February 3, 2021
I built a really complex :-) U-Tube manometer to measure the pressure in the fuel tank as I was pressure testing it. It is a really simple device that is nothing more than a piece of flexible clear tubing shaped in a U. One end vents to the atomosphere and the other is connected to the pressure source, and then it is filled about half full of water. (A little food coloring would help the visibility of the water)
The basic theory of operation is this, when pressure is applied to one side of the manometer the water is displaced the other direction. The pressure can be read directly by measuring the distance between the two levels of water. For fuel tank testing the pressure that you would want to use is about 1 psig. This equates to about 24" of water (sometimes shown as 24 inH2O).
I built my manometer out of a piece of 1/2" clear vinyl tubing, a 2x4 and some duct tape. You can see a picture of it here.
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