A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A Absolute Error The difference between the analytical result and the known true value.
Accuracy Defined as the agreement of a measurement with the known true value for the quantity being measured.
Alkylation The transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion or a carbene (or their equivalents). In oil refining contexts, alkylation refers to a particular alkylation of isobutane with olefins. It is a major aspect of the upgrading of petroleum.
Alkylation Process Alkylation process for motor fuel production catalytically combines light olefins, which are usually mixtures of propylene and butylenes, with isobutane to produce a branched-chain paraffinic fuel.
Alkylate Good gasoline blending component being high in octane and low in vapour pressure.
Alkanes also known as paraffins are chemical compounds that consist only of the elements carbon (C) and hydrogen (H) (i.e. hydrocarbons), wherein these atoms are linked together exclusively by single bonds (i.e. they are saturated compounds) without any cyclic structure (i.e. loops). Alkanes belong to a homologous series of organic compounds in which the members differ by a constant relative atomic mass of 14.
Alkene An alkene or olefin is an unsaturated chemical compound containing at least onecarbon to carbon double bond.
Analyzer An Analyser (Analyzer) is a device which can measure the physical or chemical properties of substances.
Aromaticity A chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. It can also be considered a manifestation of cyclic delocalisation and of resonance.
ATEX ATEX (from the French ATmouspheres EXpolosives) is a name commonly given to a harmonised set of European standards relating to explosives and atmospheres and the standards of equipment and protective systems used in them. ATEX regulations relate to gases, vapours dusts. Equipment for use in hazardous areas in Europe must comply with and in most cases be thrid party certified to the ATEX standards. ATEX certified equipment is acceptable in most markets outside Europe and can form the basis for local approvals without additional testing.
ASTM American Society for Testing Materials
B
Barrel The standard barrel of crude oil or other petroleum product (abb' bbl) is 42US gallons (34.972Imperialgallons or 158.987L). This measurement originated in the early Pennsylvanian oil fields, and permitted both British and American merchants to refer to the same unit, based on the old English wine measure, the tierce.
Benzene (benzol) An organic chemical compound and a known carcinogen with the molecular formula C6H6. It is sometimes abbreviated Ph–H. Benzene is a colourless and highly highly flammable liquid with a sweet smell and a relatively high melting point. Because it is a known carcinogen, its use as an additive in gasoline (petrol) is now limited, but it is an important industrial solvent and precursor in the production of drugs, plastics, synthetic rubber, and dyes . Benzene is a natural constituent of crude oil, but it is usually synthesized from other compounds present in petroleum. Benzene is an aromatic hydrocarbon.
Biofuel Broadly defined as solid, liquid, or gas fuel derived from recently dead biological material, most commonly plants. This distinguishes it from fossil fuel, which is derived from long dead biological material.
Biomass A term used to describe living and recently dead biological material such as trees (woody biomass), or crops, e.g., wheat or corn, grasses and waste organic material (non-woody biomass) which can be used as fuel. This excludes organic materialwhich has been transformed by geological processes into substances such as coal or petroleum.
Bitumen is a mixture of organic liquids that are highly viscous, black, sticky, entirely soluble in carbon disulphide, and composed primarily of highly condensed polycyclic hydrocarbons. Naturally occurring or crude bitumenis a sticky, tar-like form of petroleum which is thick and heavy and so it must be heated or diluted before it will flow. At room temperature, it is much like cold molasses. Refined bitumen is the residual (bottom) fraction obtained by fractional distillation of crude oil. It is the heaviest fraction and the one with the highest boiling point, boiling at 525°C (977°F). Commonly used in road surfacing or in roofing materials.
Boiling The application of heat to a liquid to change it to a vapour.
Boiling point The maximum temperature at which a liquid can remain a liquid.
C
Catalysis Is the process in which the rate of a chemical reactionis increased by means of a chemical substance known as a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed. Thus, the catalyst may participate in multiple chemical transformations, although in practice catalysts are sometimes consumed in secondary processes.
Catalyst A substance that accelerates the rate of a chemical reaction without itself being affected. In refining catalysts are used in the cracking process to produce blending components for fuels.
