thermometer : an instrument that measures temperature. Thermometers provide a way to estimate temperature from its effect on a substance with known characteristics, such as a gas that expands when heated. Various types of thermometers measure temperatures by measuring the change in pressure of a gas kept at a constant volume, the change in electrical resistance of metals, or the galvanic effect of dissimilar metals in contact. The most common thermometer is the mercury-filled glass tube, which indicates temperature by the expansion of the liquid mercury. thief : a device that is lowered into a tank to take an oil sample at any depth. The sample will subsequently be used to determine the quality of the oil in the tank. thief : to obtain a sample of oil from a tank using a thief. time-proportional sample : an automatic sample usually obtained from a pipeline and taken at regular timed intervals. tolerance : the range of variation permitted in maintaining a specific dimension in machining a part. Example, a shaft measurement could be 2.000 inches ± 0.001 (50 millimeters ± 0.025). This means that any measurement from 1.999 inches to 2.001 inches (49.975 millimeters to 50.025 millimeters) would be acceptable. turbine fuel : a fuel oil, similar to diesel fuel, which is used to run gas turbines.
turbine meter : a velocity-measuring device for fluids in which the flow is parallel to the rotor axis and the speed of rotation is proportional to the rate of flow. In liquid turbine meter measurement, the meter and electronic instrumentation are combined to measure total flow and / or flow rate within the piping system. ullage tape-and-bob procedure : see outage tape- and-bob procedure . vacuum breaker : a device used to prevent a vacuum from occurring in a tank, vessel, piping, etc. valve : a device used to control the rate of flowina line, to open or shut off a line completely, or to serve as an automatic or semiautomatic safety device. Those used extensively includethe check valve, gate valve, needle valve, plug valve, and pressure relief valve. Vapour : a substance in the gaseous state that can be liquifiedby compression or cooling. Vapour loss : the loss of hydrocarbons through evaporation. Vapour pressure : the pressure exerted by the Vapour of a substance when the substance and its Vapour are in equilibrium. Equilibrium is established when the rate of evaporation of the substance is equal to the rate of condensation of its Vapour.
striking plate : a plate on the bottom of a storage tankor on the datum plate that is directly below the reference point on the hatch. This location is where the innage bob comes to rest when the tank is gauged and serves as the zero point for all innage measurements. sulfur (S) : a pale yellow, nonmetallic chemical element. In its elemental state free sulfur has a crystalline or amorphous form. In many gas streams, sulfur may be found as volatile sulfur compounds - hydrogen sulfide, sulfur oxides, mercaptans, carbonyl sulfide.Reduction of their concentration level is necessary for corrosioncontrol and,in many cases, necessary for health and safety reasons. tank bottoms : the settling in the bottom of a storage tank.
tank calibration : see tank strapping .
tank strapping : measuring a tank in order to obtain certain of its dimensions, such as the depth of the tank inside and outside, the circumference of each ring on the tank, and the height of the liquid in the tank, so as to be able to produce a capacity table. tetraethyl lead : an anti-knock compound for motor gasoline. It is being phased out as lead is a pollutant. thermohydrometer : a combination hydrometer- thermometer designed to measure density and temperature of a liquid.
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