TY  - GEN
AU  - Dixon, Matthew
AU  - Sansó, Esteban
AU  - Rodríguez, Germán
ED  - Instituto Argentino del Petróleo y del Gas, IAPG
ED  - Congreso Latinoamericano y del Caribe de Refinación (7mo. : 2025 oct. 28-30 : Buenos Aires)
TI  - Sampling liquids in a sample cylinder: Vapor space and outage tubes
N2  - When sampling liquids using sample cylinders, there are few things more important than overpressure protection. Liquids typically have higher rates of thermal expansion than the metal sample cylinders in which they are contained, which can cause problems if the temperature of the cylinder rises after the sample is taken. Due to the incompressible nature of liquids, this expansion of the liquid can create immense hydraulic pressure that can damage or even rupture the sample cylinder.
The cylinder can be protected using rupture discs or relief valves, but both solutions usually result in the reléase of the sample, or a portion of the sample, to the atmosphere. This presents a myriad of problems, especially if the sample is toxic to the environment or to the personnel transporting the cylinder to the laboratory. As such, when taking liquid samples in a cylinder, rupture discs and relief valves are commonly seen as secondary methods of overpressure protection, not the primary method.
The most common primary method of overpressure protection is to avoid filling the cylinder 100% liquid-full in the first place. Leaving some gas, also known as a vapor space, in the cylinder with the liquid sample provides that sample a place into which it can expand in the event of a rising temperature. Because this vapor space is compressible, the liquid can expand into the space, compressing that gas. This will still result in a pressure rise but not the exponential and catastrophic
increase that can be experienced by a cylinder that is 100% liquid-full. There are many methods that can be used to create a vapor space, a few of which will be described. However, one of the most simple and effective methods is to use an outage tube. The intent of this paper is to describe the use of outage tubes, explain how they can be used to create the requisite vapor space, and describe how to ensure that the resulting vapor space is sufficiently sized for the
application
UR  - https://biblioteca.iapg.org.ar/ArchivosAdjuntos/7moCongresoRefinacion2025/REF018.pdf
ER  -