ISO 15519-2:2015

INTERNATIONAL ISO
STANDARD 15519-2
First edition
2015-06-01
Specifications for diagrams for
process industry —
Part 2:
Measurement and control
Spécifications pour schémas de l’industrie de traitement —
Partie 2: Mesurage et contrôle
Reference number
ISO 15519-2:2015(E)
©
ISO 2015

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ISO 15519-2:2015(E)

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© ISO 2015, Published in Switzerland
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ISO 15519-2:2015(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope .1
2 Normative references .1
3 Terms, definitions, and abbreviated terms .1
3.1 Terms related to control . 1
3.2 Document types . 3
3.3 Abbreviated terms . 3
4 Documentation and process control principles.3
4.1 Introduction . 3
4.2 Diagram types, structures, and life cycle aspects . 4
4.3 Process control interrelations . 5
4.4 Information exchange between process and control systems . 6
5 Exchange of process control information .7
5.1 Symbols for information exchange . 7
5.1.1 General. 7
5.1.2 Placement of information inside the PCI symbol. 8
5.1.3 Placement of information outside the PCI symbol . 9
5.2 Letter codes . 9
5.2.1 General. 9
5.2.2 Representation of letter codes for process variables . 9
5.2.3 Representation of letter codes for control functions.10
5.2.4 Sequence of letter codes for control functions .11
5.2.5 Modifying letter codes .12
5.3 Reference designation .13
6 Representation in general .13
6.1 General .13
6.2 Signal lines .13
6.3 Graphical symbols .14
6.3.1 General.14
6.3.2 Instruments with integrated display .14
6.3.3 Multifunction instruments .14
6.3.4 Instruments forming a group .15
6.3.5 Differentiating of representation .15
6.3.6 Graphical symbol “groups” in diagrams .15
7 Representation in diagrams .15
7.1 Introduction .15
7.2 Process flow diagram, PFD .16
7.2.1 Description . . .16
7.2.2 Application .16
7.2.3 Contents . .16
7.2.4 Representation .17
7.3 Process and instrumentation diagram, PID .18
7.3.1 Description . . .18
7.3.2 Application .18
7.3.3 Contents . .18
7.3.4 Representation .19
7.4 Process control diagram, PCD .20
7.4.1 Description . . .20
7.4.2 Application .21
7.4.3 Contents . .21
7.4.4 Representation .21
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7.5 Typical diagrams, TYD .22
7.5.1 Description . . .22
7.5.2 Application .22
7.5.3 Contents . .22
7.5.4 Representation .22
Annex A (informative) Graphical symbols for connections main process equipment,
measurement, actuation, and control .24
Annex B (informative) Examples of representation of measurement, control, and
actuation tasks .34
Annex C (informative) Diagram examples .36
Annex D (informative) Information exchange between process and control system .40
Annex E (informative) Relationship between terms for closed loop control, measurement,
actuation, etc. .42
Bibliography .43
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ISO 15519-2:2015(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT), see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 10, Technical product documentation, SC 10,
Process plant documentation.
ISO 15519 consists of the following parts, under the general title Specifications for diagrams for
process industry:
— Part 1: General rules
— Part 2: Measurement and control
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ISO 15519-2:2015(E)

Introduction
0.1 General
The ISO 15519 series consists of standards for specification of diagrams for process industry, published
under the general title: Specification for diagrams for process industry.
This International Standard specifies preparation of different types of diagrams and use of graphical
symbols, letter codes, and reference designation in diagrams. This International Standard addresses
all process industry fields for example chemical, petrochemical, power, pharmaceutical, foodstuff,
pulp, and paper.
This part of ISO 15519 deals with representation of measurement, actuation, and control in process
diagrams which in this context covers process flow diagrams (PFD), process and instrument diagrams
(PID), process control diagrams (PCD), and typical diagrams (TYD).
0.2 Engineering interrelations
Process diagrams, which represent the configuration of the process system and of the measurement,
actuation, and control systems, involves engineering disciplines like process, mechanical,
instrumentation, electrical, and control as illustrated in Figure 1.
Key
1 process
2 mechanical
3 instrumentation
4 electrical
5 control
A measurement
B actuation
Figure 1 — Interrelations between engineering disciplines
Figure 1 illustrates the discipline complexity of process systems which force diagrams not only to
focus on individual disciplines but overlap to neighbouring disciplines. This is, for example, done in the
process and instrumentation diagram which shows mechanical, instrumentation, and electrical objects
in same diagram.
As process engineering by tradition is an ISO discipline and control engineering is IEC discipline
representation of measurement and control in diagrams need to be coordinated and unambiguously.
