[DeadlyMuffin]

I put together a DIY CO2 regulator setup that I'm having trouble with. I'm using a Victor regulator, and a Swagelok S series (SS-SS2-A to be exact) valve to meter the CO2 flow.

With the regulator set at 10psi, which is as low as I can get it, I'm getting more bubbles than I want even with the valve completely closed.

Has anyone else used S series valves in this kind of setup? Does it sound like I've got a defective part, or the wrong part for the job?

 

[Darkblade48]

Just curious as to why you have the needle valve before the solenoid...most people have it the other way around.

Also, I used the exact same metering valve and was able to get it down to 1 bubble per 3-4 seconds.

I do not believe that particular metering valve was designed to be closed completely either, so if you did, it may have damaged it.

 

[DeadlyMuffin]

I put it in front of the solenoid because it was convenient with the parts I had. I don't think it it makes a difference.

I read the Swagelok writeup on these valves, they have a stop to keep them from being closed too far and getting damaged so I'm skeptical that I damaged it that way. It was bought off ebay though, so who knows what the previous owner did to it.

What was your pressure behind your valve? If my regulator went lower than 10psi I'd be able to drop the flow rate that way.

 

[Bandit1200]

In my experience the lower the psi, the harder it is to get a consistent flow rate out of the system. I usually run mine in the 15-20 range.

 

[oldpunk78]

Those things come from the factory so that when closed, it's not really closed. You'll need to take the handle off and reset the zero point to what ever you want. Know that it's easy to break the needle off if you close the valve completely.

 

[Darkblade48]

What was your pressure behind your valve? If my regulator went lower than 10psi I'd be able to drop the flow rate that way.

I could still adjust it with a delivery pressure of 5 PSI.

 

[DeadlyMuffin]

I could still adjust it with a delivery pressure of 5 PSI.

That's probably the difference. I can't get much lower than 10psi with the regulator I'm using.

Those things come from the factory so that when closed, it's not really closed. You'll need to take the handle off and reset the zero point to what ever you want. Know that it's easy to break the needle off if you close the valve completely.

You're right, they're not designed to completely close. I didn't know they could be modified though! I didn't see how to do it from the diagram on the Swagelok site, how do you get it apart?

edit: Do I loosen the top set screw, unscrew the handle slightly, then retighten the set screw? That would put the handle slightly higher up on the stem.

 

[oldpunk78]

^ basically, all you have to do is loosen the Allen on the end and slide the handle out until you hit your lowest desired rate. Move it too much and tighten it down too hard and you'll break it. Go in small increments.

If set correctly, you'll have about one turn to from zero to about one and a half bubbles per second.