Accuracy: a measure of how closethe test result will be to the truevalue of the property beingmeasured; a relative term in the sense that systematic errorsor biases can exist but be smallenough to be inconsequential.

Acidity: the capacity of an acid toneutralize a base such as ahydroxyl ion (OH-).

Acid number: a measure of thereactivity of petroleum with acaustic solution; given in termsof milligrams of potassium hydroxide that are neutralizedby one gram of petroleum.

Acid sludge: the residue left aftertreating petroleum oil with sul-furic acid for the removal ofimpurities; a black, viscous sub-stance containing the spent acidand impurities.

Additive: a material added to an-other (usually in small amounts)to enhance desirable propertiesor to suppress undesirable prop-erties.

Adsorption: transfer of a sub-stance from a solution to the

surface of a solid, resulting in relatively high concentration ofthe substance at the place ofcontact; see also Chromato-graphic adsorption.

Air-blown asphalt: asphalt pro-duced by blowing air throughresidua at elevated temperatures.

Albertite: a black, brittle, naturalhydrocarbon possessing a con-choidal fracture and a specificgravity of approximately 1.1.

Alicyclic hydrocarbon: a com-pound containing carbon andhydrogen only that has a cyclicstructure (e.g., cyclohexane); alsocollectively called naphthenes.

Aliphatic hydrocarbon (saturated):a compound containing carbonand hydrogen only that has eitheran open-chain structure (e.g.,ethane,butane,octane) or a cyclicstructure (e.g., cyclohexane) inwhich the full valency of carbon(4) is satisfied by another atom.

Aliphatic hydrocarbon (unsatu-rated): a compound containingcarbon and hydrogen only thathas either an open-chain struc-

GLOSSARY

The following list represents a selection of definitions that are commonlyused in reference to petroleum analysis and will be of use to the reader.

365

366 glossary

ture (e.g., ethylene, butene) or acyclic structure (e.g., cyclohex-ene) in which the full valency ofcarbon (4) is satisfied by anotheratom and by at least one multi-ple bond.

Aliquot: that quantity of materialof proper size for measurementof the property of interest; testportions may be taken from thegross sample directly, but oftenpreliminary operations such asmixing or further reduction inparticle size are necessary.

Alkalinity: the capacity of a baseto neutralize the hydrogen ion(H+).

Alkylate: the product of an alkyla-tion (q.v.) process.

Alkylation: in the petroleum indu-stry, a process by which an olefin(e.g., ethylene) is combined witha branched-chain hydrocarbon(e.g., iso-butane); alkylation maybe accomplished as a thermal oras a catalytic reaction.

Alumina (Al2O3): used in separa-tion methods as an adsorbentand in refining as a catalyst.

American Society for Testing andMaterials (ASTM): the officialorganization in the UnitedStates for designing standardtests for petroleum and otherindustrial products.

Aniline point: the temperature,usually expressed in °F, abovewhich equal volumes of a petro-leum product and aniline are

completely miscible; a qualita-tive indication of the relativeproportions of paraffins in apetroleum product that are mis-cible with aniline only at highertemperatures; a high anilinepoint indicates low aromatics.

Analytical equivalence: the accept-ability of the results obtainedfrom the different laboratories; arange of acceptable results.

API gravity: a measure of the light-ness or heaviness of petroleumthat is related to density andspecific gravity.

°API = (141.5/sp gr @ 60°F) – 131.5

Apparent bulk density: the densityof a catalyst as measured; usu-ally loosely compacted in a container.

Apparent viscosity: the viscosity ofa fluid, or several fluids flowingsimultaneously, measured in aporous medium (rock) andsubject to both viscosity and per-meability effects; also calledeffective viscosity.

Aromatic hydrocarbon: a hydro-carbon characterized by thepresence of an aromatic ring orcondensed aromatic rings; ben-zene and substituted benzene,naphthalene and substitutednaphthalene, phenanthrene andsubstituted phenanthrene, aswell as the higher condensedring systems; compounds thatare distinct from those of

glossary 367

aliphatic hydrocarbon (q.v.) oralicyclic hydrocarbon (q.v.).

Aromatization: the conversion ofnonaromatic hydrocarbons toaromatic hydrocarbons by (1)rearrangement of aliphatic (non-cyclic) hydrocarbons (q.v.) intoaromatic ring structures and (2)dehydrogenation of alicyclichydrocarbons (naphthenes).

Asphalt: the nonvolatile productobtained by distillation and subsequent treatment of theresiduum of an asphaltic crudeoil; a manufactured product.

Asphaltene fraction (asphaltenes):the brown to black powderymaterial produced by treatmentof petroleum, petroleum re-sidua, or bituminous materialswith a low-boiling liquid hydro-carbon, e.g., pentane or heptane;soluble in benzene (and otheraromatic solvents), carbon disul-fide, and chloroform (or otherchlorinated hydrocarbon sol-vents).

Asphaltene association factor: thenumber of individual asphaltenespecies that associate in nonpo-lar solvents as measured bymolecular weight methods; themolecular weight of asphal-tenes in toluene divided by themolecular weight in a polarnonassociating solvent, such asdichlorobenzene, pyridine, ornitrobenzene.

Asphaltic pyrobitumen: see As-phaltoid.

Asphaltite: a variety of naturallyoccurring dark brown to black,solid, nonvolatile bituminousmaterial that is differentiatedfrom bitumen primarily by ahigh content of material insolu-ble in n-pentane (asphaltene) orother liquid hydrocarbons.

Asphaltoid: a group of brown toblack, solid bituminous materialsthe members of which are dif-ferentiated from asphaltites bytheir infusibility and low solubil-ity in carbon disulfide.

Asphaltum: see Asphalt.

Associated molecular weight: themolecular weight of asphaltenesin an associating (nonpolar)solvent such as toluene.

Atmospheric residuum: a resi-duum (q.v.) obtained by distilla-tion of a crude oil underatmospheric pressure, whichboils above 350°C (660°F).

Atmospheric equivalent boilingpoint (AEBP): a mathematicalmethod of estimating the boil-ing point at atmospheric pres-sure of nonvolatile fractions ofpetroleum.

Attapulgus clay: see Fuller’s earth.

Average particle size: the weightedaverage particle diameter of acatalyst.

