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High pressure co2 hose

Discussion in 'CO2 Enrichment' started by AtticusFynch, Sep 21, 2017.

  1. AtticusFynch

    AtticusFynch New Member

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    So like a lot of other folks, I've found it would be a lot more convenient to store my c02 cylinder on its side, but have read that that's a no-no due to the risk of it freezing up the regulator.

    That got me wondering, however - what if I used a high-pressure c02 line to separate the regulator from the cylinder - something like this: https://www.kegconnection.com/high-pressure-hose/

    Seems to me this would work fine with a cylinder on its side as long as I mounted the regulator above it. Opinions?
     
  2. David Cottle

    David Cottle New Member

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    CO2 in the cylinder is liquid, with a vapor space above. You want to withdraw the vapor (gas), and the cylinder has to be upright to do that. With the cylinder on its side (and enough liquid left in it), you risk admitting liquid to the (gas) regulator, which you don't want. Ever try using a propane torch upside down? It doesn't work!.
    As long as there is liquid left in the cylinder, pressure will be the vapor pressure of liquid CO2 corresponding to the temperature of the liquid. Rapid vapor withdrawal will cool the liquid due to the latent heat of vaporization and vapor pressure will drop accordingly. But at slow withdrawal rates, cylinder temperature will stay close to ambient, and pressure will remain constant until there is no more liquid, at which point cylinder pressure will start to drop, indicating it's time to get a refill.
     
    Mooner and Phishless like this.
  3. Phishless

    Phishless Lifetime Member
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    Don't do it, regulator should never receive liquid.
    If it were on it's side the head space would force liquid until the level reached the bottom of valve.

    Can you mount remotely and run a low pressure line to your tank?
     
  4. AtticusFynch

    AtticusFynch New Member

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    Obviously I missed something in my thinking here - my intuition was that as long as the regulator were above the tank, liquid wouldn't make it to it. But perhaps I'm not accounting for the pressure, and what would really happen is there'd be a bubble ogf gas at the top of the tank, but liquid would still be forced up the line.

    Anyway, I'm going to do something along the lines of what Phishless suggests - keep the cylinder upright in a different spot nearby and run the CO2 line to the tank. thanks!
     
  5. Phishless

    Phishless Lifetime Member
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    What method of introducing CO2?
    Reactor or atomizer?
     
  6. AtticusFynch

    AtticusFynch New Member

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  7. Phishless

    Phishless Lifetime Member
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    They need like 30PSI to operate which is fine.
     
  8. AtticusFynch

    AtticusFynch New Member

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    Hm, you might have inadvertently solved another mystery I was having. I was working on setting up my new GLA CO2 system earlier today, and I couldn't get any flow at their recommended 10 psi working pressure. I had to crank it up to about 30 to get gas to pass through. I emailed GLA support, and they chalked it up to a sticky check valve, but sounds like it might have been the diffusor!

    Which leads to another possibly dumb question: if I have the bubble counter dialed down to a few bps, will the pressure between the regulator and the diffusor eventually equalize with the working pressure of the regulator? I.e. if I put my solenoid on a timer as I intend to do (as soon as the timer arrives from Amazon), will I get flow again in the morning with this setup?
     
  9. burr740

    burr740 ~~ Lover of Micros ~~
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    The pressure will eventually become whatever the working pressure gauge on the regulator is set to. Running higher pressure with a really low bubble count is fine, but it might take a little while for the CO2 to finally push through, 30 min etc

    Strange they tried to tell you its the check valve. Those inlines clearly state 30 psi
     
  10. AtticusFynch

    AtticusFynch New Member

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    I suspect it just didn't occur to him that I was using an inline diffusor. I don't recall mentioning it in our conversation.
     
  11. VaughnH

    VaughnH Lifetime Charter Member
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    If you use the regulator with liquid CO2 running through it the bubble rate will go sky high! The flow of liquid through a tiny orifice is a lot higher in mass flow rate than the flow of gas through that same orifice at the same pressure. In short, the regulator would not work at all with liquid CO2.
     
