This was one of my very first brewing projects and itís incredibly simple. I had a 12 gallon kettle with a welded coupler and ball valve. The problem was: How do I measure the volume in the kettle?
Many people use a diptube (or their brewing spoon) and mark off gradations on it. Thatís a fine process and works well. I still use that in other applications. Okay, onto the show.
Unscrew the ball valve from the kettle.
Add a nipple to the outside of the kettle and put a tee on the other end with the 90 degree port facing up. (yes, I said nipple)
Screw in a MPT to 3/8Ē hose barb onto the port facing up.
Screw in the ball valve on the remaining side of the tee.
Install a hose onto the barb and cut its length a bit over the top of the kettle. Itís best to use a small hose clamp where the hose attached to the barb.
Slide copper pipe over the tube. One thatís slightly larger than the hose. Mark the pipe where it reaches the top of the kettle.
Remove the pipe and whip out the dremel. First cut the pipe at the marked point.
Next, cut out a viewing window in the pipe. Make sure it has some structural integrity left.
Reinstall the pipe over the hose.
The construction is now complete. You will need to fill the kettle gradually with a calibrated measuring device. With a permanent marker, mark the hose at each level (half gallon or gallon marks as you see fit)
Note, the only drawback to this method is that the level shown in the site tube is not accurate when the ball valve is open. Not a big deal! If you wanted, you could add a stopper to the top of the tube while it was draining if you really needed to know the level at that time. Iíve never needed to know.