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So, like one of the posted comments above, I am just learning about Co2 systems, and would like to take a step back. What does a metering valve do? I have a stock Co2Art Elite system as shown below, with the needle valve circled.
It is just a knob and the amount that I have to turn it to dial my bubble rate is so incredibly tiny, that I can’t really “fine tune” it as I would like. It is usually not enough or too much.
These metering valves you have pictured have dials with numbers - does that mean they can be adjusted more precisely? Do they sort of ‘click’ on each number or is it still very minute turns that are hard to not go too much? (hope I’m making myself clear). Can I simply unscrew my current needle valve and replace it with one of the metering valves, if I chose to do so?
Thanks for your help.
 

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So, like one of the posted comments above, I am just learning about Co2 systems, and would like to take a step back. What does a metering valve do? I have a stock Co2Art Elite system as shown below, with the needle valve circled.
It is just a knob and the amount that I have to turn it to dial my bubble rate is so incredibly tiny, that I can’t really “fine tune” it as I would like. It is usually not enough or too much.
These metering valves you have pictured have dials with numbers - does that mean they can be adjusted more precisely? Do they sort of ‘click’ on each number or is it still very minute turns that are hard to not go too much? (hope I’m making myself clear). Can I simply unscrew my current needle valve and replace it with one of the metering valves, if I chose to do so?
Thanks for your help.
It does the same thing your current needle valve does, just with greater precision. Because that co2art model has the solenoid and valve manifolds integrated like it does, it's not as simple as swapping out valves. You could replace that whole 'post-body' section (solenoid and valve/bubble counter) with a different solenoid and valve. I actually have a co2art regulator i have done that for:

1028071


There's a new solenoid (blue arrow), then a flow meter with a high precision, low flow metering valve (red arrow), and a cheap back-pressure needle valve (green arrow). The benefit of this is that it's outrageously precise and stable. That flow meter has a 150mm scale, and every day - without fail - the float is sitting at 85mm.

Sounds like you have a small tank, so a flow meter may not be appropriate, but a new solenoid/valve/bubble counter could get you rock-steady co2 flow rates.
 

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It does the same thing your current needle valve does, just with greater precision. Because that co2art model has the solenoid and valve manifolds integrated like it does, it's not as simple as swapping out valves. You could replace that whole 'post-body' section (solenoid and valve/bubble counter) with a different solenoid and valve. I actually have a co2art regulator i have done that for:



There's a new solenoid (blue arrow), then a flow meter with a high precision, low flow metering valve (red arrow), and a cheap back-pressure needle valve (green arrow). The benefit of this is that it's outrageously precise and stable. That flow meter has a 150mm scale, and every day - without fail - the float is sitting at 85mm.

Sounds like you have a small tank, so a flow meter may not be appropriate, but a new solenoid/valve/bubble counter could get you rock-steady co2 flow rates.
I’m not sure I‘m following. My tank is 68g. The solenoid on my system is not integrated as far as I can tell, but the needle valve might be built into the bubble counter.. I’m not sure why I would need a different solenoid or a flow meter. I would just like a needle valve that is not so sensitive that the slightest touch gives me too much adjustment.
I would like to be able to replace my current valve with one that will allow me to tune it easier.
Can that not be done?
 

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I’m not sure I‘m following. My tank is 68g. The solenoid on my system is not integrated as far as I can tell, but the needle valve might be built into the bubble counter.. I’m not sure why I would need a different solenoid or a flow meter. I would just like a needle valve that is not so sensitive that the slightest touch gives me too much adjustment.
I would like to be able to replace my current valve with one that will allow me to tune it easier.
Can that not be done?
sorry, you said your bubble rate was incredibly tiny, i assumed that implied a small tank.

a flow meter is useful for larger tanks with bubble rates that are so high as to be uncountable. the tank that flow meter is on is 68g also.

in that co2art model, the expandable manifold blocks containing the needle valve connect to the block with the solenoid piston in what i think is a proprietary way. that's what i meant by integrated. i could be wrong about that.
 

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Ah, I meant that the amount that I need to turn the needle valve knob is tiny - I barely touch it and it will increase the bubbles tenfold. That is what I call too sensitive. I’m looking for a valve that I can turn to the next number or line and have the bubble rate go up only a small amount so I can increase my rate in smaller increments.

Is this what a metering valve does?

My rate now is already way more bbs than I can count but am only getting slightly less than a 1 pt drop in pH.
 

