costs. I'm guessing it won't be that much.

aga - 1-12-2016 at 11:40

I got a cheap single-stage vac pump from Italy off ebay.

After a Lot of abuse it stopped working.

All it needed was taking apart and the rust cleaning off, then it worked fine again for simple vac needs (which is all i have).

http://www.sciencemadness.org/talk/viewthread.php?tid=66097

Still working fine today, although it did work better with just baby oil.

Db33 - 1-12-2016 at 15:17

Quote: Originally posted by Magpie

I would guess that would be OK as long as this is a small quantity like 500mL.

Why can't you use a $20 aspirator. Calculate your water costs. I'm guessing it won't be that much.

i have an aspirator but i dont have a faucet to use it on, and making a recirculating station seems like it would take be too much of a pain.

zed - 1-12-2016 at 15:48

Good enough. But, an aspirator is extremely useful. Quiet, and extremely adjustable. And, it can, of course, be used without the presence of electricity. Uses up a lot of water that way, but perhaps the water can be diverted to your garden. There are times when electricity and chemistry, aren't friends.

wg48 - 1-12-2016 at 15:56

Don't forget the ballast.

If you have regular rotary vane pump it frequently has a ballast. The ballast lets a controlled amount of air in to the pump that helps to stop condensable gases from condensing in the pump or the oil.

The procedure for pumping gases that may condense in the pump is to run the pump with the ballast open and at the conclusion of pumping run the isolated pump for say an hour with the ballast open to flush out volatile contaminates left in the pump.

So if you must pump gases like chlorine or nitric acid vapours with out a trap the above procedure should help.

Here is some info on ballasts:
https://avs.org/AVS/files/06/0613373e-c93e-4bc6-8b79-38a1e19...

XeonTheMGPony - 3-12-2016 at 07:06

And pre-heating the pump goes a looong way.

I use my vacuum pump for dehydrating hvac systems that I flushed with isopropyle alcohol.

That can destroy your pump easy if not care full, I pre heat the pump by running it blanked off till hot to the touch and as said above I ballast the pump as I start till bulk of it is removed then seal the air bleed for ultimate vac.

Cold trap is your best defense to help protect the pump.

I am building a deep vacuum chamber, So I am building a refrigerated cold trap (2 stage, first stage 134a second stage will be R-507 or R-410a at -50c)

Normal is Acetone and dry ice for small batch run set ups (-80c) that is the future target of building an auto cascade

But most runs I just ordered a Water aspirator as water pumps are cheap and so are 55g barrels! ( http://www.ebay.ca/itm/262437828357 ) As they are by far the best thing for simple distilations, no issues with worrying about the far more expensive and complicated vacuum pumps that you need when you need a real vacuum like H2SO4 distillation or Mercury distillation.

http://www.ebay.ca/itm/DC12V-45W-Diaphragm-Water-Pump-With-P...

You can get cheaper ones!

[Edited on 3-12-2016 by XeonTheMGPony]

Db33 - 3-12-2016 at 16:04

Quote: Originally posted by XeonTheMGPony

And pre-heating the pump goes a looong way.

I use my vacuum pump for dehydrating hvac systems that I flushed with isopropyle alcohol.

That can destroy your pump easy if not care full, I pre heat the pump by running it blanked off till hot to the touch and as said above I ballast the pump as I start till bulk of it is removed then seal the air bleed for ultimate vac.

Cold trap is your best defense to help protect the pump.

I am building a deep vacuum chamber, So I am building a refrigerated cold trap (2 stage, first stage 134a second stage will be R-507 or R-410a at -50c)

Normal is Acetone and dry ice for small batch run set ups (-80c) that is the future target of building an auto cascade

But most runs I just ordered a Water aspirator as water pumps are cheap and so are 55g barrels! ( http://www.ebay.ca/itm/262437828357 ) As they are by far the best thing for simple distilations, no issues with worrying about the far more expensive and complicated vacuum pumps that you need when you need a real vacuum like H2SO4 distillation or Mercury distillation.

http://www.ebay.ca/itm/DC12V-45W-Diaphragm-Water-Pump-With-P...

You can get cheaper ones!

[Edited on 3-12-2016 by XeonTheMGPony]

i thought someone said that a pump like that wasnt enough to make a good enough vacuum?

also would this aspirator work cuz this si the one i have.

zed - 3-12-2016 at 17:47

Looks OK to me.

A side note though....An aspirator can pull enough vacuum to collapse a 55 gallon drum. That drum has a lot of surface area, the metal isn't usually very thick, and an imperfect vacuum, is still vastly less than normal atmospheric pressure. Jewelers used to use an aspirator with a 55 gallon drum in line, to store vacuum. Good way to boil investment, in route to lost wax casting. Turn the valve, and instant decompression! Except, sometimes the drum would collapse, at a bad time, and screw up the process.

https://www.youtube.com/watch?v=zdoWE_Vr8b8

Now, I have a stainless steel beer keg, that I figure to be a lot sturdier than your average 55 gallon drum. I plan to put it to the test.

[Edited on 4-12-2016 by zed]

NedsHead - 3-12-2016 at 18:57

While we're on the subject of vacuum pumps I found that (iso 32 hydraulic oil and hydraulic jack oil) are a cheap source of bulk vacuum pump oil, I use this product on my machinery http://www.penriteoil.com.au/products.php?id_categ=5&id_... and discovered it's also suitable for vac pumps

XeonTheMGPony - 3-12-2016 at 19:46

Beer kegs are amazing I speak from a ton of experience on that! they will hold all the vac you can throw at em!

NeonPulse - 9-12-2016 at 16:23

I actually built a vacuum aspirator pump exactly like Nurdrages unit and it actually performs quite well. It works just as well as he shows in his video. The whole thing cost around 50$ to construct and I must say it was $ well spent for a cheap reliable vacuum source. I was able to distill acetone with only it's evaporation cooling effect at around 18c.
The only problem is the one way valve in the aspirator is shit. It hardly stops the water from being sucked back when you kill the vacuum but for this reason it is advisable to add a quality check valve to the vacuum line. Also as Nurdrage suggested you can enhance the vacuum by using a fluid like ethylene glycol. You can buy premixed 5l bottles at most car products stores which are 50% and if used ice cold you should get a substantial increase in vacuum power. A medium esky cooler shoul work as a reservoir to keep the working fluid cold enough along with some gel filed freezer bricks.

[Edited on 10-12-2016 by NeonPulse]

Sulaiman - 10-12-2016 at 02:26

for vacuum filtration and reduced pressure distillation I have been sucessfully using one of these
http://www.ebay.co.uk/itm/DC12V-DC-Micro-Piston-Vacuum-Pump-...

materials exposed to the gas flow are POM and silicone rubber - so far no problem.

Magpie - 10-12-2016 at 08:27

Quote: Originally posted by NeonPulse

The only problem is the one way valve in the aspirator is shit. It hardly stops the water from being sucked back when you kill the vacuum but for this reason it is advisable to add a quality check valve to the vacuum line.
]

You can install a tee with a valve opening to the atmosphere. This valve is normally closed. Before turning off the water open this valve slowly. This will gently bring the system to atmospheric pressure. Then turn off the water.

edit: see the brass valve/tee combo in the picture:

[Edited on 10-12-2016 by Magpie]