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0.3 Control system technology and influence on documentation
The technological development within Information Technology constantly challenges the process
industry to use “state of the art” technology for engineering of process and control systems. This
puts pressure on the standardization organisations to deliver up to date International Standards. As
development time and expected lifetime of a standard at present is overtaken several times by the IT
development, the standard developers need to develop standards which focus on basic principles and
rules to secure high quality documentation and exchange of information.
At present, the configuration and functionality of the process control system are programmed direct
in modern control system as control Programmable Logic Controller (PLC) and Distributed Control
Systems (DCS). In addition, these systems are self-documenting which could lead to the assumption that
traditional diagram documentation are superfluous.
Diagrams are however an important tool for documentation and representation of process system
information in all lifecycle phases of a process plant. In the development and engineering phase, diagrams
are used also for exchange and sharing of technical information between engineering disciplines and in
operation and maintenance phases diagrams are used in daily operation and as part of operation and
maintenance manuals.
0.4 Letter codes
ISO 14617-6, 7.3.1 have been moved to this part of ISO 15519 and the description has been changed to
“Letter codes for Process Control Information (PCI)”.
ISO 14617-6 will be revised at first periodical review or revision after publication of this International
Standard.
0.5 Figures
Figures in this International Standard are only examples for illustration of a given rule in the standard.
0.6 Reference designation
In this part of ISO 15519, IEC 81346-1, IEC 81346-2, and ISO/TS 81346-3 are used to illustrate the
application of reference designation in diagrams.
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INTERNATIONAL STANDARD ISO 15519-2:2015(E)
Specifications for diagrams for process industry —
Part 2:
Measurement and control
1 Scope
This part of ISO 15519 provides rules and guidelines for representation of measurement, control, and
actuation in diagrams for process industry.
General rules and guidelines for preparation of diagrams for process industry, for example types
and descriptions of diagrams, layout of diagrams, graphical symbols, lines and connection, reference
designation, are given in ISO 15519-1.
Rules and guidelines for preparation of electrotechnical diagrams are given in IEC 61082-1.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 10209, Technical product documentation — Vocabulary — Terms relating to technical drawings,
product definition and related documentation
ISO 14617 (all parts), Graphical symbols for diagrams
ISO 15519-1, Specification for diagrams for process industry — Part 1: General rules
IEC 81346-1, Industrial systems, installations and equipment and industrial products — Structuring
principles and reference designations — Part 1: Basic rules
IEC 81346-2, Industrial systems, installations and equipment and industrial products — Structuring
principles and reference designations — Part 2: Classification of objects and codes for classes
ISO/TS 81346-3, Industrial systems, installations and equipment and industrial products — Structuring
principles and reference designations — Part 3: Application rules for a reference designation system
3 Terms, definitions, and abbreviated terms
For the purposes of this document, the terms and definitions given in ISO 15519-1, ISO 10209, IEC 81346-
1, and the following apply.
3.1 Terms related to control
3.1.1
actuator
functional unit that generates from the controller output variable the manipulated variable to drive the
final controlling element
Note 1 to entry: If the final controlling element is mechanically actuated, it is controlled via an actuated drive. The
actuator drives the actuating drive in this case.
Note 2 to entry: See Annex E for the relationship between related terms.
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[SOURCE: IEC 60050-351:2013, 351-28-07]
3.1.2
closed-loop control
process whereby one variable (quantity), namely the controlled variable is continuously measured,
compared with another variable (quantity), namely the reference variable, and influenced in such a
manner as to adjust to the reference variable
Note 1 to entry: Characteristic for closed-loop control is the closed action in which the controlled variable
continuously influences itself in the action path of the closed loop.
[SOURCE: IEC 60050-351:2013, 351-26-01]
3.1.3
control function
manipulation via the final controlling element of process media or process objects in order to bring the
media or object into a condition or state defined by the process control system on basis of measured
process variables and pre-defined values
3.1.4
control loop
assembly of elements incorporated in the closed action of a closed-loop control
[SOURCE: IEC 60050-351:2013, 351-26-11]
3.1.5
final controlling element
functional unit forming part of the controlled system and arranged at its input, driven by the manipulated
variable and manipulating the mass flow or energy flow
Note 1 to entry: If the final controlling element is mechanically actuated, an additional actuator (positioner) is
used in some cases.
Note 2 to entry: The output variable of the final controlling equipment is usually not free from feedback. The
interface between the actuator and the final controlling element should therefore be selected in such a way that
the manipulated variable is not affected by feedback from the final controlling element.
Note 3 to entry: See Annex E for the relationship between related terms.
