Liquid Oxy question

[HOSS]

So apparently my oxygen supplier has two different types of liquid oxy tanks - high pressure (200something) and low pressure (30something). I've used the high pressure ones before, I'm assuming since our torches don't need a lot of pressure the low pressure type should be fine too (maybe even, better?), but before I order one and possibly end up with something useless I thought I should try to get confirmation. The welding people that work there are no help. Anybody know the deal with this?

[wildrokproductions]

High pressure= tank like a t or k or whaterever letter
Low pressure = liquid..

[Glassroots]

Go with the 500. I have used both types many times and now only get the 500 because.....

I does not bleed as often if you don't use it

it works better with multiple torches, especially when you need that extra oxy for your gtt or whatever

trust me on this, you will get more for your money

[Kool]

Yeah, the 500's are the way to go if you can get them. Vents less often (if at all). But most places don't have or won't get a 500. So normally your choice is between a 230 and a 350. Go with the 350.

BTW, the number just represents at what pressure the thing is designed to vent.

[HOSS]

High pressure= tank like a t or k or whaterever letter
Low pressure = liquid..


I thought so too until recently... but thats not what I'm talking about. Check out the different pressures listed on the liquid tanks

Taken from the Airgas website:


OX 180LT22 - Liquid Oxygen Industrial 180LTRS 22PSI

OX 265LT350 - Liquid Oxygen Industrial 265Ltrs 350Psi

OX 180LT230SS - Liquid Oxygen Industrial 230PSI 180LTRS

OX 450LT500 - Liquid Oxygen Industrial 450Ltrs 500Psi



Yeah, the 500's are the way to go if you can get them. Vents less often (if at all). But most places don't have or won't get a 500. So normally your choice is between a 230 and a 350. Go with the 350.


According to the guy I talked to, my only choices from them out of the list above are the 180 liter, 22 psi and the 180 liter, 230 psi. I think he also mentioned a 30something PSI, that seemed worth considering (might have been a different grade). The 230 they carry apparently has a large base with wheels welded on, that won't fit through the 3 foot wide door of my studio. And I guess there's no 350s or 500s at this location... Bummer. :bangHead:


BTW, the number just represents at what pressure the thing is designed to vent.

Ahhhhh ok, I was assuming the PSI listed was the the pressure of the oxy in the tank, and the guy I was talking to seemed to think the same. So I guess that means the 22psi would probably be venting all the time? Definitely don't want that. Guess I'm kinda screwed. :/

Thanks for the info guys, think I'm a bit less confused now. But still stuck changing greenies all the time. :crazy:

[Greymatter Glass]

not to thread jack, but related question...

New 180L dewer like-new for $1500... do it?

[Kool]

not to thread jack, but related question...

New 180L dewer like-new for $1500... do it?

:) New or like-new...which is it?

If it's new or close enough, I'd do it for sure...that's a good deal.

If it ends up being well used, search more I think there are "rebuilds" out there for a lot cheaper....I seem to remember prices of $750 and $900. Of course, if it's local to you that makes a difference too.

I'm getting jealous of your spot the more you get it going, Doug.

[somewhere]

not to thread jack, but related question...

New 180L dewer like-new for $1500... do it?

stainless steel or ferrous? I almost bought one myself but decided I'd leave the maintenance to them. My oxy place also charges more on a fill for customer owned tanks. I also get free delivery which wouldn't work for customer owned.

One more,
make sure they fill locally or you'll need to buy two.

I was looking at $800 fro a three year old lazer tank stainless.

[FiredDesires]

It seems to me, months ago in a discussion about LOX tanks, somebody mentioned that there is some type of screw (somewhere) that you can manipulate a little bit, to make the tank vent less often/at a different pressure. I'll have to go on a search.
It is all too scary for me to be monkeying around with anything other than hooking the green line up and opening the valve right now! I'm sure these companies have this info (like posted above) for a reason. I'm not sure which LOX I get, but the venting has been different on the last three I have ordered.
My supplier is nice enough to order them for me from Seattle but virtually knows nada about them, "your on your own, Cat...I just order them!" At 78.00 a K tank, I can vent off over 1/3 of the LOX and still be money ahead. How many K tanks in one of these LOXes anyway, does 16 sound right?

[mistahead]

the low pressure one just meens that its set to start venting once it reaches 30 psi..
so dont do it...ive already made that mistake for you!!

[HOSS]

the low pressure one just meens that its set to start venting once it reaches 30 psi..
so dont do it...ive already made that mistake for you!!


Thanks, I'm glad I asked about it here first. :) Apparently to get a 500psi I have to sign a 7 year lease or somesuch, so I ended up with a 200liter, 230psi. Its been ok so far, but I only work about 4-5 hours a day and that pressure gauge is slowly creeping up on the 200... would be nice to know what screw to turn to set it a little higher, although I'm sure it would piss off the Airgas guys.

