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Author: Subject: Best way to reduce noise/silence a vacuum pump?
beerwiz
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[*] posted on 29-8-2016 at 00:35
Best way to reduce noise/silence a vacuum pump?


I do vacuum distillations quite often using a rotary vane vaccum pump and the noise during the distillation is annoying and unbearable. Running distillations for hours at a time with these noise levels is a problem.

What is the best way to run the pump silently or at least to a more quiet level?

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Lefaucheux10
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[*] posted on 29-8-2016 at 01:18


hi guy,

Why not use a long vacuum tube to permit the pump to be far away from you ?

instead you can use insulation wool to do a box for the pump but it will probably heat the pump up
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j_sum1
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[*] posted on 29-8-2016 at 01:21


Check out Nurdrage's latest offering released today. He sets up a nice little operation using an aspirator (available from dechem and nanshinsales amongst others). He makes a good case for using these in a variety of situations including mentioning noise issues. He also discusses their limitations, how they can be made even more effective and when they should be avoided.

You might want to consider his setup.




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Mechanical Animal
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[*] posted on 29-8-2016 at 01:31


Personally, I direct the output of my pump into a container full of fiber glass to dampen the sound of the exhaust and I put that container along with the pump into a heavy wooden cabinet about 5 or so feet from my work area. I still hear the pump but it's anything but loud. Also, if you need/want to get your pump further away from you, you can use push-to-connect fittings and polyethylene tubing that can be bought at any hardware store in rolls of 25 and 50 feet for only a couple bucks. This translucent tubing is fairly flexible but rigid enough to hold even high vacuum and polyethylene is compatible with more solvents, fumes, vapors, gases, etc than your pump and its oil so it will resist anything that you would subject your pump to
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XeonTheMGPony
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[*] posted on 29-8-2016 at 03:31


Quote: Originally posted by Mechanical Animal  
Personally, I direct the output of my pump into a container full of fiber glass to dampen the sound of the exhaust and I put that container along with the pump into a heavy wooden cabinet about 5 or so feet from my work area. I still hear the pump but it's anything but loud. Also, if you need/want to get your pump further away from you, you can use push-to-connect fittings and polyethylene tubing that can be bought at any hardware store in rolls of 25 and 50 feet for only a couple bucks. This translucent tubing is fairly flexible but rigid enough to hold even high vacuum and polyethylene is compatible with more solvents, fumes, vapors, gases, etc than your pump and its oil so it will resist anything that you would subject your pump to


That's good advice, but then going one step further a 3 sided box lined with 2 inches of fiber glass open side aimed out a window or into a panel of fiber glass set back a foot will drastically reduce ambient noise.

I use rotary vans for every thing often and yes it does get dreadfully tedious!
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PHILOU Zrealone
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[*] posted on 29-8-2016 at 06:05


Put the pump onto silent blocks.

Put the pump into vaccuum :D;):P ... Just cynical




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[*] posted on 29-8-2016 at 07:36


You could run the pump in a different room and just have a long vacuum line.

Rotary vane pumps are notoriously noisy without a decent amount of backpressure. The vanes clatter around when there is insufficient pressure to keep them in place. You could try partially blocking off the exhaust, but then you'd have the hiss to deal with still.




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aga
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[*] posted on 29-8-2016 at 07:37


Just switch it off ;)

... then buy a quieter one.




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[*] posted on 29-8-2016 at 08:14


I have a related problem with my rotary vane vacuum pump. When I want to control the vacuum to something less than full vacuum I bleed air into the suction. But this causes a significant amount of oil loss thru mist in the exhaust. Is there a better way to do this? Or is this just "the nature of the beast" and I have to live with it?



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aga
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[*] posted on 29-8-2016 at 08:30


I get the same with mine.

It's on the wooden floor of the shed, so the oil does a great job of protecting the wood, and makes it much more flammable.




