Althoughgaseous at normal temperatures and pressures, the gases making up themixturethatis natural gasare variable in form and may be found either as gases or as liquids under suitable conditions of temperature and pressure. Net volume : the total volume of liquid in a tank after adjustments have been includedfor S&W content, temperature, and density. Compare gross volume. NIST abbr: the National Instituteof Standardsand Technology . observed volumes : thosevolumes of liquid orgas that are indicated by the register on the meter. Compare true volume . octane level : a measure of the antiknockproperties of a fuel. oil-water interface : the boundary between the oil on top and the water below when both are contained in the same vessel. opening gauge : the measurement of liquidin a tank before a deliveryor receipt. Compare closing gauge. outage measurement : a measure of the space between the top of the liquid in a tank and the reference point on the gauge hatch. outage tape-and-bob procedure : a methodof measuring the liquid level in a tank by measuring the space between the top of the liquidin a tank and the reference point on the gauge hatch.
pressure gauge : aninstrumentthat measuresfluid pressureand usually registersthe difference between atmospheric pressure and the pressure of the fluidby indicatingthe effect of such pressures on a measuringelement (e.g., a column of liquid, pressure in a Bourdon tube,a weighted piston, ora diaphragm). pressure-reducing valve : atype of valvethat changes the upstreampressure to a lower downstream pressure. pressure relief valve : avalve that opens at a preset pressure to relieve excessive pressures within a vessel or line.Also called a pop-off valve or safety relief valve. pressure surge : a sudden increase in pressure in fluid flowing in a pipe or in liquid flowing into a storage tank. probe : any small device that, when broughtinto contact with or inserted into a system, can make measurements on that system. In sampling, probes are inserted into pipelines so that small samples of liquid can be removed and then stored for future testing.
manifold valve : a valve placed in a series of piping that is called a manifold. master meter : a meter that is proved using a certifiedprover and then used to calibrate other provers or to prove other meters. liquid displacement : the crude oil or product that is forced into the hatch or up around the edges of a floatingroof by the weight of the roof. Meniscus : the curved upper surface of a liquid column, concave when the containingwalls are wet by the liquid (negative meniscus) and convex when not (positive meniscus). Liquid-in-glass thermometer : a type of thermometer in which the sensitive part of the instrument consists of liquid contained in an envelopeof glass. Meter : a device used to measure and often record volumes,quantities, or flow ratesof gases,liquids,or electric currents. Naphtha : a volatile, flammable liquid hydrocarbon distilled from petroleum and used as a solvent or a fuel. Natural gas : a highlycompressible, highly expansible mixture of hydrocarbons with a low specific gravity and occurring naturally in a gaseous form. Besides hydrocarbon gases, natural gas may contain appreciable quantities of nitrogen, helium, carbon dioxide, hydrogensulfide,and water Vapour.
psia abbr: pounds per square inch absolute.
Rankine temperature scale : a temperature scalewith the zero point at absolute zero. On the Rankine scale, water freezes at 491.60º and boils at 671.69º.
Compare innage tape-and-bob procedure.
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