Co2 pressure gauges - The Planted Tank Forum

 
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post #1 of 11 (permalink) Old 03-07-2013, 11:59 PM Thread Starter
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Co2 pressure gauges

Hey,

Just set up a new co2 system with a single stage dual gauge regulator with a magnetic solenoid valve. It all looks to be running great, and I have done a soap leak test, Which seems to be all good.

The high gauge is around 650psi and has remained stable overnight and all day through on and off periods.

The low gauge works at around 32 psi. Here is my question, when the solenoid shuts off the gauge increases over a few minutes to about 35 psi where it will remain until the solenoid turns back on in the morning when it will reduce back to 32 and continue normal operation. I'd this normal and how could I tell if there is a leak?

I have checked through the other leak test thread and it all seems to be good, but to ease my paranoia I wonder if I can do a full submersion test on the regulator? If I take the solenoid off its metal bar and hold the regulator under water and look for bubbles?... Keeping the gauges above water.

How can I remove the regulator from the co2 tank while maintaining low-gauge working pressure inside the reg to check for leaks?

Cheers for any help.

Last edited by Aquaflow; 03-08-2013 at 10:16 PM. Reason: Different question
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post #2 of 11 (permalink) Old 03-08-2013, 10:17 PM Thread Starter
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post #3 of 11 (permalink) Old 03-08-2013, 10:41 PM
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Originally Posted by Aquaflow View Post
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The slight rise in pressure when the solenoid closes is normal. You are reading into this too much.

What would Honey Badger do?
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post #4 of 11 (permalink) Old 03-08-2013, 11:03 PM Thread Starter
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Lol thanks I think I am! Just heard a few horror stories and since it's in my bedroom I wanna make sure I don't gas myself in my sleep.

Forgive an over cautious noob :-D
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post #5 of 11 (permalink) Old 03-08-2013, 11:50 PM
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The slight fluctuation in delivery pressure is to be expected.

I would be more concerned that you are only reading 650 PSI on the high pressure gauge. If this is a new cylinder, then either they did not fill it, or the high pressure gauge is broken.

For reference, a new cylinder should read about 800-1000 PSI, depending on temperature.

Anthony

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post #6 of 11 (permalink) Old 03-09-2013, 12:55 AM Thread Starter
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Yeah it seems to be pretty stable. I'm leaving the co2 off til the morning to make note of any major jumps. Well it's a refurbished fire extinguisher, which I am led to believe when full should read about 700psi. I think they just haven't filled it up all the way because the gauge seems to work fine when I released all the co2 from the reg and "re-boosted" it it went straight back to 650. The thought did cross my mind about that though.
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post #7 of 11 (permalink) Old 03-09-2013, 01:25 AM
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Well, when they fill a CO2 cylinder - *any* CO2 cylinder - it will almost immediately go to around a certain point, which is a somewhat variable pressure at which CO2 gas turns to liquid (somewhere around 850 psi at room temp), and then, while still filling (the weight will increase) it will stay at that same pressure.

When used, it's the reverse. It will stay at 800-ish psi until nothing but gas is left in the cylinder, which will be at less than 5% of the total CO2 volume (meaning, for 95%+ of the life of the fill, pressure will stay at 800 psi). At that point, pressure will begin dropping.

What's happening is one of two things, assuming you don't have a massive leak: One, the cylinder was barely filled, and within a couple weeks it will be empty. Or two, your gauge is either broken or off by about 150 psi. In the first case, you need to give the gas store a piece of your mind. In the second case, you can either live with the funky gauge, or replace it.

If it's just off by 150 psi, you'll see when the pressure starts declining and there's no reason to make any changes unless your OCD kicks in (mine would, so no criticism there on my part).

If it's done broke and still reads 650 when the pressure is actually at zero (and the gas is gone), I'd advise replacing it. Probably $15 shipped for a basic brass gauge from Evilbay or a brewing shop. If you have a Milwaukee, Azoo, Aquatek, Dici, or any of their clones, definitely replace it. If it's an industrial single stage reg, there's less worry - you probably won't get any significant EOTD.
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post #8 of 11 (permalink) Old 03-09-2013, 01:44 AM Thread Starter
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Ok thanks. Could be because my room is really cold most of the time and the tank is by a drafty windows (I hope). Or it could be the gauge, but it does flick down to zero when I dump the pressure. I'm thinking it might just be inaccurate.
Yeah it's pretty much identical to those aquatek ones with the solenoid. So are the brass gauges a universal fit pretty much? Might be worth getting one on my next co2 tank if the problem persists.
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post #9 of 11 (permalink) Old 03-09-2013, 02:04 AM
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Originally Posted by Aquaflow View Post
Ok thanks. Could be because my room is really cold most of the time and the tank is by a drafty windows (I hope). Or it could be the gauge, but it does flick down to zero when I dump the pressure. I'm thinking it might just be inaccurate.
Yeah it's pretty much identical to those aquatek ones with the solenoid. So are the brass gauges a universal fit pretty much? Might be worth getting one on my next co2 tank if the problem persists.
it is your room temp, before last couple weeks the co2 reads 650psi too, while it was around 60 Fahrenheit in my house, cold.
now I see the psi goes back up to 750 psi, a couple more weeks will be 800psi.
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post #10 of 11 (permalink) Old 03-09-2013, 02:24 AM Thread Starter
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Originally Posted by Bettatail View Post
it is your room temp, before last couple weeks the co2 reads 650psi too, while it was around 60 Fahrenheit in my house, cold.
now I see the psi goes back up to 750 psi, a couple more weeks will be 800psi.

I hope so, it is probably about 58-62 f by the window! I might stick my aquarium thermometer to the fire extinguisher to check . That's a relief I hope it goes up when it gets warmer then. Thanks!
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post #11 of 11 (permalink) Old 03-10-2013, 10:55 PM Thread Starter
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Ok so I found this chart for co2 temperature-pressure relationship. It also explains why we don't see a change in the pressure gauge until there is about 10-15% left in the tank! pretty helpful.

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