SIST EN 60534-8-4:2016

Industrial-process control valves - Part 8-4: Noise considerations - Prediction of noise generated by hydrodynamic flow (IEC 60534-8-4:2015)

This part of IEC 60534 establishes a method to predict the noise generated in a control valve
by liquid flow and the resulting noise level measured downstream of the valve and outside of
the pipe. The noise may be generated both by normal turbulence and by liquid cavitation in
the valve. Parts of the method are based on fundamental principles of acoustics, fluid
mechanics, and mechanics. The method is validated by test data.

Stellventile für die Prozessregelung - Teil 8-4: Geräuschbetrachtungen - Vorausberechnung der Geräuschemission für flüssigkeitsdurchströmte Stellventile (IEC 60534-8-4:2015)

Vannes de régulation des processus industriels - Partie 8-4: Considérations sur le bruit - Prévisions du bruit généré par un écoulement hydrodynamique (IEC 60534-8-4:2015)

L'IEC 60534-8-4:(2015) établit une méthode pour prévoir le bruit engendré dans une vanne de régulation par un écoulement liquide et le niveau de bruit mesuré en aval de la vanne et à l'extérieur de la tuyauterie. Le bruit peut être généré à la fois par des turbulences normales et par la cavitation du liquide dans la vanne. Des parties de cette méthode sont basées sur des principes fondamentaux de l'acoustique, de la mécanique et de la mécanique des fluides. Cette méthode est validée par des résultats d'essai. Cette troisième édition annule et remplace la deuxième édition parue en 2005, dont elle constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) Le bruit hydrodynamique est prévu en fonction de la fréquence;
b) Suppression du rapport de puissance acoustique.

Regulacijski ventili za industrijske procese - 8-4. del: Obravnava šuma - Predvidevanje šuma, ki ga proizvaja hidrodinamični pretok (IEC 60534-8-4:2015)

Ta del standarda IEC 60534 določa metodo za predvidevanje šuma, ki ga v regulacijskem ventilu proizvaja hidrodinamični pretok, in nastale ravni šuma, izmerjene v smeri toka v ventilu in zunaj cevi. Šum lahko proizvajata običajna turbulenca in kavitacija tekočine v ventilu. Deli metode temeljijo na temeljnih načelih akustike, mehanike tekočin in mehanike. Metodo potrjujejo rezultati preskusov.

General Information

• Status: Published
• Publication Date: 16-Jun-2016
• ICS: 17.140.20 - Noise emitted by machines and equipment
• ICS: 23.060.40 - Pressure regulators
• ICS: 25.040.40 - Industrial process measurement and control
• Technical Committee: MOV - Measuring equipment for electromagnetic quantities
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 10-Dec-2015
• Due Date: 14-Feb-2016
• Completion Date: 17-Jun-2016
• Ref Project: EN 60534-8-4:2015 - Industrial-process control valves - Part 8-4: Noise considerations - Prediction of noise generated by hydrodynamic flow

Relations

• Replaces: SIST EN 60534-8-4:2007 - Industrial-process control valves -- Part 8-4: Noise considerations - Prediction of noise generated by hydrodynamic flow
• Effective Date: 01-Jul-2016
• Replaces: SIST EN 60534-8-4:2007 - Industrial-process control valves -- Part 8-4: Noise considerations - Prediction of noise generated by hydrodynamic flow
• Effective Date: 28-Jan-2023
• Replaces: SIST EN 60534-8-4:2007 - Industrial-process control valves -- Part 8-4: Noise considerations - Prediction of noise generated by hydrodynamic flow
• Effective Date: 07-Jun-2022

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 60534-8-4:2016
01-julij-2016
1DGRPHãþD
SIST EN 60534-8-4:2007
5HJXODFLMVNLYHQWLOL]DLQGXVWULMVNHSURFHVHGHO2EUDYQDYDãXPD
3UHGYLGHYDQMHãXPDNLJDSURL]YDMDKLGURGLQDPLþQLSUHWRN,(&
Industrial-process control valves - Part 8-4: Noise considerations - Prediction of noise
generated by hydrodynamic flow (IEC 60534-8-4:2015)
Stellventile für die Prozessregelung - Teil 8-4: Geräuschbetrachtungen -
Vorausberechnung der Geräuschemission für flüssigkeitsdurchströmte Stellventile (IEC
60534-8-4:2015)
Vannes de régulation des processus industriels - Partie 8-4: Considérations sur le bruit -
Prévisions du bruit généré par un écoulement hydrodynamique (IEC 60534-8-4:2015)
Ta slovenski standard je istoveten z: EN 60534-8-4:2015
ICS:
17.140.20 Emisija hrupa naprav in Noise emitted by machines
opreme and equipment
23.060.40 7ODþQLUHJXODWRUML Pressure regulators
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
SIST EN 60534-8-4:2016 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60534-8-4:2016

