# vacuum pump filtration



## Acid_Bath76 (Oct 25, 2011)

I want to purchase a vacuum pump to assist in filtration, and was curious what you all were using/recommend. I've looked at the KNF models, but that stuff is expensive! Your thoughts?


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## nickvc (Oct 25, 2011)

It really depends on your needs and how much work the pump has to have. I've got by with a second hand vacuum pump that's separated by a caustic trap from the acidic solutions. It's not perfect but I got it for around $75, also its not for use in acid applications but by been careful and using a trap it's survived so far. You can also create a vacuum using a hand pump and I'm sure there are post about those here on the forum.


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## grim (Oct 25, 2011)

hi dont know if this helps but when i worked for a cabinet shop in orlando we used vacum pumps for laminated curves and i know we used to get the pumps from a small place outside of atlanta so it might be worth checking out woodworking supply houses if i can remember were we used i will drop you a line


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## kadriver (Oct 25, 2011)

I purchased one of these about 13 months ago and it still runs fine.

It is a stand-alone unit that runs right out of the box.

$79 at Harbor Freight

http://www.harborfreight.com/25-cfm-vacuum-pump-98076.html

kadriver


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## kadriver (Oct 25, 2011)

Here is an inexpensive vacuum gauge that I used with my filter rig.

$15 at Harbor Freight.

http://www.harborfreight.com/fuel-pump-and-vacuum-tester-93547.html


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## niteliteone (Oct 26, 2011)

kadriver said:


> I purchased one of these about 13 months ago and it still runs fine.
> 
> It is a stand-alone unit that runs right out of the box.
> 
> ...



This pump should work quite a while. have a couple myself. 8) 
They are for air conditioning system evacuation so they have a resistance to acids. Just be sure to change the oil after every couple of uses. the oil contains acid neutralizers but they only last so long. the refrigeration pump oil is only a few dollars a bottle.
Just be careful, they will pull a vacuum down to about 100 micron, or to say they can implode your glassware if your filter gets to restricted. :shock: 
Tom C.


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## gold4mike (Oct 26, 2011)

I'm using a compressor from a water cooler I scrapped last spring. I've had to use a valve to reduce the suction on the thing. It will perforate the filter paper in my Buchner funnel, especially as the filter paper's pores start to plug with use.

Does anyone have a good idea how much suction is suggested for use with a Buchner funnel setup?


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## qst42know (Oct 26, 2011)

Something under the blow out pressure I would expect.

:mrgreen: Sorry, I couldn't resist. :mrgreen:


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## Acid_Bath76 (Oct 26, 2011)

harbor freight.. I should have known. They sell just about everything else! We've got one in town. I'll stop by on my way to the kitchen.


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## kadriver (Oct 28, 2011)

niteliteone said:


> Just be careful, they will pull a vacuum down to about 100 micron, or to say they can implode your glassware if your filter gets to restricted



I use a 2000 ml pyrex filter flask with a 110mm & 90mm ceramic buchner type funnels. 

Sometimes the filter gets nearly totally clogged so only slight drips are dropping from the tip of the funnel.

To speed the filtering up, I pulled the vacuum down so far that it pegged the vacuum gage at maximum vacuum.

Over 29 inches of vacuum on both the 1000ml & 2000ml filter flasks and have never seen one implode.

Has anyone ever experienced a vacuum filter flask implosion during use?

kadriver


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## Acid_Bath76 (Oct 28, 2011)

I'm thinking of bypassing the erlenmyer flask if possible. I want try and set a large buchner funnel above a five gallon bucket. Using a locking lid, and drilling a hole towards the upper portion of the bucket. Using some sort of super glue or other resistant adhesive, screwing in a polypropylene nipple for the tubing to fasten to. Maybe this will work. We'll see. I still need to get my incinerator up and running. So much on the plate.


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## gold4mike (Oct 28, 2011)

It should work fine with a tightly sealed 5 gallon bucket. I've used my water cooler compressor to siphon liquid off the top of a bucket with cemented PM's on the bottom into another bucket.

I used a hole saw to cut a hole in the lid of a bucket so my rubber cork would fit snugly, pushed the glass tubing through the cork to the bottom of the bucket then pulled it back up one inch and siphoned all the liquid to that point. 

I removed the lid and poured what was left into a 4 liter beaker, diluted, let settle again, then siphoned off the liquid above the now more obvious cemented solids.

This is a big time saver since you don't have to hold the tubing and can do something else while the siphon is working.


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## qst42know (Oct 28, 2011)

I have collapsed 5 gallon buckets by vacuum as well as 55 gallon poly drums. They hold a specific weight but they're not meant for inward pressure. They cave in suddenly without warning and should not be trusted.

You could put your flask in the bucket to contain any possible implosion.


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## glondor (Oct 29, 2011)

Vacuum will implode very strong things. http://www.youtube.com/watch?v=Zz95_VvTxZM


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## 4metals (Oct 29, 2011)

Well maybe you shouldn't use a tank car for a vacuum reciever!