Cavitation The formation of vapour or gas filled cavities in liquids. This can be due to high vapour pressure or can arise due to the reduced pressure at the inlet to a pump causing local vapourisation. Cavitation means that the pump is now pumping gas and not liquid and could be damaged. Any restriction to the pump inlet such as a pressure drop from a long pipe run will aid cavitation. To de crease cavitation the pipe runs on a pump inlet should be as short as possible and the pump should be run at the lowest speaad compatible with the duty.
Cetane number A measure of the ignition quality of diesel fuel. The hugher the cetane number, the more easily the fuel is ignited under pressure.
Cloud point A temperature at which wax crystals form when cooling a hydrocarbon liquid such as diesel.
Colour Test APhA (American Pharmaceutical Association) ASTM D1209 Visual Colour test for lighter shades of yellow (for products normally regarded as colourless). The sample colour is compared to the colour of solutions made up by diluting a stock solution of a Platimun Cobalt standard which is assigned an ALPHA colour of 500 with distilled water (assigned an ALPHA colour of 0).
Colour test ASMT (ASMT D1500) Visual colour test for darker (reddish brown) samples. Samples are placed in a sample test jar and the depth of colour judged against a range of standard coloured glass filters. The colour is rated from ASTM 0 (lightest) to ASTM 8.0 (darkest) in 0.5 intervals. If a colour is just lighter or darker than the nearest colour standard it is reported to the nearest colour as 'H' or 'L'.
Colour test Saybolt (ASMT D156-00) Visual colour test for lighter (reddish brown) samples in which a graduated glass tube is filled with sample and the level adjusted so that the depth of colour when viewed from the top of the tube matches the depth of colour of standard coloured glass filters housed in an identical tube. The tube is calibrated in intervals from +30 (lightest colour) to -16 (darkest colour). The test is applicable to jet fuels, kerosines, napthas and waxes. If the sample colour is darker than -16 Saybolt the ASTM D1500 colour test should be used instead. The colour is reported to the nearest whole scale number.
Cracking Secondary refining process using heat and/or catalyst to break down large chemical components into smaller, lighter ones which can be used as blending components in fuels.
Crude oil An unrefined mixture of naturally occuring hydrocarbons which have widely differing densities and properties. Crude oil contains sulphur, nitrogen and oxygen, as well as traces of metals, e.g., nickel or vanadium. Crudes like North Sea Brent, which are low in sulphur, are termed 'sweet', having properties that are more highly valued.
D
Diesel (derv) A light hydrocarbon mixture which is slightly heavier than kerosene used in engines which ignite fuel through compression generated heat rather than spark ignition as in a petrol engine. The term 'derv' is derived from the expression "diesel engine road vehicle".
Distillate Any petroleum product produced by boiling crude oil and collecting the vapours produced as a condensate in a seperate vessel. Most refinery products can be classed as distillates; petrol, which is a light distillate, gas oil, middle distillate, or fuel oil, a heavy distillate.
Distillation The primary distillation processa method of separating chemical substances based upon their volatilities
Distillation Analyser The separation and measurement of the differing fractionation points of hydrocarbon liquids, multiple measuring points between 5-95%
E
Ethers Important family of oxygenates used in gasoline blending pool. Most common being MTBE (Methyl Tertiary Butyl Ether)
F
Fast loop A way of reducing the response time of a sample conditioning system where there is a long distance between the sample take off point and the analyser sample conditioning system. A loop of pipework is made from the sample take off point to the analyser sample conditioning system and back to the process. For sample to flow around the loop a different pressure is needed. Sometimes it is possible to return the loop to a lower pressure part of the process or to use the differential pressure around a control valve to drive the loop. If no differential pressure can be arranged a (fast loop) pump will be required to provide it. Ideally a fast loop pump should be located as close to the process as possible to avoid caviatation.
Fire point Commonly confused with Flashpoint. The firepoint is the temperature at whicha liquid will catch fire due to temperature alone without a source of ignition.
Flashpoint The lowest temperature at which a liquid is capable of forming an inflammable vapour with air. It is an important factor to be conidered when using, transporting and storing fuels. Below the flashpoint temperature the liquid wll not ignite. There are a number of standard flashpoint test methods that use different apparatus and procedures and give different results
Freeze point The freeze point is the point where the wax formed in the freezing process (cloud point) disappear on re heating.
