Chemical Forums
Specialty Chemistry Forums => Citizen Chemist => Topic started by: KYPowerlifter on January 17, 2009, 05:41:01 PM
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Hello:
[I have been a member here in the past but, for some odd reason, had to re-register]
I've decided to purchase a vacuum pump or some reasonable facsimile. After a degree of looking, I have a question or two...
1) Thoughts on this one: http://images.google.com/imgres?imgurl=http://www.labequip.com/stock/pictures/24178.jpg&imgrefurl=http://www.labequip.com/itemcatalog/stkno/24178/Fisher-Scientific-Maxima-D4A/Rotary-type-Vacuum-Pump.html&usg=__Sxfv0SzQGrHeZle_swCa-JEFim8=&h=385&w=640&sz=33&hl=en&start=1&sig2=vwCC304C243QZiF5M6XHzw&um=1&tbnid=QyCZeWhWj_A8_M:&tbnh=82&tbnw=137&ei=xA9ySfmqGZbGtgfy58HmCA&prev=/images%3Fq%3DFisher%2BScientific%2BMaxima%2Bmodel%2BD4A%2BRotary%2BVacuum%2BPump%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DN
2) There is one other I am curious about:"Surco Vac vacuum pump. Model: 5711 130. 115 volt. Unit pulls down to 25 inHg."
I have come to question just how much vacuum, in terms of " hg, one needs for the vast majority of experiments that the 'citizen chemist' might engage in. I have come at this problem from two angles, to wit: the notion of using a recirculating system, via a jet pump and a glass aspirator, or using one of the above type pumps with a cold trap (likely improvised).
Price, of course, being the prohibiting factor, I have considered it and it seems close between the two.
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Indeed!
Your post and the link are helpful. I am aware of the pump parameters but not so much the applications. You explanation in the post answers my question.
If I cannot purchase an actual pump of reasonable quality and 'strength', I will rig up a jet pump and employ a glass aspirator (water jet). I have considered a large plastic tote for a vessel and a 'Sears' 3/4 hp shallow well jet pump (pumps 40/60 psi): http://www.sears.com/shc/s/p_10153_12605_08302518000P?vName=Lawn%20&%20Garden&cName=OutdoorDecor&sName=Fountains%20&%20Pumps&psid=FROOGLE01&sid=IDx20070921x00003a along with a glass aspirator: http://kantu200scientificstore.ecrater.com/product.php?pid=2634947 and give that a go.
Thank you
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I bought this Vacuum pump today (Fisher Maxima D4A):
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fwww.quickstopauctions.com%2FEbayPicturesBS%2F08899%2F1.jpg&hash=8b934a05dc335cb44355f401309ef845d0a845f1)
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=310115264470
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Dear KYPowerlifter;
Congratulation!! - Great, take care for it with a cool trap!
Good Luck!
ARGOS++
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Cold Trap:
These seem to be quite expensive but very necessary. Argos has been extremely helpful and has me wondering, is their any way of improvisation here?
Is using an acetone/dry ice combination a reasonable substitute for liquid nitrogen?
Lab Setup:
With a view towards organic chem, could you guys give me some tips on basic lab setup vis-a-vis equipment?
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Honestly, I wouldn't use liquid nitrogen. While unlikely, you have the potential to condense oxygen in a liquid nitrogen trap. While unlikely, this liquid oxygen has the potential to rapidly expand (i.e. explode).
I'd stick with dry ice/acetone.
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Dry Ice and Acetone, or Dry Ice and isopropyl alcohol is usually cheaper than liquid nitrogen, and works pretty damn well. If you are that worried about getting something in your pump, then go through a couple of traps connected in series.
It is true with liquid nitrogen you can at times make liquid oxygen, which is dangerous. But if you pull a vacuum before you put the trap in the liquid nitrogen you will be fine.
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wouldn't that defeat the purpose of the trap?
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Whew... it looks like liq N could end up being a large investment. Perhaps I am misunderstanding things but it appears that it is much like welding gases, it's the vessel that costs you... I also assume I'll have to find it 'locally', living in Western Kentucky this could prove difficult.
I could be wrong, but "Argos++" is 58 years old, according to his profile, and likely works as a chemist. So I suppose I'll have to trust him.
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Tried to edit my other post and add this addendum but must have hit "quote"...
Is my second question impossibly vague, re: lab setup?
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wouldn't that defeat the purpose of the trap?
No.
You set up what you are going to pull a vacuum on with a valve. Close the valve and turn on the vacuum. This will be a closed system and remove all the oxygen from the trap. Then you put the trap in the liquid nitrogen, and then you open the valve to your container and pull the vacuum on your chemistry!
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Oh ok, shlenck flask, right?