bleed valve : a special valve used
closing gauge : the measurement of liquid in a tank after a delivery or receipt. Compare opening gauge. composite sample : a blend of spot samples mixed in equal proportions for testing. condensate : a light hydrocarbon liquid obtained by condensation of hydrocarbon Vapours. It consists of varying proportions of butane, propane, pentane, and heavier fractions, with little or no methane or ethane. core sample : a spot sample of the contents of an oil or oil products storage tank usually obtained with a thief, or core sampler, at a given height in the tank. critical zone : in tanks with floating roofs, the vertical range in which the gauging measurements are not accurate because the roof is neither fully floating nor fully supported on its legs. custody transfer : the changing of the ownership or the responsibility for quantities of gas, petroleum, or petroleum products. datum plate : a metal plate attached to the tank shell on or near the bottom and located directly under the gauge reference point to provide a fixed contact surface from which liquid depth measurements can be made.
all-level sample : taken by lowering the stoppered device to the bottom of the outlet suction level, but always above any free water, then opening the sampler and raising it at a uniform rate such as it is between 70% and 85% full when withdrawn from the product. American Society for Testing and Materials (ASTM) : organization that sets guidelines for the testing and use of equipment and materials. Angle-stem assembly : a type of thermometer used on oil tanks. The graduated part of the thermometer is angled at least 90º from the temperature-sensitive portion. The angle conforms to the shell of the tank and permits easy reading of the instrument. API gravity : measure of the density or gravity of liquid petroleum products derived from relative density. API MPMS abbr: American Petroleum Institute’s Manual of Petroleum Measurement Standards. ASTM abbr: American Society for Testing and Materials. Baffle : a partial restriction, generally a plate, placed to change the direction, guide the flow, or promote mixing within a tank or vessel. Bleed : to drain off liquid or gas, generally slowly, through a valve called a bleeder. To bleed down, or bleed off, means to release pressure slowly from pressurized equipment.
to bleed pressure slowly from a line or vessel. Also called a blow-down valve. blending stock : a petroleum product that is mixed, or blended, with another petroleum product. block-and-bleed valve : a high-integrity valve with double seals and with provision for determining whether either seal leaks. bottom sample : a sample obtained from the material near the bottom surface of a tank, container, or line at a low point. capacity table : a table that indicates the quantity of liquid contained in a tank at any given level. Carrier : a pipeline, trucking company, or marine transportation company that transports oil or gas. centrifugal pump : a pump with an impeller or rotor, an impeller shaft, and a casing, which discharges fluid by centrifugal force. centrifuge : a machine that uses centrifugal force to separate substances of varying densities. A centrifuge is capable of spinning substances at high speeds to obtain high centrifugal forces. check valve : a valve that permits flow in one direction only. If the gas or liquid starts to reverse, the valve automatically closes, preventing reverse movement. Commonly referred to as a one-way valve.
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