Potential density
Potential density is a dynamically important property: for static stability potential density must decrease upward. If it doesn't, a fluid parcel displaced upward finds itself lighter than its neighbors, and continues to move upward; similarly, a fluid parcel displaced downward would be heavier than its neighbors. This is true even if the density of the fluid decreases upward. In stable conditions (potential density decreasing upward) motion along surfaces of constant potential density (isopycnals) is energetically favored over flow across these surfaces (diapycnal flow), so most of the motion within a 3-D geophysical fluid takes place along these 2-D surfaces.
DM3 density meter
The DM3 weighs media (slurry) as it travels through a metered section of pipe using a patented, high resolution load cell. Using linear, direct sensing of mass per unit volume, measurement system within a reinforced rubber tube. This in-line section of pipe calculates % dry solids, wet density and wet or dry mass flow units. When coupled with compatible volumetric flow meters and processing units, this system gives a true value for density and mass flow. The DM3 is a bi-directional unit which allows media to flow continuously through either ends. "C" Clamps located within the DM3 allows the flow tube to withhold high levels of pressure encountered. The flow tube was designed to focus on the highest amount of accuracy, resolution, and least amount of weight without compromising mechanical stability and reliability. Because of the sensitivity of measurement provided by DM3, each unit must be programmed and calibrated to accommodate the variation in Earth's gravitational force.