Barrel: the unit of measurement ofliquids in the petroleum indus-try; equivalent to 42 U.S. stan-dard gallons or 33.6 imperialgallons.

368 glossary

Base number: the quantity of acid,expressed in milligrams of potas-sium hydroxide per gram ofsample, that is required to titratea sample to a specified end point.

Basic nitrogen: nitrogen (in petro-leum) that occurs in pyridineform.

Basic sediment and water (BS&W,BSW): the material that collectsin the bottom of storage tanks,usually composed of oil, water,and foreign matter; also calledbottoms.

Baumé gravity: the specific gravityof liquids expressed as degreeson the Baumé (°Bé) scale; forliquids lighter than water:

Sp gr 60°F = 140/(130 + °Bé)

and for liquids heavier thanwater:

Sp gr 60°F = 145/(145 – °Bé)

Bauxite: mineral matter used as atreating or chromatographicagent; hydrated aluminum oxideformed by the chemical weath-ering of igneous rocks.

Bbl: see Barrel.

Bentonite: montmorillonite (amagnesium-aluminum silicate);used as a treating agent.

Benzene: a colorless aromaticliquid hydrocarbon (C6H6).

Benzin: a refined light naphthaused for extraction purposes.

Benzine: an obsolete term for lightpetroleum distillates covering

the gasoline and naphtha range;see Ligroine.

Benzol: the general term thatrefers to commercial or technical(not necessarily pure) benzene;also the term used for aromaticnaphtha.

Between-laboratory precision: seeInterlaboratory precision, Inter-mediate precision, and Pre-cision).

Billion: 1 ¥ 109

Bitumen: a semisolid to solid hydr-ocarbonaceous material foundfilling pores and crevices ofsandstone, limestone, or argil-laceous sediments.

Bituminous: containing bitumenor constituting the source ofbitumen.

Bituminous rock: see Bituminoussand.

Bituminous sand: a formation inwhich the bituminous material(see Bitumen) is found as afilling in veins and fissures infractured rocks or impregnatingrelatively shallow sand, sand-stone, and limestone strata; asandstone reservoir that isimpregnated with a heavy,viscous black petroleum-likematerial that cannot be retrievedthrough a well by conventionalproduction techniques (see alsoTar sand).

Black oil: any of the dark-coloredoils; a term now often applied toheavy oil (q.v.).

glossary 369

Blown asphalt: the asphalt pre-pared by air blowing a residuum(q.v.) or an asphalt (q.v.).

Boiling range: the range of tem-perature, usually determined atatmospheric pressure in stan-dard laboratory apparatus, overwhich the distillation of an oil commences, proceeds, and finishes.

Bottoms: the liquid that collects inthe bottom of a vessel (towerbottoms, tank bottoms) duringdistillation; also the deposit orsediment formed during storageof petroleum or a petroleumproduct; see also Residuum andBasic sediment and water.

British thermal unit: see Btu.

Bromine number: the number ofgrams of bromine absorbed by100 g of sample, which indicatesthe percentage of double bondsin the material.

Bromine index: the number of mil-ligrams of bromine that willreact with 100 g of the sample;used mostly for stocks that havean unusually low olefin content.

Brønsted acid: a chemical speciesthat can act as a source ofprotons.

Brønsted base: a chemical speciesthat can accept protons.

BS&W: see Basic sediment andwater.

Btu (British thermal unit): theenergy required to raise the tem-

perature of 1 lb of water 1°Fahrenheit.

Bubble point: the temperature atwhich incipient vaporization of aliquid in a liquid mixture occurs,corresponding with the equilib-rium point of 0% vaporizationor 100% condensation.

Bumping: the knocking against thewalls of a still occurring duringdistillation of petroleum or apetroleum product that usuallycontains water.

Burning point: see Fire point.

Burning-quality index: an empiri-cal numerical indication of thelikely burning performance of afurnace or heater oil; derivedfrom the distillation profile (q.v.)and the API gravity (q.v.), andgenerally recognizing the factorsof paraffinicity and volatility.

C1, C2, C3, C4, C5 fractions: a com-mon way of representing frac-tions containing a preponder-ance of hydrocarbons having 1, 2,3, 4, or 5 carbon atoms, respec-tively, and without reference tohydrocarbon type.

Carbene: the pentane- or heptane-insoluble material that is insolu-ble in benzene or toluene but issoluble in carbon disulfide (orpyridine); a type of rifle used forhunting bison.

Carboid: the pentane- or heptane-insoluble material that is insolu-ble in benzene or toluene and isalso insoluble in carbon disulfide(or pyridine).

370 glossary

Carbon-forming propensity: seeCarbon residue.

Carbonizable material: constitu-ents of a petroleum product thatform a carbonaceous residuewhen treated with sulfuric acid.

Carbonization: the conversion ofan organic compound into charor coke by heat in the substan-tial absence of air; often used inreference to the destructive dis-tillation (with simultaneousremoval of distillate) of coal.

Carbon rejection: upgrading pro-cesses in which coke is produced,e.g., coking.

Carbon residue: the amount of car-bonaceous residue remainingafter thermal decomposition ofpetroleum, a petroleum fraction,or a petroleum product in alimited amount of air; also calledthe coke- or carbon-forming propensity; often prefixed by theterms Conradson or Ramsbottomin reference to the inventors ofthe respective tests.

Catalyst: a chemical agent that,when added to a reaction(process) will enhance the con-version of a feedstock withoutbeing consumed in the process.

Catalyst selectivity: the relativeactivity of a catalyst with respectto a particular compound in amixture, or the relative rate incompeting reactions of a singlereactant.

Catalytic cracking: the conversionof high-boiling feedstocks into

lower-boiling products by meansof a catalyst that may be used ina fixed bed (q.v.) or fluid bed(q.v).

Cat cracking: see Catalytic crack-ing.

Cetane index: an approximation ofthe cetane number (q.v.) calcu-lated from the density (q.v.) andmid-boiling point (q.v.); see alsoDiesel index.

Cetane number: a number indicat-ing the ignition quality of dieselfuel; a high cetane number rep-resents a short ignition delaytime; the ignition quality ofdiesel fuel can also be estimatedfrom the following formula:

diesel index = [aniline point (°F) ¥ API gravity]/100

Characterization factor: the UOPcharacterization factor K,defined as the ratio of the cuberoot of the molal average boilingpoint, TB, in degrees Rankine(°R = °F + 460), to the specificgravity at 60∞F/60∞F:

K = (TB)1/3/sp gr

which ranges from 12.5 for paraf-finic stocks to 10.0 for the highlyaromatic stocks; also called theWatson characterization factor.

