Economical oxygen generation for industry question

[MikeSmith]

Hello I am purchasing an oxygen filling plant from ogsi or airsep for my shop we go through about a half a liquid per day about 90 liters give or take , I'm planning on getting the setup to fill 8 cylinders ( k tanks ) per day and buy a bank of 24 k tanks and just fill them all , it all sounds great ? But I'm asking you guys if there are any drawbacks ? Is working on 93% any different than 99% from a Lox tank ? Does this seem like the way to go over a liquid ? Ill be saving in the long run but I'm just curious what your thoughts on the pros and cons may be of this setup for a large glass studio ? Noise pollution ect ... Ty for your input !

[skip]

have you looked into getting a larger capacity liquid tank. Cornerstone has a huge one and there is a transmitter that signals airgas when it gets low. They bring a liquid oxy truck and fill the tank from the truck. Not sure what the fill price is but it's got to be very inexpensive compared to liquid dewars.

[misled youth]

the micro bulk systems are great, i almost went that way back when i ran full time prodo.
they drop a tank in yard kind of like a LP tank. digital flow control's and never freezes.
there is 18 k tanks in a 4500 lox tank if i remember correctly.
i think if you are going through that much, you are going get tired of switching k tanks real quick.

if it was me, i would look into the micro bulk system

[glassblowingBiker]

If you can get it go micro bulk all the way
Yes you will see a slight dif in filled tanks over liquid

[Greymatter Glass]

I've done the math on the Pro-4 and Pro-8 ... which if you're using over 2700cuft of oxygen a day, I'm not even sure those machines can deliver that can they? ... anyways....

Depends on where you're at in the country, here I pay just shy of 12¢ per kWh and I can get 180L of LOX for $120. There was no way the $10-12k investment in my own plant and 12¢ kWh to run it would pay off... when I did the numbers it was a 30+ year break even point assuming no maintenance and no rate increase on power, which is unlikely.

So yeah, I would look into a micro bulk solution, call around, talk to plant manager and sales people, have them come to your site and get an estimate on it. If you're within 100 miles of a commercial air liquification plant it will almost always be cheaper to use liquid than to make it yourself.

As for 93% vs 99.5% purity, well, I've used concentrators, I FEEL like I could tell the difference, and there's certainly a difference in the math, but it's pretty minor. Flow and pressure are certainly much larger concerns.

You could maybe talk to someone at a gas supplier and see if they can make a custom blend of 93% oxygen and 7% nitrogen, and see what you think, you're a big enough customer that you should know someone on the plant side of your supplier right? I know I can get stuff like that if they're not busy and I am willing to wait a few days.

[VinE]

What do you guys make mostly? What torches you running? Probably be noisey. u looked into the new high volume 02 machines. they seem quieter.

[istandalone24/7]

out of curiosity, what benefit is a 93/7 blend of oxy and nitrogen?

[dustyg]

out of curiosity, what benefit is a 93/7 blend of oxy and nitrogen?

It lets you try concentrator-purity before you decide to buy a bunch of concentrators.

[VinE]

^^Tanked and liquid o2 is 99% pure o2.
Concentrators vary in purity : 93-99%. Most glass/welding/hobby 5-10lpm push between 95 and 97

[LarryC]

Most glass/welding/hobby 5-10lpm push between 95 and 97

Where did these numbers come from? At what percentage of rated output are these specc'ed out at? My research suggests that reality is substantially lower than this at anywhere near full output.

[dustyg]

^^Tanked and liquid o2 is 99% pure o2.
Concentrators vary in purity : 93-99%. Most glass/welding/hobby 5-10lpm push between 95 and 97

Do they? Most of the listings I see say 93% (or less) +-3%. Even the higher-end Sequel Integras and Regalias only claim 91% +-3%, and this is with medical units, before their output is pumped up (and, some claim, purity is decreased - can we get some tests?) by the after-market modifiers like UO.

[istandalone24/7]

can't be too low....my ex15's don't trip the "low o2" sensor on my homefill?

