Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

इंटरनेट मानक

“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda

“Invent a New India Using Knowledge”

“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru

“Step Out From the Old to the New”

“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan

“The Right to Information, The Right to Live”

“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam

“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS 4639-6 (2002): Petroleum Industry - Terminology, Part 6:Meaurement [PCD 3: Petroleum, Lubricants and their RelatedProducts]

IS 4639( Part 6 ) :2002ISO 1998-6:2000

W??Rrm\ in

~ H * – ?Ewkii

WT6 WFr

( Wa7 g=7@wT )

Indian Standard

PETROLEUM INDUSTRY — TERMINOLOGYPART 6 MEASUREMENT

(First Revision )

ICS 10.040.75;75.080

4261s 2002

BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHiiDUR SHAH ZAFAR MARG

NEW DELHI 110002

March 2002 Prica Group 10

Petroleum Products Sectional Committee, PCD 3

NATIONAL FOREWORD

This Indian Standard ( Part 6 ) ( First Revision ) which is identical with ISO 1998-6:2000 ‘Petroleumindustry — Terminology — Part 6: Measurement’ issued by the International Organization for Standardization( ISO ) was adopted by the Bureau of Indian Standards on the recommendation of Petroleum ProductsSectional Committee and approval of the Petroleum, Coal and Related Products Division Council.

This standard was published in 1968 with a view to eliminate the ambiguity arising from differentf“I‘,

interpretations of terms used in petroleum trade and industry, and to establish a generally recognized‘f !‘ i

terms. Since the industry has progressed manifolds over the years, a need was felt to bring in newer*,,,,,{

terms. The Committee, therefore, decided to revise this standard to completely align with ISO 1998-6 :2000 under the dual numbering system. Accordingly, the title has been changed as ‘Petroleumindustry — Terminology : Part 6 Measurement’.

~“,.

It is envisaged to issue this standard in different parts, each dealing with a specific aspect. The other j~

parts in this series are as under: k:,,.!

Part 1

Part 2

Part 3

Part 4

Part 5

Part 7

Raw materials and products$.:

I

!:

Properties and tests

,.

Exploration and production

Refining \

Transport, storage, distribution

Miscellaneous terms

Part 99 General and index s

The English version of the text of ISO Standard has been retained without deviations for publicationas Indian Standard. Certain conventions are, however, not identical to those used in Indian Standards. i’~

!;Attention is particularly drawn to the following:

a)

b)

Wherever the words ‘International Standard’ appear referring to this standard, they should beread as ‘Indian Standard’.

Comma ( , ) has been used as a decimal marker while in Indian Standards, the current practiceis to use”a’ point ( . ) as the decimal marker.

For tropical countries like India, the standard temperature and the relative humidity shall be taken as27 * 2°C and 65 * 5 percent respectively.

IS 4639 ( Part 6 ) :2002

ISO 1998-6:2000

1 Scope

Indian Standard

PETROLEUM INDUSTRY — TERMINOLOGYPART 6 MEASUREMENT

( First Revision)

This part of ISO 1998 introduces a list of equivalentEnglish and French terms, in use in the petroleumindustry to indicate the measurement of crude oils andpetroleum products, together with the correspondingdefinitions in the two languages.

ISO 1998 is intended to cover the purposes of thispart of petroleum industry dealing with crude oils andpetroleum products, that means all related operationsarising from the production field to the final user. It isnot intended to cover either petroleum equipment, orany operation in the field. However some pieces ofequipment or some operations of exploration andproduction are defined. The corresponding termswere introduced only when they appear in a definitionof a product or process and when their definition wasfound necessary for understanding or for avoiding anyambiguity. Where a terminology of petroleumequipment is needed, it corresponds to the scope oflSO~C 67 Materia/s, equipment and offshorestructures for petroleum and natural gas industries.

2 Normative reference

The following normative document contains provisionswhich, through reference in this text, constituteprovisions of this part of ISO 1998. For datedreferences, subsequent amendments to, or revisionsof, any of these publications do not apply. However,parties to agreements based on this part of ISO 1998are encouraged to investigate the possibility ofapplying the most recent edition of the normativedocument indicated below. For undated references,the latest edition of the normative document referredto applies. Members of ISO and IEC maintainregisters of currently valid International Standards.

ISO 1998-99:2000, Petroleum industry — Termino-logy — Part 99: General and index.

3 Term numbering

The general classification and numbering systemused in ISO 1998 employs digits grouped in threecategories:

X.yy.zzz

where

x is the part number of ISO 1998, in this casePart 6;

yy is the subcategory in which the termappears. Part 6 has seven subcategories:

10

20

30

40

50

60’

99

static measurement

dynamic measurement

statistical analysis of measurement

sampling

properties and instrumentation

calibration and standards

J,acronyms

zzz is the serial number of the individual term.

4 Index

See ISO 1998-99.

5 Order of listing

Terms are listed in serial number order.

1

IS 4639 ( Part 6 ) :2002

ISO 1998-6:2000

6 Bibliography

Several definitions in this part of ISO 1998 are takenfrom the following standards.

ISO 4006:1991, Measurement of //uid f/ow inclosed conduits — Vocabulary and symbols.

ISO 4259:1992, Petro/eum products — Determi-nation and application of precision data in relationto methods of test.

OIML R 117:1995, Measuring systems for /iquidsother than water.

VIM: 1993, International vocabulary of basic andgeneral terms in metrology.

However, some definitions in this part of ISO 1998may differ from the definitions contained in VIM ; theyare then indicated by the mention “adapted from VIM”.

The defirutions in this part of ISO 1998 relate solely tocommon usage in the petroleum industry. They arenot intended to take precedence over VIM definitions,especially in applications where the latter may havelegal standing.

6.10 Static measurement

6.10.019calibrated volumevolume of a proving tank between the “empty” and“full” conditions when operated according to theconditions specified on its calibration certificate

6.10.025bottom calibrationdetermination of the partial capacities of the lowerportions of a tank

6.10.032calibration tabletank capacity tabletank tablecapacity tabletable, often referred to as a calibration table, a tanktable or tank capacity table, showing the capacities of,or volumes in, a tank corresponding to various liquidlevels measured from a reference point

6.10.033capacitytotal volume of a tank

6.10.046critical zonelevel range, close to the bottom of a floating roof tank,in which there are complex interactions and effects asthe floating roof comes to rest on its legs

NOTE The zone is usually clearly marked on tankcapacity tables. Measurements for custody transferpurposes should not be made within it.

6.10.047critical zone heightupper limit of the critical zone

NOTE This term can also bewhich one or more of the floatinglegs first touch the tank bottom.

6.10.049datum pointposition. used as the datum incalibration table

defined as the level atroof or floating blanket

the preparation of a

NOTE This position may differ from the gaugereference point (5.20.21 5).

cf. reference point (6.1 0.21 7)

6.10.050deadwoodany tank fitting which affects the capacity of a tank

6.10.051positive deadwoodfitting whose capacity adds to the effective capacity ofthe tank

6.10.052negative deadwoodfitting whose volume displaces liquid and reduces theeffective capacity of the tank

6.10.059dipinnagedepth of a liquid in a tank

6.10.060dip pointpoint on the dip-plate which the dip-weight touchesduring gauging and from which the measurements ofthe oil and water depths are taken

$

2

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ISO 1998-6:2000

NOTE The dip point usually corresponds with thedatum-point, but when this is not so the difference in levelbetween the datum-point and the dip point has to beallowed for in the calibration table [see dip-plate(5.20.213)].