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SIST EN 60534-8-4:2016


EUROPEAN STANDARD EN 60534-8-4

NORME EUROPÉENNE

EUROPÄISCHE NORM
December 2015
ICS 17.140.20; 23.060.40; 25.040.40 Supersedes EN 60534-8-4:2005
English Version
Industrial-process control valves - Part 8-4: Noise considerations -
Prediction of noise generated by hydrodynamic flow
(IEC 60534-8-4:2015)
Vannes de régulation des processus industriels -  Stellventile für die Prozessregelung -
Partie 8-4: Considérations sur le bruit - Prévisions du bruit Teil 8-4: Geräuschbetrachtungen - Vorausberechnung der
généré par un écoulement hydrodynamique Geräuschemission für flüssigkeitsdurchströmte Stellventile
(IEC 60534-8-4:2015) (IEC 60534-8-4:2015)
This European Standard was approved by CENELEC on 2015-10-20. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN 60534-8-4:2015 E

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SIST EN 60534-8-4:2016
EN 60534-8-4:2015
European foreword
The text of document 65B/1005/FDIS, future edition 3 of IEC 60534-8-4, prepared by SC 65B
"Measurement and control devices", of IEC/TC 65 "Industrial-process measurement, control and
automation" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
EN 60534-8-4:2015.
The following dates are fixed:
• latest date by which the document has to be implemented at (dop) 2016-07-20
national level by publication of an identical national
standard or by endorsement
(dow) 2018-10-20
• latest date by which the national standards conflicting with
the document have to be withdrawn

This document supersedes EN 60534-8-4:2005.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 60534-8-4:2015 was approved by CENELEC as a
European Standard without any modification.
2

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SIST EN 60534-8-4:2016
EN 60534-8-4:2015
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications
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.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is
available here: www.cenelec.eu.

Publication Year Title EN/HD Year
IEC 60534-1 -  Industrial-process control valves - EN 60534-1 -
Part 1: Control valve terminology and
general considerations
IEC 60534-2-3 -  Industrial-process control valves - EN 60534-2-3 -
Part 2-3: Flow capacity - Test procedures
IEC 60534-8-2 -  Industrial-process control valves - EN 60534-8-2 -
Part 8-2: Noise considerations - Laboratory
measurement of noise generated by
hydrodynamic flow through control valves
IEC 60534-8-3 -  Industrial-process control valves - EN 60534-8-3 -
Part 8-3: Noise considerations - Control
valve aerodynamic noise prediction method

3

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SIST EN 60534-8-4:2016

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SIST EN 60534-8-4:2016



IEC 60534-8-4

®


Edition 3.0 2015-09




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE











Industrial-process control valves –

Part 8-4: Noise considerations – Prediction of noise generated by hydrodynamic

flow




Vannes de régulation des processus industriels –

Partie 8-4: Considérations sur le bruit – Prévisions du bruit généré par un


écoulement hydrodynamique














INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 17.140.20; 23.060.40; 25.040.40 ISBN 978-2-8322-2879-1



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 60534-8-4:2016
– 2 – IEC 60534-8-4:2015 © IEC 2015
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols . 7
5 Preliminary calculations . 9
5.1 Pressures and pressure ratios . 9
5.2 Characteristic presssure ratio x . 9
Fz
5.3 Valve style modifier F . 10
d
5.4 Jet diameter D . 10
j
5.5 Jet velocity. 10
5.6 Mechanical power W . 10
m
6 Noise predictions . 10
6.1 Internal sound pressure calculation . 10
6.2 Transmission loss . 13
6.3 External sound pressure calculation . 14
7 Multistage trim . 14
7.1 General . 14
7.2 Preliminary calculations . 15
7.3 Prediction of noise level . 15
7.3.1 General criteria . 15
7.3.2 Multistage devices (see Figures 1 and 3) . 15
7.3.3 Fixed multistage devices with increasing flow areas (see Figure 2) . 16
Annex A (informative) Examples of given data . 21
Bibliography . 31

