TheBlindGenius (Stranger)
04-10-02 19:51
No 295055
      Separatory Funnels  Bookmark   

Are there any disadvantages to using globe-shaped funnels instead of the more traditional pear-shaped ones? Also, when doing an extraction or anything else that requires a sep funnel, is it acceptable to use, for example, 4 1000 ml sep funnels in four separate extractions or whatever, instead of 1 4000 ml funnel? are there any disadvantages in doing this? swim asks this because she has noticed that a lot of people stress having the hugest sep funnel available.
(Distinctive Doe)
04-10-02 20:08
No 295063
      hmmm  Bookmark   

Never used a globe shaped one, but i can't imagine there is any difference.  The larger funnels seem to more commomly bee globe shaped, this is most likely due to some aspect of the glass blowing or that they are stronger.  Its also probably easier to hold a heavy 4L sphere than it is to hold a heavy 4L cone.

Yes its fine to use 4 1000mL sep funnels instead of one 4000mL.  The obvious this is that it will take more time, alot more if you only have one 1000ml funnel.  If you use more than one you'll have to wash them all.   But on the other hand, if you break the 4L your SOL and they are expensive, but if you break a 1L then its not as bad.

I would say buy every size sep. funnel if ya can afford itsmile

Those who give up essential liberties for temporary safety deserve neither liberty nor safety
04-10-02 20:40
No 295074
      Globular Funnels  Bookmark   

Globular funnels are somewhat less convenient to use in extraction, as they don't center as easily, and the interphase goes a little faster when draining it. They are ideal for conversion into a Perkin triangle as shown in Post 288323 (lugh: "Perkin triangle", Newbee Forum) in the illustration, or any other use where one wished to have a round bottomed flask with a valve at the bottom smile As far as extraction, SWIL has a few, but none larger than 2 L smile instead of using the larger ones, SWIL uses a glass jug or carboy or a PE drum, using stirring for agitation, and a siphon to separate the layers smile The interphase layer is put into a smaller container to separate it, eventually it fits within a 2 L funnel laugh SWIL says shaking a 6 or 12 L funnel is a lot of unecessary work laugh
(Hive Addict)
04-10-02 21:54
No 295107
      balance  Bookmark   

i like globular funnels for their balanace.  a pear shapped funnel is lighter on the tapered side because there is less fluid.  a full 4L globe funnel is easier to shake, imho.

the disadvantage to a globe funnel is you have less control while draining, because the bottom is less tapered. 

you milage may vary.

i learned a thing or two from charlie dontcha know.
(Hive Bee)
04-10-02 21:58
No 295108
      advantage:  Bookmark   

the main advantage to a globe shaped funnel, espescially if your doing extractions is added surface area.  Less agitation/waiting time is nessisary. any two layers have more contact with each other, thus there is a 'wider' door for contact.

04-11-02 05:09
No 295324
      The popping technique  Bookmark   

SWIS has found that the pear shaped funnels are better suited for the popping of your np into the h2o. Their is a proper way of useing your sep funnel, it is not just shaking it but more of a popping of the contents that pushes the np thru the h2o and vice versa.
Take your funnel and raise so the top is lower than the tip
now lower the tip and as you feel the contents rushing towards the tip via gravity quickly snap the funnel back in the direction of your body. If that makes sence and if you did it right you should hear a popping sound sometimes almost sounds like you cracked the glass. What this does is push your np thru your h20 instead of just shaking them together.