IEC 60534-2-4:2009

IEC 60534-2-4 ®
Edition 2.0 2009-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial-process control valves –
Part 2-4: Flow capacity – Inherent flow characteristics and rangeability

Vannes de régulation des processus industriels –
Partie 2-4: Capacité d’écoulement – Caractéristiques intrinsèques de débit et
coefficient intrinsèque de réglage

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IEC 60534-2-4 ®
Edition 2.0 2009-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial-process control valves –
Part 2-4: Flow capacity – Inherent flow characteristics and rangeability

Vannes de régulation des processus industriels –
Partie 2-4: Capacité d’écoulement – Caractéristiques intrinsèques de débit et
coefficient intrinsèque de réglage

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
K
CODE PRIX
ICS 23.060.40; 25.040.40 ISBN 978-2-88910-207-5
– 2 – 60534-2-4 © IEC:2009
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL-PROCESS CONTROL VALVES –

Part 2-4: Flow capacity –
Inherent flow characteristics and rangeability

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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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 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 IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60534-2-4 has been prepared by subcommittee 65B: Devices and
process analysis, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This second edition cancels and replaces the first edition published in 1989. This edition
constitutes a technical revision. The main changes with respect to the previous edition are
listed below.
This standard has been revised to:
a) update the normative references;
b) delete the terminology included in IEC 60534-1;
c) transform the previous Note 1 in Clause 6;
d) redraw the graphics;
e) delete the previous Figure 3.

60534-2-4 © IEC:2009 – 3 –
The text of this standard is based on the following documents:
FDIS Report on voting
65B/704/FDIS 65B/713/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 60534 series, under the general title Industrial-process control valves,
can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition; or
• amended.
– 4 – 60534-2-4 © IEC:2009
INDUSTRIAL-PROCESS CONTROL VALVES –

Part 2-4: Flow capacity –
Inherent flow characteristics and rangeability

1 Scope
This part of IEC 60534 applies to all types of industrial-process control valves. It defines how
to state typical control valve inherent flow characteristics and inherent rangeabilities. It also
defines how to establish criteria for adherence to manufacturer-stated flow characteristics.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
or the referenced document (including any amendments) applies.
IEC 60534-1:2005, Industrial-process control valves – Part 1: Control valve terminology and
general considerations
IEC 60534-2-3, Industrial-process control valves – Part 2-3: Flow capacity – Test procedures
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60534-1 and the
following apply.
3.1
flow coefficient
(see IEC 60534-1, 4.6)
3.2
rated flow coefficient
(see IEC 60534-1, 4.6.3)
3.3
relative flow coefficient (Φ)
Φ is the relative flow coefficient at 0 % relative travel
[IEC 60534-1, 4.9 modified]
3.4
travel
(see IEC 60534-1, 4.5.2)
3.5
rated travel
(see IEC 60534-1, 4.5.3)
3.6
relative travel (h)
(see IEC 60534-1, 4.5.4)
60534-2-4 © IEC:2009 – 5 –
3.7
nominal slope
slope of the best fit line
for an ideal inherent linear flow characteristic, the nominal slope is: m
Φ −Φ
=
with m
h
for an ideal inherent equal percentage flow characteristic, the nominal slope is: n
⎛ ⎞
⎜ ⎟
with n = log
⎜ ⎟
Φ
⎝ ⎠
3.8
inherent flow characteristic
(see IEC 60534-1, 4.9)
3.8.1
ideal inherent linear flow characteristic
(see IEC 60534-1, 4.9.1)
3.8.2
ideal inherent equal percentage flow characteristic
(see IEC 60534-1, 4.9.2)
3.9
inherent rangeability
ratio of the largest flow coefficient (Φ ) to the smallest flow coefficient (Φ ) within which
max min
the deviation from the stated inherent flow characteristic does not exceed the allowable
deviation stated in Clause 7
[IEC 60534-1, 4.11 modified]
4 Symbols
Table 1 gives an overview of the symbols used in this standard.
Table 1 – Symbols
Symbol Description Unit
Φ Relative flow coefficient Dimensionless
C Flow coefficient (K , C ) Various (see
v v
IEC 60534-1)
C Flow coefficient (K and C ) at rated travel Various (see
R
v v
IEC 60534-1)
d Nominal valve diameter mm
h Relative travel Dimensionless

– 6 – 60534-2-4 © IEC:2009
5 Typical inherent flow characteristics
The typical inherent flow characteristics and the values of n, m and Φ for a specific size, type
and trim configuration of a control valve shall be stated by the manufacturer either graphically
or in tabular form.
When tabulated, specific flow coefficients shall be stated for the following travel positions: at
5 %, 10 %, 20 %, and every subsequent 10 % of rated travel up to and including 100 % (see
Figures 1 and 2).
The manufacturer may publish flow coefficients in addition to those at the above stated travel
positions.
In addition, the manufacturer is encouraged to specify the generic name of a specific flow
characteristic, such as "linear" or "equal percentage", if applicable, following the terms and
definitions of IEC 60534-1.
The manufacturer shall state the largest flow coefficient that meets the criteria of Clause 7, if
it is less than the rated flow coefficient (see Figures 1 and 2).

60534-2-4 © IEC:2009 – 7 –
1,0 000
E
D
C
Φ
0,1 000
A
B
0,0 100
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0
h
IEC  574/09
Key
A tolerance band
B minimum Φ within tolerance band and slope requirements (0,025 3)
C valve specimen test points
D manufacturer stated characteristic
E maximum Φ within slope requirements (1,0)
h relative travel
Φ relative flow
Φmax 1,000
Inherent rangeability of test specimen: = = 39,5
Φmin 0,025 3
Figure 1 − Example of an equal percentage characteristic valve specimen compared to
manufacturer-stated flow characteristic
...