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[*] posted on 29-8-2016 at 10:46


Quote: Originally posted by Magpie  
I have a related problem with my rotary vane vacuum pump. When I want to control the vacuum to something less than full vacuum I bleed air into the suction. But this causes a significant amount of oil loss thru mist in the exhaust. Is there a better way to do this? Or is this just "the nature of the beast" and I have to live with it?


just the way she works, you can make a better scrubber though that will help
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Dr.Bob
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[*] posted on 30-8-2016 at 05:44


You can always build a vacuum controller, where you have two valves, one limiting the flow to the vacuum pump, and one bleeding air into the system. There are even switching controllers which do this automatically, which are useful if trying to use a high vacuum to create a mild vacuum. But I prefer to use a weaker pump when I want a low vacuum, the ones for rotovaps or a diaphragm pump or aspirator are all good choices then.

For noice, enclosing the pump or putting it in another room are OK, but the longer the vac line, the lower the ultimate vacuum. Fine for most cases, but bad for high vacuum work. And insulating the pump can cause it to overheat, we had cases of that when people put them in boxes with fiberglass insulation, so make sure that you create a cooling airflow through the box as well. If the pump is pulling a high vacuum, there will be almost no flow from it, so it will not cool well.
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[*] posted on 30-8-2016 at 06:58


based on only a little experience using a Chinese 2-stage rotary vac pump,

most of the noise and all of the gasses/vapours can be vented away using just flexible hose from the output port.

using my pump on a wooden table amplifies the mechanical noise
using it on the concrete floor is much quieter.
On an old carpet mat on the concrete floor even quieter.

[Edited on 30-8-2016 by Sulaiman]




CAUTION : Hobby Chemist, not Professional or even Amateur
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[*] posted on 30-8-2016 at 07:52


Quote: Originally posted by aga  
Just switch it off ;)


OK so he was probably joking but, if your system doesn't leak, what is the pump doing once it has pulled the air out of the system?
Fit a set of suitable valves and turn the pump off once it has done its job.
You might need to turn it back on again from time to time to compensate for leaks but if that's a problem then you don't have a proper system set up.

Also- long pipes are a bad idea for vacuum systems.
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[*] posted on 30-8-2016 at 13:24


Quote: Originally posted by Magpie  
I have a related problem with my rotary vane vacuum pump. When I want to control the vacuum to something less than full vacuum I bleed air into the suction. But this causes a significant amount of oil loss thru mist in the exhaust. Is there a better way to do this? Or is this just "the nature of the beast" and I have to live with it?[/rquote
I use a vacuum control. Several types; one bleeds part of the suction with a needle valve, the other is a manostat. I have two types made of glassware. One (Cartesian) uses Hg vapor pressure and a float, the other uses a low vapor pressure organic compound. There's diagram of the latter in Vogel's 3rd. I had a glassblower make it. It's for sale for the right price. It's limited to the vapor pressure of the liquid inside and the orifice of a bubbling tube. Cartesian manostats are a little dicey to set up but work well provided you get leak out of the system. NB: low oil levels make mechanical vane pumps louder. Aspirators are fine with moderate vacuum requirements. I use a double aspirator pump for my Buchi evaporators.




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S.C. Wack
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[*] posted on 30-8-2016 at 14:54


Agilent makes an isolation box that fits standard pumps; this is something I saw on ebay once. It was fantastically expensive new, and heavy. Looked like it cost about $60 to make. The Quiet Cover.

BTW a good pump will run too hot (maybe even with a fan) with air bled into it and it's just unthinkable anyways IMHO. Why not have a cheap pump for that.

[Edited on 30-8-2016 by S.C. Wack]




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[*] posted on 30-8-2016 at 15:46


My pump is cheap: $100 from Harbor Freight. At first I thought that running air trough the pump would cool it then I realized moving air takes work.



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[*] posted on 30-8-2016 at 15:49


At work, we have a couple of those agilent isolation boxes to house the noisy roughing pumps of the mass spectrometers. They are not cheap but it would cost more to duplicate one ourselves. They really are very simple. Just a box of thin sheet metal with foam on the inside. It is very effective and if you only have to pay material costs it would be an excellent solution. A Waters employee told me many labs have a separate room to house roughing pumps and use a longer vacuum hose, but you'd need to have space for that and there is also the problem of heat dissipation to deal with.

[Edited on 30-8-2016 by phlogiston]




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[*] posted on 13-9-2016 at 13:52


Use an old refrigerator, drill a snug hole through the side for your vacuum, turn it on when using the vacuum pump (cooling)



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