Engineering Glossary for Custody Transfer & Metrology
A practical terminology reference used across the Pro meter EM Series for custody-transfer projects, metrology, verification, proving, engineering, data control and technical audit.
Introduction
Metrology is an exact science. But it is spoken by engineers, designers and experts from different countries, and a common technical language of metrology matters here more than it may seem at first glance.
The paradox is that, over time, there is not less confusion in the industry — there is more. There are several objective reasons for this.
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First — the commercialization of documentation. Standards and technical materials have become commercial products protected by copyright: they cannot be freely quoted or reproduced in large fragments. Authors have to look for synonyms instead of using exact wording — and this is one source of terminological divergence.
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Second — artificial complication. Some new terms and interpretations appear not because of practical necessity, but to provide a basis for yet another dissertation topic.
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Third — gaps in the normative framework. For many concepts, there is simply no single precise definition, and an engineer has to interpret the term in relation to a specific project.
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Fourth — excessive academic complexity in fundamental documents. Things that are simple in essence are presented in deliberately complex language, while definitions that actually require clarification are hidden behind overly academic wording. Specific industry projects require a narrower, more practical glossary.
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Fifth — requirements for the preparation of diploma and dissertation work, which encourage the invention of new synonyms where an established term already exists. Restrictions on quoting large fragments from standards and Recommendations on Metrology also play a role.
This is not a complete list. There may be other reasons; I have highlighted those I consider the most noteworthy.
As a result, on every major project, practising engineers gradually develop their own “internal” glossary, understood only by the participants in that particular project.
A typical case. At a meeting of a representative international commission reviewing a custody transfer metering station on a transit corridor, one of the commission members asked me in front of everyone:
There was a pause — reduced relative to what exactly?
- To the measurement conditions?
- To the measurement range?
- If to the range — then which one: the specified manufacturer's range or the actual operating range?
In professional discussion, all these variants may be referred to by the same term.
The commission members nodded — the question was closed.
Such situations are not uncommon in the industry, and it is precisely from situations like these that project-specific glossaries emerge in practice.
This material is an attempt to bring together the terms and definitions that are actually used in the metrological part of hydrocarbon transit corridors. Some definitions are taken from official sources; others are Pro meter interpretations formulated for a practical understanding of the substance, rather than for conformity with an academic style of presentation.
Pro meter materials are developed by a private company and are based on many years of practical experience. They do not have the status of an official normative document.
Glossary
Below is a selected set of EM-20 terminology used in Pro meter materials on custody transfer, metrology, engineering design, verification, proving, operation, data and technical audit.
1. System, Project and Commercial Result
A metrologically organized part of a custody transfer facility comprising the primary measuring instruments, calculation algorithms and associated elements that generate the product quantity and quality result.
The complete organizational and technical facility: the custody transfer metering system, process piping, control room, power supply, automation, laboratory interface, operations, documentation and auxiliary systems.
Measurement of product quantity and quality parameters for settlement between the parties to a commodity transfer and for issuing a commercially significant result.
The value of a measured quantity together with the associated metrological and documentary information sufficient for technical assessment and subsequent verification.
The degree of closeness of a measurement result to an accepted reference or true value; within the project, it is assessed through specified metrological characteristics and error limits.
A Pro meter working term describing the degree of confidence in a specific result: how correctly it is generated, transmitted, processed, stored and how independently it can be confirmed.
The ability to substantiate a measurement result through a continuous evidential chain of measurements, protocols, certificates, archives, signatures and controlled data versions.
The set of organizational, technical and methodological activities that ensure measurement uniformity, traceability, the required accuracy and documented measurement results.
The initial project document defining the system purpose, ranges, accuracy requirements, equipment, algorithms, interfaces, verification, documentation and acceptance requirements.
2. Basic Metrological Terms
A technical device intended to perform measurements and having specified metrological characteristics.
The difference between a measurement result and an accepted reference value; within the project, it is considered as a combination of random and systematic components.
Measurement error expressed as the ratio of the absolute error to the reference or measured value, usually as a percentage.
The largest error permitted by the applicable normative document, procedure, type certificate or contractual requirement.
A component of measurement error that remains constant or changes in a predictable manner during repeated measurements and may be associated with a specific source or condition.
A component of measurement error that varies unpredictably during repeated measurements under the same conditions and is evaluated using statistical methods.
