chemrox - 12-12-2007 at 00:37
I need a powder addition funnel of about 250 ml capacity .. I'm looking for the screw auger type that allows pressure equalization. Ideas. sources or
if you want to sell or trade please post or PM. There was one on LabX but too small, alas. New, they are quite dear.
Klute - 12-12-2007 at 08:33
Adding solids in a reaction flask you do not want to open can be quite a challenge!
What I've used in the pass, because I didn't want to pay the price of such an apparatus, was to use a CaCl2 guard, that's tilted downwards with a
roughly 120° angle. A kind of rubber stopper, with a small hole in the middle is used to prevent the drying agent from falling, but I manadged to
find a similar plastic stopper that fits in nicely. When mounting the setup, I fill the guard with the powder I want to add, and I delicately push the
rubber stopper to get the powder to fall in the reaction flask through a side neck.
This is a kind of DIY powder addition funnel, and it has a few drawbacks:
-it's not very practical to use as if you push too hard, the stopper sometime bumps and throws too much powder in. It's difficult to control eaxtly
how much you are going to add at the time. Also, a certain amount of solid stays in the piece, as it can't be pushed right through, and some solid
will stays on the side of the neck.
-It's impractical to recharge, especially when you really can't open the setup for only a few seconds, and has a rather small capacity. In your
case, I realise it's hardly an option, except if you have a similar piece of glassware in the 250mL range..
-it can't be used with powders that will attack/stain the rubber/plunger. Also, a refluxing solvant can damadge the stopper if it's used on the side
neck. Using it on top of a straight condenser will cause alot of powder to stay on the sides of the condenser.
If it can help... Anyone else with similar ideas?
[Edited on 12-12-2007 by Klute]
roamingnome - 12-12-2007 at 11:55
http://www.arrowmark.com.au/images/rcbs-uniflow.jpg
a cross over from the world of reloading. designed for acurate gunpowder charges. It could be modified im sure to the glass ware of your size. i
cant say about the pressure issues though. A classien adapter with the reflux coloumn on the side?
chemrox - 12-12-2007 at 12:20
I have two of these. I'll take a hard look at them. I doubt they will be gas tight or even close to gas tight. They are constructed of Al or
anodized Al too, aren't they? I don't think I would want to put STAB in that. It's a good thought though and I'm going to look at it. Thanks. As
for Klutes idea, I (in my mind) constructed the same kind of thing. It's manipulating that stopper that worries me. Also, if all the powder doesn't
fall by gravity, there's no way to push it as with an auger.
evil_lurker - 12-12-2007 at 13:13
I have one, but I want to keep it.
I can also order you a new one from Chemglass, but it will cost around $200-250 or so.
[Edited on 12-12-2007 by evil_lurker]
Fleaker - 12-12-2007 at 13:30
I'd offer too, it's not much cheaper from Ace and I can get a 15% discount. I have a 1000mL and a 500mL PTFE auger pressure equalized powder addition
I can possibly loan you. U2U?