Proper building of a compressed oxygen tank system
After seeing Trey and the Wonka's ideas for building a compressed tank O2 system I have decided to take the plunge and build one myself to save dragging K tanks into the basement.
So here's the plan. I have a EX-15 now. I was thinking of either buying a second one and daisy chaining them together and feeding that into the vacuum side of the Gast oil less vacuum compressor (a ROA model rated to 100 psi) and bringing the compressed air out a storage tank 30 or 60 gallon with a 80-100 psi compressor pressure switch. Or buying a Hurricane and putting that in place of the 2 EX-15s. Thoughts? Also apart from cleaning the tank and perhaps the head of the ROA since its used, anything else I should be looking for? Also what should I use to clean the tank / head to take out any oil residue and obviously not leave any propellant or carbon residue behind? Thanks!! |
Ummm..........
http://www.gastmfg.com/technicalfaqrocr.html Particularity these lines........ Q: Can water be pumped through my unit? A: No, clean dry air only Or.... Q: Can I pump explosive gas through my LOA? A: No, none of Gast models are able to pump explosive gases. To me ALMOST PURE oxygen is explosive gas.... Dale |
I'd recommend contacting Trey Cornette before going much further with this. He's had some valuable experiences. This doesn't strike me as something to take on without a great deal of careful research on how to build high-pressure oxygen systems and how to avoid unintended explosions. I think Trey, and perhaps others, can help you understand the difficulties associated with eliminating residual oils or other volatile/combustible residues left over from manufacturing a given gas storage tank and how to incorporate the right safety features.
Trey alluded in a post to something coming out on the market that may make it less interesting to make your own system. He seemed pretty excited about it. I don't know when it will come available, but perhaps he can tell you more. Linda |
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And I agree to a point but they are oil less laboratory, vacuum pumps designed for oxygen / mixes. I think they mean acetylene / propane gases when they make that claim but I understand your point. |
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Assumption on the surface of what they are saying can be dangerous.... Yes oxygen by its self is not really explosive except when introduced to oils (or other fuels) ..... Then the classification changes..... There is a difference between a $80 used vacuum/pressure pump and a $5000 (RIX) microboost compressor.... There might be a better choice (brand-model) than the one you are looking at, I think it needs more research........ Dale |
Seriously, contact Trey. There may already be something either available or about to be available that will do what you want. I haven't heard anyone being satisfied with a Hurricane on the Phantom, or really any oxycon, but Trey hinted that this new thing should power torches in that class beautifully.
Also, and not sure if it was Wonka or someone else, but another LE'er tried building a holding tank for his big torch and didn't seem to be all that happy with it. A lot of hooey to make it, the tank apparently didn't last much longer thank a K-cylinder, and I think it took 12 hours to fill it back up each time (do you remember that post, Dale?). I've got a Phantom, too, and after reading that thread, I've been very interested in what Trey mentioned, myself. In the meantime, why not just blackpipe your 02 into your basement and leave the K-cylinder outside at ground level, like your propane (you DO have your propane tank outside, right??)? I did that for my basement studio. Way easier than dragging K-tanks downstairs, and will let you enjoy your Phantom while you do more research. Linda |
Interesting read on just "one" oxygen system........
