ShadowWarrior4444
Hazard to Others
Posts: 226
Registered: 25-4-2008
Member Is Offline
Mood: Sunlight on a pure white wall.
|
|
Aspirator Recomendations
Since I've seen various posts regarding the purchase and quality aspirators, I thought it might be useful to start a thread on it.
I'll start with a request for an assessment of the quality of this aspirator (from one of my favorite companies):
http://cynmar.com/item_detail.aspx?ItemCode=VAC54137
And perhaps a useful inclusion, this vacuum gauge:
http://cynmar.com/item_detail.aspx?ItemCode=VAC54178
I have purchased from Cynmar in the past, and can attest to the quality of their merchandise, prices, and customer service.
An analogous ebay version is pricier, and seemingly less functional: Avogadro's Lab Supply
|
|
|
evil_lurker
National Hazard
Posts: 767
Registered: 12-3-2005
Location: United States of Elbonia
Member Is Offline
Mood: On the wagon again.
|
|
Both crap. I got an aspirator from Cynmar one time and it shot more water out the side arm than it did the outlet! This is the one you want:
http://vwrlabshop.com/polypropylene-vacuum-pump-aspirator-na...
As far as gauges, if you intend to do a fractional distillation under vacuum, you need a mercury manometer... there really is no substitute. For the
money, the $117 Ace Glass 8733-07 "stick" manometer can't be beat. Simply evacuate using a mechanical pump down to <1mm, open slooowly and the
mercury gets sucked right up the center tube. Takes about 60-70g of mercury to fill it up IIRC. To use, start up your vacuum system, let it run for a
bit, then open up the stopcock by giving it a little twist, watch the mercury in the center tube drop, when it stops read on the sides. Much much more
accurate than any mechanical or electronic gauge IMO.
You also need some vacuum tubing. I've used the Tygon R-3603 with decent success. 1/4" seems to be the closest fit for most lab needs, however why the
hell St. Gobain doesn't make 5/16" heavy wall is beyond me. Closest they have is 5/16" ID and 5/8" OD, which is supposedly rated for 29.9 inches of
vacuum. According to them they could do a custom run for me, but I would need some folks to go in on orders, preferably whole 50 foot rolls.
[Edited on 20-5-2008 by evil_lurker]
Not all chemicals are bad. Without chemicals such as hydrogen and oxygen, for example, there would be no way to make water, a vital ingredient in
beer.
|
|
|
detritus
Harmless
Posts: 19
Registered: 27-4-2008
Member Is Offline
Mood: No Mood
|
|
hmm - maybe that water-squiring aspirator was just a bum unit. I used those metal aspirators at school and they were pretty good, easily pulled down
to 50mm and often down to 25-30 after running a bit. Our setups had a long exit hose on the tail to prevent splashing, maybe it helps the vacuum too.
|
|
|
zeppelin69
Harmless
Posts: 46
Registered: 20-2-2007
Member Is Offline
Mood: No Mood
|
|
I bought the vwr aspirator recomended in this thread and it works great, when I'm running it by itself. At first I thought it was because my pump was
too weak, so I bought a 1/2 hp (1870 gph IIRC) pump from harbor frieght recomended elsewhere on this site, but I still can't get a vacuum when I run
the line out of the aspirator to my condensor. This my first attempts at vacuum distillation so I am obviously clueless. Sould I just run the
aspirator by itself on the 1/2 hp pump and the condensor on my weak pump? Basicaly, if someone wouldn't mind filling me in, I would like to know all
the ins and outs of setting up my rig the right way. What order everything should be connected in etc. Thanks for all of the help guys, it's much
appreciated.
|
|
|
bio2
Hazard to Others
Posts: 447
Registered: 15-1-2005
Member Is Offline
Mood: No Mood
|
|
Good grief!
Check for leaks and make sure the correct end is hooked up.
|
|
|
zeppelin69
Harmless
Posts: 46
Registered: 20-2-2007
Member Is Offline
Mood: No Mood
|
|
The aspirator is hooked up correctly, it pulls a vacuum fine when it is the only thing connected to the pump. The problem is that when I connect
another line from the "exit" of the aspirator to my condensor, it stops working. Untill that is I disconnect the line from the "exit" and turn the
pump off and back on. Does the aspirator have to be hooked up after the condensor? As far as I can tell I have no leaks. If it will help I can post a
picture of my attempt to set everything up, tomorrow. Thanks again for all of your help.
|
|
|
evil_lurker
National Hazard
Posts: 767
Registered: 12-3-2005
Location: United States of Elbonia
Member Is Offline
Mood: On the wagon again.
|
|
You do not connect anything to the aspirator other than the vacuum line on the side of the aspirator. The long tubing on the discharge of the outlet
should be around 1" or so from the surface of the water.
If you want to run a second line for coolant to the condender you must plumb it in-line before the aspirator, not after.
Not all chemicals are bad. Without chemicals such as hydrogen and oxygen, for example, there would be no way to make water, a vital ingredient in
beer.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
