IEC PAS 61987-1:2002

IEC/PAS 61987-1
Edition 1.0
2002-08
Industrial-process measurement and control –
Data structures and elements in
process equipment catalogues –

Part 1:
Measuring equipment with analogue
and digital output
PUBLICLY AVAILABLE SPECIFICATION

INTERNATIONAL Reference number
ELECTROTECHNICAL
IEC/PAS 61987-1
COMMISSION
IEC/PAS 61987-1
Edition 1.0
2002-08
Industrial-process measurement and control –
Data structures and elements in
process equipment catalogues –

Part 1:
Measuring equipment with analogue
and digital output
PUBLICLY AVAILABLE SPECIFICATION

INTERNATIONAL Reference number
ELECTROTECHNICAL
IEC/PAS 61987-1
COMMISSION
– 2 – Copyright © 2002, IEC
CONTENTS
FOREWORD.3

INTRODUCTION.4

1 Scope .6

2 Normative references .6

3 Terms and definitions .7

4 Metadocuments .7

4.1 General .7

4.2 Determination of structure and elements .9
5 Metadocument for process measuring equipment .10
Annex A (normative) Classification of terms as a function of measuring equipment .18
Annex B (informative) Classification of terms as a function of measurement principle.20
Annex C (informative) Alphabetical list of terms, definitions and sources.38
Annex D (normative) Document type definitions (DTD) and metadocument of the standard
in SGML notation.44

INTERNATIONAL ELECTROTECHNICAL COMMISSION

___________
INDUSTRIAL-PROCESS MEASUREMENT AND CONTROL –

DATA STRUCTURES AND ELEMENTS IN PROCESS

EQUIPMENT CATALOGUES –
Part 1: Measuring equipment with analogue and digital output

FOREWORD
A PAS is a technical specification not fulfilling the requirements for a standard, but made available to
the public.
IEC-PAS 61987-1 has been prepared by subcommittee 65B: Devices, of IEC technical committee 65:
Industrial-process measurement and control.
The text of this PAS is based on the This PAS was approved for
following document: publication by the P-members of the
committee concerned as indicated in
the following document:
Draft PAS Report on voting
65B/454/PAS 65B/457/RVD
Following publication of this PAS, the technical committee or subcommittee concerned will investigate
the possibility of transforming the PAS into an International Standard.
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the
two organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any

divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
The text of this PAS is based on a projected standard under development by SC65B/WG10.
Annexes A and D form an integral part of this PAS. Annexes B, C, and E are for information
only.
This PAS shall remain valid for no longer than 3 years starting from 2002-09. The validity may
be extended for a single 3-year period, following which it shall be revised to become another
type of normative document, or shall be withdrawn.

– 4 – Copyright © 2002, IEC
INTRODUCTION
In recent years, industry has become alert to the fact that a great deal of time and effort is

wasted in the transposition of measuring equipment data from one form to another. The

technical data of an instrument, for example, may exist at the manufacturer’s as two separate

data sets for paper and electronic presentation: the end-user requires much the same data for

works standards, engineering data bases or commercial data bases. In most cases, however,

the data cannot be automatically re-used because each application has its own particular data

storage format.
A second problem that belies the re-use of technical data is the content of the data sets and

elements themselves. There is little agreement between manufacturers on what information a
technical data sheet should contain, how it should be structured, or how the results, e.g. of
particular performance tests, should be presented. When transferring this information into a
data base, an end-user will always find gaps and proprietary interpretations that make the
task more difficult.
This document aims to solve these problems by defining data structures, and their content for
industrial process measuring and control equipment. It builds upon the assumption that, for a
given class of measuring equipment, e.g., pressure measuring equipment, temperature
measuring equipment or electromagnetic flow-measuring equipment, a set of non-proprietary
structures and data elements (terms) can be specified.
Part 1 of the document is applicable to electronic catalogues of process measuring equipment
with analogue and digital output. Further parts with similar classification structures will be
produced for measuring equipment with binary output and interface equipment in the future.
(The structure already contains a great many data elements that are common to measuring
equipment with binary output.) Similarly the informative Annex B has been prepared with a
view to future standardisation.
The document is not intended as a replacement for existing standards, but rather as a guiding
document for all future standards which are concerned with the specifications of process
measuring equipment. Every revision of an existing standard should take account of the data
structures and elements defined in Clause 5 of this document or work towards a
harmonisation.
Annex A contains a tabular overview of the classification and catalogue structure of process
measuring equipment. Annex B contains tables with a further sub-classification for specific
measured variables.
Where possible, existing terms from international standards have been used to name the data
elements within the structures. In accordance with ISO 10 241, Annex C of the document