6.10.061dipped volumeobserved volume of material calculated to becontained within a tank using the dip and tankcalibration table

6.10.075equivalent dipdepth of liquid in a tank corresponding to a givenullage

6.10.080floating markmark apparently occupying a position in the three-dimensional space formed by a stereoscopic fusion ofa pair of photographs and used as a reference markin examining or measuring the stereoscopic model

6.10.081floating-roof masstotal mass of a floating roof, inclusive of any extraload on it

NOTE The mass of the floating roof may be increasedby extraneous matter, such as rainwater, snow or debris,which should be taken into account.

6.10.084free waterwater that exists as a separate layer within a tank

NOTE It typically lies beneath the oil.

6.10.085free water levellevel of water that exists as a separate layer within thetank

NOTE The volume corresponding to the level willinclude the volume of any deposited sedment that may bepresent.

&lo.095gaugingprocess of taking all the necessary measurements ina tank in order to determine the quantity of liquidwhich it contains

NOTE In the French language, the term “jaugeage”also covers all the measurement operations made tomeasure the tank capacity up to one or several level(s).

6.10.100gross observed volumevolume of oil including dissolved water, suspendedwater and suspended sediment but excluding freewater and bottom sediment, measured at the oiltemperature and pressure prevailing

NOTE 1 This may be either the volume in a tank or thedifference between the volumes before and after a transfer.

NOTE 2 The acronym GOV is generally used rather thanthe full term.

6.10.101net observed volumevolume of oil excluding total water and total sedimentmeasured at the oil temperature and pressureprevailing

NOTE 1 This may be either the volume in a tank or thedifference between the volumes before and after a transfer.

NOTE 2 The acronym NOV is generally used rather thanthe full term.

6.10.103gross standard volumevolume of oil including dissolved water, suspendedwater and suspended sediment but excluding freewater and bottom sediment, calculated at standardconditions

NOTE 1 This may be either the volume in a tank or thedifference between the volumes before and after a transfer.

NOTE 2 The acronym GSV is generally used rather thanthe full term.

6.10.104net standard volumevolume of petroleum liquids, excluding sediment andwater, corrected to standard conditions of temperatureand pressure

NOTE 1 This may be either the volume in a tank or thedifference between the volumes before and after a transfer.

NOTE 2 The acronym NSV is generally used rather thanthe full term.

6.10.112HTG reference pointstable reference point from which the HTG sensor

positions are measured

3

IS 4639 ( Part 6 ) :

ISO 1998-6:2000

6.10.113

2002

hydrostatic tank gaugingmethod of direct measurement of liquid mass in astorage tank based on measuring static pressurescaused by the liquid head above the pressure sensor

NOTE The acronyms HTG is often used rather thanthe full term.

6.10.121inner orientationprocess of determining, mathematically, the interiorperspective of the photographs at the time ofexposure in an analytical stereoplotter

NOTE The calibrated focal length, the location of thecalibrated principal point and the calibrated lens distortionare the principal factors used in the calculation.

6.10.130latitudehorizontal circumference on the surface of a sphere

6.10.131longitudecircumference on the surface of a sphere passingthrough the north and south poles

6.10.132equatorlargest horizontal circumference of a spherical tank

6.10.140liquid leveldistance between the surface of the liquid in a tankand the gauge reference point, measured by dippingor unaging along the centreline of the dip hatch

NOTE When a ship is in a list or trim condition, theheight measured by the gauge may be vertical or at rightangles to the task bottom,dependingon the type of gaugingequipmentused.

6.10.142Littlejohn gripquick-release clamp and handle attachment that isfitted around a strapping tape, enabling it to be pulledto the correct tension

6.10.149longitudinal planevertical plane runningtank

6.10.153measurement ticket

parallel to the centreline of the

written acknowledgement of the receipt ,or delivery ofa quantity of crude oil or petroleum product, includinga record of the measurement data

NOTE It may be a form to be completed, a data printout or a data display depending on the degree ofautomation, remote control, or computerization, previouslydescribed as “run ticket” and “receipt and delivery ticket”.

6.10.154measuring lineline (longitudinal, transverse or vertical) on a three-dimensional rectangular grid with a pitch not greaterthan 5 m

NOTE Measurement for calibration purposes is takenalong these measuring lines.

6.10.160north polezenith, or highest point of a spherical tank shell, animaginary point in most spherical tanks due to thepipe tower or other appurtenances

6.10.161south polenadir, or lowest point of a spherical tank

6.10.170open capacitycalculated capacity of a tank or part of a tank beforeany allowance has been made for deadwood

6.10.183pin-heightlower limit of the critical zone; tti level at which thefloating roof or floating cover rests fully on its legs

6.10.194product heel massmass of product below the bottom HTG (6.99.050)sensor

6.10.148longitudinal lineline formed by a longitudinal plane crossing ahorizontal plane

4

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IS 4639 (Part 6):2002

ISO 1998-6:2000

6.10.195product heel volumeobserved volume of product below the bottom HTG(6.99.050) sensor, calculated by subtracting the watervolume from the total heel volume

6.10.209referee method of tank calibrationapplication of the strapping method of tank calibrationto give an accurate calibration of a tank for custodytransfer purposes or to provide a basis for assessingthe accuracy of other methods of tank calibration

6.10.210reference datum of high pressure tankreference point located above the isolation valve of anautomatic gauge in a pressure vessel and used tocheck the gauge calibration

NOTE This point may be in the level-gauge glass.

6.10.212reference heightdistance betweenreference point

6.10.213reference line

the dip datum point and the upper

vertical line established, by means of an opticalreference line device, at predetermined positionsaround a vertical cylindrical tank from which offsetmeasurements are made when calibrating a tankusing the optical reference line method

6.10.2.15offsethorizontal measurements made from a reference lineto the tank wall when calibrating a tank using theoptical reference line method

NOTE 1 Reference offsets are offset measurementsmade from the reference line to the tank wall at the height ofthe reference circumference measurement.

NOTE 2 The term is also used in ship tank calibrationwhere an offset is a measurement taken from a horizontalline parallel to the tank wall.

6.10.216reference planeplane parallel to a side wall, end wall or tank bottomwhich passes through a reference line

NOTE This term applies to the calibration of ships’tanks.

6.10.217reference pointpoint to which all measurements subsequent tocalibration are related

6.10.219reference target pointfixed point clearly marked on the inside surface of thetank shell wall

6.10.220tank-calibration reference temperaturetemperature at which the calibration of a tank hasbeen calculated

6.10.223relative orientationprocess of determining the relative position andattitude of a pair of overlapping photographs bymathematical analysis to create a stereoscopic model

6.10.252section lineline formed by a section plane crossing a horizontalplane

6.10.253section planeplane parallel with the fore and aft end walls of aship’s tank

6.10.260slope distancedistance measured from the electro-optical distanceranging instrument to a target point on any givencourse of the tank shell wall

6.10.269step-overdevice used in strapping for measuring the distanceapart along the arc of two points on a tank shell whereit is not possible to use a strapping tape directlybecause of an intetiening obstruction, e.g. aprotruding fitting

5

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IS 4639 (Part 6):2002

ISO 1998-6:2000

6.10.270step-over constantdistance between the measuring points of a step-overas measured along the arc of the particular course ofthe tank concerned

6.10.271step-over correctiondifference between the apparent distance betweentwo points on a tank shell as measured by a strappingtape passing over an obstruction and the true arcdistance as measured by a step-over, i.e. the step-over constant

6.10.272stereoscopic modelthree-dimensional model formed by intersectinghomologous rays of a pair of overlapping photographs

6.10.273stereoscopic photographset of photographs of an object taken from twodifferent positions so that they may form astereoscopic model of the object depicting it as if itwere in three-dimensional space

6.10.275strapping methodmethod of tank calibration in which the capacities arecalculated from the measurement of the externalcircumferences, due allowance being made for thethickness of the shell of the tank

6.10.276strapping tapespecially designed and calibrated steel measuringtape graduated in units of length and used for takingcircumferential measurements in tank calibration

6.10.283suspended waterwater contained within the oil that is finely dispersedas small droplets

NOTE It may, over a period of time, either collect asfree water or become dissolved water, depending on theconditions of temperature and pressure prevailing.