I've been using strong vacuum for filtration for years and have never seen a vacuum ehrlenmeyer flask, or a 5 gallon vacuum jar, or even a 72 liter spherical receiver collapse from the vacuum. 

Their shapes and design thickness make them sturdy enough to handle it. A 5 gallon pail is another story.


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## niteliteone (Oct 29, 2011)

I myself have never seen it happen either, but when I was shopping for some of my glassware I read it on a manufactures web site.
This is one site that lists a rated vacuum.
http://www.vgdusa.com/filter-flask.htm
Their's a big difference between 29" vacuum and 100 micron especially if you add a scratch or two to the flask.
Just be careful and keep glassware in good condition. 
Tom C.


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## Harold_V (Oct 30, 2011)

4metals said:


> Their shapes and design thickness make them sturdy enough to handle it. A 5 gallon pail is another story.


Indeed it is!
When I moved from Utah to Washington, numbered amongst my possessions were two 55 gallon plastic drums. They were washed and sealed with the factory plugs for transport. When I arrived in Washington, they were partially collapsed, simply from the change in atmospheric pressure (4,200' down to 1.300')

In order to restore them to their round condition, they were left in the sun until they had warmed and expanded--at which time the plugs were loosened. 

Harold


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## gold4mike (Nov 4, 2011)

I haven't included a gauge in the loop yet on my setup but I did make sure to reduce the suction enough that it wouldn't cause a lot of turbulence around the siphon tube. If it stirs up the sediment too much it defeats the purpose of siphoning the liquid off the top.

Since it can siphon more or less unattended once it is setup, I didn't need to be in a big hurry to complete the transfer.


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## Noxx (Nov 12, 2011)

My vacuum source was a water pump with a water injector (venturi tube) in closed loop.


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## jaythenutz (Nov 12, 2011)

I'm thinking of bypassing the erlenmyer flask if possible. I want try and set a large buchner funnel above a five gallon bucket. Using a locking lid, and drilling a hole towards the upper portion of the bucket. Using some sort of super glue or other resistant adhesive, screwing in a polypropylene nipple for the tubing to fasten to. Maybe this will work. We'll see. I still need to get my incinerator up and running. So much on the plate.

i have set a similar rig as the one you speak of and from trial and error and error and error . don't waste your time and money on super glue pipe dope or any other common adhesive. Trust me Go to OSH or Walmart and get a tube of Shoe-Goo. after that stuff sets up it is completely resistant to all chemicals.well i have never used for pure sulfuric. but the seems i did 1 1/2 years ago are still going strong and i have passed lots of AR AP And acid Clorox hot and cold this stuff is awesome. 
Its around 5 bucks for a good size tube.

//Jay


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## 4metals (Nov 12, 2011)

> I want try and set a large buchner funnel above a five gallon bucket.



If you do this and use a vacuum you will have a collapsed bucket on your hands and the associated mess and loss of values. It may appear to be working but as the paper clogs, the vacuum inside the bucket will increase and it will fail. It is not made for vacuum.


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## depperl001 (Nov 12, 2011)

4metals said:


> > I want try and set a large buchner funnel above a five gallon bucket.
> 
> 
> 
> If you do this and use a vacuum you will have a collapsed bucket on your hands and the associated mess and loss of values. It may appear to be working but as the paper clogs, the vacuum inside the bucket will increase and it will fail. It is not made for vacuum.



I think the gent is saying that the funnel is above the plastic bucket so there would be no vacuum in the bucket. If I am wrong my apologies.

Regards,

Josef Vavryn


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## saadat68 (Oct 31, 2018)

Hi
What is difference between siphoning and decanting ?
When we siphon/decant a solution with vacuum pump and hose (without funnel) ,is it decanting or siphoning? 

Thanks


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## butcher (Oct 31, 2018)

What I call siphoning, is where the liquid above is normally sucked out using a hose and suction source without disturbing the solution, or the contents that have settled, where decanting is carefully pouring solution out of the vessel trying not to disturb the settled materials, there are other methods such as using wicks or wicking off a liquid.


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## g_axelsson (Oct 31, 2018)

https://en.wikipedia.org/wiki/Decantation
https://en.wikipedia.org/wiki/Siphon

/Göran


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## saadat68 (Oct 31, 2018)

Thank you
So siphoning is correct for pouring out solution with vacuum pump and hose


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## Palladium (Oct 31, 2018)

I call it vacuum decanting.


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## butcher (Nov 1, 2018)

yes, you are probably the guy who started calling them things under the car next to the muffler a cat too!


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## snoman701 (Nov 1, 2018)

butcher said:


> yes, you are probably the guy who started calling them things under the car next to the muffler a cat too!



Mine is loud, obnoxious and occasionally smells strange...I call it a dog.


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## g_axelsson (Nov 1, 2018)

When I use a pump I usually call it pumping....

Göran


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