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Ah, I meant that the amount that I need to turn the needle valve knob is tiny - I barely touch it and it will increase the bubbles tenfold. That is what I call too sensitive. I’m looking for a valve that I can turn to the next number or line and have the bubble rate go up only a small amount so I can increase my rate in smaller increments.

Is this what a metering valve does?

My rate now is already way more bbs than I can count but am only getting slightly less than a 1 pt drop in pH.
I see. yes, a precision metering valve will give you more turns per unit change in flow (there are probably more appropriate technical terms that i'm not using).
 

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Ah, I meant that the amount that I need to turn the needle valve knob is tiny - I barely touch it and it will increase the bubbles tenfold. That is what I call too sensitive. I’m looking for a valve that I can turn to the next number or line and have the bubble rate go up only a small amount so I can increase my rate in smaller increments.

Is this what a metering valve does?

My rate now is already way more bbs than I can count but am only getting slightly less than a 1 pt drop in pH.
Coarseness or "sensitivity" doesn't really define
if it's a metering valve.
you can have larger flow metering valves that "we " can't use but fine for larger flow demands.

Metering Valves
that are designed to provide accurate and stable control of flow rates in analytical,instrumentation,and research applications.It is a valve with infinite positioning and variable control that is capable of regulating the flow of fluid. A needle valve is a type of metering valve.
In our use most if not all are needle valves w/ fine needles in the few degree taper range.
Increase the metering valve to large angles say 10-20 degrees and it is still a metering valve .. for something..
Ours are like 1-3 degrees for the most precise low flow rates..

In your example it may be a fine metering valve for larger expected flow rates that you want controlled.

About the only thing that "may" define it is that there are many turns..
But again, that is dependent on what it is designed for..

Say small medium and large flow. A large flow rate metering valve will do what you see.
So each is defined by it's range not how many turns you want it to do..
 

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Coarseness or "sensitivity" doesn't really define
if it's a metering valve.
you can have larger flow metering valves that "we " can't use but fine for larger flow demands.



In our use most if not all are needle valves w/ fine needles in the few degree taper range.
Increase the metering valve to large angles say 10-20 degrees and it is still a metering valve .. for something..
Ours are like 1-3 degrees for the most precise low flow rates..

In your example it may be a fine metering valve for larger expected flow rates that you want controlled.

About the only thing that "may" define it is that there are many turns..
But again, that is dependent on what it is designed for..

Say small medium and large flow. A large flow rate metering valve will do what you see.
So each is defined by it's range not how many turns you want it to do..
As to your problem.. instead of removing both solenoid and metering valve you can just add a second metering valve and just open the old one to full..

SMC AS-1000 added in line is a cheap add on.

Would need m5 fitting and washer w/ hose barb to fit hose.
Normally would be between solenoid and bubble counter but not sure that is really necessary..
 

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Discussion Starter #34
Ah, I meant that the amount that I need to turn the needle valve knob is tiny - I barely touch it and it will increase the bubbles tenfold. That is what I call too sensitive. I’m looking for a valve that I can turn to the next number or line and have the bubble rate go up only a small amount so I can increase my rate in smaller increments.

Is this what a metering valve does?

My rate now is already way more bbs than I can count but am only getting slightly less than a 1 pt drop in pH.
most listed here are low flow range aerospace industrial, or chromatography device grade metering valves with the low CV (max) rate.
You can also dig the PDF to check their max flow rate for air at specific outlet/inlet pressure differential.
The actual precision of fine tuning bubbles of a metering valve, is the CV rate at around 0.00025, you can check the PDF CV curve/chart of a specific valve, if a valve have manageable turns at around CV = 0.00025, this valve is what you are looking for and will handle the bubble rate well.

Flow meters too, the models listed here not only handle the mini-scale flow rate well, they also give you actual flow rate of co2 in SCCM and total volume versus time.
 

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Discussion Starter #35 (Edited)
Any one wants to DIY a two stage co2 system, right now there are some swagelok S series metering valve SS-SS4-VH, vernier handle version, available on evil bay.
The same metering valve is at upper right in above picture.

Evil bay item number : 324555777352
edited.

all things well
 

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Anyone have experience with Dakota Instruments valves? I see it listed in the OP, but curious if anyone has tried them. Seems like it could be a good option for someone wanting an off-the-shelf solution.

Cv = 0.0008 at 16 turns full open (200ccm air max) for $91 (brass) or $151 (stainless).

 
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