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CO2 Pressure Regulator Theory of Operation

Discussion in 'CO2 Enrichment' started by Jim Miller, Mar 9, 2011.

  1. Jim Miller

    Jim Miller Lifetime Charter Member
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    I think EOTD is a huge misnomer used to cover up inattention to detail on the part of owners per my posts on this thread.

    The performance claims of the single stage SR250 Victors would seem to indicate that no big spurt of pressure should be expected from them. Is that what you are referring to?

    I doubt that anyone would really notice a "bubble rate" increase with a 4psi rise in pressure even if they are running 10psi or so.

    EOTD implies a sudden and unpredictable rise in pressure. I'm not saying it can't happen, especially with poorly designed regulators that may have sticky moving parts or low diaphragm to orifice ratios. But I'd love to test actual regulator units that have been "accused" of dumping to see what they really do as the tank pressure drops.

    As far as I can tell a new Victor SR250-580 is about $250. I assume a -320 would be similarly priced.

    Edit: I just found an SR250B on Amazon for $143. VTS-250 were $250. The single stage is getting there in price...

    The SR250 isn't often seen on Ebay for some reason. The dual stage used regulators are far more plentiful.

    Either $250, (plus needle valve and solenoid) or Ebay (plus serious vise and wrench grappling) means no joy for >90% of planted tank enthusiasts.

    There's got to be a better way. I'm on the hunt.
     
    #21 Jim Miller, Mar 27, 2011
    Last edited by a moderator: Mar 27, 2011
  2. Biollante

    Biollante Lifetime Charter Member
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    I Love Smart People!

    Hi Jim,

    There simply has to be a better way than we are currently injecting CO2.:gw

    I seriously appreciate your efforts and explanations… :cool:

    Biollante
     
  3. Jim Miller

    Jim Miller Lifetime Charter Member
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    I don't consider myself smart. I've worked with so many people over the years that are far my superior in that respect that I consider myself average at best.

    I do try to figure things out in detail and it takes me quite a bit of time. I'm persistent and try to get things right.

    If I find out I goofed somewhere or someone else points it out that's fine with me. That will just make everything clearer.

    If it was easy to dispense a few milligrams a day at 1bar from 800psi, 20lb containers and do so safely and inexpensively I'm sure it would have been done already. I'm not foolish enough to claim for certain that I'll accomplish it but it will be fun trying.

    Analyzing in detail the current situation is the first step.
     
  4. Biollante

    Biollante Lifetime Charter Member
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    Sometime Hard to Separate Smart & Persistent

    Hi Jim,

    I am not so sure the “would have been done already part,”:rolleyes: my experience with the “hobby” has been that so much “knowledge” in the planted tank realm is based on people repeating what someone else said decades ago…:p

    As far as I can determine the innovation in the planted tank world (hardware anyway) comes from the hydroponics folks, which is to say the growers of a certain Mexican ditch weed (yes, for medicinal purposes only:eek:) and the “reefer community” (as in saltwater reef).:)

    Biollante
     
  5. Jim Miller

    Jim Miller Lifetime Charter Member
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    that would be "reefers" and "reefers".:p

    jim
     
  6. Jim Miller

    Jim Miller Lifetime Charter Member
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    The molar mass of CO2 is 44gm/mol. Assuming my calculation of 25gm/day for 8 hrs, that means 860ugm/sec or 20umol/sec. Interesting that the name for molecular weight and the value we might be using is similar to a quite different but similar sounding name for the light values in PAR and amounts we might also chose. Totally different units of course. Just struck me...
     
  7. Tom Barr

    Tom Barr Founder
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    Well, we had a discussion at some point somewhere about the needle valves etc........and you could change the bubble rates with the output pressure, say move it from 10psi to say 20psi.

    This is true........but..........I've not seen the output pressure change at the end of the tank pressure as the tank pressure declines.

    Never.

    This is something I've watched many times. We do not change the out put pressure as a matter of habit, so the specific issue is "what occurs to the bubble rates and output pressure as the tank empties"
    I've not measured any significant difference in bubble rates or the out out pressures when this emptying occurs.
    As far as the rest, a good needle valve, solenoid etc, check valve.......thick walled tubing etc.....I use low pressure needle wheel, so there's no back pressure.
     
  8. Jim Miller

    Jim Miller Lifetime Charter Member
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    Interesting information. Some questions: any information on which models of regulators you were using for these observations? Dual or single stage regulators? Were you running the tank all the way to empty or just down a bit?