A non-negative parameter characterizing the dispersion of quantity values that can reasonably be attributed to the measurand.
A structured assessment of the contributions of individual system components to the overall error of the measurement result.
A tabular or calculation model of uncertainty sources, their standard uncertainties, sensitivity coefficients and the resulting combined uncertainty.
The property of a measurement result whereby it can be related to an established reference through a documented, unbroken chain of calibrations or verifications, each contributing to the measurement uncertainty.
Confirmation that a measuring instrument or system complies with specified metrological requirements in accordance with the procedure established by the applicable regulatory framework.
Establishing, under specified conditions, the relationship between indications of a measuring instrument and values reproduced by measurement standards, together with evaluation of the relevant characteristics.
A scheme for transferring the value of a unit from measurement standards to working measuring instruments and further to the custody transfer result, identifying the individual stages, methods and permitted contributions.
An instrument, system or object intended to reproduce, maintain or transfer a quantity value with established metrological traceability.
A measurement standard used for regular transfer of the value of a unit to working measuring instruments or to other instruments at a lower level of the verification chain.
3. Mērīšanas līdzekļi, algoritmi un verificēšana (proving)
Mērīšanas līdzeklis produkta masas plūsmas vai masas noteikšanai; Pro meter projektos tas parasti ir viens no galvenajiem komercuzskaites mērīšanas sistēmas mērījumu kanāliem.
Plūsmas mērītājs, kurā plūsmas ātrums tiek pārveidots turbīnas rotācijā; tā raksturlielumu novērtēšanā jāņem vērā plūsmas diapazons un iespējamās nelinearitātes.
Mērīšanas līdzeklis nepārtrauktai produkta blīvuma mērīšanai plūsmā, ko izmanto masas aprēķinos, parametru pārrēķinos un mērījumu kvalitātes kontrolē.
Skaitļošanas ierīce, kas saņem mērījumu signālus, izpilda apstiprinātus algoritmus, korekcijas un aprēķinus, kā arī veido arhīvus un fiskālos pārskatus.
Etalona iekārta plūsmas mērītāju metroloģisko raksturlielumu pārbaudei vai apstiprināšanai, salīdzinot to rādījumus ar reproducētu tilpumu vai citu atskaites vērtību.
Atestēta vai kalibrēta šķidruma tilpuma vērtība, kas atbilst pruvera mērīšanas posmam starp noteiktajām robežām, pārrēķināta uz noteiktiem atskaites apstākļiem un izmantota kā atskaites lielums proving un aprēķinos.
Metode pruvera bāzes tilpuma noteikšanai vai apstiprināšanai, izspiežot ūdeni un mērot izspiestā ūdens tilpumu ar kalibrētu Test Measure, piemērojot nepieciešamās temperatūras un spiediena korekcijas.
Sertificēts tilpuma mērs, ko water draw laikā izmanto kā tilpuma darba etalonu pruvera bāzes tilpuma noteikšanai vai apstiprināšanai un kam ir dokumentēta metroloģiskā izsekojamība.
Bezizmēra korekcijas koeficients, ko piemēro plūsmas mērītāja rādījumam, pamatojoties uz salīdzinājumu ar etalonu; vispārīgā veidā MF = Qreference / Qmeter.
Pārveidošanas koeficients, kas sasaista plūsmas mērītāja impulsu skaitu ar izmērītā daudzuma vienību; to izmanto mērīšanas un skaitļošanas traktā.
Plūsmas mērītāja raksturlieluma nelinearitātes matemātiska vai aparatūras kompensācija darba diapazonā, izmantojot tabulu, interpolāciju vai aproksimācijas funkciju.
Plūsmas diapazons, kurā sistēmai un konkrētajam mērīšanas līdzeklim jāatbilst noteiktajām prasībām attiecībā uz precizitāti, atkārtojamību un algoritmu piemērojamību.
Praktiska procedūra plūsmas mērītāja salīdzināšanai ar pruveri vai citu etalonu, lai noteiktu tā raksturlielumus, noteiktu MF un apstiprinātu mērījumu kanāla piemērotību.
Faktisko procesa un apkārtējās vides parametru kopums, kas ietekmē rezultātu: plūsma, spiediens, temperatūra, blīvums, vibrācija, plūsmas režīms un citi faktori.
