Originally Posted by birkey
Does the amount of vacuum/pressure change what thickness of fluid should be used
Just make a “U” tall enough to cover the pressure range you expect without blowing the water out. The dia. of the tubing does not matter; use clear Tygon tubing from the hardware store, I like 3/8”. Hook up to the pressure you want to measure, just take a tape measure and measure the difference in height between the two columns of water, that will be your pressure (inches of water pressure). 1 inch of water @ 60 deg F = .0361 psi .
You can add some food coloring to dye it if you like.