I have been on this hunt for a while. There’s a few points I need to make here.
- Tubing quality, size, material, etc will all depend on a) your vacuum levels required b)your materials going through the hose
- Flexible tubing is for the most part porous and the deeper the vacuum the more you’ll need thicker walls.
- Get flexible tubing that is a little smaller than the barb size so 3/8" barb would need 5/16" ID tubing
If you need higher vacuum levels (≤50micron), then you’ll need very thick wall tubing. I would recommend either rubber or metal and really nothing else and keep your lines short. PVC and vinly type materials are porous and will break down when exposed to terpenes, acetone, hydrocarbons etc. Rubber is pretty resilient but flexible, so you’ll just need some thick wall tubing. It’s been used in labs for a long time.
5/16" ID tubing you’ll need 1/4" wall
3/8" tubing will need 5/16" wall
1/2" tubing will need 3/8" wall