This paper, courtesy of Yokogawa Corporation of America, covers level measurement using differential pressure (DP) level transmitters. A DP level transmitter uses the head pressure and specific gravity of the media to infer the level in the vessel. It is a widely-used level technology having the advantage of being based on a well-understood principle. It is an excellent selection for clean liquids but also works well with viscous liquids and slurry/sludge; but, is not recommended for solids. The disadvantage is the limited temperature operating envelope of the transmitter. Adding a remote diaphragm seal system to the DP transmitter overcomes this limitation.