Liquid Oxygen Help Needed

[Logan]

Just getting back on liquid oxygen after using tanks for the past year. Ive had issues with venting in the past. After a recent search I discovered that you can adjust the head pressure on the tanks so that venting is not such a problem. My tank has a different set up than the ones Ive seen. Please help me make sense of the pressure adjuster(econimizer) set up. The metal cap on top actually screws in and out, revealing a chart of different pressures. It was all the way on, so turned it counter clockwise until it showed 120. Havent messed with any of srews yet.

Thanks!

[Forche]

That it's ur pressure builder not ur vent.tanks are rated to release at certain psis. Try to get a tank with a 350 rating...there should be a tag on ur vent output. Also I have my pressure system (the orange dealy) to 240 with a release rated at 350.

[Louie HaHa]

I have never used a dewer that looked exactly like that, with the screw top chart deal on top. However, the best things to ensure you don't vent is to maintain the pressure under what the relief valve pressure is set at (usually like 230 lbs) and to tighten the 'liquid' valve. When I say tighten it, I mean crank the shit outta that puppy. Usually I wouldn't recommend tightening any valve that hard, but that's the way I've found to cut down on venting. I learned it from a few different guys in a shop I worked at. It may be that I usually tighten it down once I notice it was already venting, and by that time it's pretty frozen, so it might be because it's frozen that you have to crank so hard. Use a towel/glove/etc if it is frozen.


Hope this helps.

[Slow]

Call your oxygen supplier and ask them.


maintain the pressure under what the relief valve pressure is set at

Also, this. If you blow enough glass, you'll never hear the tank vent.

[hashmasta-kut]

those are usually good tanks. all the ones i have gotten like that have been awesome. the silver thing with the readings is to set where you want your tank pressure to sit. the green handle(Mine are black and a different shape) is to open the pressure builder. if its open it will build pressure. make sure its closed if you are having too high a psi, and unscrew the top thing to read around 60 or 80. if you dont have enough pressure open the green handled valve a bit. if your tank is closer to empty you will have to open the green handle further to engage the pressure builder. you can hear it when its working, a slight hiss inside.

[Logan]

Should of mentioned the vent pressure is rated a 350. Im trying to figure out how to set the head pressure. Im hoping its just the big cap on top that screws in and out. The guys on the phone and the delivery guy didnt seem to know anything about adjusting it. Might have to call again and see if i can get someone on the phone who has a clue.

[hashmasta-kut]

Call your oxygen supplier and ask them.



Also, this. If you blow enough glass, you'll never hear the tank vent.


lol whatever, man, i have had tanks that i worked like damn crazy and they vent out in 5 days. i would work them at 5 am and then be goin out at ten or 11 pm and still the damn things can vent like hell if they are fucked.

[Logan]

Thanks Hashmasta!

[hashmasta-kut]

Should of mentioned the vent pressure is rated a 350. Im trying to figure out how to set the head pressure. Im hoping its just the big cap on top that screws in and out. The guys on the phone and the delivery guy didnt seem to know anything about adjusting it. Might have to call again and see if i can get someone on the phone who has a clue.


it is man, that top thing is the head pressure thingy. but if your tank has sat for awhile, and has high pressure built up, it will have to be worked hard or vented so it can sit at the level indicated by that gauge.

[menty666]

You might want to go to your supplier and ask them for a tank meet and greet.

It's like when I rented a skid steer, I made sure the delivery guy gave me the 10 cent tour so I didn't kill myself.

Safety first...

[Slow]

That sucks man. Maybe the pressure builder was set too high? I'd call the supplier and complain if it's really that bad. Come to think of it, I did have a dewar vent like crazy a few years ago; when I called my supplier they asked that I not mess with it (their policy, I guess), but they did give me 1/2 off my next 2 lox tanks.

[hashmasta-kut]

You might want to go to your supplier and ask them for a tank meet and greet.