contains an alphabetical list of terms, definitions and sources.
SGML (Standard Generalised Mark-Up Language) to ISO 8879 provides one possible
standardised means of exchanging structured document data free of layout information. To
this end, Annex D contains a Document Type Description and Metadocument of Clause 5 of
the document. Since the drafting of this document, XML, a simplified subset of SGML, has
been developed for Internet applications. As a result it is well supported and provides a viable
alternative to SGML.
The present document conforms with STEP: Standard for the Exchange of Product Model
Data. The data model of the STEP application protocol 212, 221 and 231 (Electrotechnical
Design and Installation; Functional Data and 2D Representation and Process Design: Specs
of Major Equipment) is described in ISO 10 303.212, .221 and .231 respectively and can
reproduce the data field of the DTD as per this document. This includes, e.g. product
structure data, dimensional data, electrical connection data, and product properties such as
measuring range or power supply. The STEP application protocols 212, 221 and 231 define

the objects and their inter-relationships only. Descriptive attributes as described in the

document can be assigned to an object as aggregative property lists.

In defining data elements to fill the proposed data structure for process equipment

catalogues, the present document is also relevant to IEC 61360 (Data Element Type

Definition). It was considered beyond the scope of the document, however, to classify the said

elements according to this scheme, since the main objective lies in the structured

presentation of data. In practice a number of elements have already been defined and appear

in commercial databases structured according to the present document.

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INDUSTRIAL-PROCESS MEASUREMENT AND CONTROL −

DATA STRUCTURES AND ELEMENTS IN PROCESS

EQUIPMENT CATALOGUES −
Part 1: Measuring equipment with analogue and digital output

1 Scope
This document defines data structures and elements for industrial process measurement and

control equipment with analogue or digital output. It applies to the production of catalogues of
process measuring equipment supplied by the manufacturer of the product.
The document shall also serve as a reference document for all future standards which are
concerned with process measuring equipment catalogues. In addition, it is intended as a
guide for the production of further standards on process equipment documentation for similar
systems, e.g., for other measuring equipment and actuators.
2 Normative references
This document contains provisions from other publications which are indicated by dated and
undated references. These normative references are cited at the pertinent positions in the text
and the appropriate publications are listed below. In the case of dated references, subsequent
changes to or revisions of these publications belong to this document only if they have been
integrated by changes to or revision of the present document. In the case of undated
references, the latest edition of the cited publication is valid.
ISO 704:2000, Terminology work – Principle and methods
ISO 8879:1986 + A1: 1988, Information Processing – Text and office systems – Standard
Generalized Markup language (SGML)
ISO 10241:1992, Preparation and Presentation of Publications with Terminological
Determinations; Standards
ISO 10303-1:1994, Industrial Automation Systems and Integration – Product Data
Representation and Exchange – Part 1: Overview and fundamental principles
ISO 10303-212, Product Data Representation and Exchange – Part 212: Electrotechnical

design and installation.
ISO 10303-221, Product Data Representation and Exchange – Part 221: Functional data and
2D representation.
ISO 10303-231, Product Data Representation and Exchange – Part 231: Process
design/specs of major equipment.
IEC 60050(351):1998, International Electrotechnical Vocabulary – Chapter 351: Automatic
control
IEC 60068 (all parts), Environmental testing standards
IEC 60529:1989, Degree of Protection provided by Enclosures (IP Code)

