Figure 4 (left) and Figure 5 (right). A U-tube manometer measures the output pressure of a regulator supplying gas to propane or natural gas equipment (left). To work it, measure the difference in heights of the two sides to determine the pressure in inches of water column. In this case, the inlet side is at 17 inches on the left side and 28-3/4 inches on the right side, so the pressure is 11-3/4 inches water column. Note the ruler has measurements on both sides, so you’ll want use the same side to measure the water column height.

Editor’s Note: More details about testing regulator pressure appear on page 9 of this issue’s Special Report.