Chelating agents: complexformingagents with the ability to solubi-lize heavy metals.

Chemical octane number: the oc-tane number added to gasolineby refinery processes or by theuse of octane number (q.v.)

glossary 371

improvers such as tetraethyllead.

Chromatographic adsorption: selec-tive adsorption on materialssuch as activated carbon,alumina, or silica gel; liquid orgaseous mixtures of hydrocar-bons are passed through theadsorbent in a stream of diluent,and certain components arepreferentially adsorbed.

Chromatography: a method ofseparation based on selectiveadsorption; see also Chromato-graphic adsorption.

Clay: silicate minerals that alsousually contain aluminum andhave particle sizes less than 0.002 mm; used in separationmethods as an adsorbent and inrefining as a catalyst.

Cloud point: the temperature atwhich paraffin wax or other solidsubstances begin to crystallize orseparate from the solution, im-parting a cloudy appearance tothe oil when the oil is chilledunder prescribed conditions.

Coal: an organic rock.

Coal tar: the specific name for the tar (q.v.) produced fromcoal.

Coal tar pitch: the specific namefor the pitch (q.v.) producedfrom coal.

Coke: a gray to black solid car-bonaceous material producedfrom petroleum during thermalprocessing; characterized by

having a high carbon content(95%+ by weight) and a honey-comb type of appearance andinsoluble in organic solvents.

Coke number: used, particularly inGreat Britain, to report theresults of the Ramsbottomcarbon residue test (q.v.), whichis also referred to as a coke test.

Coker: the processing unit inwhich coking takes place.

Coking: a process for the thermalconversion of petroleum in whichgaseous, liquid, and solid (coke)products are formed.

Color stability: the resistance of apetroleum product to colorchange caused by light, aging,etc.

Combustible liquid: a liquid with aflash point in excess of 37.8°C(100°F) but below 93.3°C(200°F).

Composition: the general chemicalmakeup of petroleum.

Composition map: a means ofillustrating the chemical makeupof petroleum with chemicaland/or physical property data.

Con Carbon (Conradson carbonresidue): see Carbon residue.

Conradson carbon residue: seeCarbon residue.

Contaminant: a substance thatcauses deviation from the normalcomposition of a product.

Conventional recovery: primaryand/or secondary recovery; often

372 glossary

includes tertiary (enhanced)recovery methods.

Conversion: the thermal treatmentof petroleum that results in theformation of new products bythe alteration of the originalconstituents.

Conversion factor: the percentageof feedstock converted to lightends, gasoline, other liquid fuels,and coke,

Cracked residua: residua that havebeen subjected to temperaturesabove 350°C (660°F) during thedistillation process.

Cracking: the thermal processes bywhich the constituents of petro-leum are converted to lower-molecular-weight products.

Cracking temperature: the tem-perature (350°C/660°F) at whichthe rate of thermal decomposi-tion of petroleum constituentsbecomes significant.

Crude assay: a procedure fordetermining the general distilla-tion characteristics (e.g., distilla-tion profile, q.v.) and otherquality information of crude oil.

Crude oil: see Petroleum (crudeoil).

Crude still: distillation (q.v.) equip-ment in which crude oil is sepa-rated into various products.

Cut point: the boiling temperaturedivision between distillationfractions of petroleum.

Cyclic hydrocarbons: see Alicyclichydrocarbon

Cyclization: the process by whichan open-chain hydrocarbon struc-ture is converted to a ring struc-ture, e.g., hexane to benzene.

Dealkylation: the removal of analkyl group from aromatic compounds.

Deasphaltened oil: the fraction ofpetroleum after the asphalteneshave been removed.

Deasphaltening: removal of a solidpowdery asphaltene fraction frompetroleum by the addition oflow-boiling liquid hydrocarbonssuch as n-pentane or n-heptaneunder ambient conditions.

Deasphalting: the removal of theasphaltene fraction from petro-leum by the addition of a low-boiling hydrocarbon liquid suchas n-pentane or n-heptane; morecorrectly, the removal of asphalt(tacky, semisolid) from petro-leum (as occurs in a refineryasphalt plant) by the addition ofliquid propane or liquid butaneunder pressure.

Decolorizing: removal of sus-pended, colloidal, and dissolvedimpurities from liquid petro-leum products by filtering,adsorption, chemical treatment,distillation, bleaching, etc.

Dehydrating agents: substancescapable of removing water(drying, q.v.) or the elements ofwater from another substance.

Delayed coking: a coking processin which the thermal reactionsare allowed to proceed to com-

glossary 373

pletion to produce gaseous,liquid, and solid (coke) products.

Density: the mass (or weight) of aunit volume of any substance ata specified temperature; see alsoSpecific gravity.

Desorption: the reverse process ofadsorption whereby adsorbedmatter is removed from theadsorbent; also used as thereverse of absorption (q.v.).

Desulfurization: the removal ofsulfur or sulfur compounds froma feedstock.

Diesel fuel: fuel used for internalcombustion in diesel engines;usually the fraction that distillsafter kerosene.

Diesel cycle: a repeated successionof operations representing theidealized working behavior ofthe fluids in a diesel engine.

Diesel index: an approximation ofthe cetane number (q.v.) ofdiesel fuel (q.v.) calculated fromthe density (q.v.) and anilinepoint (q.v.).

diesel index = aniline point (°F) ¥ API gravity/100

Diesel knock: the result of adelayed period of ignition andthe accumulation of diesel fuelin the engine.

Distillation: a process for separat-ing liquids with different boilingpoints.

Distillation curve: see Distillationprofile.

Distillation loss: the difference, ina laboratory distillation, be-tween the volume of liquid originally introduced into thedistilling flask and the sum of theresidue and the condensaterecovered.

Distillation profile: the distillationcharacteristics of petroleum andpetroleum products showing thetemperature and the percentagedistilled.

Distillation range: the differencebetween the temperature at theinitial boiling point and at theend point, as obtained by the dis-tillation test.

Dropping point: the temperatureat which grease passes from asemisolid to a liquid state underprescribed conditions.