  12. rajkm

    rajkm Article Editor
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    You can do it if you have a long enough hose for gas expansion. The liquid will turn to gas if there is room for expansion.
    A CO2 cylinder is never filled fully. There is a pocket on top for allowing for expansion.
    The tube can do the same.
    You will need to open the cylinder valve while upright. Once the pressure is equalized between the cylinder and regulator you can slowly lay it flat. This way you start with a pocket of gas in the tube. After that when you lay down the tank, there no sudden rush of liquid to the regulator and any liquid trying to enter the tube will have headroom to expand.
     
  13. VaughnH

    VaughnH Lifetime Charter Member
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    Assume you follow the procedure per rajkm: your CO2 tank is upright, the CO2 in the tube to the solenoid valve is gas. Now you lay the CO2 tank on its side. Nothing changes yet: the CO2 tubing is still full of CO2 gas at room air temperature. All of this system is under the aquarium, with the CO2 tube going up to the top of the aquarium to the diffuser in the tank. So the high point is the tubing at the top of the aquarium. Now you open the solenoid valve, this allows the pressurized CO2 in the tank to enter the CO2 tubing, but only the liquid CO2 because the gaseous CO2 is in a "bubble", a long thin one, along the length of the tank, not at the valve on the tank. As the liquid CO2 enters the tubing it almost instantly changes to dry ice, the solid form of CO2. This process cools the regulator to a very low temperature. The dry ice slowly changes to gaseous CO2, raising the pressure and temperature in the CO2 tubing and increasing the bubble rate as it does that. When the pressure finally stabilizes and the bubble rate is what you had set the needle valve to, the pressure in the CO2 tubing is below the regulator pressure setting, so it opens again and repeats the process. I suspect the regulator would have frozen up, then perhaps will warm up again and repeat the process again. I doubt that this would ever work satisfactorily, but I have never tried it. CO2 is a very tricky substance that likes to be either solid or gas, and it absorbs a lot of heat from whatever it touches to power its transition from liquid to solid to gas. It cannot exist as a liquid except under high pressure - around 500-700 psi. When liquid CO2 changes to dry ice, solid CO2, it becomes very cold, possibly causing the plastic CO2 tubing to lose its strength and to burst.
     
    #13 VaughnH, Oct 20, 2017
    Last edited: Oct 20, 2017
  14. VaughnH

    VaughnH Lifetime Charter Member
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    This is a very interesting question! I have been thinking about it for a couple of days now. CO2 cannot exist as a liquid unless it is at a pressure around 700 psi or higher. So, if you run liquid CO2 through a regulator set at 100 psi, for example, the drop in pressure through the regulator causes the liquid CO2 to almost instantly change to solid CO2. You can stop this only if you can transfer enough heat to the stream of liquid CO2 fast enough to almost instantly change it to CO2 gas. A regulator, like we use, cannot possibly do that. So, trying to do that would just plug the regulator passages with solid CO2 - dry ice. If the regulator keeps working the pressure of that solid CO2 would never go high enough to change it back to a liquid, and it would still take heat to make the phase change from liquid to gas. The regulator temperature would quickly drop to about the temperature of dry ice, probably weakening the metal parts, and making the rubber parts hard and brittle. This would ruin the regulator.

    Fire extinguishers work by using an orifice to limit the flow of liquid CO2 out of the tank, and the CO2 comes out as CO2 snow, dry ice snow. The metal parts that include that orifice get very cold as the fire extinguisher is used, but there is enough mass of metal so that the heat energy it stores is high enough that the metal parts that you touch don't get dangerously cold. That heat energy converts some of the ejected CO2 snow to CO2 gas. It is that CO2 gas that propels the blast of CO2 snow.

    Now I hope I can stop thinking about this and move on to other thoughts!
     
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