6.10.293targetpredetermined position distinctively marked on theinside surface of the tank for the stereophoto-grammetry

6.10.294target pointone of a series of points on the inside surface of thetank shell wall to which slope distance, vertical andhorizontal angles are measured

6.10.301total calculated volumegross standard volume plus the free water measuredat the temperature and pressure prevailing

NOTE The acronym TCV is generally used rather thanthe full term.

6.10.302total observed volumevolume of oil including total water and total sediment,measured at the oil temperature and pressure {

prevailing1

NOTE 1 This may be either the volume in a tank or thedifference between the volumesbeforeand after a transfer. {

~NOTE 2 The acronym TOV is generally used rather than ,the full term.

6.10.304total standard volume ~total volume at standard temperature and pressure

,....~

NOTE The acronym TSV is generally used rather than ?

the full term. i...

6.10.306total waterthe sum of all the dissolved, suspended and freewater in a cargo or parcel of oil

6.10.307traverse pointposition on the inside surface of the tank above whicha theodolite is set for determining the coordinates of atarget

6.10.309ullageoutagedistance between the surface of a liquid in a tank anda fixed reference point on the top of the tank

NOTE The term can also describe the capacity of atank not occupiedby the liquid.

.

6

IS 4639 ( Part 6 ) :2002..

ISO 1998-6:2000 4

6.10.312uilage pressurepressure in the ullage space of the tank

6.10.313ullage volumevolume of the ullage space in a tank, obtained bysubtracting the liquid volume from total tank capacity

6.10.314ullage reference pointpoint clearly marked on the dip-hatch, or on a platesuitably located above or below the dip-hatch, andsituated above the mdximum level in the tank toindicate the point from which measurements of ullageare taken

6.10.315upper reference pointpoint clearly defined on the dip-hatch directly abovetbe dip-point to indicate the position at which dippingor unaging shall be carried out

6.10.321vertical lineline formed by a section plane on the side walls andformed by a longitudinal plane on the fore and aft endwalls

6.10.329water bottomlayer of water at the bottom of a tank, of such depthas to completely cover the bottom

6.10.330water cutwater dip(static measurement) level or volume of free water ina tank

6.10.334working method of tank calibrationapplication of the strapping method of tank calibrationby a simplified procedure that may result in some lossof accuracy and is unsuitable for assessing othermethods

6.10.400clingage(static measurement) material which adheres to thesurfaces of tank walls and structures, both horizontaland vertical, within empty or part-empty tanks otherthan bottom surfaces

NOTE In French, the English term “clingage”. is oftenused.

6.10.410on-board quantitysum of liquid volume and non-liquid volume in cargotanks just before loading, excluding clingage,hydrocarbon vapours and the content of associatedpipelines and pumps

NOTE The acronym OBQ is generally used rather thanthe full term.

6.10.411quantity remaining on boardsum of liquid volume and non-liquid volume in cargotanks just after discharge has been completed,excluding clingage, hydrocarbon vapours and thecontents of associated pipelines and pumps

NOTE The acronym ROB is generally used rather thanthe full term.

6.10.416liquid volumemeasurable amount of material which is free-flowingat the time of measurement

NOTE The material can be oil or free water, or both.

6.10.417non-liquid volumemeasurable amount of material which is not free-flowing at the time of measurement

NOTE It can include any one or a combination ofhydrocarbon waxes, water/oil emulsions, inorganicmaterials, or solidified cargo.

6.10.433wedge formulamathematical means to assess small quantities ofmeasurable liquid and/or non-liquid material which isin a wedge configuration and does not touch allbulkheads of the vessel’s tank

NOTE The formula’ is based on the characteristics ofcargo compartments, vessel trim and the depth of thematerial.

6.10.434wedge tablevessel’s cargo-tank volume table based on ‘compartment characteristics for use when the cargodoes not touch all bulkheads of the tanks

7

IS 4639 ( Part 6 ) :2002

ISO 1998-6:2000

6.10.440 6.10.442bottom sediment total sedimentmixture of non-hydrocarbon solids present in a tank sum of suspended and bottom sedimentas a separate layer at the bottom

6.10.441suspended sedimentnon-hydrocarbon solids present within the oil, but notin solution

...

8

6.20 Dynamic

6.20.010metering conditions

measurement

conditio~s of the liquid of which the volume is to bemeasured, at the point of measurement

NOTE Example: temperature and pressure of themeasured liquid.

[OIML R 117:1995]

6.20.040clingage

(dynamic measurement) liquid film that adheres to theinside surface of a volumetric or prover tank after ithas been emptied

6.20.050water cutwater dip(dynamic measurement) volume of free water passingthrough a pipeline

6.20.090base volumecalibrated volume of a pipe prover at referenceconditions of temperature and pressure

6.20.100proving in dynamic measurementtechnique whereby a meter factor or k-factor isestablished, using a volumetric or gravimetric prover

6.20.101on-line provingprocess where a meter is provedsame flow conditions and with theoccur during the throughput

cm-line under thesame products as

6.20.102central provingprocess where a meter is proved in a laboratory onproducts of varying viscosity and over a range offlowrates

NOTE An equation, determined by means of apolynomial, is often applied to predictthe meter or k-factorfor variousviscositiesand flowrates.

6.20.105pipe provermeter-proving device consisting of a section of pipe inseries with the meter and through which the liquidflows during the proving run

IS 4639 ( Part 6 ) :2002

ISO 1998-6:2000

NOTE 1 The pipe is constructed to close tolerances andcontains a discdacer which sweetx an accuratelydeterminable volu’me of liquid between the detectors. ‘

NOTE 2 Pipe provers are divided into two types :conventional pipe provers or small volume provers.

6.20.106hi-directional proverpipe prover designed to enable proving runs to bemade in both directions alternately

6.20.107small volume proverpipe prover consisting of a honed cylinder, with apiston rod whose linear movement is measured byexternal (non-invasive) detectors

NOTE They are typically of smaller dimensions thanthe equivalent conventional pipe prover.

6.20.109flashingformation of vapour when the local pressure at a pointwithin the liquid falls below the saturated pressure ofthe liquid at the operating temperature

6.20.110cavitation

-“

phenomenon following flashing where the pressurerecovers above the vapour pressure and the vapourbubbles collapse

6.20.115control chartgraphical technique of statistical control in whichmeasurements are plotted against time in order toassist in the monitoring of ongoing measurements

6.20.116Shewhart chartchari (first developed by Walter A. Shewhart) onwhich limits are drawn and values of a variable plottedand monitored

NOTE If the values lie within the chosen limits then thesystem can be considered to be in control. A learning periodinvolving at least 10 consecutive results is required in orderto establish the control limits. The confidence limits chosenare based on a probability of 95 % or 99 O/O.

9

IS 4639 (Part 6):2002

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6.20.117cumulative-sum chartcusum chartcontrol charl on which are plotted accumulated valuesof the variable

NOTE Straight lines are fitted to the points; wherechanges in slope of the fitted lined occur, they indicate thepossible occurrence of “events” which may meritinvestigation.