Figure 1 – Examples of multistage trim in globe and rotary valves . 16
Figure 2 – Example of fixed multistage device with increasing flow area . 17
Figure 3 – Example of multistage trim in globe valve . 17
Figure 4 – Globe valve (Cage trim, V-port plug) . 18
Figure 5 – Globe valves (parabolic-plug) . 18
Figure 6 – Multihole trims. 19
Figure 7 – Eccentric rotary valves . 19
Figure 8 – Butterfly valves . 20
Figure 9 – Segmented ball valve – 90°travel . 20
Figure A.1 – The influence of the x value on prediction accuracy . 30
Fz


Table 1 – Numerical constants N . 9
Table 2 – Typical values of Aη . 11
Table 3 – Indexed third octave center frequencies and “A” weighting factors. 13
Table A.1 – Calculation: Examples 1 to 3 . 22

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SIST EN 60534-8-4:2016
IEC 60534-8-4:2015 © IEC 2015 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

INDUSTRIAL-PROCESS CONTROL VALVES –

Part 8-4: Noise considerations –
Prediction of noise generated by hydrodynamic flow

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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). 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. 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 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
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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 60534-8-4 has been prepared by subcommittee 65B: Measurement
and control devices , of IEC technical committee 65: Industrial-process measurement, control
and automation.
This third edition cancels and replaces the second edition published 2005. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Hydrodynamic noise is predicted as a function of frequency.
b) Elimination of the acoustic power ratio

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SIST EN 60534-8-4:2016
– 4 – IEC 60534-8-4:2015 © IEC 2015
The text of this standard is based on the following documents:
FDIS Report on voting
65B/1005/FDIS 65B/1017/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 in the IEC 60534 series, published 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 stability 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.

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SIST EN 60534-8-4:2016
IEC 60534-8-4:2015 © IEC 2015 – 5 –
INTRODUCTION
It is valuable to predict the noise levels that will be generated by valves. Safety requirements,
such as the occupational health standards require that human exposure to noise be limited.
There is also data indicating that noise levels above certain levels could lead to pipe failure or
affect associated equipment. See IEC 60534-8-3. Earlier hydrodynamic noise standards relied
on manufacturer test data and were neither generic nor as complete as desired. The method
can be used with all conventional control valve styles including globe, butterfly, cage type,
eccentric rotary, and modified ball valves.
A valve restricts flow by converting pressure energy into turbulence, heat and mechanical
pressure waves in the fluid contained within the valve body and piping. A small portion of this
mechanical vibration is converted into acoustical energy. Most of the noise is retained within
the piping system with only a small portion passing through the pipe wall downstream of the
valve. Calculation of the mechanical energy involved is straightforward. The difficulties arise
from determining first the acoustic efficiency of the mechanical energy to noise conversion
and then the noise attenuation caused by the pipe wall.
This part of IEC 60534 considers only noise generated by normal turbulence and liquid
cavitation. It does not consider any noise that might be generated by mechanical vibrations,
flashing conditions, unstable flow patterns, or unpredictable behaviour. In the typical
installation, very little noise travels through the wall of the control valve body. The noise
predicted is that which would be measured at the standard measuring point of 1 m
downstream of the valve and 1 m away from the outer surface of the pipe in an acoustic free
field. Ideal straight piping is assumed. Since an acoustic free field is seldom encountered in
industrial installations, this prediction cannot guarantee actual results in the field.
This prediction method has been validated with test results based on water covering a
majority of control valve types, in the DN 15 to DN 300 size range, at inlet pressures up to
15 bar. However, some types of low noise valves may not be covered. This method is
considered accurate within ± 5 dB(A), for most cases, if based on tested values of x using
FZ
the method from IEC 60534-8-2. The applicability of this method for fluids other than water is
not known at this time.

