API MPMS 8.2:1995 pdf download.Manual of Petroleum Measurement  Standards Chapter 8‑Sampling
3 Definitions
3.1 automatic sampler: A device used to extract a rep- resentative sample from the liquid flowing in a pipe. The au- tomatic sampler generally consists of a probe, a sample extractor, an associated controller, a flow-measuring device, and a sample receiver. 3.2 automatic sampling system: A system that consists of stream conditioning, an automatic sampler, and sample mixing and handling. 3.3 dissolved water: Water in solution in petroleum and petroleum products. 3.4 emulsion: An oil/water mixture that does not readily separate. 3.5 entrained water: Water suspended in oil. Entrained water includes emulsions but does not include dissolved wa- ter. 3.6 flow proportional sample: A sample taken from a pipe such that the rate of sampling is proportional, through- out the sampling period, to the flow rate of liquid in the pipe. 3.7 free water: Water that exists as a separate phase. 3.8 grab: The volume of sample extracted from a pipeline by a single actuation of the sample extractor. 3.9 homogeneous: When a liquid composition is the same at all points in the container, tank, or pipeline cross sec- tion. 3.10 isokinetic sampling: Sampling in such a manner that the linear velocity of the liquid through the opening of the sampling probe is equal to the linear velocity of the liq- uid in the pipeline at the sampling location and is in the same direction as the bulk of the liquid in the pipeline approaching the sampling probe.
4 Significance and Use
Representative samples of petroleum and petroleum prod- ucts are required for the determination of chemical and phys- ical properties, which are used to establish standard volumes, prices, and compliance with commercial and regulatory specifications. 4.1 APPLICABLE FLUIDS This standard is applicable to petroleum and petroleum products with vapor pressure at sampling and sample stor- age temperature less than or equal to 101 .32 kilopascals (14.7 pounds per square inch absolute). Reference API MPMS Chapter 8.4 when sampling for RVP determination. 4.2 NONAPPLICABLE FLUIDS Petroleum and petroleum products whose vapor pressure at sampling and sample storage conditions are above 101.32 kilopascals (14.7 pounds per square inch absolute) and liquefied gases (for example, liquefied natural gas, liq- uefed petroleum gas) are not covered by this standard. In addition, petroleum asphalts are not covered by this standard. While these methods will produce a representative sam- ple of the flowing liquid into the sample receiver, specialized sample handling may be necessary to maintain sample in- tegrity of more volatile materials at high temperatures or ex- tended residence times in the receiver. Such handling requirements are not within the scope of this method. The procedures for sampling these fluids are described in ASTM Methods D1265, D923, D1145, and GPA 2166.