IEC 60654 (all parts) Industrial-process measurement and control equipment; Operating

conditions
IEC 60751 (1983), Industrial platinum resistance thermometer sensors

IEC 60770-1:1998, Methods of evaluating the performance of transmitters for use in

industrial-process control systems

IEC 61000 (all parts), Electromagnetic compatibility (EMC)

IEC 61069-5 (all parts), Industrial-process measurement and control - Evaluation of system

properties for the purpose of system assessment
IEC 61082 (all parts), Preparation of documents used in electrotechnology
IEC 61298 Parts 1 to 4, Process measurement and control devices: General methods and
procedures for evaluating performance
IEC 61326-1:2000, Ed. 1.2 Consolidated Edition, Electrical equipment for measurement,
control and laboratory use – EMC requirements – Part 1: General requirements
IEC 61360 (all parts), Standard data element types with associated classification scheme for
electric components
IEC 61508 (all parts): Functional safety of electrical/electronic/programmable electronic
safety-related systems
IEC 82045-1 (2001): Document management – Part 1: Principles and methods
3 Terms and definitions
The nomenclature adopted in the data structure defined in Clause 5 is based on terms and
concepts drawn from international standards. In order to facilitate the use of the document, an
alphabetical list of terms with definitions and normative references is to be found in the
informative Annex C.
Clause 5 also includes so-called search terms. A search term is a related designation or
concept, but is not necessarily a synonym. It is intended for electronic searches only, and
must not be substituted for the preferred term. Search terms are not included in Annex C.

Each term in Clause 5 is accompanied by an explanation of what is to be entered in the data
element. These explanations are informative only, and do not constitute normative definitions.
4 Metadocuments
4.1 General
Metadocuments describe the non-proprietary structures and data elements (terms) of a class
of process measuring equipment. They serve as specimen and procedural instructions for the
production of process equipment catalogues by the equipment manufacturer.
Metadocuments form a document hierarchy corresponding to the hierarchical classification of
the process measuring equipment. A metadocument can exist at each level of the hierarchy
which describes structures and data elements (terms) common to all equipment at this
hierarchical level. Metadocuments at lower hierarchical levels inherit the structure and data
elements (terms) from the metadocuments at levels above them.

– 8 – Copyright © 2002, IEC
Figure 1 shows the classification scheme for process measuring equipment on which this

document is based. Process measuring equipment may be subdivided into continuous

measuring equipment (with analogue and digital output) and limit detecting equipment (with

binary output). The metadocument defined in Clause 5 defines the common structures and

data elements (terms) that are to be found at this level in the hierarchy.

Each piece of equipment is designed to measure one or more process variables, e.g. level,

pressure, flow or temperature. To fully define the technical data of say, a flowmeter, additional

data elements, e.g. inlet and outlet run, must be added to data structure inherited from the

level above.
The methods used to measure a particular process variable form a further level in the
hierarchy. Thus flow may be measured by a differential pressure transmitter, a variable area
flowmeter, an electromagnetic flowmeter etc. Depending on the measuring method used,
additional elements must again be added to the structure to adequately characterise the
equipment. Such additional elements have already been defined for the measurement
methods shaded grey in Figure 1.
Measurement
equipment
W (Weight,
D (Density) L (Level) P (Pressure, ∆p) R (Radiation) T (Temperature)
F (Flow)
Mass)
E (Electrical S (Speed, Rotat.,
Q (Quality)
variables)   Frequency)
Differential Resistance
Hydrostatic Capacitance
Oscillation
pressure thermometer
Radiometric Variable area Displacement Inductance Thermocouple
Electromagnetic
Ultrasonic Buoyancy Strain gauge Pyrometer
Refractive
Expansion
Ultrasonic Ultrasonics Frequency
index
etc.
Bimetallic
Vortex Microwave Force
strip
Positive Hot/cold
Laser/optical Displacement
displacement conductor
etc. etc.
Turbine Radiometric
Capacitance
Coriolis
Thermal Vibration
Included in overview tables
Annex B
etc. etc.
Figure 1 – Classification scheme for process measuring equipment

