# [Wet Thumb Forum]-CO2 Control



## Bill Davies (Oct 21, 2003)

In a phone conversation that I had with Mr."H" today, I was telling him about my gas control system. He suggested that I share it with you. I have 2 - 58g, 1 - 30g, 1 - 20g, and 1 - 15g tanks. These are set up as three "stations". I was turning on the gas with one solenoid controlled by the lighting timer of one station. I run my gas at 10psig. Since it is virtually impossible to synchronize the timers I encurred problems with lights on but no gas, or lights off but gas still flowing, also minor end of tank "blow off". I'm correcting this by having a constant pressure in the supply line to each station. I use a standard CO2 regulator with one addition. I have added a Clippard (www.clippard.com) piston type regulator after the standard regulator. The maximum psi on this adjustable unit is 20psig. You can buy them in various pressure ratings from Aquabotanic, I believe. This prevents blow off. I have a Clippard solenoid valve at each station controlled by that stations lighting timer. The solenoids can be ordered in various coil voltages. I use a 12vdc coil with the power being supplied by a "wall wart". These solenoids require only 6.7 watts so a wall wart rated at 300ma or larger is sufficient. These can be bought at Radio Shack, flea markets, or salvaged from old electronic gadgets. (Take them from your kids video games when they're not looking.) Clippard makes small manifolds and other items which lend themselves wonderfully to our purpose. Questions?? Contact me.


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## Bill Davies (Oct 21, 2003)

In a phone conversation that I had with Mr."H" today, I was telling him about my gas control system. He suggested that I share it with you. I have 2 - 58g, 1 - 30g, 1 - 20g, and 1 - 15g tanks. These are set up as three "stations". I was turning on the gas with one solenoid controlled by the lighting timer of one station. I run my gas at 10psig. Since it is virtually impossible to synchronize the timers I encurred problems with lights on but no gas, or lights off but gas still flowing, also minor end of tank "blow off". I'm correcting this by having a constant pressure in the supply line to each station. I use a standard CO2 regulator with one addition. I have added a Clippard (www.clippard.com) piston type regulator after the standard regulator. The maximum psi on this adjustable unit is 20psig. You can buy them in various pressure ratings from Aquabotanic, I believe. This prevents blow off. I have a Clippard solenoid valve at each station controlled by that stations lighting timer. The solenoids can be ordered in various coil voltages. I use a 12vdc coil with the power being supplied by a "wall wart". These solenoids require only 6.7 watts so a wall wart rated at 300ma or larger is sufficient. These can be bought at Radio Shack, flea markets, or salvaged from old electronic gadgets. (Take them from your kids video games when they're not looking.) Clippard makes small manifolds and other items which lend themselves wonderfully to our purpose. Questions?? Contact me.


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## BobAlston (Jan 23, 2004)

The clippard pressure control device after the regulator is something I have considered doing. Did you use the one that limits the pressure only or the one that vents the excess pressure?

Seems like you did a fairly elaborate method to simply turn off co2 at night. Many people such as myself leave co2 on all the time. So it would seem that a single solenoid on one timer would be sufficient.

One suggestion, since you run your gas at 10 psi, your clippard secondary regulation allows your co2 flow to double. I would think it would be preferable to run the normal regulator at just below the clippard regulator say 8 psi and then use a clippard at 10. that way only a 20% increase in gas flow would happen at end of tank dump.

However, if you monitor your co2 tank weekly you should see the beginning of pressure drop and be able to refill the co2 tank without incident.

Just curious what needle valves do you use at each tanks?? I would guess probably Clippard MNV-4k2.

Bob

High Pressure CO2 sources, needle valves, information:
http://members.cox.net/tulsaalstons/AquaticPlants.htm#High%20Pressure%20CO2


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## Bill Davies (Oct 21, 2003)

The regulator does not vent. There is no reason for that. Leaving the CO2 running is a waste besides the plants make their own and the fish certainly don't need it. The pressure into the Clippard regulator is about 50psig. I have two 20# tanks and I only pay for the gas put in the tank by weight. I use the MNV-4-K2 type valve and the EC-2M-12-L solenoid.