[VinE]

Do they? Most of the listings I see say 93% (or less) +-3%. Even the higher-end Sequel Integras and Regalias only claim 91% +-3%, and this is with medical units, before their output is pumped up (and presumably purity is decreased) by the after-market modifiers like UO.
Yea the hobbycons like what you mentioned are kinda janky for running big flames. I was lumping industrial and hobbycons together to make a general point.

[LarryC]

Do they? Most of the listings I see say 93% (or less) +-3%. Even the higher-end Sequel Integras and Regalias only claim 91% +-3%, and this is with medical units, before their output is pumped up (and, some claim, purity is decreased - can we get some tests?) by the after-market modifiers like UO.

After discussing this with some of the industrial suppliers I am getting the impression that at maximum output 90% might be more accurate on most medical units.

[dustyg]

After discussing this with some of the industrial suppliers I am getting the impression that at maximum output 90% might be more accurate on most medical units.

Industrial suppliers have a dog in the fight, though. I'd like some independent studies. Maybe if we had an oxygen purity tester to pass around. . .

[STROKER]

My pro 8 is rated at 96% pure according to a very expensive meter.
I tested it while the tank was in various stages of filling and it is quite consistant.
As for work8ng it. I dont think it is enough difference to hardly notice.
Liquid is a tad hotter but I can do anything on my delta that a blower on liquid could.
Once the purity goes below 90 the flame gets noticeably cooler and less friendly. Then the machines are no good to us.
I have said it before. These set ups dont come close to replacing liquid. But if that is not an option and you want alot of o2 then this is a great route.

[Greymatter Glass]

I think there's a few things getting confused here....


Oxygen USP, i.e. "medical grade" is only required to be 93% purity. When they "certify" a line of patient administered medical oxygen concentrators they make sure the design is technically capable of supplying 93% then they test each unit over a period of 8 hours and make sure the unit, when running within it's specified operating parameters, generates an average of at least 93%.

There are sensors in the little units that sort of monitor purity, in the case of an Invacare Platinum XL I think it sets off the alarm around 72 or 73% which is a signal that it's time to get the unit serviced or replaced.

There is a label in the unit that says they produce a range from like 86 to 97% purity depending on many factors such as altitude, age of the zeolite sieve bed, flow rate, and the condition of the filters... What they can't change is the ratio of oxygen in air, that's pretty much hard wired to 20.8%.

In use the lower the flow rate the higher the purity (usually), but it's not going to be major, maybe you'll get 96% at 1lpm and 93% at 10lpm on a 10lpm unit.


The bigger PSA concentrators like a Pro-4 or Pro-8 system work the exact same way, there are 2 or 4 tubes that act as molecular sieves, and a compressor alternately fills and purges them to capture the oxygen (and smaller molecular gases) and purge everything bigger than O2 molecules. But they are larger and more efficient, and therefore when they're running properly and maintained well they often produce a higher purity in practice (it's the same technology, so it's not magic, just numbers). Still, an old poorly cared for Pro-8 could produce less purity than a new top of the line home medical concentrator.... it all comes down to how well maintained each piece of equipment is.


And like Jay said, I don't think they're really a replacement for liquid O2 except under some very specific circumstances.

[VinE]

^ exactly doug. I remember a couple years ago; Natefizzle hooked one up without an air dryer and killed the seive beds of his instantly . moisture from condensation from compressors will fuck your purity quick. So logic would dictate that if you live in an area that has high humidity/heat you should make sure you have dry air feeding your unit. As far as being a replacement for liquid...
....all depends on what you are making and what type of torch you are using. If you have some unnecessaryly big uber torch and you want to make sure your 4" marbles strike out clear in the flame then by all means forego estblishing equity in your equipment and the concept of R.O.I.

.The concept of using a big torch as a crucible seems od inefficent for making. large peices...if you want to make big stuff in boro buy a crucible, don't try to make your torch one...it wastes fuel. If most of what you make can fit in a bread box and weighs less than 3lbs i couldn't see how you would notice much difference .