4.2 Determination of structure and elements

The chapters of the metadocument are to be structured for all process measuring equipment

as follows:
1 Identification
2 Application
3 Function and System Design
4 Input
5 Output
6 Performance Characteristics
7 Operating Conditions
7.1 Installation
7.2 Environment
7.3 Process
8 Mechanical Construction
9 Operability
10 Power Supply
11 Certificates and Approvals
12 Ordering Information
13 Documentation
Fig. 2 – Chapter structure of the metadocument for process measuring equipment
Process measuring equipment may comprise one or more modules combined in different
ways: e.g. for temperature it may comprise a sensor (thermocouple or resistance
thermometer) and a temperature transmitter. Such modular measuring equipment can be
described using the data structure for the corresponding equipment class, either for the
equipment as a whole or for each separate module, according to the manufacturer's
preference. The equipment architecture and the way in which the modules work together is

always to be described under Chapter 3 of the metadocument, Function and System Design.
Data structures and elements (terms) common to all process measuring equipment are
compiled in Clause 5 of this document. Document Type Definitions (DTD) necessary for
electronic data exchange by SGML and computer supported processing of equipment
documentation are to be found in Annex D.
The metadocument of the measuring equipment for particular measured variables is
summarised in Table 1, Annex A. Annex B contains tables for the measurement methods
which have so far been considered. The tables indicate general specifications to be made in
all documents and particular specifications to be made for the different types of measurement
equipment, i.e. for flow, level, pressure, temperature and density. Terms and definitions for
specific measuring equipment and measurement methods are not the subject of this
document, but are included in informative Annex B for completeness.

– 10 – Copyright © 2002, IEC
This document shall be used by the equipment manufacturer, in that he takes the
metadocuments and organises the technical data for his measuring equipment under the

structure and data elements (terms) defined for each chapter. The document may also contain

photographs and drawings.
5 Metadocument for process measuring equipment

NOTE 1 At the start of each clause, e.g. 5.1, it is stated what information is expected to be entered at that point in
the structure. The information itself is then entered under the appropriate data element. Where necessary, the

vendor/manufacturer is free to specify additional, non-standard data elements at each point in the structure.

NOTE 2 For the preparation of metadata, see also IEC 82045, for the preparation of diagrams, tables and lists,

see also IEC 61082.
NOTE 3 If no data element is specified for a part of the structure, the vendor/manufacturer is free to present his
information as he likes under the structure heading, e.g. by the use of non-standard data elements.
NOTE 4 For SGML documents, information must be entered in each data element. If a data element does not
NOTE 5 Non-standard data elements within an SGML document cannot be searched for by name, but can be
found indirectly under the structure heading.
5.1
identification
The information necessary for unambiguous identification of the measurement equipment
shall be specified here. This information may be supplemented by illustrations, e.g. drawings
or photographs.
5.1.1
document identification
The type, code number, and if appropriate, the revision number of the document.
5.1.2
date of issue
The date of issue of the document.
NOTE The vendor/manufacturer is encouraged to supplement this information with a ”valid until” date.
5.1.3
product type
The type of product, e.g. capacitance level transmitter, differential pressure transmitter, Pt100
resistance thermometer, variable area flowmeter.
5.1.4
product name
The product name under which the measuring equipment is marketed and, where appropriate,
its model number.
5.1.5
vendor/manufacturer
The name of the vendor/manufacturer responsible for the measurement equipment, optionally
with address.
5.2
application
The applications for which the measurement equipment is designed, together with the reasons
for its use shall be specified here.
5.3
function and system design
The means by which the physical quantity is acquired, processed and output as a signal by
the measurement equipment shall be specified here. The measuring principle and the
components comprising the measurement equipment shall be specified. Terms such as those

listed in IEC 60770-1 Annex A (transmitter, meter, indicator, switch, transducer and sensor)

should be used. If appropriate, the signal processing including any diagnostic functions shall

be described.
5.3.1
measuring principle
The principle used and the physical quantity measured in order to determine the measured