http://www.lampworketc.com/forums/sh...d.php?t=132037 Dale |
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Dave, If i were in your position, I would try using a solvent like acetone to clean out the used tank of the oil residue (pour it in, shake, and empty and repeat maybe 2 more times), hook the tank up to the input side of the compressor (with an opening on the other end of the tank) and use the vacuum to draw fresh air into the tank and the volatized solvent fumes out of the tank (i would do this outside of course), and I would keep it on until there is no longer any solvent fumes coming out of the output side of the compressor. I would give it a lot of extra time to make sure there is no longer any acetone in the tank, as oxygen plus acetone in the confined tank is not a good thing. So it would be of the utmost importance to make absolutely sure that no solvent or solvent fumes remain in the tank. Then it would be time to plumb and test the system (outside and safely away from others, of course). But this is only what I would do in your situation, so do not take this as a recommendation for how you should proceed. You must make your own call. But if you decide to do this or something similar, make sure you think it through completely, and eliminate risks involved, as it will be your @ss and perhaps others that are nearby that are on the line. Remember, Oxy+fuel in a confine space is nothing to F around with, so if you do decide to clean your used tank with a solvent to prepare it for use as an oxygen holding tank, you must make sure that there is absolutely no solvent left in the tank before you fill it with oxygen. This is common sense and based on your post, you already know this, but it is the single most important goal to implement if you move forward on your project. That being said, I am sure that other folks that recommend not doing it are going to post on this topic very soon, and you should definitely consider what they say, as they may raise safety considerations that you might not have thought of. A flashback arrestor at the o2 holding tank output may be warranted. Just a note, I believe that when Trey put his system together and he first filled the tank with oxy, he did it outside in an open area away from himself and others, for safety reasons. I would also set up the system first and get it running before buying a second concentrator (I would not get a hurricane in lieu of 2 ex15s). And if I were to buy a second concentrator, I would get it from craiglist, as deals are to be had (i.e. I got a 10 lpm used medical oxycon for $200 with low hours and in perfect condition). Good luck, and please post more info and any lessons learned if you proceed with your project. |
Dave,
also, you might want to take a look at the tank fill system I put together that I use on a regular basis and keep me supplied with oxy. You will have to register with GLDG though. http://www.thegldg.com/forum/showthread.php?t=26729 The sytem is a high pressure system and is not the same as your planned system, but it never hurts to look at how other systems work. FYI, I will also be putting together a system (using a thomas compressor) like Trey's and your planned system when I find the motivation (or it finds me). |
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Glad you got hold of Trey. I'm sure he had great pointers for you
Metalbone makes some very important points about choice of solvents and ensuring that these have fully outgassed before closing up your tank. Be aware that not all solvents work equally on all greases. For example, you might be tempted to just use isopropyl alchohol. All isopropyl alchohol does for many common cutting oils and greases used for machining is just hold the oil as droplets in a colloidal suspension - doesn't actually dissolve it, and tends to leave a fair amount of oil residue behind without a fair amount of vigorous mechanical agitation (like wiping or ultrasonic cleaning). Acetone is a little better, but leaves a thin film behind when it dries and will miss some oils. If you can get hold of a really strong industrial degreaser, one way to clean your tank would be several generous rinses with that, followed by several rinses of acetone, and finally by high purity isopropyl alcohol. The reason for the sequence is that each degreaser will attack different types of oils that might be present, and the IPA at the end removes the film acetone tends to leave behind. I used a process similar to this when I was building ultra pure hydrogen gas systems for semiconductor fabrication. I used solvents like benzene and MEK as the first solvents in a series of 4-5 solvents to clean the parts for my system. Note that benzene, for example, is carcinogenic and is always used under a fume hood in industrial applications like mine. I highly recommend you research recommended methods for cleaning high-pressure 02 systems. The process is likely to be similar, but there may be some good strong solvents you can use to precede acetone in lieu of things like benzene. Good idea to test your set-up in the steel container you mentioned. If you can do it so that you're not in the container with it....ideal. |
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No reason to wait for a overpriced off-the-shelf system to hit the market when you can do it yourself... |
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Looks like mine is going to cost about $900 with a used Gast and a compressor tank from Loews. Getting all the right fittings will be the oddest part I think. |
on my system, I am planning on running 2 10 lpm medical oxycons and have the holding tank bleed off to a hose at 100 psi. I'll route the bleedoff hose back to the oxycon intakes, which should slightly increase the purity above the oxycon's normal range. I don't like the system design where a pressure switch shuts both the compressor and oxycons off at a set psi (i.e. 100 psi) because the oxycons produce their best purity when they're constantly running...intermittant on/offs on the oxycon will probably lower the purity. So rather than a pressure switch, I'll just use a pressure relief valve so that the compresor and oxycons constantly run.
On your fittings, hit up ebay, there are tons of fittings for low psi applications. personally, I am digging my high pressure system...just a couple of K tanks, some oxycons, a couple of high pressure medical compressors, and high pressure fittings. It is the same high pressure as everyone else that runs off tanks...no big deal and minimal safety issues if common sense is used. So when you get up and running, post a series of photos and narratives of the system as you put it together, and a breakdown of the costs. That would be a good benchmark for folks to assess the costs and features of the off-the-shelf systems, if and when they are finally available. Based on what Ro posted, the new Rix microboost is much improved, but that $5k+ cost is still a definite deal breaker. |
I like the bleed off idea. I wonder if there is a way to shutdown the compressor and then bleed off the oxycons till the compressor kicks in? Would be the best of both worlds but can't figure anyway it would be possible.