Fractional distillation Used in oil refineries, this process separates crude oil into useful substances (or fractions) having different hydrocarbons with different boiling points. The crude oil fractions having a higher boiling point with more carbon atoms, a higher molecular weight, being darker in colour and more viscous, and significantly more difficult to ignite and to burn.
Fuel cell A process that converts chemical energy into a fuel such as, gas, petrol or hydrogen into electric current either to drive an electric motor or to generate power.
Fuel oil A heavy residue, black in colour, used to generate power or heat by burning in furnaces.
G
Gas to liquids (GTL) AThe production of liquid fuels from natural gas, coal or biomass, often using a process know as Fisher-Tropsch, or development thereof, that was first demonstrated in the early 1920s.
Gas oil A middle distillate used in diesel engines or as heating fuel.
Gasoline Commonly called petrol in the UK, gasoline or motor spirit is a volotile, flammable liquid hydrocarbon refined from crude oil and used to fuel spark ignition internal combustion engines.
Ground level ozone Naturally occuring compound which is also formed by the interaction of VOCs, NOx and sunlight, giving rise to smog an poor low-level visibility, particularly diring hot sunny spells.
I Infrared analyser An Analyser that used the absorbtion of radiation in the infrared spectrum to measure a component of interest. Many types of carbon bonds absorb infrared radiation of specific waveengths. the pattern of the absorbtion canbe used to identify unknown components in the lab. A process analyser working with known components measures the absorbtion of infrared radiation at specific wavelengths to measure the quantity of a known component present.
Infrared spectrum That part of the electromagnetic spectrum that begins at wavelengths just beyond the highest visible wavelength at about 800nm. The region from about 800nm-2500nm wavelength is termed the near infrared (NIR). The mid and far infrared regions occur at longer wavelengths. NIR radiation is transmitted by glass and fibre optics and is commonly used in process analysis. Mid IR radiation is strongly absorbed by glass and fibre optics (and the samples themselves) so is less practical for process ananlysis even though mid and far infrared spectrums contain more detailed information that NIR spectrums. (see also visible and UV spectrum).
O Opacity Opacity is defined as the degree to which a substance is opaque.
S Sample System Method of conditioning a sample in terms of pressure, temperature, flow etc in order to present the sample to a process analyser in a suitable state.
T Total Organic Carbon (TOC) analyser After pretreatment to remove inorganic Carbon (carbonates) TOC analysers use thermal or chamical oxidation (using Hydroxyl radical or UV catalysed persulphate) to oxidize organic Carbon to Carbon Dioxide. The Carbon Dioxide is then measured by an infrared analyser or other means and the result back calculated to give the carbon content.
Total Oxygen Demand This si the oxygen required to oxidise the pollutants in water. As the primary oxidation product will be carbon dioxide there is generally a good relationship between TOC and TOD.
U Ubbelohde viscometer Employs a capillary based methd of measuring viscosity and is recommended for cellulosic polymer solutions which have a higher viscosity.
Ullage The amount by which a container or tank falls short of being full. The area within a vessel that does not contain liquid.
Ultra Violet (UV) UV light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays.
Uranium (U) Heavy silver-white metallic element which is radioactive, toxic, and easily oxidised. Extracted from minerals including uranite and carnotite it is processed for use in research and the nuclear industry.
UV spectrum That part of the electromagnetic spectrum that begins at wavelengths just below the lowest visible wavelength at 400nm-200nm. The UV spectrumis less used for process analysis but some compounds show UV absorbtion for example olefins, aromatics, chlorine, hydrogen sulphide and mercury. back to top
V Vacuum distillation Vacuum distillation is distillation under reduced pressure. At reduced pressures substances have reduced boiling points. Vacuum distillation allows distillation of substances that would decompose upon distillation at normal pressures. In an oil refinery crude oil is first subjected to atmospheric distillation to separate the more volatile components. The pressure is then reduced to separate the less volatile components without decomposition.
Vapour Pressure Vapour pressure is the pressure exerted by a vapour in equilibrium with its solid or liquid phase at a particular temperature. Vapour pressure increases with temperature and is a measure of volatility. Volatile material evaporates more readily than non-volatile material because it has a higher vapour pressure. If the vapour pressure of a liquid reaches that of the surrounding atmosphere bubbles of vapour will form in the liquid and the liquid will boil. Water at sea level (atmospheric pressure 100kPa) boils at 100 degrees C. This means that at 100 degrees C water has a vapour pressure of 100kPa. On top of Mount Everest the atmospheric pressure is about 26kPa. Water has a vapour pressure of 26kPa at 70 degrees C so it will boil at 70 degrees C on top of Mount Everest. So boiling point decreases with decreasing applied pressure. This principle is used in vacuum distillation.