variable.
5.3.2
equipment architecture
The components, devices, assemblies or systems used to perform the measuring activity.
Search terms: modularity
5.3.3
communication and data processing
The components, hardware and software for communication with external systems and
execution of complex functions.
5.3.4
climate class
The climatic conditions, i.e. ambient temperature, pressure and humidity, to which the
measuring equipment can be subjected during operation (including shutdown), transport and
storage (over land or sea), e,g, as specified in IEC 60654-1.
5.3.4
dependability
Information on the dependability of the equipment as defined in IEC 61508. The scheme as
per IEC 61069, Part 5 should be followed.
5.3.4.1
reliability
Where appropriate, the mean time between faults (MTBF), fault tolerance, internal
redundancy etc. shall be entered here.
5.3.4.2
maintainability
Where appropriate, any special tools, the smallest replaceable units, any consumables
required for the correct operation and maintenance of the equipment shall be entered here.
5.3.4.3
integrity
Where appropriate, any mechanism which ensures the integrity of the equipment output on
the discovery of a fault shall be described here.
5.3.4.4
security
Where appropriate, any measures or conformance to recognised standards or regulatory
guidelines regarding access authorisation to and protection of device data shall be entered
here.
5.4
input
Information on the measured variable shall be entered here, i.e., the physical,
physicochemical or chemical quantity, the size of which is to be acquired and indicated by the
measurement.
– 12 – Copyright © 2002, IEC
5.4.1
measured variable
The variable(s) measured by the equipment.

For multi-sensor instruments, the various main measuring sensors and/or the auxiliary

sensors, supporting the main sensor(s) shall be defined.

5.4.2
measuring range
The measuring range that the equipment has been designed to measure.

The measuring range is defined by a lower and an upper range-limit. Within this range,

measurements are made within the accuracies specified in Clause 5.6.

In addition, depending upon the physical quantity being measured, adjustment ranges for the
lower and upper range-limits or a turndown ratio may also be specified. These may be
expressed as a percentage of the maximum span, as absolute values or as a ratio.
NOTE 1 The way in which the measuring range is expressed is a matter of convention and may differ according to
the physical quantity measured and type of instrument.
NOTE 2 For some measurements, additional information on the physical starting point of the measuring range
must be specified, e.g. for ultrasonic level measurement.
NOTE 3 The accuracies specified in Clause 5.6 must also apply after any permitted adjustments to the measuring
range have been made, or the associated accuracies must be stated.
5.5
output
The information signal (output) after the processing of measured variable(s) shall be specified
here. For analogue and digital equipment, the size of output signal indicates unequivocally the
size of the measured variable.
Where the process measuring equipment has more than one output, all shall be described.
5.5.1
output signal
The type and characterising quantities of the output signal.
The output signal might be electrical, mechanical, hydraulic, pneumatic, optical, digital etc. It
may be variable over a specified range or assume specific values only. If the output is
configurable, the possible operating modes should be described.
If the output of a device, element or system is a foreign system interface, then the physical
layer, transmission rate, transmission protocol and primary information parameters should
also be specified.
EXAMPLE 1  4 mA - 20 mA analogue signal, configurable as binary signal 8/16 mA.
EXAMPLE 2  Digital signal as floating point number to IEC 60754.

5.5.2
signal on alarm
The value(s) or status assumed by the output signal when there is a fault in the process
measuring equipment.
5.5.3
load
The electrical, optical, pneumatic, hydraulic or mechanical load presented to the output of a
device, element or system by the external devices connected to it.
5.6
performance characteristics
Specifications regarding e.g. the accuracy and dynamic behaviour of the measurement
equipment under operating and reference conditions shall be made here.

• For measurement equipment with a span setting and analogue output, the performance

characteristics concerning accuracy shall be expressed in relation to the span. If one

value only is stated, it must be applicable to all permitted span settings.

• For digital output equipment, characteristics shall be expressed in relation to the reading

or upper range-limit.
NOTE 1 For reference conditions refer to IEC 61298-1

NOTE 2 For details on performance testing and presentation of the results, see in particular IEC 61298, Parts 1 to
4 and IEC 60770 Part 1 as well as the test standards quoted in the normative references.

