most valves have a very small diameter and cant be used to add powders through them easily.
is there some way to connect a vacuum tight WIDE mouth PTFE or stainless steel valve
to a ground glass or flange joint?
usually this is done like this?
ground glass joint > ptfe adapter with thread > threaded stainless steel (butterfly) valve
or when using flange
flange joint > viton or PTFE ring > stainless steel (butterfly) valve > screw on bolt flange tightener
needs to be vacuum tight.
Fyndium - 13-5-2021 at 12:21
Both sides of the system must be equally evacuated, otherwise interesting phenomenon will occur when valve is opened.
Idk about commercial solutions, but DIY you could use adapters to fit an ordinary SS butterfly valve from water/pneumatics/similar systems. They are
designed to handle high pressures, so they will also do great in vacuum.
In general, though, powder addition has always been a bit tricky and it works much better at a larger scale. Screw conveyors are probably the most
common way to administer powders or granulated material.Dr.Bob - 13-5-2021 at 17:27
A powder addition funnel will be much easier, and most are already pressure equalized, so they work. Most other things are not going to work well.LuckyWinner - 13-5-2021 at 18:27
correct, I do know about powder addition funnels but they will get clogged if you
keep them attached and distill off solvents after your powder was added.
if you want an all in 1 reactor for multi step reactions,
I can only think of a wide mouth valve with a powder
conveyor belt hovering over the hole.
once powder was added you simply close to valve.
this is for a 1 liter vessel. just doing this for fun.
[Edited on 14-5-2021 by LuckyWinner]Sulaiman - 14-5-2021 at 06:23
I put powder in rbf using a simple funnel
and add liquid via a pressure equalised funnel
PS dont forget to weigh the rbf before and after adding the powder.
[Edited on 14-5-2021 by Sulaiman]zed - 14-5-2021 at 18:20
Powder addition funnel? Yeah, expensive. I have a link. I'll go fetch.
Yup! I remembered true. Our friend uc235 uses one in a permanganate oxidation.
Great addition funnel, but expensive. A nice one might cost over a hundred bucks U.S.. Pre-owned of course. God only knows what list price would
be, on a new one.
Much more so to glass than to SS or HDPE funnel, or teflon...
Some powders take me 30 min to add to a flask, and I mean before it's set up on its stand and boiled. It'll be add powder to HDPE funnel, use wooden
BBQ skewer or my ceramic thing that looks like a fencing sword, that I can sharpen with diamond/hone.
Once clogged I usually poke the tool through and do a 360° gyrating motion.
I suppose if said powder were dried, pulverized, dried, pulverized, added to an ante-chamber sort of funnel, like stopcock on top and on bottom, and
possibly ultrasonic waves or a vibrating device? should work well with teflon
I put powder in rbf using a simple funnel
and add liquid via a pressure equalised funnel
PS dont forget to weigh the rbf before and after adding the powder.
[Edited on 14-5-2021 by Sulaiman]
[off-topic] ahh Sulaiman! Haven't seen you around in a bit. Just wanted to let you know that I've fully embraced your thermometer system, but with
one modification. No oil or any liquid at all in the glass sleeve. I blow/stretch them thin. Every time I get dead on perfect readings. Plus I
have meter long K-type wires/sensors. which is great.
Also, your dismissal of temp control in almost all situations, was a serious paradigm shift for me. Much obliged.
Sorry for OT everyone!
[/Off-Topic]
[Edited on 18-5-2021 by earpain]
OP:
Ok my answer wasn't helpful most likely. I definitely know how there's those certain times where whatever solid, powdered reagent it is, it can and
must be added as a powder.
Last idea that comes to mind is: solid-into-solid absorption?
As in, fine mesh silica, impregnated with your reagent. All the journals do it these days for strong oxiders and reducers....And if properly
prepared, the silica should return to it's water-like free flowing ultra fine dust state. In which case an additional funnel would definitely work
