API MPMS 19.3A:1997(R2012) pdf download.Manual of Petroleum Measurement Standards Chapter 19.3—Evaporative Loss Measurement
3 Terminology
3.1 DEFINITIONS For the purposes of this standard, the following deÞnitions apply. 3.1.1 data acquisition: The process of receiving signals from the sensors, determining the values corresponding to the signals, and recording the results. 3.1.2 deck: That part of a ßoating roof which provides buoyancy and structure, and which covers the majority of the liquid surface in a bulk liquid storage tank. The deck has an annular space around its perimeter to allow it to rise and descend (as the tank is Þlled and emptied) without binding against the tank shell. This annular space is closed by a ßexi- ble device called a rim seal. The deck may also have penetra- tions, closed by deck Þttings, which accommodate some functional or operational feature of the tank. 3.1.3 deck fitting: The device which substantially closes a penetration in the deck of a ßoating roof in a bulk liquid storage tank. Such penetrations are typically for the purpose of accom- modating some functional or operational feature of the tank. 3.1.4 external floating roof: A ßoating roof that is exposed to the ambient environmental conditions by virtue of being in a bulk liquid storage tank that does not have a Þxed roof at the top of the tank shell. External ßoating roofs are thus distinguished from internal ßoating roofs, which are located in tanks that do have a Þxed roof to protect the ßoat- ing roof from environmental exposure. External ßoating roofs are typically designed in accordance with Appendix C of API Standard 650.3.1.5 floating roof: A device that ßoats on the surface of the stored liquid in a bulk liquid storage tank. A ßoating roof substantially covers the liquid product surface, thereby reduc- ing its potential for exposure to evaporation. Floating roofs are comprised of a deck, a rim seal, and miscellaneous deck Þttings. 3.1.6 indicator: An instrument that displays or records signals received from a sensor. The indicator is typically con- structed to express the signal in units that are useful to describe the observed value of measurement. For example, an electronic signal may be received by the indicator as volts, but then displayed as pounds. An indicator may be incorpo- rated into an electronic data acquisition system. An electronic data acquisition system typically has the capability to be pre- programmed to record data at prescribed intervals, to analyze the data that has been received, and to electronically store the results. 3.1.7 instrument: A device used in the measurement pro- cess to sense, transmit, or record observations.