5.6.1
maximum measured error
The maximum measured error as determined e.g. by the method described in IEC 61298-2.
5.6.2
hysteresis
The hysteresis as determined e.g. by the method described in IEC 61298-2.
5.6.3
non-repeatability
The non-repeatability as determined e.g. by the method described in IEC 61298-2. The non-
repeatability is synonymous with repeatability error.
NOTE 1 According to IEC 61298-2, the accuracy of the equipment is adequately expressed by the three quantities
specified in subclause 5.6.2, 5.6.3 and 5.6.4. If desired, the manufacturer may also express accuracy in terms of
inaccuracy and hysteresis , or non-linearity/non-conformity, hysteresis and dead band. These alternatives are not
included at this level of the SGML structure.
NOTE 2 Standardised accuracy classes also exist for some types of process measuring equipment. These should
be specified at a lower hierarchical level .
5.6.4
start-up drift
The start-up drift as determined by e.g. the method described in IEC 61298-2.
5.6.5
long-term drift
The long-term drift as determined by e.g. the method described in IEC 61298-2.
5.6.6
influence of ambient temperature
The effect of temperature changes on the output signal as determined by e.g. the method
described in IEC 61298-2.
NOTE IEC 61298-2 expresses the influence as the average error over the entire ambient temperature range. It
may also be expressed as % of span over a given temperature span.

5.6.7
influence of medium temperature
The effect of changes in medium temperature on the output signal determined and expressed
in a similar manner to the influence of ambient temperature, see Subclause 5.6.6.
Where appropriate, for equipment not in direct contact with the process medium, this
information can be given in the form of a derating curve of ambient temperature versus
process temperature. Otherwise “not applicable” should be entered.
5.6.8
settling time
The settling time as determined by e.g. the method described in IEC 61298-2.
Search terms: rise time; response time

– 14 – Copyright © 2002, IEC
5.7
operating conditions
The conditions under which the measuring equipment can be operated within its specified

accuracy limits and without permanent impairment of its operating characteristics shall be

specified here. A distinction is made between normal operating conditions, operating limits

and storage and transport conditions, see Annex C.

5.7.1
installation
The installation conditions, in particular any special precautions necessary to obtain the
specified performance of the measuring equipment, shall be specified here.

5.7.1.1
installation instructions
Brief instructions, and if appropriate warnings, relevant to the mounting of measuring
equipment so as to obtain the best performance. These might include orientation, cable
length, inlet and outlet run (for flow), emitting angle (microwave and ultrasonics) etc.
5.7.1.2
start-up conditions
The conditions to be upheld at the measuring point to ensure correct start-up of the
measurement equipment. If special precautions must be taken to avoid e.g. pressure or
thermal overload, these should be stated.
5.7.1.3
warm-up time
The time required after energising the measuring equipment before its performance
characteristics apply.
NOTE Although many modern instruments warm up in a matter of seconds, some systems take considerably
longer, e.g. radiometric level and density measurement or temperature measurement (where the warm-up time is
dependent upon the response time of the complete thermometer including the inset and thermowell).
5.7.2
environment
The environmental conditions under which the measuring equipment can be stored and
operated within its specified accuracy limits and without permanent impairment of its
operating characteristics shall be specified here.
5.7.2.1
ambient temperature range
The range of ambient temperatures within which the measuring equipment is designed to
operate within specified accuracy limits.

Search terms: normal operating temperature, operating temperature, nominal temperature
range, working temperature
5.7.2.2
ambient temperature limits
The range of ambient temperatures to which the measuring equipment may be subject when
in operation without permanent impairment of operating characteristics.
Search terms: Limiting temperature range
5.7.2.3
storage temperature
The ambient temperature range within which the measuring equipment may be safely
transported and stored.
Search terms: Transportation temperature

5.7.2.4
immunity to temperature change

The ability of the measuring equipment to withstand given changes in ambient temperature.

