1-10 SCFH is equiv. to .5-5LPM..
You need to sort of guess at what volume of CO2 you will use..
I personally just "drip" small amounts of CO2 into smaller tanks (none larger than a 55)
so almost ANY flowmeter won't work for me..
.5 to 2.5 SCFH === .2 to 1.2LPM
.5-5 SCFH === 2.5 to 2.5LPM
Would be my only choices..
You need to check w/ flowmeter people.. : )
What tank size is a start..
Nothing is "solid' so to speak.. Spaces between molecules or "crystals" maxtrixs ect.. soo some things allow things to leak out.
Also some substances naturally "dissolve" things into them..
At least as I understand the Universe..
almost all common tubing is fairly impervious to CO2 except Silicone tubing..
technically that only really matters w/ high pressures and length of tubing runs..
At worst one could lose a few $'s per year..unless an extreme setup....
Even the venerable ADA only uses silicone for the "last mile" since it is much easier on glass stuff..
I found it more difficult to find tubing that "fits" things more of an issue than the type of tubing.
Oh and some does have a tendency to harden faster than other tubing so replacement costs could come into play..
And pressure ratings..a lot of tubing "we" use is "technically" not rated for like 30-50psi..though I've never heard of any tube blowouts..