oxygen tank Question

[JuicyHaze]

looking into getting an oxygen tank so i can have an at home workspace. How long would a tank this size(see link) full of oxygen last if i just left my torch running hours wise? (on a midrange with minor) Would it outlast the gas in a standard sized grill propane tank,trying to get a rough estimate in hours on each typ of tank so i know how often ill be refilling.

http://www.ebay.com/itm/20-CF-welding-cylinder-tank-bottle-OXYGEN-BRAND-NEW-/130480043514?pt=LH_DefaultDomain_0&hash=item1e613775fa

[jr23]

waste of time that tank might last a hr give or take a bit.


go lease a k tank

[elad65]

At 20 cu ft a 5 gallon propane tank will out last about 50 refills of the small oxygen bottle. What you need to be looking at is at least a 200 cu ft (with 2 zeros) oxygen cylinder and not a 20 cu ft cylinder. What "jr23" said, you might get a hour and its not cost effective to refill as many time as its going to take to get same performance as a 200 cu ft cylinder for the difference in cost of fill. A fill of a 20 cu ft may cost you $15 and a fill of a 200 cu ft may cost you $25 ( dollar amounts are just for example).

Elad

[Icarus]

You would hate that. Plus, it would probably only cost you a few bucks less to fill than a 250 cf tank would.

[jr23]

Yep elad65 I think he sold his vehicle to start lampworking and does not like the public.

better get you social skills up for getting best price on oxy in your area.


A tank lease should be around a 100 and come full on a k tank. then 15 bucks a year or somthing.

Place I got mine never charges me the yearly fee

[B.C. Creations]

is this a joke? i see this thread going south in an instant

[Matt P]

That tank is a joke. Portable on site welding, but even a welding shop would laugh at using it regularly. I have a 155 cf tank, not sure what they call it. A "K" tank is bigger than it though buy a bit. I can fit the 155cf tank in my car though so that's why I went with it.

I know you hate the general public and can't seem to work with them, but the internet and online shopping will only get you so far. You need to go into the place you'll be getting oxy from and talk to them for a while about options. Some places its best to lease or rent tanks with regular, and small fees. Other places/situations its better to purchase a tank from them and exchange it when its empty. I bought a tank from the welding place, rather than renting because of my sporadic refill schedule.

You're gonna have to deal with an oxy/welding supply company anyway, might as well get used to it now. They'll give you all the info you need. Its usually way cheaper to rent than to buy your own tank, but I had the money laying around and looked at it as an investment, now no matter what happens to my life, I OWN a complete lampworking set up.

My 155 cf oxy tank gets refilled at least a few times before I refill the bbq tank. Propane is super cheap, and generally lasts a lot longer. I even switch my tank back to my bbq for grilling and it lasts a lot longer than my oxy :D

take that info and run with it before this thread falls apart buddy....seriously, just go talk to you oxy supplier, you need to be their buddy if you want to be a lamper.

oh, and getting an answer on how long it'll last is difficult. Use google/search function to find out the flow rates of your torch and you can get a real answer on how many hours of fully open valves your torch will run a tank. but, that's not that useful to you yet. I work an hour a night mon-friday if I'm lucky, and then around 5 hours on the weekends, and my 155 cf tank gets me through a week of that.....usually! well, more like most of that week, not quite all. And I'm running a midrange too :D

[bildo]

A k tank would last me less than 8 hours. A t tank lasts me less than 12 hours. Dude go with the liquid tank. You are a full timer right? No job. No income. I think it would be really hard to used compressed oxy if you are having to get it filled every other day. go BIG. remember: you are now a professional.

[LarryC]

A K tank is 330 cf....i usually go through my ks in about 12 hours.

[JuicyHaze]

thanks for the input.

[Greymatter Glass]

There is no such thing as a "K" tank as a standard industry-wide measurement of tank size or capacity for oxygen.

Various cylinder manufacturers use various numbers and letters for model number, and gas suppliers do the same for their products - there is no industry standard nomenclature for tank sizes.


