RadonAway 50020 U-Tube Easy-Read Manometer

The clear tubing that comes with the manometer is 3/16” outside diameter and an 1/8” inside diameter.

I doubt it since there is no gauge to measure air pressure or flow rate. But I do know that it does a great job on indicating that there is a flow of air in a pipe.

The liquid is in the unit, it is the blue color in the photograph.

No, just slide the tube about 1 inch into the hole drilled into the PVC pipe and you're all set.