NOTE IEC 60068-2-14 describes tests to simulate both sudden changes (Test Na) and gradual changes (Nb) in

ambient temperature. The test(s) used, together with the conditions, should be presented in accordance with the

standard.
Search term: thermal cycling; temperature cycling

5.7.2.5
shock resistance
The ability of the measuring equipment to withstand sudden mechanical loading without

permanent impairment of operating characteristics as described in IEC 61298-3.
5.7.2.6
vibration resistance
The ability of the measuring equipment to withstand sinusoidal vibrations without permanent
impairment of operating characteristics as described in IEC 61298-3.
5.7.2.7
electromagnetic compatibility
The electromagnetic compatibility of the measuring equipment expressed as either the results
of the individual tests e.g. IEC 61000-4 series or conformance to a particular standard, e.g.
IEC 61326-1, which incorporates these tests.
Search terms: electromagnetic interference, electromagnetic immunity, RFI
5.7.3
process
The allowable process conditions under which the measurement equipment can be operated
within its specified accuracy limits and/or without permanent impairment of its operating
characteristics shall be specified here.
NOTE 1 For the purposes of this document, the term wetted-part refers not only to parts directly in contact with
the process medium, but also to those parts of non-contact measuring equipment that intrude into the process
vessel.
NOTE 2 If a data element is not relevant to a particular piece of measuring equipment, “not applicable” shall be
entered.
5.7.3.1
process temperature range
The range of temperatures within which the wetted parts of the measuring equipment are
designed to operate within specified accuracy limits.
5.7.3.2
process temperature limits
The range of temperatures to which the wetted-parts of the measuring equipment may be
subject without permanent impairment of operating characteristics.
NOTE If higher temperatures are allowed for short periods, e.g. for cleaning in process, then these, together with
the permissible length of time, shall be stated.
5.7.3.3
process pressure range
The range of pressures within which the wetted parts of the measuring equipment are
designed to operate within specified accuracy limits.
5.7.3.4
process pressure limits
The range of pressures to which the wetted-parts of the measuring equipment may be subject
without permanent impairment of operating characteristics.

– 16 – Copyright © 2002, IEC
NOTE For temperature measurement this is not a fixed value. The maximum pressure is dependent e.g. on the

immersion depth of the thermometer, the process temperature, the viscosity of the medium and the flowrate.
Guidelines for water and air are sufficient.

5.8
mechanical construction
The mechanical construction of the measuring equipment shall be specified here. Details shall

be given of all parts of direct relevance to its use, e.g. process connections, seals, wetted

parts, electrical connections, special cases (special materials, special versions) and

accessories.
5.8.1
design
The design of the measuring equipment, e.g. compact instrument, head transmitter, 19" plug-
in card etc.
5.8.2
dimensions
The principle dimensions of the measuring equipment.
NOTE 1 The dimensions should be expressed at least as "length x breadth x height", and where appropriate be
supported by a dimensional drawing.
NOTE 2 The clearances required for the mounting of the instrument should also be indicated.
NOTE 3 Where several equipment versions are available, dimensions and weight may be presented together or
under Subclause 5.8.5, process connection, as appropriate. A note to this effect should then be entered in
Subclauses 5.8.2 and 5.8.3.
5.8.3
weight
The weight of the measuring equipment or its component parts.
5.8.4
material
The materials used in the construction of the equipment, in particular for parts which come
into contact with the process or environment.
5.8.5
electrical connection
Information regarding the provisions for electrical connection(s) of the measuring equipment.
NOTE In addition to the degree and type of protection afforded by the device enclosure, this might include, e.g.,
type of terminal, type of cable, cable cross-section, cable gland, galvanic isolation etc. for both signal and power
circuits.
5.8.5.1
degree of protection
The degree of ingress protection of the enclosure expressed as an IP rating to IEC 60529 or
other internationally recognised enclosure classification.
Search terms: ingress protection; enclosure classification
5.8.5.2
type of protection
The type of protection offered by the enclosure against the ignition of a surrounding explosive
atmosphere, e.g. EEx ia, Ex d.
5.8.6
process connection
Where appropriate, the type of process connection(s) used by the measuring equipment,
indicating nominal diameters, rated pressures and standards. See also Note 3 in Subclause
5.8.2.
5.9
operability
Details of the design, operating concept, structure and functionality of the human interface

shall be specified here. Operating elements, displays, foreign system interfaces (when

allowing human operation), testing and configuration elements, e.g. solder bridges, DIP-

switches, re-ranging elements, handheld terminals, auxiliary stations shall be described here.