(True) Vapour Pressure (TVP) The Reid vapour pressure test uses a 4:1 vapour to liquid ratio. Under these conditions the more volatile components evaporate preferentially into the vapour space. This means that the composition of the vapour is different from that of the liquid so that they are not in true equilibrium. The TVP is essentially the vapour pressure measured at the liquid surface with no vapour space. This means that in general RVP will be somewhat higher than the TVP at 100 degrees F on the same sample. This effect is more noticeable at lower vapour pressures and can generally be ignored at vapour pressures above 100kPa or so. Correlation formulas exist for converting RVP into TVPand vice versa. For a pure substance there should be no difference between TVP and RVP. TVP at line temperature (not the standardised 100 degrees F) is an important property in crude oil pipelines to ensure that vapour does not form which is detrimental to pumps designed for liquids. RVP at 100 degrees F may be correlated to TVP at another temperature.
Viscometer Analyser designed to measure viscosity. A Petroleum test that determines vapour pressure at 100 degrees F in a standard apparatus at vapour liquid ratio of 4:1. The Reid vapour pressure result is approximately the true vapour (TVP) pressure at 100 degrees F. There are several ASTM vapour pressure test methods that mostly approximate TVP but in general the results are correlated back to Reid vapour pressure. Reid vapour pressure is a significant factor in the storage and perfomance of Motor Gasoline.
Vapourisation The process of becoming a vapour. The change from a liquid or solid to a vapour.
Velocity A vector quantity whose magnitude is a body's speed and whose direction is the body's direction of motion. Rapidity or speed of motion. Velocity is a vector quantity.
Viscosity The resistance of a substance to flow. For example, water has a lower viscosity than molasses and flows more easily. Viscosity is related to the concept of shear force; it can be understood as the effect of different layers of the fluid exerting shearing force on each other, or on other surfaces, as they move against each other. Viscosity lies behind the skin friction component of drag. Kinematic Viscosity is a measure of the rate at which momentum is transferred through a fluid. It is measured in Stokes. Dynamic viscosityis a measure of the ratio of the stress on a region of a fluid to the rate of change of strain it undergoes. It is equal to the kinematic viscosity times the density of the fluid. It is measured in pascal seconds or poise.
Viscosity Index (ASTM D2270 Viscosity index (VI) is a measure of the viscosity change of oils with temperature. Viscosity is measured at 40 degrees C and 100 degrees C and the index calculated according to ASTM 2270. Higher VI oils (VI = 100+) show low variation of viscosity with temperature. Lower VI oils (VI = 40) have amuch greater variation. Generally lubricating oils should be viscostatic, maintaining its viscosity over a wide temperature range.
Visible Spectrum That part of the electromagnetic spectrum that is visible to the human eye. It covers the aproximate wavelength range of 400nm (violet) to 780nm (red).
Viscometer Analyser designed to measure viscosity.
Voltage A measure of the potential difference in an electrical circuit, expressed in volts.
W Water Gauge An instrument indicating the level of water, as in a boiler, tank, reservoir or stream.
Wavelength The distance between one peak or crest of a wave of light, heat, or other energy and the next corresponding peak or crest. The distance between two points of the same phase in consecutive cycles of a wave. It is equal to the speed of the wave divided by it's frequency, and to the speed of a wave times it's period.
Wheatstone Bridge A Wheatstone Bridge is a measuring instrument invented in 1833, and later improved. It is used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. Its operation is similar to the original potentiometer.
Wobbe Index (WI) The Wobbe Index is the main indicator if interchangeability of fuel gases such as natural gas, LPG, and town gas, and is frequently defined in the specifications of gas supply and transport utilities. the Wobbe Index is used to compare the combustion energy output of different compositions fuel gases in an appliance.
Z Zeolites (Greek, zein, "to boil"; lithos, "a stone") are hydrated aluminosilicate minerals and have a micro-porous structure.