10.1 Introduction
Automatic sampling systems are most commonly used on crude oil movements to take a representative sample which is then analysed to determine physical properties such as density and sediment & water (S&W). These analytical results are then used to calculate the custody transfer figures, assist in mass balance management, and often determine the price paid for the oil. It is generally considered that if an automatic sampling system performs correctly i.e. meets the required performance criteria as stipulated in “API MPMS Chapter 8.2 Standard Practice for Automatic Sampling of Petroleum and Petroleum Products”, the sample collected is more representative of the liquid sampled than is achievable by other recognised industry sampling practices e.g. sampling static tanks. 10.2 Automatic Sampling The ultimate objective of using an automatic sampling system is to produce a representative sample for analysis purposes The image defines the process (note: If no upstream pipeline mixing, the sample point needs to be positioned at a point in the line that affords a good natural mixing process due to the configuration of the line. e.g. ship's manifold or downstream of pumps/meters).
Automatic sampling systems can be fixed or portable and are divided into two types: in-line or slip stream sample loop, commonly referred to as fast loop. Each system design has a sample extraction mechanism that isolates a sample from the stream.
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