NOTE The operability of a device can be assessed and documented as described in IEC 61069-6 (1998).

5.10
power supply
The permanent or temporary power to be supplied to the measurement equipment in order to

maintain its function, and which cannot be taken from the input signal, together with the
permissible tolerances for the power supply, shall be specified here.
EXAMPLES:
Electrical power supply:
• Voltage
• Frequency
• Harmonic distortion level (for a.c. supply)
Residual ripple (for d.c. supply)
• Power consumption
Pneumatic power supply:
• Pressure
• Oil and dust content
• Dew point of air supply
• Air consumption
Hydraulic power supply
5.11
certificates and approvals
Certificates, approvals and other formal documentation concerning the measurement
equipment shall be specified here, e.g. legal requirements, regulations, technical guidelines,
approvals and test certificates.
Examples are electrical area classification, marine approvals, sanitary approvals, CE Mark
etc.
5.12
ordering information
The information required for the procurement of the measurement equipment shall be
specified here. Normally, the information is summarised in the form of an ordering table.
Details of the equipment type, software and firmware version as well as the order number
should be given.
5.13
documentation
A bibliography of documentation relevant to the measuring equipment shall be specified here,
e.g. operating manuals, specifications of components and auxiliary equipment etc.

– 18 – Copyright © 2002, IEC
Annex A
(normative)
Classification of terms as a function of measuring equipment

The table summarises the data structure defined in Chapter 5 as a function of process

variable.
Classification and documentation structure

of process equipment (measuring

equipment) 02.11.2001
1 Identification
Document identification
Date of issue
Product type
Product name
Vendor/Manufacturer
2 Application
3 Function and System Design
Measuring principle
Equipment architecture
Communication and data processing
Climate Class
Dependability
Reliability
Maintainability
Integrity
Security
4 Input
Measured variable
Measuring range
5 Output
Output signal
Signal on alarm
Load
6 Performance characteristics
Maximum measured error
Hysteresis
Non-repeatability
Start-up drift
Long-term drift
Influence of ambient temperature
Influence of medium temperature
Settling time
Dependent on
construction
Measuring equipment
Flow
Level
Pressure
Temperature
Density
Classification and documentation

structure of process equipment
(measuring equipment) 02.11.2001

7 Operating Conditions
7.1 Installation
Installation instructions
Start-up conditions
Warm-up time
7.2 Environment
Ambient temperature range
Ambient temperature limits
Storage temperature
Immunity to temperature change
Shock resistance
Vibration resistance
Electromagnetic compatibility
7.3 Process
Process temperature range
Process temperature limits
Process pressure range
Process pressure limits
8 Mechanical Construction
Design
Dimensions (length x breadth x height)
Weight
Material
Electrical connection
Degree of protection
Type of protection
Process connection
9 Operability
10 Power Supply
11 Certificates and Approvals
12 Ordering Information
13 Documentation
Measuring
equipment
Flow
Level
Pressure
Temperature
Density
– 20 – Copyright © 2002, IEC
Annex B
(informative)
Classification of terms as a function of measurement principle

In the following tables, each measurement principle considered to date for a particular

process variable is assigned to a column. The document structure and data elements are

assigned to the rows.
• If a light in the column “. equipment” is shaded, the corresponding data element has

been inherited from process equipment level: the data element applies to all measurement

principles.
• If a light in this column is not shaded, then the data element has been added to the
structure. It applies to a particular measurement principle only if the associated light in the
following columns has been shaded.

B.1 Additional data elements proposed for flow measurement principles

Classification and documentation

structure of flow measuring equipment

02.11.2001
1 Identification
Document identification
...