The only "K" (just K, no other identifiers) tank out there is serviced by Scott here's the relative breakdown by supplier:

Scott: K
Airliquide: 49
AirGas: 300
Linde: 049(T)
Matheson: 1L
Praxair : T/UT

The IMPORTANT info about these tanks:

DOT 3AA
2400 psig
approx 277scf
9.25" OD
55" high WITHOUT valve
143 pounds tare
2990 Cu.in. / 49 liter water volume

Linde and Praxair both have other tanks with K in their designation.

Linde has a 044(K) that is 232scf (Scott "A", Airgas "200", Matheson "1A", Praxair "K/UK")

Praxair usually the source of the confusion about this "K" nomenclature.

Praxair services K/UK, 3K and 6K tanks. They are 232scf, 338scf, and 433scf respectively. The 3k and 6k are heavy wall tanks that are the same internal dimensions as a K/UK but are filled to either 3000psig or 6000psi and are not commonly used in welding or glass blowing (they would ruin standard regulators and require special valves).

back to the OP: your minor has a maximum flow rate of 16scfh, your tank holds about 20cf of oxygen, so if you keep your minor flame very small you might pull 3 or 3.5 hours of use out of it, but you'll be making small pendants, earrings, rings, etc - probably can't make more than oil burners with that flame.

The midrange has a higher flow rate, well in excess of 20scfh, draining a small tank in minutes.

[Matt P]

Its not cheap or easy to get into lampworking, but many of the big expenses are upfront costs, as opposed to regular overhead. Sure I have to pay to fill my oxy tank, but I only had the large expense of buying it once. Same goes with my ventilation, kiln, torch, hoses, regs. These are things that do need to be replaced, but if you buy quality products they can last for years and years. Once you really get a complete set up, your only expenses will be oxy/LP, glass, electricity. And those things, compared to the actual start up costs, are very minimal.

Keep that in mind with these purchases, like your hoses. You got nice brand new ones, they're gonna last a while. Now that headache over with and you (or us) don't have to think or deal with it. Same as your torch a few weeks ago.

Slowly but surely you're getting a set up. Get your torch lit, make some janky stuff, take pictures and happily surprise many people on this forum!

And remember, when you hear people talking about burning through K tanks in a day, you won't be capable of that financially, material wise, or likely even with patience. If you've got a vehicle that can move a K tank back and forth, as well as a moderately healthy back, I would recommend getting the biggest tank you can. Because if you really do stick with this, you'll be burning through small ones really quickly in the near future. I wish I had a bigger thank, but my vehicle setup doesn't allow it. My 155 cf tank does the trick, but its a pain sometimes.

And for a "simpler" (read:vague) explanation, my tank is about sternum/chest height. The K tanks are even taller, and very noticeably wider.

[LarryC]

There is no such thing as a "K" tank as a standard industry-wide measurement of tank size or capacity for oxygen.



I get them at Praxair and they are marked K and 330scf right on the collar. Thought that was an industry standard cylinder size. They measure 9.5" W X 60 inches T. Thanks for the heads up.

[Greymatter Glass]

I gotta see a pic, I have looked far and wide for information about so called "K" tanks, the ONLY reference I've found is via the praxair website, and they didn't list a size. The other charts I have seen list a K tank in whatever format as smaller tanks.

I've asked the plant manager at Airgas and he's heard the term, but couldn't tell me what it actually means - and it's always been glass blowers asking about them...

If indeed praxair refers to a 330scf tank as a K tank I stand corrected for the sake of Praxair's internal classification of their common tank sizes - but i still maintain that "K" isn't any kind of standard in the industrial gas industry.

[SpitfireMurphy]

I just looked at my latest purchase receipt..... From California Tool and Welding supply... 251cf.... $18.29 out the door
When I moved here I priced all 4 oxygen suppliers, and the other companies here locally wanted a lot more

I started put renting a couple of them many many years ago....then bought a couple and have been swappimg the empties for full ones ever since.

My advice would be to rent 1 or 2 of the big ones until you make enough money to buy your own.

[menty666]

Isn't the one linked to the same size as in those little welding cart packages Harbor Freight sells?

To chime in with the others, I lease my tanks (K, 300cf, whatever you want to call them) and I think the lease itself costs me about 35.00 a tank per year. I got the fill down to 16.50 per, so a touch over 20.00 after fees and taxes.