Drying: removal of a solvent orwater from a chemical sub-stance; also referred to as theremoval of solvent from a liquidor suspension.

Dry point: the temperature atwhich the last drop of petroleumfluid evaporates in a distillationtest.

Ebullated bed: a process in whichthe catalyst bed is in a suspendedstate in the reactor by means ofa feedstock recirculation pumpthat pumps the feedstockupward at sufficient speed toexpand the catalyst bed atapproximately 35% above thesettled level.

Effective viscosity: see Apparentviscosity.

374 glossary

Engler distillation: a standard testfor determining the volatilitycharacteristics of a gasoline by measuring the percentage distilled at various specified temperatures.

Enhanced oil recovery: petroleumrecovery after recovery by con-ventional (i.e., primary and/orsecondary) methods (q.v.).

Entrained bed: a bed of solid par-ticles suspended in a fluid (liquidor gas) at such a rate that someof the solid is carried over(entrained) by the fluid.

Ethanol: see Ethyl alcohol (etha-nol or grain alcohol).

Ethyl alcohol (ethanol or grainalcohol): an inflammable organiccompound (C2H5OH) formedduring fermentation of sugars;used as an intoxicant and as afuel.

Evaporation: a process for concen-trating nonvolatile solids in asolution by boiling off the liquidportion of the waste stream.

Expanding clays: clays that expandor swell on contact with water,e.g., montmorillonite.

Explosive limits: the limits of per-centage composition of mixturesof gases and air within which anexplosion takes place when themixture is ignited.

Extractive distillation: the separa-tion of different components ofmixtures that have similar vaporpressures by flowing a relatively

high-boiling solvent, which isselective for one of the compo-nents in the feed, down a distil-lation column as the distillationproceeds; the selective solventscrubs the soluble componentfrom the vapor.

FCC: fluid catalytic cracking.

Feedstock: petroleum, heavy oil, orbitumen as it is fed to the re-finery; a refinery product that is used as the raw material for another process; the term isalso generally applied to rawmaterials used in other industrialprocesses.

Filtration: the use of an impassablebarrier to collect solids thatallows liquids to pass.

Fire point: the lowest temperatureat which, under specified condi-tions in standardized apparatus,a petroleum product vaporizessufficiently rapidly to formabove its surface an air-vapormixture that burns continuouslywhen ignited by a small flame.

Flammability range: the range oftemperature over which a chem-ical is flammable.

Flammable: a substance that willburn readily.

Flammable liquid: a liquid with a flash point below 37.8°C(100°F).

Flammable solid: a solid that canignite from friction or from heatremaining from its manufacture,

glossary 375

or which may cause a serioushazard if ignited.

Flash point: the lowest tempera-ture to which the product mustbe heated under specified condi-tions to give off sufficient vaporto form a mixture with air thatcan be ignited by a flame.

Floc point: the temperature atwhich wax or solids separate as adefinite floc.

Fluid catalytic cracking: crackingin the presence of a fluidized bedof catalyst.

Fluid coking: a continuous flu-idized solids process that cracksfeed thermally over heated cokeparticles in a reactor vessel togas, liquid products, and coke.

Fly ash: particulate matter pro-duced from mineral matter incoal that is converted duringcombustion to finely dividedinorganic material and whichemerges from the combustor inthe gases.

Fractional composition: the com-position of petroleum as determined by fractionation(separation) methods.

Fractional distillation: the separa-tion of the components of aliquid mixture by vaporizing andcollecting the fractions, or cuts,which condense in different tem-perature ranges.

Fractionating column: a columnarranged to separate variousfractions of petroleum by a

single distillation, which may betapped at different points alongits length to separate variousfractions in the order of theirboiling points.

Fractionation: the separation ofpetroleum into constituent frac-tions with solvent or adsorbentmethods; chemical agents suchas sulfuric acid may also be used.

Fuel oil: also called heating oil; adistillate product that covers awide range of properties.

Fuller’s earth: a clay that has highadsorptive capacity for removingcolor from oils; attapulgus clay isa widely used fuller’s earth.

Functional group: the portion of amolecule that is characteristic ofa family of compounds anddetermines the properties ofthese compounds.

Gas oil: a petroleum distillate withviscosity and boiling rangebetween those of kerosene andlubricating oil.

Gasoline: fuel for the internalcombustion engine that is com-monly, but improperly, referredto simply as “gas.”

Gilsonite: an asphaltite that is>90% bitumen.

Glance pitch: an asphaltite.

Grahamite: an asphaltite.

Grease: a solid to semisolidproduct that is a lubricating fluidthat has been gelled with a thick-ening agent so that the lubricant

376 glossary

can be retained more readily inthe required area.

Green acids: water-soluble prod-ucts from the refining of mineral(white) oil

Gum: an insoluble, tacky semisolidmaterial formed as a result of thestorage instability and/or thethermal instability of petroleumand petroleum products.

Heating oil: see Fuel oil.

Heavy ends: the highest-boilingportion of a petroleum fraction;see also Light ends.

Heavy fuel oil: fuel oil with a highdensity and viscosity; generallyresidual fuel.)

Heavy oil: petroleum having anAPI gravity of less than 20∞;petroleum that is recoverable inits natural state by conventionaloil well production methods in-cluding currently used enhancedrecovery techniques.

Heavy petroleum: see Heavy oil.

Heteroatom compounds: chemicalcompounds that contain nitro-gen and/or oxygen and/or sulfurand /or metals bound withintheir molecular structure(s).

Homogeneity: the degree to whicha property or substance is ran-domly distributed throughout amaterial; homogeneity dependson the size of the units underconsideration. A mixture of twosolids may be inhomogeneous at

the molecular or atomic levelbut homogeneous at the particu-late level.

Hot filtration test: a test for the sta-bility of a petroleum product.

Hydrocarbon compounds: chemi-cal compounds containing onlycarbon and hydrogen.

Hydrocarbon-producing resource:a resource such as coal and oilshale (kerogen) that producesderived hydrocarbons by theapplication of conversion pro-cesses; the hydrocarbons so produced are not naturallyoccurring materials.

Hydrocarbon resource: resourcessuch as petroleum and naturalgas that can produce naturallyoccurring hydrocarbons withoutthe application of conversionprocesses.

Hydroconversion: a term oftenapplied to hydrocracking (q.v.)