6.20.119moving average chartcontrol chart, often used to monitor any long-term driftin meter factor readings, on which are plotted theaverages of successive measurements

NOTE The average is usually based on either fiveconsecutive readings or ten. The first reading is droppedand a new reading incorporated in the moving average.

6.20.120control limitslimits applied to a control chart to establishthe scatter of the data is due entirely toinfluences

whetherrandom

NOTE When associated with 95 % confidence levels,they are termed “inner” or “warning” limits (if all the data liewithin these limits then the measurement system can besaid to be in control). When associated with 99 %confidence levels, they are termed “outer” or “action” limitsand are used to detect any outliers which may indicate thatthe measurement system is out of control.

6.20.125Coriolis meterflowmeter which uses the interaction between themass flow of the fluid and the oscillations of thevibrating conduits for mass flowmetering purposes

NOTE The Coriolis meter can also be used as acontinuous density meter (6.50.021 ).

6.20.126direct mass meterself-contained integrating measuring device whichmeasures continuously the mass of fluid passingthrough it, using a process in which signals generatedin proportion to the mass flow rate are detected andconverted to a mass flow measurement signal

{

. ~!

:,i~

6.20.127displacement meter

!’

meter which measures the volume flowing in a closedconduit by dividing it into discrete quantities by meansof a close-fitting or semi-rotary assembly in the meterbody

, >.,,‘!,,.

NOTE The quantity passing through the meter is afunction of the number of operating cycles of the assembly.

ii,,

6.20.128 ~

reference meterflowmeter employed to prove other flowmeters

NOTE This meter is usually proved over a range offlowrates and on products of varying viscosity in order toderive a number of corrections which can be applied tobring meter readings to standard conditions.

turbine meterj~

meter which provides a pulsed output at a frequency .:

proportional to the angular velocity of a bladed rotormounted in the meter body and driven by the fluid flow

NOTE The output is proportional to the volumetricflowrate of the fluid. “ “

6.20.131vortex-shedding meterflowmeter which comprisessuccession of vortices areside of the bluff body

NOTE For a given range

----.’

a bluff body from which ashed alternately on each

j

of flowrate, the frequency atwhich the vortices- are shed is directly proportional to theflowrate and can be counted using a wide variety ofsensors.

6.20.135linearity of metermaximum and minimum limits of k-factor, meter factoror error within which the calibration curve fits over astated flow range

6.20.136turndown ratio of a metereffective flow range over which the meter factor islinear

6.20.137indicated volumechange in meter reading that occurs during a transferthrough the meter

10

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IS 4639 ( Part 6 ) :2002

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1,

6.20.138gross volumeindicated volume multiplied by the meter factorappropriate to the liquid and flowrate, withoutcorrection for temperature and pressure

6.20.141k-factornumber of pulses generated by a meter while a unit ofvolume is passing through it

6.20.142meter factorratio of the actual volume of liquid passed through ameter to the volume indicated by it

NOTE 1 In practice this is the prover volume divided bythe meter reading, each corrected to common conditions.

NOTE 2 This term can also be defined as the ratio of thek-factor obtained on proving a meter to the original ornominal (maker’s figure) &factor.

6.20.143scaling factornumerical factor which converts the pulse count of ameter to the required units of volume

6.20.145curve fittechnique of fitting a curve to a number of meterfactors or k-factors

NOTE A polynomialor the followingtypes of curve areusually employed:

linear (y=ax+b)

logarithmic (y=a+blru)

exponential (y= ati)

power (y= a.i?)

6.20.150cyclic distortionany periodic variation in the frequency generated by ameter, that may be caused by mechanical asymmetrywithin the meter or by the addition of accessoriessuch as temperature compensators.

6.20.151intra-rotational linearityquantitative measure of thespacing between the pulsesmeter at constant flowrate

degree of regularity ofproduced by a rotating

NOTE This is generally expressed as the standarddeviation of pulse spacing about the mean pulse spacing.This measure will include cyclic and non-cyclicmeasurements introduced by the meter mechanism.

6.20.155detector of a proverdevices that sense precisely, by direct or indirectmeans, the position of the displacer at each end of theprover’s calibrated volume

NOTE For small-volume provers the detectors areusually mounted externally for measuring the distancetravelled by the piston rod connected to the internaldisplacer.

6.20.170electronic headelectronic device fitted to a flowmeter that hasrealtime data-processing capability and enablescorrection factors to be applied continuously to themeter output registered by the device

6.20.180flying start and stopprocedure which involves obtaining the opening andclosing meter readings of the proof whilst the meter isin”operation

6.20.181standing-start-and-stopproving technique in which the flow through the meterand the proving device is started at the beginning andstopped at the end of the proving process

6.20.185flow conditioninggeneral term describing methods for eliminating theeffect of irregular velocity distribution (swirl) in thepipework upstream of the meter

6.20.186flow conditionerdevice inserted in a conduit to reduce the straightlength needed to obtain a regular velocity distribution

6.20.190gatinginitiation and cessation of pulse totalization in acounter, e.g. by pipe prover detectors

11

IS 4639 (Part6) :2002

ISO 1998-6:2000

6.20.195launch/receive chamberenlarged section at each end of a hi-directional pipeprover and in which the displacer rests betweenproving runs

6.20.205passone single movement of the displacer between twodetectors in a pipe prover

6.20.215pulse interpolationelectronic technique for enhancing the resolution of agated pulse count

6.20.216pulse interpolation divisorratio of the enhanced pulse frequency of the pulsesgenerated by the meter, used in the phase-locked-loop system of pulse interpolation

6.20.235round-trip volumesum of the swept volumes in both the forward andreverse directions in a hi-directional prover

6.20.240runset of consecutive passes that is in any particularcase deemed to be necessary to derive a single valueof meter factor or k-factor suitable for reporting

6.20.260swirlcondition of flow in which the liquid flowing throughthe pipework upstream of a meter rotates andfluctuates in velocity relative to the average flowrate

NOTE Flow conditioning is one method employed toeliminate this undesirable effect.

6.20.270totalizermechanical or electronic device for integrating anddisplaying the throughput of a flowmeter

6.20.285displacer in a pipesphere or piston whichvolume of a pipe prover

sweeps out the calibrated

12

6.30 Statistical analysis ofmeasurement

6.30.001errordifference between a computed or measured quantityand the true value

6.30.002absolute errorterm sometimes used when it is necessary todistinguish error from relative error

NOTE This should not be confused with absolute valueof error, which is the modulus of the error.

6.30.003relative errorerror of measurement divided by the true value of themeasurand

NOTE Since the true value cannot be determined, inpracticea conventionaltrue value is used.

[Adapted from VIM 1993: 3-12]

6.30.004random errorresult of a measurement minus the mean that wouldresult from an infinite number of measurements of thesame measurand carried out under repeatabilityconditions

NOTE 1 Random error is equal to error minus systematicerror.

NOTE 2 Because only a finite number of measurementscan be made, it is possible to determine only an estimate ofrandom error.

[VIM 1993: 3-13]

6.30.005systematic errormean that would result from an infinite number ofmeasurements of the same measurand carried outunder repeatability conditions minus the true value ofthe measurand

NOTE 1 Systematic error is equal to error minus randomerror,

NOTE 2 Like true value, systematicerror and its causescannot be completely known.

[Adapted from VIM 1993:3-1 4]

IS 4639 ( Part 6 ) :

ISO 1998-6:2000

6.30.008spurious errorerror which invalidates a measurement

2002

NOTE It generally has a single cause such as theincorrect recording of one or more significant digits or themalfunction of instruments.