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Actually its quite simple........ A solenoid valve (open when NOT energized) put in line with "tee" fitting between oxycon output and input to vacuum pump.... When tank pressure low, tank high/low pressure switch call for pump to turn on, also closes solenoid, when tank reached max pressure switch cuts power to pump, also cuts power to solenoid so output of oxycons is now "free flowing" to atmosphere (or where ever)... Remember solenoid is open under a no power situation and closed when energized..... IF you cant find a solenoid, with those conditions, you use solenoid that closes when energized and you invert control of solenoid with relay.... When tank pressure switch is low and calls for compressor/pump to start it also calls relay to operate, relay opens contacts in circuit to solenoid and it actually closes, cutting off venting to atmosphere... Dale |
if i have a choice between passive routing and active routing, i'll take the passive route because it is cheaper and simpler.
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Leaving the generators on all the time is an interesting idea. Right now mine shut off. I have the flow set at about 7 on each so I am already getting a nice purity as far as generators go. I have not had any problems with purity. I think the few minutes of lower purity at start up doesn't really seem to effect the overall purity that much when its mixed in with the volume of the 29 gallon holding tank.
I am always looking for something better though. I have a good line on solenoid valves and it would be super easy to plumb and wire it. I will have to give it some thought. :-D |
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With proper design of control circuit anything is possible, You just have to decide what is going to be master controller, and in this case it would seem that pressure switch on tank is it... Everything else can a "slave" of that. Be it off/on electrically or open/close solenoid valving..... Dale |
How long does it take to pressurized the system from empty. Little bit of time? hours days? Do you leave it running all the time even if you aren't going to torch for a couple of days?
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If the tank will be at max presure for hours, and the compresor and/or oxycons are off, then there is no way the system could be at max for hours unless the torch is not running. If the torch is being used, once the tank pressure falls below the prescribed pressure (less than a few hours with a 30-gallon tank), the system fires up again. |
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For the system you are talking about, once you stop torching for the day, you shut the whole system down, and the pressure in the holding tank remains until the start of your next session (unless there is a leak). |
You guy are starting to over think this.......If you use holding tank pressure as a "control" and if torch is shut down for a few days, system will self shut down when tank is at max PSI....... As soon as soon as tank reaches "minimum" pressure (low pressure for switch) system cycles on again.... It just repeats the cycle depending on PSI in holding tank......
Its no difference than the sequence in a basic home handyman's or large commercial air compressor........ Just more hardware to control.... Dale |
Dale I agree, I'm thinking leaving it on basically full time unless you know you are going to be off the torch for a few days. Just try for maximum air tightness of hoses and such to keep the compressor from cycling alot.
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its a matter of how one chooses to operate ones equipment. I don't like the idea of setting up and leaving alone a piece of equipment that can turn itself on. I just don't want to leave open the possibility that when I am out to dinner or sleeping, the compressor/oxycon can start itself if there is a pressure leak or if someone that happens to be in the garage decides to see what this do-hickey does.
I would rather have an on/off switch or power strip that I can turn off when I stop torching without wondering if the thing is on when I am not around. |
It is a quandary and I'm thinking if I'm going to be off a the torch for awhile the powerstrip is a perfect shutoff to make sure there are no weird "zombie" electronic moments
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MY 80/100 pressure switch has a shut off on it. I turn it off if I am not going to be on the torch for a few days. If I am working the next day I just leave it on. My system is pretty tight but it will cycle once over night. I really need to get everything sealed up good but would rather be on the torch. My 29 takes a little over 20 minute or so to fill up. The other day I did a 2 inch boro marble and had almost 2 hours in it. Looked at my tank pressure after I was finished and it was at 40 psi. Still a ways from 25psi where I have the reg set and I would start to notice some drop off. So I feel pretty confident in saying I get 2 hours 100% on either my Phantom or Barracuda with this system. |
Did I say anywhere along the way one can't have a master switch if its personal preference........ I was trying to get into overall operation for a functional worry free system....... Also think about it, there are air compressors out there that cycle all the time and are never "turned" off, but here we are dealing with almost pure oxygen..... But you are correct one should have master switch...
Dale |
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