Sniffity
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Vaccum Pump - Confused
Hey,
I was searching online for a vacuum pump, and came across this:
http://www.labdepotinc.com/Product_Details~id~100~pid~61232....
Basically, it says two things:
• Vacuum to 54.1cm (21.3 in.) Hg
• Pressure to 35psi intermittent, 10psi continuous
Besides the unecessary confusion in using two different units... What's the difference between vacuum and pressure?
Also, when I'm told that I can have 2.13 in Hg as vacuum, does it mean I'll have 2.13 in Hg BELOW atmospheric pressure, or 2.13 in Hg remaining as
pressure in the system when the vacuum pump is turned on?
Really confused by all this, needless to say I've never purchased one of these things before. A complete run-down would be GREATLY appreciated.
-Sniff
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Marvin
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"30 inches of vacuum" would be a 'full' vacuum.
Practically this is only a useful measure for low performance pumps. Anything else will talk about residual pressure. That pump may have some
advantages but for most tasks an aspirator will work better for vacuum.
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dermolotov
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Does anyone have a cheaper source for a vacuum? Under $100?
I've just been (very efficiently) using my home central vacuum as a source for vacuum filtration. But I hate bringing my set up home every time to
perform a simple filtration.
PS. Sorry to threadjack. Just hoping for one link and I'm gone.
[Edited on 27-12-2014 by dermolotov]
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macckone
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A water aspirator pump and a high flow garden fountain water pump
Should cost about $30 US. If you have to buy a bucket add 5.
Add ice and calcium chloride for lower pressures.
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S.C. Wack
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Quote: Originally posted by Sniffity  | | Besides the unecessary confusion in using two different units... What's the difference between vacuum and pressure? |
Vacuum isn't measured in PSI. Pressure is, so...two units. Vacuum is how much it sucks...from gauge...= difference from atmospheric. It sucks down
that much mercury. Pressure is how much it blows...from gauge
unsigned
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dermolotov
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| Quote: Originally posted by macckone | A water aspirator pump and a high flow garden fountain water pump
Should cost about $30 US. If you have to buy a bucket add 5.
Add ice and calcium chloride for lower pressures. |
Wow. Even better. Thanks.
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ahill
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I've got one of these.
$15 - available all over the place (search for ROB-10398 - I got mine from littlebird electronics)
Its a bit noisy - but according to the gauge on the hand pump I have, it does 20"Hg !
Using it, I can boil water at 70 ~ 80C
I dont know how robust it will prove - but I did accidentally suck a strong solution of sodium hydroxide thru it a few weeks ago (wear eye protection
kids !) - and have used it a few times since - and it seems fine.
I am tempted to get another one, to both act as a spare, and to see how low it will go if I connect them back to back.
[Edited on 15-1-2015 by ahill]
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Bert
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Mood: " I think we are all going to die. I think that love is an illusion. We are flawed, my darling".
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You know- Two of those little 12V pumps IN SERIES... Just thinking...
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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