A simple question for those that did well in chemistry class -

As memory serves, yes, CO2, at ambient temperature, will be heavier than the majority of air(that being Oxygen and Nitrogen).

And doing a little math to help myself, Oxygen is generally in form of O2, so CO2 would be heavier(notice the extra letter) and Nitrogen, generally found in gaseous state of N2 is lighte rthan oxygen.

Nitrogen is ~70% of the air in our atmosphere, and Oxygen ~16%, so yes.

Plus there's fact that survivalists, for food storage, will stick a hose of C02 canister into bottom of bucket, and expect CO2 to stay in there and replace the air, so must be same weight or heavier.
 
Well, it was a question based on some ignorance but I figured with three atoms CO2 would be heavier, but its good to ask. So I guess that kills that.

Oh well.

Thanks a bunch. RL
 
In case you're interested CO2 weighs 44, O2 weighs 32 and N2 weighs 28 (molecular weights).

Anthony Lasome
 
OK give it up Roger
what are you up to now:confused:

I know carbon monoxide is heavier
it use to get me under the cars all the time in the shop.
that's why I'm brain dead now:(

I could tell you a navy story that almost killed
me and another guy in the lower decks of a decommissioned ship

when a bank of CO2 bottles were lite-off for fun..
eight cylinders of co2 will force the O2 right
out of three decks of hull real fast.
 
I figured some body would ask what kind of a hair brain scheme I was up to now.

Dan, some few days back (I think it was IG) started a thread about heat treating in a open ended pipe. That got me wondering about doing that with stainless except using a small open ended foil packet, so that the stainless could be removed quickly for quench - yet still minimize decarb. Well, I tried that and the results were not good enough. So then I wondered about the same thing except this time elevate the back (closed) end of the open ended foil packet and placing a dry ice nugget in the back of packet. If CO2 is heavier than air why try it since the CO2 will fall out of the packet and be replaced by oven air.

That was the reason for my question. Back to the drawing board.

RL
 
The fact that CO2 is heavier than air makes possible a neat little trick you can try on your friends (it works great on drunks ;) :D ).

Fill a small glass, that will fit inside of another larger glass, with vinegar. Put it inside the larger glass and then add some baking soda, but not enough to cause the foam to overflow. This will create carbon dioxide gas that will overflow and fill the bottom of the larger glass. Carefully remove the smaller glass with as little air disturbance as possible.

Light a candle and tell you intoxicated audience that you are going to put out the candle with water that they cannot see. Carefully pour the seemingly empty glass over the candle flame. It will snuff out as quick as if you really had dumped water on it. In fact you actually are pouring something.
If they didn't see you make the CO2 this one will probably cause them to drink a few more from thinking about it.
 
Kevin, what are your thoughts about having the CO2 foil packet (packet open at the upper end) slightly tilted upward in the HT oven with a blade within the packet?? Do you believe the CO2 would remain enough within the packet during HT to reasonably protect the steel from oxygen? I have, in my thoughts, ruled out anything combustable to aquire the CO2 because the combustion could cause a low pressure area. That is why I began to wonder about using a small amount of dry ice as the CO2 source.

Roger
 
Rodger, it's a good idea but it seems like it would "chimney" and draw in " ambient air" when it was heated.
 
If your doing an air quench could you just use something like the shield gas set up on a welder? CO2 tanks aren't that expensive.
 
they use argon now for this
co2 will work but may hurt the elements in the ele oven.
 
Any gas in a strongly heated environment like an oven will be subject to convection that will mix anything pooled in an open container like an envelope. This is really just a restatement of what Peter Nap said above.

If you want to use a non-reactive gas, you need to have it fill the whole space.
 
--------------
Originally posted by shgeo
Any gas in a strongly heated environment like an oven will be subject to convection that will mix anything pooled in an open container...If you want to use a non-reactive gas, you need to have it fill the whole space.
--------------

Steve, In the interest of furthering Roger along the slippery slope he's working on ;) , how about we semi-close the container holding the blade and non-oxygen gas. Wouldn't want to close it tightly. That would have too much KA-BOOOOM potential when the solid dry ice gets converted to CO2 gas!! ;)

I've attached a diagram of a loosely-closed canister with an oversized lid that could rise up a bit if the internal pressure in the can gets too high and thus "burp" out the excess pressure. I would guess you could also drill a small hole in the lid to constantly equalize minor pressure changes between the inside and the outside of the canister.

The lid has a clamping device to hold the blade by its tang in the CO2 atmosphere. Its handle (shown truncated in the diagram) would be long enough for Roger to grab hold of when he wants to do the quick quench dance.

I drew the canister showing the side of the blade being down for clarity sake on the lid clamp (oh okay, it's really just easier to draw it that way & I'm feeling lazy today :rolleyes: ), but in reality you'd want to suspend the blade in the can with the edge or spine down to reduce warping possibilities.

(edited to add) If the atmosphere inside the canister gets contaminated with oxygen when the blade gets yanked out for quenching and you need to do another heat cycle (not sure if that's done with stainless), you could just stick another chunk of dry ice into the can while you've got the lid off for doing the quench.

Alternatively, to equalize pressure between the inside and the outside of the canister you could also file some notches around the rim of the canister. Since the lid fits somewhat loosely, there could always be one or more of the notches open (by not having the lid flange pressed against it) to bleed off some of the pressure inside the can. How many notches to file and what size to make them is at the discretion of the person designing it.

The balancing act on the notches is to make enough to bleed off pressure without creating a large enough interface area for gas concentration differences to mix across. IIRC that's called osmotic pressure. But that term could easily be wrong because it's been WAY too many years since I warmed a seat in a lecture hall. ;)
 
Rokjok,
If we get that complex, we might as well use Argon which is really inert. Or build a vacuum chamber.

I wish there was a product to coat blades that would work up to the 2000°F range. I have had very good results with Turco from K&G on treatments up to 1870° on D2, but when I tried it on some S30V at 2000°, I lost em to bad decarb.
 
Back when I was in the battery industry casting thin lead battery plates we had an oxidation problem in the ladles. The fix was to partially cover the ladle but leave several vent holes, run a small volume natural gas line into the ladle and burn off the leaking gas at the vent holes. The lead was protected by a non oxidizing atmosphere while in the ladle and the burnoff helped with heating the molten lead. Should work inside a non sealed forge. Definitely would not do it in a forge with a tight door on it.
 
Originally posted by george tichbourne
Definitely would not do it in a forge with a tight door on it.
Click to expand...

C'mon George! Where's your sense of adventure!:D

A friend of mine did that with flatulence one time...we are still searching for him.

Craig
 
I've suggested a couple of times about filling the pipe with sand to even out the temperature. I guess the idea is too stupid to get a reply but it would seem that, with the dry ice to replace the O2 and the sand to keep air movement to a minimum, that it would work.
??
Still trying, Lynn
 
You must log in or register to reply here.
Back
Top