    Even Victor claims their single stage products move upward in output pressure as the tank falls. It's the reason they sell dual stage units.

    Jim
     
  9. Matt F.

    Matt F. Lifetime Charter Member
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    I think there needs to be a certain level of clarification made here. I don't know how significant an EOTD (Droop) is for our applications. BUT we have to remember that a lot of the regulators we use for our aquariums aren't made for them. In the case of dual stage regulators, they serve a real world purpose as opposed to a single stage. Neither have a "poorer" design. Just different uses.

    Although I like the idea or tweaking a regulator's mechanical internals to better suit our needs as aquarists and planted tank enthusiasts, how practical is this quest?

    Tom doesn't have a problem with victor's single stage regulators and a lot of us don't have a problem with dual stage units. From what I have read, most people are happy with their azoo or milwaukee.

    put simply, if EOTD's (droop effect) effect is minimal, and all that is needed even in the worst situation is to watch the gauge weekly, then why are we even having this discussion?

    I'm just adding a bit of critical thought to this.

    I think the issue was voiced by Biollante when he states, "There simply has to be a better way than we are curretly injecting co2."

    What are we trying to do here? The total eradication of algae will never happen. My plants are doing well w/ 216 watts of t5ho and injected co2...okay, I use glut, too, sooo...

    There are two issues as I see it: providing a constant delivery pressure when connected to a finite source AND best diffusion methods. I think diffusion methods need improvment...gas delivery is okay for our needs.

    If EOTD isn't as much an issue for the fauna, provided enough flow, what about the flora? Something as minor as a plugged diffuser (product of lax maint) can cause algae blooms. Clearly, the issue here isn't the regulator's mechanical function.
     
    #29 Matt F., Mar 27, 2011
    Last edited by a moderator: Mar 27, 2011
  10. Matt F.

    Matt F. Lifetime Charter Member
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    Every regulator company in the business from concoa to matheson trigas, to victor all state that the droop effect is a real issue with single stage regulators. The question is how much does this affect the delivery accuracy into our tanks? Some say it's not even an issue with single stage units. Maybe for hypercritical lab applications it's more apparent.

    I'd like to see a study focus on the decay characteristics of popular aquarium brand single stage regulators as the tank pressure drops.
     
    #30 Matt F., Mar 27, 2011
    Last edited by a moderator: Mar 28, 2011
  11. Jim Miller

    Jim Miller Lifetime Charter Member
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    I think I've stated my objectives clearly but I'll repeat them again:

    I'd like to see if there is a way to lower the cost of reliable delivery of CO2. That cost, ease of use and, by some accounts, reliability is currently dominated by the regulator and needle valve combination.

    I'm starting by testing what are available as regulators to see what works well and what is accused of not working well to compare their differences if any.

    I'm taking into account the rest of the typical system components to ensure that optimization of one element doesn't adversely affect the total system reliability, cost or ease of use.

    I'm not at this time working on diffusers or reactors other than ensuring that delivery can occur to either by appropriate output pressure. Their cost is minimal and the selection is highly dependent on tank size and method of filtration.

    My ability to test will be limited by my time and money to acquire specimens for testing. This won't be a quick process.

    Although I have no interest in going into business I'm optimistic that if I can identify improvements they will make their way into products eventually.

    I welcome other's suggestions and testing contributions as well.

    Jim
     
    #31 Jim Miller, Mar 28, 2011
    Last edited by a moderator: Mar 28, 2011
  12. Matt F.

    Matt F. Lifetime Charter Member
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    1) I donb't think cost is an issue. Last week, a victor hpt270 sold for $19, add a $35 fabco, a $50 burkert, and $10 npt, and you have yourself a solid unit. That's less cost than a new milwaukee or azoo, iirc. One aspect of cost that needs to be taken into account is the replacement cost of inferior parts in the long run.

    2) by what criteria are you judging "what works well" and what doesn't?

    3) what are you proposing we modify? How does this affect safety, etc.? Are you suggesting a total redesign of the regulator as we know it or just some of the part inside?

    4) what do you mean by "typical system components?" afaik, we've been posting what works well and what doesn't in our threads. Some are comfortable paying $70 for a check valve and others pay $20.