It's like when I rented a skid steer, I made sure the delivery guy gave me the 10 cent tour so I didn't kill myself.

Safety first...


depends on your guy i guess. after just a few minutes of reading on this forum i knew way more than he does. i got 99% of my liquid oxy info from searching this site.

[Logan]

Been rockin it out all day, got it from 300 down to 200. Also set the head pressure at 80. Curious to see if it goes back up by morning tomorrow. Damn it feels good to be back on liquid. No more slugging around 2 k tanks at a time in my honda accord.

[Grape]

hell yeah i feel ya liquid rocks!

[n3rd]

those are the good economizers!

[Firekist]

... i agree with everything HMK said.

someone pinch me, i must be dreaming ;)

logan, only use the big silver knob to adjust your head pressure.. not those screws.

--seth

[Julian]

Welding places WILL give you dangerously out of shape tanks, with significant vacuum leaks. The best tanks won't vent at all with light to moderate use. Tanks in bad shape will vent under moderate or even heavy use. The WORST tanks will vent insanely no matter what you do.

Airgas in Albuquerque had a habit of dropping off those dented, white painted tanks at my house Friday afternoon. In the morning, at like 2 am I'd wake up wondering... what the hell is that noise? Oh, my neighbors using a drill. Wait, it's 2 am... hmm. Then I'd go outside and yep, tank was shooting a visible plume of oxygen a foot long. After a couple of days, it would be a 16 inch icicle.

That was really cool until like the fifth time. I'd vent out excess oxy and try to use as much as I could over the weekend, since it was always a weekend (on my awesome Major Minor, no problem).

Airgas would always mutter about how I must have turned on the pressure builder, blah blah. As if I'm a total idiot, I mean I'm a glassblower. But they'd always give me a replacement tank for free, too.

Argyle Welding in Abq. actually sent over a salesman to explain the tank to me the first time I got one... it was exciting. They also wanted an $800 deposit, though. However their tanks lasted about 3 times as long on average as even the good ones from Airgas, for only twice the fill cost.

[Greymatter Glass]

The silver cap is the pressure setting for the economizer.

DO NOT mess with the small cap screws holding the thing together.

I would set it somewhere around 240psi

[hashmasta-kut]

why 240?

[Greymatter Glass]

mostly arbitrary, but it's high enough to run any torch, and below the vent pressure enough that it's unlikely the tank would vent if it has a good vacuum on it still. Natural pressure build shouldn't exceed 50psi per 24 hours, so he would be able to let the tank sit unused for 2 days that way...

Also, depending on the regulator you might need more than 100-120 psi back pressure to get proper flow.

And I am just going by the markings on the cap - you could easily guesstimate 210, 250, whatever....

As I said, mostly arbitrary. 12 years messing with these things it's just where I would set it, but I don't have any granted authority to say it has to be there, and I fully encourage experimentation - tho I would suggest to stay between 140 and 320.

[Forche]

TY Doug. It seemed my first post was ignored about the 240 setting for the economizer . I knew 80 was way too low...

[Greymatter Glass]

oh hey look at that... totally not intentional, but yeah, I think there's some kind of Zeitgeist thing going on here.

[hashmasta-kut]

interesting. i have run the last three of these typs i have gotten setting it to around 80 psi, and they have behaved well, although with heavy use i have had to crack the pressure builder.

[Logan]

Maybe I need to vent it down quite a bit to get it to stay around the set pressure. Its set at 80 right now. Over night it went from 200 up to 325. Should mention Im in central texas with 90+ degree days. Im just working solo on a red max so 240 seems a little excessive for my use.

[Forche]

:-) ..Yea I have a 3 man shop rocking lathes and deltas everyday in Tucson. 80 might be good for a single person on a max.