Hydrocracking: a catalytic high-pressure, high-temperature pro-cess for the conversion ofpetroleum feedstocks in thepresence of fresh and recycledhydrogen; carbon-carbon bondsare cleaved in addition to theremoval of heteroatomic species.

Hydrogen addition: an upgradingprocess in the presence of hydro-gen, e.g., hydrocracking; seeHydrogenation.

Hydrogenation: the chemical addi-tion of hydrogen to a material. Innondestructive hydrogenation,

glossary 377

hydrogen is added to a moleculeonly if, and where, unsaturationwith respect to hydrogen exists.

Hydrogen transfer: the transfer ofinherent hydrogen within thefeedstock constituents and prod-ucts during processing.

Hydroprocessing: a term oftenequally applied to hydrotreating(q.v.) and hydrocracking (q.v.);also often collectively applied toboth.

Hydrotreating: the removal of heteroatomic (nitrogen, oxygen,and sulfur) species by treatmentof a feedstock or product at rel-atively low temperatures in thepresence of hydrogen.

Ignitability: characteristic of liq-uids whose vapors are likely toignite in the presence of ignitionsource; also characteristic ofnonliquids that may catch firefrom friction or contact withwater and that burn vigorously.

Immiscible: two or more fluids thatdo not have complete mutualsolubility and coexist as separatephases.

Incompatibility: the immiscibilityof petroleum products and alsoof different crude oils that isoften reflected in the formationof a separate phase after mixingand/or storage.

Increment: an individual portionof material collected by a singleoperation of a sampling device,from parts of a lot separated in

time or space. Increments maybe either tested individually orcombined (composited) andtested as a unit.

Individuals: conceivable constitu-ent parts of the population.

Initial boiling point: the tempera-ture recorded when the firstdrop of liquid falls from the endof the condenser.

Initial vapor pressure: the vaporpressure of a liquid of a specifiedtemperature and zero percentevaporated.

Instability: the inability of a petro-leum product to exist for periodsof time without change to theproduct.

Interlaboratory precision: the vari-ability between test resultsobtained on the aliquots of thesame homogeneous material indifferent laboratories with thesame test method (see alsoIntermediate precision and Pre-cision).

Intermediate precision: the preci-sion obtained when an assay isperformed by multiple analystsusing several instruments in onelaboratory (see also Interlabora-tory precision and Precision.

Iodine number: a measure of theiodine absorption by oil understandard conditions; used toindicate the quantity of unsatu-rated compounds present; alsocalled iodine value.

378 glossary

Ion exchange: a means of remov-ing cations or anions from solu-tion onto a solid resin.

Isomerization: the conversion of a normal (straight-chain) paraf-fin hydrocarbon into an iso(branched-chain)-paraffin hydro-carbon with the same atomiccomposition.

Jet fuel: fuel meeting the requiredproperties for use in jet enginesand aircraft turbine engines.

Kaolinite: a clay mineral formedby hydrothermal activity at thetime of rock formation or bychemical weathering of rockswith high feldspar content;usually associated with intrusivegranite rocks with high feldsparcontent.

Kata-condensed aromatic com-pounds: Compounds based onlinear condensed aromatic hydro-carbon systems, e.g., anthraceneand naphthacene (tetracene).

Kerogen: a complex carbonaceous(organic) material that occurs insedimentary rocks and shales;generally insoluble in commonorganic solvents.

Kerosene (kerosine): a fraction ofpetroleum that was initiallysought as an illuminant in lamps;a precursor to diesel fuel.

K-factor: see Characterization fac-tor.

Kinematic viscosity: the ratio ofviscosity (q.v.) to density, both

measured at the same temperature.

Laboratory sample: a sample,intended for testing or analysis,prepared from a gross sample orotherwise obtained. The labora-tory sample must retain the com-position of the gross sample.

Lamp burning: a test of burningoils in which the oil is burned ina standard lamp under specifiedconditions to observe the steadi-ness of the flame, the degree ofencrustation of the wick, and therate of consumption of thekerosene.

Lamp oil: see Kerosene.

Lewis acid: a chemical species thatcan accept an electron pair froma base.

Lewis base: a chemical species thatcan donate an electron pair.

Light ends: the lower-boiling com-ponents of a mixture of hydro-carbons; see also Heavy ends,Light hydrocarbons.

Light hydrocarbons: hydrocarbonswith molecular weights less thanthat of heptane (C7H16).

Light oil: the products distilled orprocessed from crude oil up to,but not including, the first lubri-cating oil distillate.

Light petroleum: petroleum withan API gravity greater than 20°.

Ligroine (Ligroin): a saturatedpetroleum naphtha boiling in therange of 20–135∞C (68–275∞F)

glossary 379

and suitable for general use as asolvent; also called benzine orpetroleum ether.

Liquefied petroleum gas (LPG):propane, butane, or mixturesthereof, gaseous at atmospherictemperature and pressure, heldin the liquid state by pressure tofacilitate storage, transport, andhandling.

Liquid petrolatum: see White oil.

Lot: a quantity of bulk material ofsimilar composition whose prop-erties are under study.

Lube: see Lubricating oil.

Lube cut: a fraction of crude oil ofsuitable boiling range and vis-cosity to yield lubricating oilwhen completely refined; alsoreferred to as lube oil distillatesor lube stock.

Lubricating oil: a fluid lubricantused to reduce friction betweenmoving metal surfaces.

Mahogany acids: oil-soluble sul-fonic acids formed by the actionof sulfuric acid on petroleum distillates. They may be con-verted to their sodium soaps(mahogany soaps) and extractedfrom the oil with alcohol for usein the manufacture of solubleoils, rust preventives, and specialgreases. The calcium and bariumsoaps of these acids are used asdetergent additives in motor oils.

Maltenes: the fraction of petro-leum that is soluble in, forexample, pentane or heptane;

deasphaltened oil (q.v.); also theterm arbitrarily assigned to thepentane-soluble portion ofpetroleum that is relatively highboiling (>300∞C, 760 mm) (seealso Petrolenes).

Mayonnaise : low-temperaturepetroleum sludge; a black,brown, or gray deposit with asoft, mayonnaise-like consis-tency; not recommended as afood additive!

Measurement: the means by whichanalytical data are producedwith a specific test method.

Methanol: see Methyl alcohol.

Mercaptans: organic compoundswith the general formula R-SH.

