API MPMS Chapter 14.7

This standard serves as a reference for the selection, design, installation, operation and maintenance of single-phase dynamic liquid mass measurement systems that operate in the 350 to 688 kg/m3 (0.350 to 0.689 relative density at 60°F) density range. The mass measurement systems within the scope of this document include inferred mass measurement, where volume at flowing conditions is combined with density at similar conditions to result in measured mass, as well as Coriolis mass measurement.

Liquids with density below 350 and above 688 kg/m3 (below 0.350 and above 0.689 relative density at 60°F) and cryogenic fluids (colder than approximately -50°F) are excluded from the scope of this document, but the principles described herein may apply to such streams.

NGL product should be analyzed to determine the mixture composition. These data should be considered in making a determination of the measurement methods and equipment to be used. It is especially important to use mass measurement whenever the range of molecular sizes is great, such as in high ethane content (more than 2 to 5% ethane) raw make. It is less critical when molecular sizes are similar, such as in the case of mixed butanes.

Sampling equipment and techniques are covered including standards for analytical methods used to determine the composition of the sampled product. Equations of state and correlations used to calculate the density of the product are discussed. The standard used to convert mass to equivalent liquid volumes of components is also discussed.