6.30.007overall errorerror composed of error factors with respect tomechanical parts, data transmissions, local indicatorand/or remote indicator, but does not include othererror factors related to installation and deformation ofthe tank

6.30.008maximum permissible errorextreme value of error permitted by regulationsappertaining to that system

6.30.009short-term meter errorscatter of meter factors or k-factors obtained whenproving a meter

NOTE The scatter can either be expressed as the range

of the consecutive readings (maximum – minimum) over a

short period of time i.e. minutes, or as the random

uncertainty expressed as U = tg5,n_1s(x), where t is the

Student’s l-value for a probability of 95% and S(X) is the

observed standard deviation.

6.30.010long-term meter errorscatter of the means of sets of meter factors, carriedout over intervals of time, i.e. days, weeks, months,etc.

NOTE U = f95,n_1s(z), where S(Z)is the standard deviation

of the mean meter-factor values.

6.30.015accuracy of a measuring instrumentability of a measuring instrument to give responsesclose to the true value

NOTE “Accuracy”isa qualitativeconcept.

[Adapted from VIM 1993:5-1 8]

6.30.016repeatability of results of measurementscloseness of the agreement between the results ofsuccessive measurements of the same measurandcarried out under the same conditions ofmeasurement

-

13

IS 4639 ( Part 6 ) :2002

ISO 1998-6:2000

NOTE 1 These conditions are called repeatabilityconditions.

NOTE 2 Repeatability conditions include

— the same measurement procedure;

— the same observe~

— the same measuring instrument, used under thesame conditions;

— the same location;— repetition over a short period of time.

NOTE 3 Repeatability may be expressed quantitatively interms of the dispersion characteristics of the results.

[VIM 1993: 3-6]

6.30.017reproducibility of results of measurementscloseness of the agreement between the results ofmeasurements of the same measurand carried outunder changed conditions of measurement

NOTE 1 A valid statement of reproducibility requiresspecification of the conditions changed.

NOTE 2

—

—

—

—

—

—

—

—

NOTE 3

The changed conditions may include

principle of measurement;

method of measurement;

observer;

measuring instrument;

reference standard;

location;

conditions of use;

time.

The reproducibility may be expressed quanti-tatively in terms of the dispersion characteristics of theresults.

NOTE 4 The results considered here are usually under-stood to be corrected results.

[VIM 1993:3-7]

NOTE 5 Not usually applicable to bulk quantitymeasurement.

6.30.020uncertaintyV( )estimate characterizing the range of values withinwhich the true value of a measurand lies

NOTE 1 The symbol e is sometimes used instead of u todesignate uncertainty.

NOTE 2 Uncertainty of measurement comprises, ingeneral, many components. Some of these componentsmay be estimated on the basis of the statistical distributionof the results of series of measurements and can becharacterized by experimental standard deviations.Estimates of other components can only be based onexperience or other information.

6.30.021random uncertaintyUr( )

component of uncertainty associated with a randomerror

NOTE 1 Its effect on the mean value can be reduced bytaking many measurements.

NOTE 2 The symbol e is sometimes used instead of U todesignate uncertainty.

6.30.022systematic uncertaintyUs( )

component of uncertainty associated with asystematic error

NOTE 1 Its effect cannot be reduced by taking manymeasurements.

NOTE 2 The symbol e is sometimes used instead of U todesignate uncertainty.

6.30.025confidence levelprobability that the true value will lie between thespecified confidence limits, assuming negligiblesystematic error

NOTE This is generally expressed as a percentage,e.g. 957..

6.30.026confidence limitslower and upper limits within which the true value isexpected to lie with a specified probability, assumingnegligible systematic error

14

-

IS 4639 (Part 6):2002

ISO 1998-6:2000

6.30.027acceptable limitslimits within which the result of a measurement isacceptable relative to the true value or other specifiedvalue at a stated level of probability

6.30.030true valuevalue consistent with the definition of a givenparticular quantity

NOTE 1 This is a value that would be obtained by aperfect measurement.

NOTE 2 True values are by nature indeterminate.

NOTE 3 Although VIM recommends the indefinite article‘(a”, rather than the definite article “the” in conjunction with“true value” because there may be many values consistentwith the definition of a given particular quantity, it is widely inuse in the petroleum industry to speak of “the true value”.

[Adapted from VIM 1993:1-1 9].

6.30.031conventional true valuevalue attributed to a particular quantity and accepted,sometimes by convention, as having an uncertaintyappropriate for a given purpose

NOTE 1 “Conventional true value” is sometimes calledassigned value, best estimate of the value, conventionalvalue or reference value. “Reference value”, in this sense,should not be confused with “reference value” in the senseused in the note to 6.60.010.

NOTE 2 Frequently, a number of results ofmeasurements of a quantity are used to establish aconventional true value.

[VIM 1993:1-20]

6.30.032outlier testspecified named statistical approach to thedetermination of outlier status of a single resultamongst others

NOTE The Hawkins test is specified in ISO 4259 forthe assessment of outliers in the petroleum industry, but theGrubbs test and Dixon test are widely used in flow-meteringapplications.

6.30.035correlation coefficientindication of the closeness of the curve fit to all points:normally a value of O indicates no fit while a value of 1indicates that all the points fit the equation

6.30.040degrees of freedomquantity of information, expressed as the number ofindependent observations, on which a” varianceestimate is based

NOTE The degrees of freedom are the number ofobservations less the number of constants calculated fromthe data.

6.30.045variancemean of the squares of the deviation of a randomvariable from its mean, estimated by the mean square

6.30.050standard deviationmeasure of the dispersion of a series of resultsaround their mean, equal to the positive square root ofthe variance and estimated by the positive square rootof the mean square

6.30.051experimental standard deviationfor a series of n measurements of the same -

measurand, the quantity, S, characterizing thedispersion of the results and given by the formula

where

Xj is the result of the ith measurement;

Y is the arithmetic mean of the nconsidered

results

NOTE Considering the series of n values as a sample ofa distribution, Y is an unbiased estimate of the mean p, and~2 is an Unbiased estimate of the variance &, of that

distribution.

15

J+_

IS 4639 (Part 6):2002

ISO 1998-6:2000 --

6.30.052experimental standard deviation of the meanestimate of the standard deviation of the arithmeticmean with respect to the mean of the overallpopulation, given by the formula

6.30.058Poisson modified distributiondistribution in which the relative probability of avariable taking a value X, where x has only a positivevalue, is given by the series

[–1[Cp1,J- P(P+I P(P+?(P+2)

C+l (C+l)’2!(C +1)2 ‘ 3!(C+$3 ‘‘(1)‘k

NOTE The experimental standard deviation of the meanis sometimes incorrectly called standard error of the mean. P(P+1)(P+2)(P+3)

,4!(C+ 1)4 ‘“””1

6.30.053pooled standard deviationestimate of the standard deviation of the meter factorwhich is obtained from m sets of n proving runs usingthe equation:

where

Px-. —c

S(X)pooled = p and c are constants

6.30.059Student’s distributiondistribution of the deviations of the mean values ofrandom samples of n values from a normal distributionwith mean p expressed as a proportion of the samplestandard deviation

where

Xi is the $h reading of any set;

NOTE It is used to set the confidence limits of thepopulation mean, in particular in cases where the mean hasbeen estimated from small samples. The value of r isobtained from tables giving the number of degrees offreedom and the confidence level according to the equation:

——.xl, X2, X3, . . . . z,n are the mean values of each

set

-.

6.30.055distributionfrequency distribution which has a scatter of singlemeasurements about the mean

,,

where

6.30.056normal distributiondistribution in which the relative probability of avariable taking a value X, where x may have either apositive or negative value, is

P is the unknown population mean;

Y is the sample mean;

n is the size;

II-(x - /’)2f(x) =---& exp 202 s is the sample standard deviation.

In practice, the t-distribution values given in published tables

are usually for (n –1) degrees of freedom for a two-sided

probability of either 95 Y. or 99 %.where

P is the mean;

o is the standard deviation6.30.080Student’s rcf. Student’s distribution (6.30.059)

6.30.057gaussian distributioncf. normal distribution (6.30.056)

16

A-

IS 4639 ( Part 6‘) :2002

ISO 1998-6:2000

6.30.061frequency distributioncf. distribution (6.30.055)

6.30.062skewed distributionfrequency distribution which is not symmetrical aboutits mean value

6.30.100acceptable quality levelmaximum per cent defective (or the maximum numberof defects per hundred units) that, for purposes ofsampling inspection, can be considered satisfactoryas a process average

6.30.150extrapolationprocess of obtaining the value of a functioncorresponding to a value of the argument greater orless than the extreme values given

6.30.151interpolationprocess of obtaining the value of a functioncorresponding to a value of the argument intermediatebetween those given

6.30.152sub-tabulationprocess of interpolation used to obtain the values ofthe function corresponding to regular fractionalintervals between given values of the argument

6.30.160discriminationdiscrimination thresholdlargest change in a stimulus that produces nodetectable change in the response of a measuringinstrument, the change in the stimulus taking placeslowly and monotonically

[VIM 1993:5-1 1]

6.30.200in transit differencedifference between the total calculated volumeimmediately after a loading and the total calculatedvolume immediately before discharge

6.30.201outturn quantityquantity of oil, discharged by a vessel, usuallydetermined by measurement on shore and expressedin terms of net standard volume.

6.30.202outturn loss/gaindifference, in net standard volume, between thequantity shown on the bill of lading and the quantityshown on the outturn certificate

NOTE It may be expressed as a volume or apercentage of the bill of lading quantity.

6.30.203vessel-shore differencedifference between the total calculated volumerecorded by the vessel corrected for OBQ or ROB asappropriate, and the total calculated volume recordedby the shore

6.30.210vessel experience factormean value of the vessel load ratios (VLR) or vesseldischarge ratios (VDR) obtained using a set ofqualifying voyages

NOTE 1 The number of such qualifying voyages isnormally a minimum of five

NOTE 2 Depending on the determination, it is expressedas VEFL (VEF on loading) or VEFD (VEF on discharging).

6.30.211vessel load ratioratio of the total calculated volume measured onboard a vessel immediately after loading less theOBQ to the total calculated volume measured by theloading terminal

6.30.212vessel discharge ratioratio of the total calculated volume measured onboard a vessel immediately before discharge less theROB to the total calculated volume measured by thereceiving terminal

6.30.215volume correction factorfactor for correcting oil volumes to a standardreference temperature

6.30.216mass conversion factorfactor for converting mass to apparent mass-in-air

cf. table 56 of ISO 91-11)

NOTE The acronymWCF is generallyused ratherthanthe full term.

1) 1S091-1:1992, Petroleum measurement tables—Part 1: Tables based on reference temperatures ot15 ‘C and60 “F.

.-’-.

17

IS -4639 ( Part 6 ) :2002

ISO 1998-6:2000

6.30.250measurandquantity subjected to measurement

NOTE As appropriate, this may be the measuredquantity or the quantity to be measured.

6.30.255rangenumerical difference between the extreme values of anumber of consecutive measurements obtained overa short period of time for the same value of input

6.30.260root-sum-squaremethod combining the estimates of standard deviationor uncertainty of a number of independent variables inwhich the squares of the variables are added and thesquare root taken of the sum

NOTE This method is sometimes termed summing inquadrature.

6.30.270traceabilityproperty of the result of a measurement or the valueof a standard whereby it can be related to statedreferences, usually national or international standards,through an unbroken chain of comparisons all havingstated uncertainties

NOTE 1 The concept is often expressed by the adjective

1!

; ,!,,,traceable.

NOTE 2 The unbroken chain of comparisons is called a ~traceability chain.

NOTE 3 (applicable only to the French text).

[VIM 1993:6-10]

6.30.280 targument “.’;$independent variable of a function

{

NOTE A table is prepared with value(s) of the {independent variable(s), the value(s) extracted from the

!

table being known as the dependent value(s). &

--------.

‘i

18

IS 4639 (Patt 6):2002

ISO 1998-6:2000 4

6.40 Sampling

6.40.001sampleportion taken from a material and representative ofthe material at the point of sampling

6.40.005all levels samplesample obtained with an apparatus which fills as itpasses through the total liquid height in one direction

NOTE The container should be filled to 75 Y. or 80 Y.

of its capacity.

6.40.010top samplespot sample obtained 150 mm below the top surfaceof the liquid

6.40.011upper samplesample taken at a level of one-sixth of the depth ofliquid below the top surface

6.40.012middle samplesample taken at a level of one-half of the depth ofliquid below the top surface

6.40.013bottom samptespot sample taken from the material at the bottomsurface (floor) of a tank or container

6.40.014lower samplesample taken at a level of five-sixths of the depth ofliquid below the top surface

6.40.015skim samplesurface samplesample taken from the surface of the liquid

6.40.020composite samplesample obtained by combining a number of spotsamples in defined proportions so as to obtain asample representative of the bulk of the material

4\‘.

. . ,. .

!,,”

NOTE The usual types of composite sample areobtained by combining samples in accordance with one of t,the following: Ii

a) upper, middle and lower samples in equal proportions;

b) upper, middle and suction-level samples in equal

!

t.,“,+,proportions; ‘:!.,

c) a series of spot samples from a non-homogeneous oil ‘taken at more than three levels and blended inproportion to the quantities of oil represented;

d) individual sample from several tanks or ship’scompartments proportional to the total quantity eachsample represents;

e) a series of spot samples of equal volume obtainedfrom a flowing pipeline taken at specified intervals.

6.40.025spot samplesample taken at a specific location in a tank or from apipe at a specific time during a pumping operation

6.40.030running samplesample obtained by lowering a container from the topof the oil to the bottom and returning it to the top ofthe oil at a speed such that the container is aboutthree-quarters full when withdrawn from the oil

6.40.035representative samplesample having its physical or chemical characteristicsidentical to the volumetric average characteristics ofthe total volume being sampled

6.40.040suction-level samplesample taken at the lowest level from which liquidhydrocarbon is pumped from the tank

----

6.40.045fixed rate sampletime-proportional samplesample taken from a pipeline during the whole periodof transfer of a batch, composed of equal incrementsat uniform time intervals

6.40.050flow-proportional samplesample taken from a pipeline during the whole periodof transfer of a batch, at a rate which is proportional tothe rate of flow of the liquid through the pipeline at anyinstant

19

IS 4639 ( Part 6 ) :2002

ISO 1998-6:2000

6.40.060integrity of the samplecundition of being complete and unaltered, i.e. thesample being preserved with the same compositionas when it was taken from the bulk of the liquid

6.40.065sample conditioningpreparation of the laboratory sample for analysis,including all operations specified in the test methodprior to the drawing of the test portion

6.40.066sample handlingall operations following the completion of sampling tothe receipt of the laboratory sample in the analysinglaboratory

6.40.070calculated sample volumetheoretical sample volume obtained by multiplying thesample grab volume by the number of grabs actuallycollected

6.40.071grabportion of liquid extracted from the pipe by a singleactuation of the extracting device

NOTE The sum of all the portions results in a sample.

6.40.075sample containervessel used for the storage, transportation andpreconditioning of the total quantity, or a proportion ofthe total quantity, of the sample for analytical work orfor division into identical small sub-samples to beanalysed

6.40.076sample receivercontainer connected to automatic sampling equipmentin which the sample is collected during the samplingoperation

6.40.077sample sizevolume of sample required to be drawn

6.40.080percent defectiveone hundred times the number of defective units ofproduct contained in any given quantity of units ofproduct divided by the total number of units ofproduct, i.e.:

per cent defective =number of defective

Xloonumber of units inspected

6.40.100sampling system

system capable of extracting a representative samplefrom the fluid flowing in a pipe

NOTE This system can be automatic or manual,continuous or intermittent.

6.40.101automatic samplerdevice for the extraction of a representative samplefrom a liquid flowing in a pipe

NOTE It includes the sampling probe, together withextraction and control equipment, it may also include aspecialized sample receiver.

6.40.102automatic sampling systemsystem of sampling that provides stream conditioningbefore the operation of an automatic sampler, andmay provide sample conditioning

6.40.103sampler performance factorratio between the accumulated sample volume andthe calculated sample volume

6.40.104sampling probedevice inserted into gas or liquid to be sampled fromthe transfer line or fitted to the transfer line forcollecting a sample

6.40.105continuous samplersystem for extracting liquid from a flowing streamwhich has a device which continuously withdrawsliquid from the main pipeline in relation to flow rate, anintermediate sample receiver, and a means’ forcontrolling secondary withdrawal to a final samplereceiver

6.40.108continuous samplingsampling in which the sample is drawn from thesource continuously during the total transfer time

20

1S 4639 (Part 6):2002

ISO 1998-6:2000

6.40.107intermittent samplersystem for extracting liquid from a flowing stream, asample receiver to contain the sample grabs takenfrom the stream, and a means for controlling theamount of sample taken by varying the samplingfrequency or grab volume in relation to flowrate

6.40.108stream conditioningdistribution and dispersion of the pipeline contents,upslream of the sampling location

6.40.110isokinetic samplingsampling in such a manner that the linear velocity ofthe liquid through the opening of the sampling probeis equal to the linear velocity of the liquid in thepipeline at the sampling location and is in the samedirection as that of the bulk of the liquid in the pipelineapproaching the sampling probe

6.40.120sampling frequencynumber of grabs taken in unit time

6.40.121sampling intervaltime between successive grabs

6.40.122sampling locationcross-section of the pipe where the sampling probe is,or is proposed to be, located

6.40.123sampling ratioquantity of pipeline contents represented by one grab

NOTE it can be expressed as either thecubic metres per grab, or the equivalent lengthin metres per grab.

6.40.124sampling line of liquefied natural gas

volume, inof pipeline,

whole line provided to carry the sample to beanalysed from the sample probe in the LNG transferline to the gas sample container including any flexibleor semi-rigid tubing

6.40.150profileset of samples taken simultaneously at several pointsacross a diameter of the pipe

NOTE The term is also used to denote the series ofsampling points themselves and the set of results obtainedby analysis of the samples taken at these points.

6.40.151profile averageaverage of the water concentration at each point inthe same profile

NOTE Profiles with less than 1 % water are neglected,

6.40.152overall meanaverage of either the point averages or the profileaverages

NOTE Note that the result is the same.

6.40.153profile testingtechnique for simultaneous sampling at several pointsacross the diameter of a pipe

NOTE Terms used in connection with profile testing areas follows: --

overall mean, point, point average, profile, profileaverage.

6.40.154pointsingle sampling orifice in the profile

6.40.155point averageaverage of the water concentration at the same pointin all profiles

NOTE Pointswith less than 1 % water are neglected.

6.40.160sample loopbypass to the main pipeline being sampled, throughwhich a representative portion of the total flow iscirculated

21

IS 4639 ( Part 6 ) :2002

ISO 1998-6:2000

6.50 Properties andinstrumentation

6.50.010thermowelimetal pocket which protrudes through the wall of apipe or tank and holds the sensing element of atemperature-measuring device

6.50.011automatic temperature-measuring systemsystem that automatically measures the temperatureof a fluid on a continuous or semi-continuous basis

6.50.012electrical averaging thermometerthermometer that measures the average temperatureof a volume of liquid in stank or the temperature atselected intervals throughout its depth

6.50.013electrical spot thermometerthermometer that measures theliquid at a particular point in aresistance

6.50.014resistance thermometer

temperature of atank by electrical

temperature-sensing element constructed frommaterial whose electrical resistance changes withtemperature in a predictable manner

6.50.015temperature compensatormechanism attached to a meter to correct for theeffect of temperature on the measured volume, or anelectronic device serving the same purpose

6.50.020density meterelectronic instrument for measuring density

NOTE Applicable only to the French language.

6.50.021continuous density metermeter in which the material flows continuously throughor around a transducer, generating a continuousdensity measurement

6.50.022in-line density meterdensity meter in which the transducer is locateddirectly within the main line or vessel and measurescontinuously

NOTE No sampling system is required.

6.50.023off-line density meterdensity meter separate from the main line or vesseland usually situated in a laboratory

NOTE This requires a discrete sample to be drawnfrom the line/vessel for analysis.

6.50.024on-line density meterdensity meter operating on a sample of the fluidwithdrawn continuously from a main line or vessel viaa sampling system

6.50.025density transducersensing component of a density meter

6.50.030servo-mechanism ---

Externally powered mechanism which is controlled bythe detecting element 1

6.50.040apparent mass in air ‘viiue obtained by weighing in air against standardmasses without making correction for the effect of airbuoyancy on either the standard masses or the objectweighed

6.50.041gross apparent mass-in-air of oilmass which a GSV (6.99.041) of oil has whenweighed in air

6.50.042net apparent mass-in-air of oilvalue that would be obtained by weighing the netstandard volume of oil in air against standard masseswithout making correction for the effect of airbuoyancy on either the standard masses or the objectweighed

22

A—

IS 4639 (Part 6):2002

ISO 1998-6:2000

6.50.050observed densityvalue required in order to enter tables 53A and 53Breferred to in IS() 91-1 l), determined with soda-limeglass apparatus at a test temperature which differsfrom the calibration temperature of the apparatus, nocorrection having been made for the thermalexpansion or contraction of the glass

NOTE A correction factor for glass expansion may berequired according to the type of equipment used to obtainthe value.

6.50.051orthobaric densitymass of the liquid occupying unit volume at a giventemperature, the liquid being in equilibrium with itsvapour

6.50.052gross standard density of oilmass per unit gross standard volume of oil(determined after homogenisation of the sample)

6.50.053net standard density of oilmass per unit net standard volume (NSV) of oil

6.50.054in-tank vapour densitydensity of vapour in the ullage space of a tank at theobserved conditions of temperature and pressure

6.50.060density pressure coefficientchange in density of the fluidgiven pressure temperature

6.50.061

per unit pressure at a

density temperature coefficientchange in density of the fluid per unit temperature at agiven temperature and pressure

1) ISO 91-1:1992, Petroleum measurement tab/esPart 1: Tables based on reference temperatures15 “C and60 oF.

—0/

6.50.070compressibility factor of gasesratio of the real volume of a given mass of gas at aspecified temperature and pressure to its volumeunder the same conditions calculated from the idealgas law

6.50.071compressibility factor of liquidsfactor obtained from parameters of density andtemperature and used with pressure data to calculatethe pressure correction factor, CPl, of a volume ofliquid

6.50.075ideal volume basisvolume calculated on the basis that the vapourbehaves like an ideal gas

6.50.076real volume basisvolume calculated on the basis that the vapourbehaves like a super-compressible gas

6.50.080gross specific energyquantity of heat released when a combustible materialis burned completely in dry air, the water vapourproduced being condensed to liquid in equilibrium withits own vapour under the specified standardconditions, and the latent heat of condensation beingincluded in the heat content

NOTE 1 The term used is “specific energy”. Historicalobsolete synonyms are “heat of combustion” and “calorificvalue”.

NOTE 2 Specific energy may be expressed on a mass orvolume basis, e.g. in megajoules per kilogram (MJ/kg) orgigajoules per cubic metre (GJ/m3).

6.50.081net specific energyquality of heat released when a combustible materialis burned completely in dry air, and the water vapourproduced is assumed to remain in the vapour phase

NOTE 1 The term used is “specific energy”. Historicalobsolete synonyms are “heat of combustion” and “calorificvalue”.

NOTE 2 Specific energy may be expressed on a mass orvolume basis, e.g. in megajoules per kilogram (MJ/kg) orgigajoules per cubic metre (GJ/m3).

23

IS 4639 ( Part 6 ) :2002

ISO 1998-6:2000

6.50.090digital signalrepresentation of the value of a variable in the form ofa series of individually distinct pulses or voltage states

6.50.095resolution of a displaying devicesmallest difference between indications of adisplaying device that can be meaningfullydistinguished

i!

NOTE 1 For a digital displaying device, this is the change ~jin the indication when the least significant digit changes by G.one step.

NOTE 2 This concept also applies also to a recordingdevice.

‘,4

[VIM 1993:5-12]~ ‘,

,?

24

IS 4639 ( Part 6 ) :2002

ISO 1998-6:2000

6.60 Calibration and standards

6.60.010reference conditionsconditions of use prescribed for testing theperformance of a measuring instrument or forIntercomparison of results of measurements

NOTE The reference conditions generally includereference values or reference ranges for the influencequantities affecting the measuring instrument.

[VIM 1993:5-7]

6.60.011standard reference conditionsbase conditionscondkions of temperature and pressure to whichmeasurements are referred for standardization

NOTE 1 For the petroleum industry, these are usually15 ‘C or 20 “C and 101,325 kPa.

NOTE 2 There is also in OIML R 117 another definitionwhich is parallel and not contradictory.

6.60.015standard scalemeasure to be used for accuracy test of the levelgauge

6.60.016reference standardstandard, generally having the highest metrologicalquality available at a given location or in a givenorganization, from which measurements are derived

[VIM 1993:6-6]

NOTE In some countries it may be a legal requirementor industry practice to use the following definition:“volumetric standard, with traceability to national standards,used in the field for the proving of a meter and forming thestandard against which the performance of the meter isexpressed”.

6.60.017secondary standardstandard whose value is assigned by comparison witha primary standard of the same parameter

NOTE Adapted from VIM 1993:6.5.

6.60.020dry measurevolumetric contents measure that is calibrated withthe internal surface free from liquid (i.e. no clingage)

6.60.021wet measurevolumetric measure that is first wetted and drained,leaving internal clingage, before receiving ordelivering water for the calibration of a measuringdevice

6.60.022wetted areaportion of the internal surface of a volumetric tankwhich has been in contact with the liquid during theproving operation

6.60.023primary measurevolumetric standard, traceable toand capable of a high degree

national standardsof resolution and

accuracy, that is calibrated gravimetrically using water

6.60.024secondary measurevolumetric standard that is calibrated by means of aprimary measure

NOTE Petroleum industry practice may lead to the useof another secondary measure, characterized by a smaller“intrinsic”uncertainty, to make this calibration.

6.60.030calibrationprovingset of operations that establish, under specifiedconditions, the relationship between values ofquantities indicated by a measuring instrument ormeasuring system, or values represented by amaterial measure or a reference material, and thecorresponding values realized by standards

NOTE 1 The result of a calibration permits either theassignment of values of measurands to the indications orthe determination of corrections with respect to indications.

NOTE 2 A calibration may also determine othermetrological properties such as the effect of influencequantities.

NOTE 3 The result of a calibration may be recorded in adocument, sometimes called a calibration certificate or acalibration report.

[VIM 1993:6.1 1]

25

IS 4639 ( Part 6 ) :

ISO 1998-6:2000

6.60.035drain timedraining time

2002

time re-quired to drain a primary or secondaryvolumetric measure according to its calibrationcertificate

6.60.040water-drawtechnique for calibrating a proving tank or pipe proverby displacing water from the prover into a primary orsecondary measure

6.60.050automatic pipetteglass or metal primary measuring instrumentdesigned to deliver automatically a precise quantity ofwater and typically used to calibrate secondarymeasures

6.60.055proving tankvolumetric standard usually consisting of a cylindricalsection with a conical top and bottom and a cylindricalneck calibrated either in units of volume or in stepscorresponding to fractions of a percentage of the tankvolume

6.60.060transfer standardstandard used as an intermediary to comparestandards

NOTE The term transfer device should be used whenthe intermediary is not a standard.

[VIM 1993:6-8]

6.60.065seraphinfenestrated neck canprimary or secondary measure having an elongatednarrow neck which has a visible liquid level and scalegraduated in increments of volume

NOTE The method of calibration should be stated onthe calibration certificate.

f.,*

6.60.070correction factornumerical factor by which the uncorrected result of a

1measurement is multiplied to compensate for !systematic error

jji~

NOTE Since the systematic error cannot be knownperfectly, the compensation cannot be complete.

26

.

6.99.010

6.99.040

6.99.041

6.99.050

6.99.060

6.99.061

6.99.070

6.99.071

6.99.090

6.99.100

6.99.101

6.99.102

6.99.110

6.99.111

6.99.120

6.99.121

6.99.130

6.99.131

6.99.132

AQL

GOV

GSV

HTG

NOV

NSV

OBQ

ROB

RTD

TCV

TOV

TSV

VCF

WCF

VDR

VLR

VEF

VEFD

VEFL

IS 4639 ( Part 6 ) :2002

ISO 1998-6:2000

6.99 Acronyms

acceptable quality level

gross observed volume

gross standard volume

hydrostatic tank gauging

net observed volume

net standard volume

on board quantity

quantity remaining on board

resistance thermometer

total calculated volume

total observed volume

total standard volume

volume correction factor

mass conversion factor

vessel discharge ratio

vessel load ratio

vessel experience factor

vessel experience factor on discharging

vessel experience factor on loading

6.30.100

6.10.100

6.10.103

6.10.113

6.10.101

6.10.104

6.10.410

6.10.411

6.50.014

6.10.301

6.10.302

6.10.304 ‘1‘*

6.30.215\)

6.30.216

6.30.212

6.30.211

6.30.210

6.30.210.’

6.30.210 j

4

27

Bureau of Indian Standards

BIS is a statutory institution established under the Bureau ofhdian Standards Act, 1986 to promoteharmonious development of the activities of standardization, marking and quality certification of goods andattending to connected matters in the country.

Copyright

BIS has the copyright of all its publications. No part ofthese publications maybe reproduced in any form withoutthe prior permission in writing of BIS. This does not preclude the free use, in the course of implementing thestandard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating tocopyright be addressed to the Director (Publications), BIS.

Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewedperiodically; a standard along with amendments is reaffirmed when such review indicates that no changes areneeded; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standardsshould ascertain that they are in possession of the latest amendments or edition by referring to the latest issueof ‘BIS Catalogue’ and ‘Standards : Monthly Additions’.

This Indian Standard has been developed from Doc : No. PCD 3 ( 1918 ).

Amendments Issued Since Publication

Amend No. Date of Issue Text Affected

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