What type of check valves are you talking about? Do you have a bubble counter? If so is it attached to your regulator or is it attached to your co2 line?
Use smaller diameter inner tubing. The smaller it is, the less likely water will traverse down it.I have a motley collection of plastic check valves: eBay, Deep Blue, Fluval, and so forth. As I am replacing one co2 tank right now, I find my needle valve full of water. And I use 3 check valves between a bubble counter and the diffuser. No one seems to be able to manufacture a simple one-way gizmo.
Ugh, like what? Down from 4mm to 0? And heat the needle valve to 100℃?Use smaller diameter inner tubing. The smaller it is, the less likely water will traverse down it.
Also, water/fluid in the NV won't damage it. Just wait for it to dry, which can take forever in such tight spaces. Increasing ambient temperature can help speed evaporation.
W/ caveats..An inexpensive plastic one works just as well (and sometimes better) than the expensive metal ones.
I think there may be some confusion here. Maybe the reference to USP plastics are not made by Arkansas Plastics? I believe Arkansas Plastics are made In Arkansas? Maybe in the Flippin area?Tygon 1/8"ID x 1/4"OD tubing:
Plastic 1/8" check valve: