I'm about ready to get started on my air pressure flood coolant system. The idea has been bouncing around in the back of my head for quite a while, and the one thing I haven't quite got figured out is the method for checking the level in recovery tank and the pressure tank. I was thinking I'ld weld a couple thicker plates on the side at the top and bottom, pipe tap them, and put in some right angle hose barbs with a bit of clear tube. I have used a tight fitting brass hose barb and a stainless hose clamp to repair an airline in the past. It worked fine. In this case though the tanks will most likely be fill with a petro chemical of some kind.
I'm trying to determine which tube I can use that will take the pressure (probably pretty low based on some experimentation), be able to withstand the coolant in the tanks, and be nice and clear for visible check of level.