Pressurized CO2 Problem

[Captain Hook]

The past 2 weeks have been frustrating for me. I get my CO2 flow rate set where I want it and a day or two later it has come to a complete stop. Every time get it going this happens.

I'm using a Clippard needle valve that I haven't had any problems with in the past. The only thing that has changed is I added a check valve to stop the backflow of water. If it stops one more time I think I will take the check valve off and see what happens.

[djlen]

Captain - is the check valve set in the right direction? What is the out-going pressure on your regulator?
This is an unusual occurrence.

Len

[Captain Hook]

Yes the check valve is definitely going the right way. I was told if you don't put it on the right way, it will stop the gas and be bad news.

Pressure on the big tank is around 800, no problems there. I have it set to give about 5 psi to the NV. Looks like the flow has already significantly reduced from what I set it at yesterday.

[djlen]

Up your out-going pressure to 12 - 18psi and it should solve the problem. Then you can slowly back it down to about 10 - 12psi.
IME 5psi is too low and often results in what you are experiencing.

Len

[Captain Hook]

Thank you Len I will try that. I know the Clippard needle valve is rated to handle up to 30 psi so there shouldn't be any problems increasing it. I've always had it at 5 psi but I'll try what you suggest.

[djlen]

I keep mine at 12psi, but I know there are others who go up into the 20's with no problem. I just like the lowest usable pressure I can have to take pressure off the line between the reg. and needle valve.

Len

[Captain Hook]

I have it set around 12 psi now but the problem keeps happening. I'm thinking about taking the check valve off and see what happens. This is starting to get frustrating!

[djlen]

If removing the check valve doesn't alleviate the problem I would push the pressure up to 20psi and see if it continues. It won't hurt anything at that pressure and if it continues you might need to replace the needle valve.
Let us know how it comes out please.

Len

[Captain Hook]

Well Len, it looks like the check valve was the problem. It's been running a couple days without it and the flow has not slowed down at all.

I don't get why the check valve is stopping the CO2. I put about a 4" section of tubing from the needle valve to the check valve and it has a really foggy build up on it now. Anyone have any thoughts on this?

Is there a certain way I should be setting up the check valve? I know the direction was right but is there a certain spot along the line it should go?(close to needle valve, close to tank, etc.)

Chris

[djlen]

Try putting it between the regulator and the needle valve. It will probably work fine in that configuration. If not you've got a bad check valve.


Len

[vic21]

C/H:
The cloudy stuff is corrosion caused by CO2. Carbolic acid. CO2 is extremely corrosive to plastic or silicone tubing. Try changing you tubing to NEW automotive brake line. This stuff is immune to CO2 corrosion. Do you have a bubble counter? If so there is likely a check valve built into the bubble counter and therwefore you do not need an inline check valve. If not consider a bubble counter with an integral check valve. This check valve will likely be stainless which is also immune to CO2. Was the inline check valve plastic? If so it is likely corroded by the CO2 and that is the likely reason for the flow stopage. The bubble counter is really useful in setting flow rate. If you do not want to go the bubble counter route get a metal check valve to terminate the corrision issue.
Cheers;

[Captain Hook]

Thanks again for all the help. It seems to be working fine without the check valve so I'm going to leave it like that for now. I just got some fairly difficult plants such Ludwigia sp. Guinea, Cyperus helferi and Limnophila aromatica so I want to make sure I have good CO2 levels.

The check valve is brass and steel. I'm going to try emailing the guy who gave it to me and see if knows what's going on.