    5) what kind of controls are you going to use to test these regulators and needle valves? What are you going to test them for specifically? How will you isolate one component from the next when testing assuming you're looking at this from a mechanistic perspective?
     
    #32 Matt F., Mar 28, 2011
    Last edited by a moderator: Mar 28, 2011
  13. Jim Miller

    Jim Miller Lifetime Charter Member
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    Matt

    Since you obviously disagree with my premise and the objectives of the test I'm not sure what the point of response is.

    After assembling my own regulator from Ebay parts I'm convinced that it isn't a viable volume solution. If it was profitable to do so there would be a vibrant business opportunity for folks such as you and I.

    I intentionally put this into a separate thread to avoid polluting or hijacking the thread which you've done so much work on and from which I benefitted.

    If you represent the majority of opinion on this forum I'll refrain from future postings.

    Jim
     
    #33 Jim Miller, Mar 28, 2011
    Last edited by a moderator: Mar 28, 2011
  14. Gerryd

    Gerryd Plant Guru Team
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    Jim,

    Even IF there is disagreement, this should not prohibit you from posting.....

    I have learned a lot from your various posts and hope you continue to participate in the community...

    Thanks,

    Gerry.
     
  15. Matt F.

    Matt F. Lifetime Charter Member
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    I agree with you when looking at the problem from a volume and manufacturing standpoint. There is virtually no way to mass produce these things and have it be cost effective without sacrificing quality. Heck, I'd love to have that kind of an option, but there are too many variables, imo. The only way to actually save money, afaik, is to hunt one down on ebay for a cheap price and build it yourself. That's the whole reason why Left C, and others have spend to much time and energy helping others build a high quality piece of equipment. That's the only option we have had to this point.

    There is much debate around the issue of single versus dual stage regulators. Recently there was a rather heated debate on TPT. What we all kinda decided was: use what works for you. Neither is better than the other. They both serve a unique purpose in the real world. The question that pops in my mind is: are we able to observe those differences when we use those regulators for our aquariums. I don't think there is an answer to this, yet.

    I'm not trying to attack you personally. Please don't think that. I am just trying to grasp what you are wanting to do in this thread. Hey, any way we can further this aspect of co2 injection, I'm game. I just struggle to see what it is you are doing specifically.

    Are we talking about modifying a regulator's internals? Are we talking about running tests to test how significant droop is and make a comparison chart between the single stage units you mentioned earlier?

    Either way, I'm sorry if I have offended. That was not my intent.

    Best,

    Matt

    EDIT: I am not trying to shoot anyone down. I believe in lively debate, and I will pose questions if I don't understand something. That said, I don't think disagreement is a bad thing as long as the attack is directed at the theory, thought process, or idea. The point where the debate crosses the line, imo, is if you start attacking the person, which has not happened at all in this thread.
     
    #35 Matt F., Mar 28, 2011
    Last edited by a moderator: Mar 28, 2011
  16. Jim Miller

    Jim Miller Lifetime Charter Member
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    Hi Matt

    I'm sure my personal stresses contributed to the misunderstanding. I apologize for that.

    I'm a retired engineer. I like to understand why things work the way they do. Especially if they're doing something undesired. I'm one of those kids that took things apart a lot. ;-)

    I'm certain that dual stage regulators work fine so no need to test those. I want to actually measure "droop" for a known good brand of single stage regulator like a Victor SR250B. Per the Victor website I strongly suspect the SR250 would be an excellent regulator but I'd still like to test it all the way to zero. Victor's documentation of the internals are sufficiently detailed that I don't think I'd need to do a tear down on it.

    Then I want to measure a variety of others as I can acquire them either by purchase or loan. I want to actually take some of the "bad actors" (if any) apart and see if there is something obvious about the construction that caused their behavior. I'd like someone to send me a Milwauke that they're fed up with so I can do a bunch of testing followed by a tear down on one of those.

    I'm also going to test a couple of regulators that are basically inflators rather than precision regulators. I want to see how bad, "bad" can be.

    I also want to test my theory that running at a higher pressure might mitigate the droop effect if any. It may well be impractical without a suitable metering device (needle valve or other).

    I'm also noodling about other means of metering without a regulator by using a solenoid working on a very small orifice.

    None of this is intended to cast aspersions on any particular manufacturer for their product. If I find some obvious defect I'll communicate it if possible to the manufacturer for their information.