Method validation: see Validation.

Methyl alcohol (methanol; woodalcohol): a colorless, volatile,inflammable, and poisonousalcohol (CH3OH) traditionallyformed by destructive distilla-tion of wood or, more recently, asa result of synthetic distillationin chemical plants.

Micelle: the structural entity bywhich asphaltenes are dispersedin petroleum.

Microcarbon residue: the carbonresidue determined with a ther-mogravimetric method. See alsoCarbon residue.

Mid-boiling point: the tempera-ture at which approximately50% of a material has distilledunder specific conditions.

380 glossary

Middle distillate: distillate boilingbetween the kerosene and lubri-cating oil fractions.

Mineral oil: the older term forpetroleum; the term was intro-duced in the nineteenth centuryas a means of differentiatingpetroleum (rock oil) from whaleoil, which, at the time, was thepredominant illuminant for oillamps.

Mineral oil (white oil): colorless or very pale oils within the lub-ricating oil boiling range and viscosity that are used for medic-inal (pharmaceutical) oils andtechnical purposes, the chief dif-ference being degree of refining.

Minerals: naturally occurring inor-ganic solids with well-definedcrystalline structures.

Mitigation: identification, evalua-tion, and cessation of potentialimpacts of a process product orby-product.

Modified naphtha insolubles(MNI): an insoluble fractionobtained by adding naphtha topetroleum; usually, adding paraf-finic constituents modifies thenaphtha; the fraction might beequated to asphaltenes if thenaphtha is equivalent to n-heptane, but usually it is not

Molecular sieve: a synthetic zeolitemineral having pores of uniformsize; it is capable of separatingmolecules, on the basis of theirsize, structure, or both, byabsorption or sieving.

Naft: pre-Christian era (Greek)term for naphtha (q.v.).

Napalm: a thickened gasoline usedas an incendiary medium thatadheres to the surface it strikes.

Naphtha: a generic term applied torefined, partly refined, or unre-fined petroleum products andliquid products of natural gas,the majority of which distillbelow 240∞C (464∞F); thevolatile fraction of petroleumthat is used as a solvent or as aprecursor to gasoline.

Naphthenes: cycloparaffins.

Native asphalt: see Bitumen.

Natural asphalt: see Bitumen.

Natural gas: the naturally occur-ring gaseous constituents thatare found in many petroleumreservoirs; there are also reser-voirs in which natural gas may bethe sole occupant.

Neutralization: a process for re-ducing the acidity or alkalinity ofa waste stream by mixing acidsand bases to produce a neutralsolution; also known as pHadjustment.

Neutralization number: the weight,in milligrams, of potassium hy-droxide needed to neutralize theacid in 1 g of oil; an indication ofthe acidity of an oil.

Nonasphaltic road oil: any of thenonhardening petroleum distil-lates or residual oils used as dustlayers. They have sufficiently low

glossary 381

viscosity to be applied withoutheating and, together withasphaltic road oils (q.v.), aresometimes referred to as dustpalliatives.

Non-Newtonian: a fluid thatexhibits a change of viscositywith flow rate.

Octane barrel yield: a measureused to evaluate fluid catalyticcracking processes; defined as(RON + MON)/2 times the gaso-line yield, where RON is the re-search octane number and MONis the motor octane number.

Octane number: a number indicat-ing the antiknock characteristicsof gasoline.

Oils (fraction): the portion of themaltenes (q.v.) that is notadsorbed by a surface-activematerial such as clay or alumina.

Oil sand: see Tar sand.

Oil shale: a fine-grained, impervi-ous sedimentary rock that con-tains an organic material calledkerogen.

Overhead: the portion of the feed-stock that is vaporized andremoved during distillation.

Oxidation: a process that can beused for the treatment of avariety of inorganic and organicsubstances.

Oxidized asphalt: see Air-blownasphalt.

Particle density: the density ofsolid particles.

Particulate matter: particles in theatmosphere or on a gas stream,which may be organic or inor-ganic and originate from a widevariety of sources and processes.

Particle size distribution: the parti-cle size distribution (of a catalystsample) expressed as a percent-age of the whole.

Pericondensed aromatic compounds:compounds based on angularcondensed aromatic hydrocar-bon systems, e.g., phenanthrene,chrysene, picene, etc.

Petrol: a term commonly used insome countries for gasoline.

Petrolatum: a semisolid product,ranging from white to yellow incolor, produced during refiningof residual stocks; see Petroleumjelly.

Petrolenes: the term applied tothat part of the pentane-solubleor heptane-soluble material thatis low boiling (<300∞C/<570∞F,760 mm) and can be distilledwithout thermal decomposition(see also Maltenes).

Petroleum (crude oil): a naturallyoccurring mixture of gaseous,liquid, and solid hydrocarboncompounds usually found trap-ped deep underground beneathimpermeable cap rock and abovea lower dome of sedimentaryrock such as shale; most petro-leum reservoirs occur in sedi-mentary rocks of marine, deltaic,or estuarine origin; recoverablein its natural state by conven-

382 glossary

tional oil well production methodsincluding currently used en-hanced recovery techniques.

Petroleum asphalt: see Asphalt.

Petroleum ether: see Ligroine.

Petroleum jelly: a translucent, yel-lowish to amber or white, hydro-carbon substance (m.p. 38–54°C)having almost no odor or taste;derived from petroleum andused principally in medicine andpharmacy as a protective dress-ing and as a substitute for fats inointments and cosmetics; alsoused in many types of polishesand in lubricating greases, rustpreventives, and modeling clay;obtained by dewaxing heavylubricating-oil stocks.

Petroleum refinery: see Refinery.

Petroleum refining: a complexsequence of events that result inthe production of a variety ofproducts.

Petroporphyrins: see Prophyrins.

Phase separation: the formation ofa separate phase that is usuallythe prelude to coke formationduring a thermal process; theformation of a separate phase asa result of the instability/incom-patibility of petroleum andpetroleum products.

pH adjustment: neutralization.

Pitch: the nonvolatile, brown toblack, semi-solid to solid viscousproduct from the destructive dis-tillation of many bituminous or

other organic materials, espe-cially coal.

PNA: a polynuclear aromatic com-pound (q.v.).

Polar aromatics: resins; the con-stituents of petroleum that arepredominantly aromatic in character and contain polar(nitrogen, oxygen, and sulfur)functions in their molecularstructure(s).