Izmērīto produkta parametru pārrēķins no faktiskajiem apstākļiem uz noteiktiem atskaites apstākļiem, izmantojot apstiprinātus algoritmus un koeficientus.
4. Data, Control and Evidential Chain
Commercially significant source and calculated data generated and retained by the system for documenting and subsequently verifying a commodity transfer transaction.
A report generated by the flow computer or an approved system, containing commercially significant values, calculations, identifiers and other data accepted by the parties as an official source.
A document recording the agreed commercial result of product transfer between the parties on the basis of established data sources.
A documented record of source data, conditions, procedures, calculations and verification results for a specific measuring instrument, measurement channel or system.
Management of metrologically significant parameters, tables, software versions, coefficients, channel settings and the history of their changes.
A defined system of criteria, levels, actions and archiving that converts a detected deviation into a controlled technical event.
Use of additional channels, lines, computers or data sources to detect failures, compare results and maintain controlled operational capability.
Duplicated measurement or signal channels used for mutual comparison, signal integrity control and timely detection of discrepancies.
Backup equipment or a channel maintained in an operationally ready state and capable of being brought into service without lengthy preparation, with synchronized configuration.
A backup arrangement that requires preparation before being placed into service; readiness is confirmed by valid certificates, current configuration, an activation procedure and a functional check.
The Pro meter documentary protection system for the result: observation → method → measurement → protocol → signature → archive → a commercially defensible and technically auditable result.
An accumulated database of operational, verification, service and event data used for trend analysis, identification of systematic effects, modernization planning and independent review of the result.
Context Determines the Term
In engineering documentation, the same English term does not always have one universal Russian equivalent. The translation depends on the function, document type, project stage and metrological meaning.
Протокол — when referring to a formalized record of a procedure, measurements and results.
Порядок / процедура — when the term describes an established sequence of actions.
Отчёт — a final engineering or technical document.
Depending on the project, this may be a Verification Report, Audit Report, Commissioning Report or Fiscal Report.
Запись — an item of documented information.
Протокол / журнал — when the record has an established form or forms part of a controlled process.
Свидетельство — in the context of verification.
Сертификат — for certification, calibration, equipment or conformity confirmation, depending on the document.
Схема — the general engineering meaning.
Поверочная схема — only in the metrological context of unit-value transfer and a system of measurement standards.
Конфигурация — the composition and settings of equipment, software and channels.
In some project documents, the appropriate Russian translation may be исполнение or компоновка, depending on context.
Компоновка — the arrangement of equipment and system elements.
Схема размещения — when referring specifically to the spatial location of equipment.
Отклонение — a neutral technical deviation of a parameter or result.
It should not automatically be translated as «несоответствие» if a failure to meet a requirement has not yet been established.
Несоответствие — failure to fulfil an established requirement identified during inspection, audit or acceptance.
Перепад давления — the difference in pressure between two points.
Потеря давления — a reduction in pressure caused by hydraulic resistance. The contexts are different.
What Is Included in the Full EM-20
The public web version presents only part of the working terminology. The full EM-20 version is intended for use together with the technical materials of the Pro meter EM Series.
- Complete engineering glossary covering custody transfer, metrology, verification, engineering design, operation and technical audit.
- RU / EN terminology and rules for selecting translations according to the engineering and documentary context.
- Abbreviations and acronyms used in Custody Transfer projects and throughout the EM Series materials.
- Formula notation and a consistent approach to the representation of metrological and calculated quantities.
- Approved Phrases and Translation Red Flags — recommended wording and cases where a literal translation may alter the technical meaning.
- Management of terminological inconsistencies — recording different interpretations, contextual limitations and rules for applying terms throughout the Pro meter EM Series.
Pro meter EM Modules
The EM Series is being published progressively in the Pro meter store. Completed modules are already available for purchase; the next materials are undergoing final editorial review, formatting and packaging.
EM-14 — Methods for Improving Accuracy and Measurement Assurance in Custody Transfer Metering Systems. The module has been published and is available for purchase in the Pro meter store.
EM-11 — measurement error and uncertainty.
EM-13 — verification protocols and evidential metrological documentation.
Both modules are currently in the final formatting and packaging stage.
Current availability, new publications and the composition of the series are updated in the EM Catalog.