ISO/NP 25878

Continuous Density Measurement ISO/NP 25878

Scope

Accuracy in the measurement of density is essential for bulk volume measurements so that the mass may be determined. Mass may be required for reporting or for other qualitative purposes. This publication covers the continuous determination of the density of liquids and gases including stable crude oils, enriched crude oils, condensates, natural gases and other liquid and gaseous products commonly encountered in the petroleum industry.

The types of metering system described in this document and where the need for continuous density measurement may be applicable are intended primarily for the measurement of petroleum for the purposes of sales, taxation or product allocation in multi-user pipelines. Dependent on usage these systems can generally all be termed custody transfer, implying a standard of accuracy that is the highest reasonably attainable in practice, taking account of the balance between cost and accuracy.

This publication describes methods for the continuous on-line real-time measurement of density in petroleum and petroleum products. The procedures for the proper installation, operation and calibration of on-line density in petroleum measurement devices are also described.
It describes equipment for continuous density measurement and covers the installation and proving of this equipment. Methods of determining density on individual samples are given in HM 7. General guidance on test methods for density, water and sediment determination and in IP Standard Test Methods for analysis and testing of petroleum and related products, and British Standards 2000 Parts (methods IP 160, IP 189, IP 190, IP 235, IP 249 and IP 365).
Accuracy in the measurement of density is essential for bulk volume measurements so that the mass may be determined and for many qualitative purposes. For these applications, this publication describes installations capable of providing an uncertainty of up to 0,15 % for liquids and up to 0,2 % for gases and condensates.