Polynuclear aromatic compound:an aromatic compound havingtwo or more fused benzene rings,e.g. naphthalene, phenanthrene.

PONA analysis: a method ofanalysis for paraffins (P), olefins(O), naphthenes (N), and aro-matics (A).

Pooled standard deviation: a weigh-ted average of individual esti-mates of the standard deviation.

Population: a generic term denot-ing any finite or infinite collec-tion of individual things, objects,or events in the broadest con-cept; an aggregate determinedby some property that distin-guishes things that do and do notbelong.

Porphyrins: organometallic consti-tuents of petroleum that containvanadium or nickel; the degra-dation products of chlorophyllsthat became included in the pro-topetroleum.

Pour point: the lowest temperatureat which oil will pour or flow

glossary 383

when it is chilled without distur-bance under definite conditions.

Precipitation number: the numberof milliliters of precipitateformed when 10 ml of lubricat-ing oil is mixed with 90 ml of petroleum naphtha of a definite quality and centrifugedunder definitely prescribed conditions.

Precision: the variability betweentest results obtained on the samematerial, using a specific testmethod.

Primary oil recovery: oil recoveryutilizing only naturally occurringforces.

Primary structure: the chemicalsequence of atoms in a molecule.

Principal components analysis: anexamination of set of data aspoints in n-dimensional space(corresponding to n originaltests) that is used to determine(first) the direction that accountsfor the biggest variability in thedata (first principal component).

Propane asphalt: see Solventasphalt.

Propane deasphalting: solventdeasphalting with propane as thesolvent.

Protopetroleum: a generic termused to indicate the initialproduct formed by changes thathave occurred to the precursorsof petroleum.

Pyrobitumen: see Asphaltoid.

Pyrolysis: exposure of a feedstockto high temperatures in anoxygen-poor environment.

Pyrophoric: substances that catchfire spontaneously in air withoutan ignition source.

Quadrillion: 1 ¥ 1015

Quench: the sudden cooling of hotmaterial discharging from athermal reactor.

Raffinate: the portion of the oilthat remains insoluble aftertreatment by a solvent.

Ramsbottom carbon residue: seeCarbon residue

Reduced crude: a residual productremaining after the removal, bydistillation or other means, of anappreciable quantity of the morevolatile components of crude oil.

Reduction: the process of prepar-ing one or more subsamplesfrom a sample; the process bywhich hydrogen is added tofeedstocks during hydrotreatingand hydrocracking processes;removal of unsaturation by theaddition of hydrogen.

Refinery: a series of integratedunit processes by which petro-leum can be converted to a slateof useful (salable) products.

Refinery gas: a gas (or a gaseousmixture) produced as a result ofrefining operations.

Refining: the process(es) by whichpetroleum is distilled and/orconverted by application of a

384 glossary

physical and chemical processesto form a variety of products.

Reformed gasoline: gasoline madeby a reforming process.

Reid vapor pressure: a measure ofthe volatility of liquid fuels, espe-cially gasoline.

Repeatability: the maximum per-missible difference due to testerror between two results obta-ined on the same material in thesame laboratory.

Reproducibility (reproducibilityinterval): the maximum permis-sible difference between tworesults obtained on the samematerial by different laborato-ries that would be equaled orexceeded in the long run in only 1 case in 20 in the normaland correct operation of themethod.

Research octane method: a test fordetermining the knock rating, interms of octane numbers, of fuelsfor use in spark-ignition engines;see also Motor octane method.

Residual asphalt: see Straight-runasphalt.

Residual fuel oil: obtained byblending the residual product(s)from various refining processeswith suitable diluent(s) (usuallymiddle distillates) to obtain therequired fuel oil grades.

Residual oil: see Residuum.

Residuum (resid; pl:. residua): theresidue obtained from petro-leum after nondestructive distil-

lation has removed all thevolatile materials from crude oil,e.g., an atmospheric (345°C/650°F+) residuum.

Resin: the portion of the maltenes(q.v.) that is adsorbed by asurface-active material such asclay or alumina; the fraction ofdeasphaltened oil that is insolu-ble in liquid propane but solublein n-heptane.

Rock asphalt: bitumen that occursin formations that have a limit-ing ratio of bitumen to rockmatrix.

Sample a portion of a populationor lot. It may consist of an indi-vidual or groups of individuals.The sample must be representa-tive of the bulk material.

Sampling: the means by which a representative sample isobtained.

SARA separation: a method offractionation by which petro-leum is separated into saturates,aromatics, resins, and asphaltenefractions.

Saturates: paraffins and cycloparaf-fins (naphthenes).

Saybolt Furol viscosity: the time, inseconds (Saybolt Furol Seconds,SFS), for 60 ml of fluid to flowthrough a capillary tube in aSaybolt Furol viscometer atspecified temperatures between70 and 210∞F; the method isappropriate for high-viscosityoils such as transmission, gear,and heavy fuel oils.

glossary 385

Saybolt Universal viscosity: thetime, in seconds (Saybolt Univer-sal Seconds, SUS), for 60 ml offluid to flow through a capillarytube in a Saybolt Universal vis-cometer at a given temperature.

Secondary structure: the orderingof the atoms of a molecule inspace relative to each other.

Sediment: an insoluble solid for-med as a result of the storageinstability and/or the thermalinstability of petroleum andpetroleum products.

Segment: a specifically demarkedportion of a lot, either actual orhypothetical.

Selective solvent: a solvent that, atcertain temperatures and ratios,will preferentially dissolve moreof one component of a mixturethan of another and therebypermit partial separation.

Separation process: a process inwhich the constituents of pet-roleum are separated, usuallywithout thermal decomposition,e.g., distillation and deasphalt-ing.

Slime: a name used for petroleumin ancient texts.

Sludge: a semisolid to solidproduct that results from thestorage instability and/or thethermal instability of petroleumand petroleum products.

Smoke point: a measure of theburning cleanliness of jet fueland kerosene and an indication

of the aromatics content of anoil.

Solubility parameter: a measure ofthe solvent power and polarityof a solvent.

Solvent asphalt: the asphalt (q.v.)produced by solvent extractionof residua or by light hydrocar-bon (propane) treatment of aresiduum (q.v.) or an asphalticcrude oil.

