Oxcy Con - purity ?

wdgross · #1 2011-06-19, 11:49am

Newbie question on the 'how to use' the oxygen concentrator. From what I've read you need to let the machine (in my case an EX-15) run for about 10 minutes to get pure oxygen. My question is what to do with the OC between beads? Between beads I usually walk around a bit to flex my legs, think about life, browse LE, etc.

Currently I have left the OC run and kept the valve on my torch open. If I turn the OC off will I have to let it run for 10 minutes before I start the next bead?

I've only used my mega/minor for one day and never gave this a thought before (in fact I'm now going back and trying to find all those threads I skipped when I was on a HH

)

Thanks for any comments - you folks have been a huge help in this new endeavor.

Eileen · #2 2011-06-19, 11:52am

I've been letting mine run, but I'm going to be watching this to see if I should be doing anything different. Good question.

squid · #3 2011-06-19, 11:53am

You should just leave it running - it is made to run 24 x 7.

wdgross · #4 2011-06-19, 12:00pm

Thanks Squid - I will leave it run till I'm done for the day.

Dale M. · #5 2011-06-20, 8:07am

Let it run for time away from torch even if more than a minute or two.... Just close fuel valve on torch and leave oxygen valve open...

In medical use they run 24/365 and are good for 20,000 to 30,000 hours of operation... (20,000 hours = 833 days or 2.28 years)....

Dale

wdgross · #6 2011-06-20, 10:17am

Quote:

Originally Posted by Dale M.

Just close fuel valve on torch and leave oxygen valve open...

Dale

Thanks Dale - that's what I've been doing now. At first I remembered the POOP thing about how to turn the torch on and then off - but figured that must only pertain to tanked oxygen, if it matters at all.

JEK3 · #7 2011-06-20, 5:00pm

Leave it on. You cause more wear and tear on the machine if you turn it off and on.

lizard13i24 · #8 2011-06-23, 3:08am

WD-
I have a 13 gallon pressure tank between my oxycon and my torch With this setup I can turn down my oxy at the torch and walk away for a few minutes with the oxycon still running. When I come back to torch turn the oxy back up and I have alittle extra push from my oxy for a few minutes. This setup also allows you to turn down your oxy at the torch for detail work without causing harmfull back pressure at the oxycon. Not sure if there is any information here at LE on how to set this up but I know there is how tos over at the melting pot. PM me if you want to know more

Sheila D. · #9 2011-06-23, 8:02am

I was just talking to my husband about this and he said it is extremely dangerous to leave the oxy on and fill the room with oxygen.Any thoughts?

cheng076 · #10 2011-06-23, 8:54am

In general the room is not sealed enough to make it a big problem. There is always the possibility that the oxygen concentration could build up to unsafe levels so I leave my vent system running also. Most of us torch with an open door or window so build up is minimized via natural air circulation/movement. In the case of an oxycon the nitrogen removed from the air is exhausted back into the room so it altimately mixes back with the escaping oxy to form the original air mixture minus what was consumed by the torch when it is lighted.

Purity - The way an oxycon works is that environmental air is pumped into one sieve bed containing a material that absorbs nitrogen under pressure while leaving the oxygen to flow out to your torch. This is called Pressure Swing Absorbtion or PSA. At the point it has absorbed all the nitrogen it can the systen switches to put air into the other seive bed. At the same time the first bed is opened to the environment and the nitrogen is exhausted out of the machine since it is also and still under pressure. This cycle repeats. Assuming the beds are/stay clean the purity is reduced whenever the cycling time (fixed)* is out of the proper range since having too much flow does not allow as much nitrogen to be absorbed so some of it flows out to the torch and too little flow lets more air into the bed canister and it, the nitrogen, cannot all be absorbed, raises the system pressures and breaks down the sieve bed material. So you can see that very low or no flow is worse for the machine than too much flow. On the other hand flow at the lower end of the range is more pure as the optimal amount of nitrogen is taken out. Simplified explanation.

PJH

* since the cycle timing is fixed by the control board the flow rate through the machine is controled by the pressure. More pressure means more flow per time period.

Sheila D. · #11 2011-06-23, 9:15am

That's the simplified explanation?! Thank you PJ.I had my husband read it too,now he understands it more.So I will leave my oxy on and the vent,gas off,when I'm taking a break.

Lyssa · #12 2011-07-11, 8:32pm

Dale, so POOP doesn't apply with an oxycon?

Please confirm.

Thanks!

Quote:

Originally Posted by Dale M.