[Kool]

... would be nice to know what screw to turn to set it a little higher, although I'm sure it would piss off the Airgas guys.

If you can take a photo showing the top of your dewar, it would easier to explain to you...there are at least 2 different types that I've used...not sure if there are other types besides those.

It's normally either a screw on a bell-shaped regulator (back it out... counterclockwise) or a vertical stainless cap-looking thing (when I had this kind, it was to be turned the opposite way, meaning you tighten it down...clockwise).

Either way , it should be fairly easy to spot b/c it's tied into the pressure-building set-up (which is hopefully labeled for you.) And sometimes the screws/caps have small markings with various numbers on them, so you know what pressure you are setting it for.

[HOSS]

Either way , it should be fairly easy to spot b/c it's tied into the pressure-building set-up (which is hopefully labeled for you.) And sometimes the screws/caps have small markings with various numbers on them, so you know what pressure you are setting it for.

I've taken a look and there's only one screw on the pressure-building thing (not counting the knob), so I guess that must be it? Its on the end of a little cannister-looking gizmo, seems promising. I'll look for any small markings or numbers on it tomorrow when there's more light, and give it a try. Thanks for the tips!

[Glassroots]

Thanks, I'm glad I asked about it here first. :) Apparently to get a 500psi I have to sign a 7 year lease or somesuch, so I ended up with a 200liter, 230psi. Its been ok so far, but I only work about 4-5 hours a day and that pressure gauge is slowly creeping up on the 200... would be nice to know what screw to turn to set it a little higher, although I'm sure it would piss off the Airgas guys.


Just so you know, adjusting that screw will only control the pressure build, not the vent psi. In other words your tank is still going to vent at 230 but if you are using a lot of gas and need it to be produced faster, that screw will control the rate at which it is produced if the pressure build is on. Thats why its better to get the 500 because it gives you more time till it vents. Look at it on the bright side, it will keep you working harder.

[HOSS]

Just so you know, adjusting that screw will only control the pressure build, not the vent psi.

Are you sure we're talking about the same thing? I know the pressure building knob will do what you're describing, but I think the cap/screw that Fred and Koolglass were talking about is a seperate part for setting the pressure that it vents at, so that I can make it higher than 230. Am I misunderstanding you KG? Getting the 500 isn't an option, they want a 7 year contract for it as stated above, and thats just nuts. And the 350 they offer won't fit through the door. You're right tho Glassroots it has been keeping me working harder. :crazy:

[Kool]

That adjustment doesn't set the tank to vent at a higher pressure. But it can still help you. The lower it is set, the less pressure the dewar will try to build, so you won't reach venting pressure as fast as you would if it was set higher.

For example, if the adjusting doohickey is set at 350, your dewar will always be trying to build pressure to maintain a pressure of 350, therefore reaching venting pressure faster. If it is set at a lower value, it will help. It is not necessary for the pressure build knob to be on for the adjustment screw to have an impact.

[HOSS]

Ahhhh ok that makes it clearer, thanks!

There are no markings on it, any idea how far I should turn it?

[Kool]

That's relative...depends where it's set at now. Small turns until you figure out what works. A couple times I thought mine didn't have markings but then realized it was just dirty as all hell.

[Mr. Whale dick]

you can tell what psi you tank vent ...it says on the vent nozzle...


that nozzle is the only deffrence between tanks venting at diff psi's

one time the delivery guy can back to the shop and switched out our nozzle to a higher one...(he had to purge all the pressure in the tank to do it)

[Greymatter Glass]

tanks are designed to vent. You can't stop it. you can minimize it.

First thing I see is that suppliers sometimes open the pressure builder when they fill the tank. if you don't need pressure, close that valve.

Next, if your tank is venting, you're just not using the O2 fast enough. You'll have to lose some.

If you have to store the tank un-used for a few days or a week or 2 then close all the valves nice and tight and open the "VENT" valve till the head pressure drops. then close that valve. it will usually stop pressure venting for at least 24-48 hours, sometimes longer depending on the tank.

A full tank has a shelf life of about 30-40 days. I've had tanks that lasted 2 months with regular but light use, i.e. a single midrange on it, 15 hours a week. Now I'm glad when a tank makes it 2 weeks, but it gets used rather than vented.

Figure you can loose up to about 5% of your liquid per day - use it or lose it.

-Doug

[FiredDesires]

So glad several of you chimed in on this thread, searching for what I was talking about wasn't forthcoming none too soon. But glad to see/hear that "I" wasn't losing my memory about this...I knew I remembered something, just couldn't put my finger on it! lol

[HOSS]

Werd. Thanks for all the helpful info folks I think I understand how they work much better now.