Solvent deasphalting: a process forremoving asphaltic and resinousmaterials from reduced crudeoils, lubricating oil stocks, gasoils, or middle distillates throughthe extraction or precipitantaction of low-molecular-weighthydrocarbon solvents; see alsoPropane deasphalting.

Solvent extraction: a process forseparating liquids by mixing thestream with a solvent that isimmiscible with part of the wastebut that will extract certain components of the waste stream.

Solvent naphtha: a refined naphthaof restricted boiling range usedas a solvent; also called petro-leum naphtha, petroleum spirits.

Solvent refining: see Solvent extra-ction.

Sour crude oil: crude oil containingan abnormally large amount ofsulfur compounds; see also Sweetcrude oil.

Specification: the data that giveadequate control of feedstockbehavior or product quality.

386 glossary

Specific gravity: the mass (orweight) of a unit volume of anysubstance at a specified temper-ature compared with the mass ofan equal volume of pure water ata standard temperature; see alsoDensity.

Specimen: see Aliquot.

Stabilization: the removal of vola-tile constituents from a high-erboiling fraction or product(stripping); the production of aproduct that, for all intents andpurposes, does not undergo anyfurther reaction when exposedto the air.

Standard deviation: a measure ofthe scatter in a set of data thatfits a Gaussian distribution; seealso Pooled standard deviation.

Steam distillation: distillation inwhich vaporization of the vola-tile constituents is effected at alower temperature by introduc-tion of steam (open steam)directly into the charge.

Storage stability (or storage insta-bility): the ability (inability) of a liquid to remain in storage over extended periods of timewithout appreciable deteriora-tion as measured by gum for-mation and the depositions ofinsoluble material (sediment).

Straight-run asphalt: the asphalt(q.v.) produced by the distilla-tion of asphaltic crude oil.

Straight-run products: productsobtained from a distillation

unit and used without furthertreatment.

Subsample: a portion taken from asample. A laboratory sample(q.v.) may be a subsample of agross sample; similarly, a testportion may be a subsample of alaboratory sample.

Sweet crude oil: crude oil contain-ing little sulfur; see also Sourcrude oil.

Synthetic crude oil (syncrude): ahydrocarbon product producedby the conversion of coal, oilshale, or tar sand bitumen thatresembles conventional crudeoil; can be refined in a petroleumrefinery (q.v.).

Tar: the volatile, brown to black,oily, viscous product from thedestructive distillation of manybituminous or other organicmaterials, especially coal; a nameused for petroleum in ancienttexts.

Tar sand: the several rock typesthat contain an extremelyviscous hydrocarbon that is notrecoverable in its natural stateby conventional oil well produc-tion methods including currentlyused enhanced recovery techni-ques; see also Bituminous sand.

Tertiary structure: the three-dimensional structure of a mole-cule.

Test portion: see Aliquot.

Thermal coke: the carbonaceousresidue formed as a result of

glossary 387

a noncatalytic thermal process;the Conradson carbon residue;the Ramsbottom carbon residue.

Thermal cracking: a process thatdecomposes, rearranges, or com-bines hydrocarbon molecules bythe application of heat withoutthe aid of catalysts.

Thermal process: any refiningprocess that utilizes heat withoutthe aid of a catalyst.

Thermal stability (thermal instabil-ity): the ability (inability) of aliquid to withstand relativelyhigh temperatures for shortperiods of time without the for-mation of carbonaceous deposits(sediment or coke).

Topped crude: petroleum that hashad volatile constituents re-moved up to a certain tempera-ture, e.g., 250°C+ (480°F+)topped crude oil; not always thesame as a residuum (q.v.).

Topping: the distillation of crudeoil to remove light fractions only

Trace element: those elements thatoccur at very low levels in agiven system.

Treatment: any method, technique,or process that changes the phys-ical and/or chemical character ofpetroleum.

Trillion: 1 ¥ 1012

True boiling point (True boilingrange): the boiling point (boilingrange) of a crude oil fraction ora crude oil product under stan-

dard conditions of temperatureand pressure.

Ultimate analysis: elemental composition.

Unassociated molecular weight:the molecular weight of asphal-tenes in a nonassociating (polar)solvent such as dichlorobenzene,pyridine, or nitrobenzene.

Uncertainty: same as standarddeviation (q.v.).

Universal viscosity: see SayboltUniversal viscosity.

Unstable: usually refers to a petro-leum product that has morevolatile constituents present or refers to the presence of olefin and other unsaturated constituents.

UOP characterization factor: seeCharacterization factor.

Upgrading: the conversion of pe-troleum to value-added salableproducts.

Vacuum distillation: distillation(q.v.) under reduced pressure.

Vacuum residuum: a residuum(q.v.) obtained by distillation ofa crude oil under vacuum(reduced pressure); the portionof petroleum that boils above a selected temperature such as 510°C (950°F) or 565°C(1050°F).

Validation: the process of provingthat an analytical method isacceptable for its intendedpurpose.

388 glossary

Viscosity: a measure of the abilityof a liquid to flow or a measureof its resistance to flow; the forcerequired to move a plane surfaceof area 1 m2 over another par-allel plane surface 1 m away at arate of 1 m/s when both surfacesare immersed in the fluid.

VGC (viscosity-gravity constant):an index of the chemical compo-sition of crude oil defined by thegeneral relation between specificgravity (sg) at 60∞F and SayboltUniversal viscosity (SUV) at100∞F:

a = 10sg – 1.0752 log (SUV – 38)/10sg – log (SUV – 38)

where the constant, a, is low forthe paraffinic crude oils and highfor the naphthenic crude oils.

VI (viscosity index): an arbitraryscale used to show the magni-tude of viscosity changes inlubricating oils with changes intemperature.

Viscosity-gravity constant: see VGC(viscosity-gravity constant).

Viscosity index: see VI (viscosityindex).

Watson characterization factor:see Characterization factor.

Wax appearance point: the tem-perature at which wax crystalsbegin to precipitate from a fuel.

Weathered crude oil: crude oilthat, because of natural causesduring storage and handling, haslost an appreciable quantity ofits more volatile components;also indicates uptake of oxygen.

Wobbe index (or Wobbe number):the calorific value of a gasdivided by the specific gravity.

Wood alcohol: see Methyl alcohol.

Zeolite: a crystalline aluminosili-cate used as a catalyst andhaving a particular chemical andphysical structure.