Let it run for time away from torch even if more than a minute or two.... Just close fuel valve on torch and leave oxygen valve open...

In medical use they run 24/365 and are good for 20,000 to 30,000 hours of operation... (20,000 hours = 833 days or 2.28 years)....

Dale

squid · #13 2011-07-11, 8:44pm

Quote:

Originally Posted by Lyssa

Dale, so POOP doesn't apply with an oxycon?

Please confirm.

Thanks!

Nope, it doesn't.

lotusbunny2009 · #14 2011-07-11, 8:53pm

I'm curious about POOP and oxycons too.

To summarize for my own understanding,

o you need to let the oxycon run for 10 minutes to build up oxygen purity and/or pressure? Which is the important factor?

o when not torching in between beads, say a few minutes, oxycon is still running--should the oxygen valve on the torch be open or closed?

o when done torching for the day, oxygen value on the torch should be left open to eliminate pressure in the oxycon?

o if oxygen value is left closed, and the built up pressure is left in the oxycon, what damage will it do to the machine?

Thanks for all your help Dale. I have learned so much technical and safety information from reading your posts. Also--love the squirrel avatar! Karen

cheng076 · #15 2011-07-12, 10:53am

lotus,

You need to run the oxycon 10 minutes to purge the system of air that enters when the system is shut down.

Between beads leave the oxycon running and torch valve open

At the end of the day shut down the oxycon and leave the torch valve open; ready for next session.

If the valve is left closed and the pressure is 'trapped' AND the oxycon is shut off there probably will not be any harm BUT if the oxycon is left on then you will damage the unit as it is not designed to operate against that kind of pressure. It has no relief safety valve.

POOP is still applicable except that instead of closing/opening the oxy valve you start/shut off the oxycon. Remember that you will have to close the oxy valve momentarily as you light the torch and when you shut off the flame.

To clarify. Enter the studio, oxy valve is open. Start oxycon and let it run 10 minutes. Light torch; close oxy valve, open propane, light flame, open oxy valve, adjust flame. Make bead. Ready to quit for the day; close oxy valve, close propane valve to extinguish flame, reopen oxy valve, shut off oxycon.

One way to think of it is that the oxy valve should always be open except to light the initial flame.

PJH

squid · #16 2011-07-12, 10:57am

I use POPO with my torch and oxycons. You can do it POOP but you don't have to.

lotusbunny2009 · #17 2011-07-13, 7:03pm

Thank you PJH! You have probably saved my oxycon! I haven't been leaving it oxygen valve open as much as I should have. So far it didn't seem to cause any problems.

Again thank you for sharing your knowledge and expertise!
Karen
lotusbunny2009

Eileen · #18 2011-07-13, 7:49pm

I could swear I read this is OK, but don't see it now.

When I start a new session, the first thing I do is make certain the torch propane is turned off just as a safety measure, turn on the oxycon while I get my stuff together I'll be using, etc. Then I go outside & turn on the propane tank, turn on the regulator, come in & momentarily turn the oxy off at the torch, light torch & turn oxy back on.

When I finish my session, with torch still lit, I go outside (just a few steps) & turn off my propane tank (leaving oxycon running & open at torch) then when the flame dies, I turn off the propane at the torch, turn off the oxycon, and then go outside & turn propane off at the regulator.

Is this part OK? I'm away from the bench a very short time.

(Left out turning on the fan to ventilate & opening window on opposite corner, but that's in there before lighting the torch)

PS. If I've asked this before I apologize, I'm getting a feeling of dejavu here, but don't really remember, maybe I'm goofy...

squid · #19 2011-07-13, 8:03pm

That's what I do too - go out and turn the propane off and let it burn off.

Eileen · #20 2011-07-13, 9:13pm

Thanks, I felt pretty good about it, figured if I was OK to sit there while it burned, I should be OK to step outside a few seconds, but I'm a worrier and like to be sure.

cheng076 · #21 2011-07-14, 9:28am

It is most often advised to burn off the pressure in your propane hose. It is probably a good idea but I do not do it. My feeling is that the hose is rated at over ten times the pressure in the hose and a few hours or days under pressure will not significantly harm it. The amount of gas in the hose is insignificant as the run is very short should it break or leak while I am not there; about 3 feet.

So, yes, add the step to burn off (releave the pressure) in your propane lines. My oxy lines are all steel pipe except for a short two foot connection from the steel piping to the 'distributor' manifold under the work bench.

Sorry I forgot to add a step that I don't do.
PJH