Locate the test point on the pipe, or a value that opens to the atmosphere, such as a gas burner or a tap. Test points vary in size and shape but usually consist of a plugged section of pipe extending from the main pipe. For example, the test point on a refrigerator gas pipe may be a plugged 1/8-inch pipe.
Remove the plug from the end of the test point, if relevant, then push the rubber cone on the end of the manometer tube, over the end of the value or test point on the pipe. Connection methods vary so consult the manufacturer's manual before use.
Ensure that the manometer is securely sealed to the pipe. Turn on the tap, if present, to complete the connection between the manometer and the pipe. Remain with the manometer and observe the reading on the dial or display. This shows the pressure in the pipe.
Close the tap, if opened, and then remove the manometer from the pipe. Replace the plug in the end of the test pipe and make certain it is secure.