The benefit to a lease is that you don't have to care about getting tanks reinspected, it's on your supplier to deal with it.

If you can, schlepp them yourselves, it's good to form a relationship with your supplier so if something goes wrong you're not a stranger on the phone bitching them out.

Get a dolly to move them though, like Gray said, they're 143 pounds of heavy metal.

[Chad S]

I've always thought there was a such thing called a K tank...

[Chad S]

Please view the following link for more detailed information regarding cylinder size comparison.

http://www.scottsemicon.com/cylsize.html

[SpitfireMurphy]

Isn't the one linked to the same size as in those little welding cart packages Harbor Freight sells?

To chime in with the others, I lease my tanks (K, 300cf, whatever you want to call them) and I think the lease itself costs me about 35.00 a tank per year. I got the fill down to 16.50 per, so a touch over 20.00 after fees and taxes.

The benefit to a lease is that you don't have to care about getting tanks reinspected, it's on your supplier to deal with it.

If you can, schlepp them yourselves, it's good to form a relationship with your supplier so if something goes wrong you're not a stranger on the phone bitching them out.

Get a dolly to move them though, like Gray said, they're 143 pounds of heavy metal.

With my owned tanks, I have never had to have them inspected....i just brimg em in and swap em for full ones...
once in a while they service the stockpile of tanks by inspecting/painting/replacing valves etc....

[Role]

Always called the 330 a K tank when they delivered them to my scuba shop for
Nitrox mix, but I'm sure that's wrong. ;)

US Gov website, points to praxair pdf.

http://amo-csd.lbl.gov/downloads/Gas_Cylinder_Size_Praxair.pdf

Seems da gubmint is going with Praxair and calls the 330 a T size.

[Greymatter Glass]

Normal MAXIMUM fill pressure here is about 2300psi
1 atm = 14.7psi

P1(V1) = P2(V2)

P1 = full tank pressure
V1 = absolute volume of tank in cubic feet
P2 = 1 atmosphere, i.e. open to environment pressure at sea level.
V2 = unknown volume of gas at 1 atm

2300(1.73) = 3979 = 14.7(V2)

V2 = 3979/14.7 = approx 270.7scf

Praxair T tank holds approximately 270scf of gas @2300psi

same math, a Scott "K" holds 275.4scf

A praxair K holds 241scf

Now, that's using the ideal gas law... oxygen isn't ideal... so could certainly put those figures in some range... +/- maybe 5-10 scf... still not getting 330cuft in a T or a K tank. Maybe if the gas was very cold when filled... but at STP the pressure would have to rise well above 2300psi to fit that much oxygen in one of those bottles.

[Role]

DOT Spec 3AA-2400 at this site:

http://www.c-f-c.com/cyl/hp3aacyl.htm

Lists the Praxair T size at 337cf at 70 degrees f.


This site lists it as 307-330cf

http://www.lindencylinders.com/industrial.html


I'm guessing they are using a different formula or a different set of physics. :D

[elad65]

Go here:

http://www.worthingtoncylinders.com/Products/Industrial-Products/Industrial-Steel-High-Pressure.aspx

And download "HIGH PRESSURE CYLINDER SPECIFICATION" Blue bar right side, middle of page. Gets you document called "HighPess.pdf". Lists all tank specifications by size (dimensions) and tank volume.

This chart also adds to the confusion.

http://www.airgas.com/content/productChart.aspx?chart_type=6

Elad

[Greymatter Glass]

ok, now we're getting somewhere....

One thing I guess I skipped over... the DOT 3AA-2400 is a 2400psi rated tank,

so

2400(1.73) = 4152 = 14.7(V2)

V2 = 4152/14.7 = approx 282scf


closer to the magic number...


Still, that math isn't going to lie, I see no way a tank with an internal volume of 1.73 cubic feet can hold 330 cubic feet of oxygen at 2400 psi


When you do the math for the one below it, a 1.53 cubic inch volume you get this:

2015(1.52) = 3083

3083/14.7 = 209.7 which they claim will hold 251 cu ft


Maybe oxygen is considerably more compressable than I understood it to be... I can do the more accurate calculations, just not in my sleep.


maybe later.

