The FieldPiece SDMN6 dual-port manometer measures both positive and negative pressure on vacuum control lines. The device will take differential pressure readings and display the difference between P1 and P2 at all times in the lower right corner of the LCD. Watch Bryan explain the different measurements on a manometer and how to prevent common mistakes in this video. Click below https://www.youtube.com/watch?v=4J_-GkWhHQI #hvac #manometer #refrigeration | HVAC School