[hashmasta-kut]

Maybe I need to vent it down quite a bit to get it to stay around the set pressure. Its set at 80 right now. Over night it went from 200 up to 325. Should mention Im in central texas with 90+ degree days. Im just working solo on a red max so 240 seems a little excessive for my use.

if this happens after you have worked it a lot still, then it may be a bad tank. that sounds way too fast for regular pressure building. i hve had three tanks like that one in that last while and they were all very docile and well behaved, never rising above a 100, and even in pretty high heat for one of them.

[Logan]

Im not really sure how the pressure system on the tanks work, but I wonder if there is a correct order of operations in dialing it all in. Such as: vent tank to desired psi, then set economizer.

If I set the economizer psi, but not drop the tank psi to the same level, should the tank psi just stay wherever it is until it gets worked down to what the economizer is set at?

[Julian]

If it's not a good tank, it doesn't really matter how you set any of this. Some gas will boil off the liquid continually no matter what. With everything set right on a really good tank, it will be less than you need to run an average torch. If it's a mediocrely maintained tank, with the same settings, much more gas will boil off than you need and there's nothing you can do. Then if it the gas pressure exceeds the pressure you have set, whether it's 120 or 200 or 300, the gas will be vented. You may be able to make it vent more slowly by changing settings... maybe not. You can certainly make it happen more quickly by turning up the pressure builder, but that's the opposite of course.

So, while it's good to understand how these settings work, keep in mind it will never make a liquid tank work like a gas tank. If you don't use enough, it will vent, period, and how much depends on the tank and whether it has had good maintenance.

[AdamCotter]

Does anyone know of a "half size" dewar? going back to tanked from Lqd SUCKS, up and down stairs. Full size wont fit . If i could afford it i'd get two more concentrators. Running a Mirage, and a Tigershark, 1-2 tanks a dday.

[Logan]

The economizer doesnt seem to do much of anything for regulating the tank pressure. I was told it was pretty new tank. Last service was may 2012. I have the silver cap thing unscrewed until it reads 80. Took the day off yesterday and it had climbed up to 375 this morning. Just been manually venting when it gets up there so I dont have it popping off. Hope it last long enough to make it more affordable than tanks. Paying 180 for fill and delivery+ 50/ month rental.

[Role]

If i could afford it i'd get two more concentrators.


If you live in MT one of my concentrators was on that train that derailed Tuesday.

UPS can't find it, It's probably laying on the tracks... Go get it... :)

[Aymie]

Alamo is cheaper than that and has the best tanks in town in my opinion.

Also, the pressure builder should always be closed. You open it to build pressure then close it when it reaches the desired point.

[hashmasta-kut]

The economizer doesnt seem to do much of anything for regulating the tank pressure. I was told it was pretty new tank. Last service was may 2012. I have the silver cap thing unscrewed until it reads 80. Took the day off yesterday and it had climbed up to 375 this morning. Just been manually venting when it gets up there so I dont have it popping off. Hope it last long enough to make it more affordable than tanks. Paying 180 for fill and delivery+ 50/ month rental.

you should probably try and get a half credit. tell them how fast i builds pressure and how many hours use you got out of it. most people can get 3 weeks at least from a liquid tank, and many running solo can go 5-6 weeks on a good tank, with moderate use.

[Logan]

Thanks for the heads up Aymie. Guess alamo is trying to pull a fast one on me then, cause they are my supplier and have been for a few years. Thats the price they have always sold me liquid for, and k tanks for 18 refill, 5 rental. What are they charging you, if you dont mind me aksing? Also, the pressure builder is definitely closed all the way. Im trying to keep the pressure down by adjusting the economizer, which doesnt seem to be doing much of anything.

[Aymie]

I don't adjust anything. I refer all questions to my delivery guy and he had things adjusted for me. But he doesn't work there anymore. Since he changed jobs I have been reluctant to get oxygen delivery elsewhere. I got really spoiled to my guy and alamo in general. I love them. I order all my fittings and hoses from them as well. It's been years since I had an account there but I believe I paid $150 fill and delivery and $50/month rent. Possible prices just went up since then. Also, I haggled for my rates, and tip very well. The tipping part helps get you way better service.