API MPMS 8.3:1995(R2010) pdf download.Manual of Petroleum Measurement Standards Chapter 8- Sampling
6 Sample
No single container type will meet requirements of all petroleum sampling operations. The following are general de- sign and construction considerations for sample containers. 6.1 CONTAINER CONFIGURATION The following describes container configuration consid- erations: a. Containers should drain continuously toward the outlet to ensure complete liquid withdrawal. b. Cylindrical containers are better suited for samples that are to be tested for free water or sediment and water (S&W). c. Containers should not have internal pockets or dead spots. d. Internal surfaces· of containers should minimize corro- sion, incrustation, water, and sediment clingage. e. Container configuration should allow for the transfer of samples from one container to another or the analytical ap- paratus while maintaining the integrity of the sample ’ s com- position. f. Containers should have an inspection cover/closure/cap of sufficient size to facilitate filling, inspection, and clean- ing. A means of installing security seals should be provided. g. Containers should allow for of a homo- geneous mixture of the sample while preventing the loss of any constituents that the representativeness of the sam- ple and the accuracy of the analytical tests. h. Containers should be made so as to avoid contamination from external water or other foreign material. i. Containers used with closed loop mixers may be equipped with a discharge line inside the container that has multiple outlet ports. Another method of achieving the effect of multiple discharge ports is to split the discharge stream coming from the mixing pump into two or more separate streams with each having its own inlet into the sample con- tamer. j. Containers used with closed loop mixers should be equipped with a pressure/vacuum relief valve set so as not to the design pressure of the container. A pressure gauge should also be provided. k. Containers used with closed loop mixers may have mul- tiple suction ports.
6.2 CONTAINER SIZE
A general rule is that both primary and intermediate con- tainers should be large enough to hold the required sample size within 80 percent of the total capacity to facilitate mix- ing and to provide for thermal expansion. The size of primary containers is determined from the sampling operation as outlined in Chapters 8.1 and 8.2 of API’s Manual of Petroleum Measurements Standards. The size of intermediate containers should be as large as practical to minimize surface tension effects with due con- sideration given to storage space requirements, shipping rules and regulations, costs, availability, and other practical considerations.