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## Bill Davies (Oct 21, 2003)

P/N MAR-1P-2


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## BobAlston (Jan 23, 2004)

The reason many people leave the co2 running vs. turning it off is that it is cheaper to do that - cost of gas - rather than buy a solenoid to shut off the gas.

Bob

High Pressure CO2 sources, needle valves, information:
http://members.cox.net/tulsaalstons/AquaticPlants.htm#High%20Pressure%20CO2


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## gsmollin (Feb 3, 2003)

This is interesting, since I had considered almost exactly this design a couple of years ago. It's nice to know it works. I never pursued it, based on an accounting exercise that showed the return on investment was negative, compared with cost of gas for an open-loop design. The dump issue I solved by running the regulator at 36 psi and using two "S" series metering valves to control the gas flow. In addition to solving the dump problem, two metering valves also solves the failure-mode problems associated with single valve systems. The MNV-4k2 is impossible to beat for price/performance ratio, but the "S" series is easier to set.


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## BobAlston (Jan 23, 2004)

Swagelok S series metering valves should be about $50 each.

Bob

High Pressure CO2 sources, needle valves, information:
http://members.cox.net/tulsaalstons/AquaticPlants.htm#High%20Pressure%20CO2


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## david lim (Mar 30, 2004)

I got mine on ebay-- 2 for $30 =)!!!! They don't show up very often though.


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## BobAlston (Jan 23, 2004)

Well if you see any more, let me know!

bob

High Pressure CO2 sources, needle valves, information:
http://members.cox.net/tulsaalstons/AquaticPlants.htm#High%20Pressure%20CO2


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## gsmollin (Feb 3, 2003)

Rex,

The accounting was for a solenoid controlled system v.s. a gas-on-24/7 system. The needle valves are held constant for that analysis. 

The dump issue compares the cost of a second regulator v.s. the second needle valve. 

However, none of these cost comparisons addresses the failure-mode-effects issues, which decided the design. Dual, tandem needle valves assures that no single-point-failure of a needle valve can inject a lethal amount of CO2 into the water.

The issue with the Clippard valve is well known. It's a great little needle valve, but actually not designed for the low flow rates in an aquarium application. It has to be forced into the shutoff region, where the pressure on the valve seat is controlling the flow, not the position of the needle in the valve. I'm just not comfortable with using it, so I got better valves. They cost more, but are worht it IMHO.


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## Bill Davies (Oct 21, 2003)

I'm sorry but I don't understand. What is an "S" series valve. Please give me a Clippard part number. Thank you.


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## gsmollin (Feb 3, 2003)

> quote:
> 
> Originally posted by Bill Davies:
> I'm sorry but I don't understand. What is an "S" series valve. Please give me a Clippard part number. Thank you.


Like Rex said... Here is the Swagelok B-SS4 very fine metering valve:

http://www.swagelok.com/PRODUCTDETAILS.asp?PartNumber=B-SS4&Price=&Picture=SS%2DSS4%2Ejpg%26CTSCKey%3D69

If that link doesn't work, just go to the home page and search on the part number.

Here is the Clippard MNV-4K2:

http://www.clippard.com/store/display_details.asp?sku=MNV-4K2

Ditto, if the link doesn't work.

Robert sells Clippard equipment, so kindly patronize him if you choose Clippard. You can find his needle valves here:

http://www.aquabotanic.com/abstore/index.html

Click on "CO2 accessories" link. The MNV-4K2 is pictured in the "4plex manifold" in the middle of the page. It's a right-angle valve, that uses the 10-32 Clippard O-ring seal on the inlet side, so you need an adapter fitting or a manifold to connect it into most CO2 systems. If you contact Robert, he can be sure you get the right adapters for your CO2 setup.


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## BobAlston (Jan 23, 2004)

And if you would like to see some quotes from users of the Swagelok and other valves, look here:

http://members.cox.net/tulsaalstons/Documents/Aquarium%20Needle-Metering%20Valve%20Recommendations.htm

Bob

High Pressure CO2 sources, needle valves, information:
http://members.cox.net/tulsaalstons/AquaticPlants.htm#High%20Pressure%20CO2


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## Bill Davies (Oct 21, 2003)

I stated that the Clippard solenoid valve is rated at 6.7 watts. I stand corrected that it is rated at 0.67 watts. (Thank you Scott).


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