Using inert gas in vacuum oven

[Hash Man]

So I just picked up the 3.2 cubic foot vac oven from bhogart, and it has an inert gas inlet. My ai ovens don't have this feature. How r u guys going about using inert gas in your oven. I am a bit confused because it seems like putting gas into the oven while it is under vacuum will affect the hg levels. Anyone have experience with this?

 

[Gray Wolf]

So I just picked up the 3.2 cubic foot vac oven from bhogart, and it has an inert gas inlet. My ai ovens don't have this feature. How r u guys going about using inert gas in your oven. I am a bit confused because it seems like putting gas into the oven while it is under vacuum will affect the hg levels. Anyone have experience with this?

We use that feature on our Cascade TEK ovens.

We just let the pump strive for full vacuum and bleed in enough N2 to keep it at the vacuum levels we want.

That prevents vacuuming too low and boiling away your target elements.

It also helps speed up the purge, because once there are very few molecules for a pump to grab onto, and the ones that are present, are so far apart that they have little pull on one another.

The N2 acts like billiard balls, knocking loose other molecules that are lingering about, and dragging them along as they pass through to the pump.

 

[Flashthunder]

I use the inert gas inlet as a safety feature as well as what GW said. Let's say you were purging etoh and you go to break the vacuum with atmosphere introducing o2 and potential static sparks in a fuel rich environment. I'm sure the chances are low but better safe than sorry.

So I just picked up the 3.2 cubic foot vac oven from bhogart, and it has an inert gas inlet. My ai ovens don't have this feature. How r u guys going about using inert gas in your oven. I am a bit confused because it seems like putting gas into the oven while it is under vacuum will affect the hg levels. Anyone have experience with this?

 

[Rickys bong]

The inert gas inlet may also help due to the partial pressure law. If a solution of oil and butane boils at a certain pressure (or vacuum level) and temperature it will stop boiling once the oven gets populated with butane even if the pressure is only a few mm of mercury.

Introducing inert gas will effectively lower the boiling temp. or cause the butane to purge faster than without using inert gas.

RB

 

[queequeg152]

the inert gas inlet is for air sensitive work... recall that these units are primarly intended for laboratory work... drying glassware or prepping sensitive catalysts, or drying sorbants etc. nitrogen is almost always used for this because it costs almost nothing.

i think argon is good for transfering sensitive dry reagents because you can literally blanket a sample in cool argon while you are weighting it and transferring it to another vessle.

its usually just dry nitrogen though, but in rare cases its a noble gas like argon.
like someone mentioned above, the nitrogen is used to replace the air that is evacuated from the oven, otherwise your nice dry glassware or reagent would get contaminated as soon as the vacuum were removed.

there are entire books written on air free technique. people will go through insanely laborious and time consuming procedures assembling glassware just to exclude some insanely small amount of atmospheric oxygen and water from their reaction.

 

[live resin]

Pretty much what GW said. I have the BHOgart 32 oven as well. I would put a VICI Metronics N2 purifier in between the tank and the oven.

Most air/moisture senstive lab work is done with Schlenk lines, which come in both borosilicate and stainless steel. I've never used a vac oven other than for purging.

 

[queequeg152]

Pretty much what GW said. I have the BHOgart 32 oven as well. I would put a VICI Metronics N2 purifier in between the tank and the oven.

Most air/moisture senstive lab work is done with Schlenk lines, which come in both borosilicate and stainless steel. I've never used a vac oven other than for purging.

the schlenks are just manifolds for the most par.... manifolds that you can pull a vaccum on and purge etc, but still a manifold.

so yea i guess you can use them to exclude air from a reaction or other process once you have all the work up done and everything is assembled, but i was talking about the actual work up, or prep work one does to exclude moisture or solvents or oxygen from reagents or glassware or catalysts etc.... PRIOR to running a reaction or performing some physical process.

there is probably nothing you can do with a vacuum oven that you cant do with a schlenk and flame or heat gun or heated bell jar or what ever, but the vacuum oven makes it alot easier?

but we never had one in any of my labs, so im just going off what ive read in the lab manual and in other shit.

 

[Gray Wolf]

So I just picked up the 3.2 cubic foot vac oven from bhogart, and it has an inert gas inlet. My ai ovens don't have this feature. How r u guys going about using inert gas in your oven. I am a bit confused because it seems like putting gas into the oven while it is under vacuum will affect the hg levels. Anyone have experience with this?

We bleed N2 through our Cascade TEK's during final finishing. Open the vacuum control wide open and control vacuum levels by how much N2 you inject.

Under the vacuum levels that we operate at, the remaining gas molecules are too far apart to have much attraction on one another and lots of them tend to be stuck to surfaces, so rattling N2 cue balls through the chamber, not only knocks some of them free, but pulls them with it as they head out through the pump.

N2 is inert, so the extract doesn't oxidize, and has extremely low moisture content, so helps dry things out as well.

PS: In reading back, I can see that this is an echo, echo, echo.............