    None of this testing will happen quickly as I really don't have the time or money to pursue it intensely. I'm under no illusions that it will produce some magic device overnight. I certainly wouldn't be producing it in any case.

    It's just another opportunity to do some diagnostic testing and have some fun that might lead to a useful outcome.
     
    #36 Jim Miller, Mar 28, 2011
    Last edited by a moderator: Mar 28, 2011
  17. Biollante

    Biollante Lifetime Charter Member
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    Please Continue

    Hi Jim,

    I really do want to encourage you to continue your exploration and your very coherent explanations.:D


    • Not every avenue of discussion has to result in a cosmic breakthrough.
    • Not every line of thought or observation has to be in and of itself part of a coherent and complete falsifiable hypothesis with everything done to some exacting standard.

    Sometimes we just are taking as close a look as we can, sometimes we “ballpark it,” sometimes we just take it apart and put it back together. Then we think about what we have seen.

    We share are observations in enough detail so others, should they be so inclined can attempt to replicate the steps taken to see if the observed results follow. This step seems offensive to the anointed here, for whatever reasons.

    Even those that do not replicate the process may think it through or research aspects to suggest improvements or suggest the methodologies to demonstrate a particular aspect.

    Maybe some of us find it interesting in and of itself.:)

    Sometimes after observation and thought a testable idea is formed, ultimately it may or may not be valid, even if valid it may or may not be practical. So what, maybe along the way we learned something.:)

    As I said earlier, for whatever reasons we in the planted tank community do not deal well with new concepts.:rolleyes:

    I have developed a pretty sizable “off-limits bucket” myself so I may not be the best one to offer advice.:p

    Biollante
     
  18. Matt F.

    Matt F. Lifetime Charter Member
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    I'm totally excited to see the results you post when the time comes. I'd love to see how the different SSRs perform given your parameters. Thanks for clarifying it for me. Your other ideas, now that I understand them, are interesting. I wonder what the outcome will be.

    If I still had my milwaukee, I'd sent it to you, but I sold it a while ago for like $40...lol

    Heck, I'll keep an eye out for a good test unit (victor and other) for you. I'd like to help if I can.

    Best,

    Matt
     
    #38 Matt F., Mar 29, 2011
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  19. Matt F.

    Matt F. Lifetime Charter Member
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    I hope you're speaking for yourself! :rolleyes: ;)

    1) you have to be able to replicate the research design, correct? And you should be able to limit the variables when you are testing for something. You should have a certain idea of what, specifically, you are testing, so in certain cases a "ballpark" approach needs to be narrowed in order to be studied accurately. Like in statistics, you're not going to get the same result 100% of the time. Limit the variables by creating certain controls. Common sense to me. I don't understand how you make the conclusion that the "anointed here" are offended.

    2) the use of industrial and hospital/lab grade regulators is relatively "out of the box" thinking. The fact that we, in the planted tank community, have gone beyond aquarium/hobby grade regulators and are having this conversation, in this thread, shows growth, imo. No problem with new concepts here. I think TBR is on the "edge" in many respects.

    Generally speaking, it's one thing to criticize, but to criticize without offering a suitable alternative is slightly pompous, imo.
     
    #39 Matt F., Mar 29, 2011
    Last edited by a moderator: Mar 29, 2011
  20. hbosman

    hbosman Guru Class Expert

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    Before I went to dual stage regulators, I would regularly see the gradual rise in output (working) pressure as the input pressure reduced. I've seen this in a Redsea and Total Beverages single stage regulator. Not realizing that when the supplied pressure dropped from 800 PSI, that there was less than 10 % CO2 left, I would daily tweak the working pressure back to my intended 10 PSI setting on a daily basis. Yep, every morning I would adjust the working pressure back to 10 PSI until the bottle was finally empty. I used 20 OZ and 24 OZ paintball cylinders and did this to squeeze a month usage out a cylinder. Maybe I shouldn't have worked so hard to save 40 cents per month. Since I did look at the working pressure on a daily basis, I never did observe the fabled EOTD. With Victor VTS 250 C dual stage regulators, I don't see the working pressure move anymore. Sometimes I do run the paintball cylinders completely empty without seeing the working pressure move.

    If I were aware that I should haved swapped tanks sooner, maybe I wouldn't have gone through the time and expense to move to dual stage regulators. But, I'm glad I did.
     
    #40 hbosman, Mar 29, 2011
    Last edited by a moderator: Mar 29, 2011
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