I think the important thing here is that there's a lot of conflicting information out there, and I'm adding to it...

[LarryC]

ok, now we're getting somewhere....

One thing I guess I skipped over... the DOT 3AA-2400 is a 2400psi rated tank,

so

2400(1.73) = 4152 = 14.7(V2)

V2 = 4152/14.7 = approx 282scf


closer to the magic number...


Still, that math isn't going to lie, I see no way a tank with an internal volume of 1.73 cubic feet can hold 330 cubic feet of oxygen at 2400 psi


When you do the math for the one below it, a 1.53 cubic inch volume you get this:

2015(1.52) = 3083

3083/14.7 = 209.7 which they claim will hold 251 cu ft


Maybe oxygen is considerably more compressable than I understood it to be... I can do the more accurate calculations, just not in my sleep.


maybe later.

I think the important thing here is that there's a lot of conflicting information out there, and I'm adding to it...

Yup. One more tidbit. These all read just above 2500 on my regulator when i get them.

[elad65]

Umm, "Ideal Gas Law" explanation and formulas can be found here for nay who wish to diddle with it.

http://www.alspecialtygases.com/volume_of_gas_in_a_cylinder.aspx

Which is basically.

Volume of Compressed Gas in a Cylinder

To find the volume of gas available from a compressed gas cylinder, we apply the Ideal Gas Law (PV = nRT). In a high-pressure cylinder, the volume will be affected by the content's compressibility factor Z (PV = ZnRT). For example, an AL cylinder of pure helium may contain 134 cu. ft. of gas while the same cylinder of pure air may contain 144 cu. ft. under the same conditions. For these practical calculations, however, we assume ideal gas behavior for simplicity.
The Ideal Gas Law PV = nRT
Where:

P is pressure
V is volume
n is the number of moles
R is the gas constant
T is the absolute temperature
When the temperature is kept constant, we can derive the equation:
P(1) x V(1) = P(2) x V(2)
Where:

P(1) is the pressure of the compressed gas in the cylinder (psi)
V(1) is the internal volume of the cylinder, often referred to as water volume (liter)*
P(2) is the atmospheric pressure (1 atm - 14.7 psi)
V(2) is the volume of gas at pressure P (2) (liter)

For example, an AL sized cylinder is filled with nitrogen at 2000 psi. What is the gas volume of nitrogen from the cylinder?

P(1) is 2000 psi
V(1) is the internal volume of AL cylinder 29.5 liter*
P(2) is 14.7 psi
V(2) is the unknown volume of gas
Solving the equation above for V(2) gives:
V(2) = [p(1) x V(1)]/P(2) = (2000 psi x 29.5 liters)/14.7 psi = 4013 liters

(approximately 140 cu. ft.)

*The water volume of the high-pressure cylinders can be found on this site under the Cylinder Specs and Packaging section.

More data on cylinder sizes.

http://www.alspecialtygases.com/Prd_high-pressure_steel.aspx

Interesting bunch of tech data.

http://www.alspecialtygases.com/Rsc_conversion_factors.aspx


Elad

[Shatner]

With my owned tanks, I have never had to have them inspected....i just brimg em in and swap em for full ones...
once in a while they service the stockpile of tanks by inspecting/painting/replacing valves etc....

Yep. I own 3 300CF tanks. When I go to get more, they just give me fresh tanks. So there's no need to worry about inspection on 'owned tanks'.

Then I switched to 180 liter LOX.

[Icarus]

When they say "inspection", I believe they mean the hydro test that is supposed to be performed every ten years. Your tank then gets stamped with that month and date. Some places will make you do a new one if your test is over five years old and they've never dealt with you before (or are dicks).

[Monkythrowpoop]

Look around on craigslist for a tank. I found an "A" tank (a little smaller than a K) for pretty cheap (they wanted $50, got $30). Then it cost me $35 to get it inspected/into rotation at my O2 supplier. When I got my Homefill I asked them to give me the tank with the newest inspection date and now I just fill that up at home. Get a tank and a homefill if you don't want to deal with the public.