[SOURCE: IEC 60050:2013, 351-28-08]
3.1.6
manipulate
to change flows of mass, energy, or information by means of a final controlling element
Note 1 to entry: Manipulating can be affected continuously or by switching operations.
Note 2 to entry: In control engineering, the final controlling element is regarded as belonging to a process.
[SOURCE: IEC 60050-351:2013, 351-22-08]
3.1.7
open-loop control
process in a system whereby one or more variables (variable quantities) as input variables influence
other variables (variable quantities) as output variables in accordance with the proper laws of the system
Note 1 to entry: Characteristic for open-loop control is the open action path or in case of a closed action path the
fact that the output variables being influenced by the input variables are not continuously influencing themselves
and not by the same input variables.
[SOURCE: IEC 60050-351:2013, 351-26-02]
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3.1.8
process variable
quantity, quality, or condition of a process media or process object which value may be subject to change
and can usually be measured
3.2 Document types
3.2.1
process flow diagram
PFD
diagram representing the configuration of a process plant or a process system by means of graphical symbols
3.2.2
process and instrumentation diagram
PID
diagram representing the technical realization of a process system by means of graphical symbols for
equipment, connections, process measurement, and manipulating objects
Note 1 to entry: The diagram type process and instrumentation diagram, used in this part of ISO 15519, is
technically identical with the piping and instrumentation diagram. The argument for change of the designation is
that the diagram type is used for both fluid and solid material processes. The abbreviation PID deviates from the
traditional used abbreviation PID for the Piping and instrumentation diagram.
3.2.3
process control diagram
PCD
diagram representing the configuration of measuring, control, and actuating functions of a process
system, by means of graphical symbols for measuring, control, and manipulating functions
3.2.4
typical diagram
TYD
diagram representing the detailed configuration of a definite measuring or actuating system which can
be referred to in an associated diagram by a graphical symbol and document reference
3.3 Abbreviated terms
IEV International Electrotechnical Vocabulary
PCD Process control diagram
PCI Process control information
PFD Process flow diagram
PID Process and instrumentation diagram
SIF Safety instrumented function
SIL Safety integrity level
TYD Typical diagram
4 Documentation and process control principles
4.1 Introduction
The clause defines principles for documentation of process control (measurement, control, and actuation)
and interchange information between process and control engineering.
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4.2 Diagram types, structures, and life cycle aspects
Diagrams are used for visual representation of process functions. Objects and connections, represented
by graphical symbols, serve as carrier of technical information either represented direct in the diagram
or in associated lists or databases.
Depending on the task of the diagram and the stage in the live cycle matrix described in Figure 3,
diagrams can represent process functions on high and generic level or on detailed and specific level.
Figure 2 represents the interrelationship between different types of diagrams from different
standardization bodies.
The grade of detailing goes from top to down. The information flow from process engineering to control
engineering is illustrated by the arrows.
Specification of amount and types of measurements and actuated objects connected to the control
system are predominately made on basis of the process and instrumentation diagram.
The process control diagram specifies configuration of control system for process systems or process
sub-systems. The information flow is showed reversible in order to illustrate the optimization process
between process and control engineering especially during conceptual engineering.
Figure 2 — Interrelationship between ISO and IEC diagrams
Rules for design of process diagrams, use of graphical symbols, etc. are described in Clauses 6 and 7.
The diagram types in Figure 2 contain differentiated types and amounts of information to suit the needs
in the actual life cycle stages of the project. Figure 3 illustrates the application of three types of diagrams
during the life cycle stages and the graduated application value of the diagrams in the different life cycle
stages represented by the width of the bars.
NOTE Life cycle stage principles are described in ISO 15226 and ISO/IEC 15288
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Figure 3 — Typical illustration of life cycle application value of diagrams
Measuring, control, and actuation are illustrated in diagrams with variable degree of detailing
depending of needs for the actual life cycle stage. In the start of a project the representation in process
flow diagrams (PFD) is pure functional. Later in the project course, when more detailed diagrams are
developed, for example: process control diagram and process and instrumentation diagrams (PID), the
amount of information is increased and the representation is extended to also to include products like
sensors built in the process system also.
4.3 Process control interrelations
The function of process control is to steer and supervise the respective processes in accordance with
predefined aims of process control engineering.
This is carried out by the following:
— recording of measured process situation (process variables);
— comparing measured values with predefined values;
— initiate actions via the control equipment and/or operator (control functions) to the final control
elements.
Figure 4 illustrates the interrelations between process (measuring and manipulating) and control
functions (control equipment and human operator).
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Figure 4 — Illus
...