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SIST EN 60534-8-4:2016
– 6 – IEC 60534-8-4:2015 © IEC 2015
INDUSTRIAL-PROCESS CONTROL VALVES –

Part 8-4: Noise considerations –
Prediction of noise generated by hydrodynamic flow



1 Scope
This part of IEC 60534 establishes a method to predict the noise generated in a control valve
by liquid flow and the resulting noise level measured downstream of the valve and outside of
the pipe. The noise may be generated both by normal turbulence and by liquid cavitation in
the valve. Parts of the method are based on fundamental principles of acoustics, fluid
mechanics, and mechanics. The method is validated by test data.
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.
IEC 60534-1, 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
IEC 60534-8-2, Industrial-process control valves – Part 8-2: Noise considerations –
Laboratory measurement of noise generated by hydrodynamic flow through control valves
IEC 60534-8-3, Industrial-process control valves – Part 8-3: Noise considerations – Control
valve aerodynamic noise prediction method
3 Terms and definitions
For the purpose of this document, all of the terms and definitions given in IEC 60534 series
and the following apply:
3.1
acoustical efficiency η
ratio of the stream power converted into sound power propagating downstream to the stream
power of the mass flow
3.2
fluted vane butterfly valve
butterfly valve which has flutes (grooves) on the face(s) of the disk. These flutes are intended
to shape the flow stream without altering the seating line or seating surface
3.3
independent flow passage
flow passage where the exiting flow is not affected by the exiting flow from adjacent flow
passages

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SIST EN 60534-8-4:2016
IEC 60534-8-4:2015 © IEC 2015 – 7 –
3.4
peak frequency f
p
frequency at which the internal sound pressure is maximum
3.5
valve style modifier F
d
ratio of the hydraulic diameter of a single flow passage to the diameter of a circular orifice,
the area of which is equivalent to the sum of areas of all identical flow passages at a given
travel
4 Symbols
Symbol Description Unit
A(f) Frequency dependent A-weighting value dBA (ref P )
o
A Valve correction factor for acoustic efficiency Dimensionless
η
(see Table 2)
c Speed of sound in liquid m/s
1
c Speed of sound in air at standard conditions = 343 m/s
a
c Speed of sound in pipe (for steel pipe 5 000) m/s
S
C Flow coefficient (K and C ) Various
v v
(see IEC 60534-1)
C Flow coefficient (K and C ) at rated travel Various
R v v
(see IEC 60534-1)
C Flow coefficents of n stages (i=1…n) in a multistage valve Various
i
(K and C ) (see IEC 60534-1)
v v
C Flow coefficent of last stage in a multistage valve (K and Various
n v
C ) (see IEC 60534-1)
v
D Internal pipe diameter m
i
D Jet diameter m
j
D Nominal valve size m
d Multihole trim hole diameter m
H
d Seat or orifice diameter m
o
F Frequency distribution function (cavitating) Dimensionless

cav
F Valve style modifier Dimensionless
d
F Liquid pressure recovery factor of a valve without Dimensionless
L
attached fittings
F
Liquid pressure recovery factor of the last throttling stage Dimensionless
Ln
F Frequency distribution function (turbulent) Dimensionless
turb
f
Frequency Hz
f Cutoff frequency Hz
c
f
Octave band frequency Hz
ji
f Ring frequency Hz
r
f
Internal peak sound frequency (turbulent) Hz
p,turb
f Internal peak sound frequency (cavitating) Hz
p,cav
K Differential pressure ratio of incipient choked flow Dimensionless
c
3 2
(approximately in the range of F to F )
L L
L External sound pressure level 1 m from pipe wall dB (ref P )
pe,1m o

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SIST EN 60534-8-4:2016
– 8 – IEC 60534-8-4:2015 © IEC 2015
Symbol Description Unit
L A-weighted external sound pressure level 1 m from pipe dBA (ref P )
pAe,1m o
wall
L A-weighted external sound pressure level 1 m from pipe dBA (ref P )
pAe,1m,i o
wall of stage i (number i from 1…n) in multistage valve
with n stages
L Internal sound pressure level at pipe wall dB (ref P )
pi o
Mass flow rate kg/s
m
n Number of stages in multistage trim Dimensionless
N Numerical constants (see Table 1) Various
N Number of independent and identical flow passages in Dimensionless
o
valve trim or throttling stage
5
P Pa
Reference pressure = 1 × 10
a
–5
P
Reference sound pressure = 2 × 10 Pa
o
p Valve inlet absolute pressure Pa
1
p Valve outlet absolute pressure Pa
2
p Inlet absolute pressure of stage i (number i from 1…n) in Pa
1,i
multistage valve with n stages
p Outlet absolute pressure of stage i (number i from 1…n) in Pa

2,i
multistage valve with n stages
p Vapour pressure of liquid Pa
v
Pressure differential Pa
∆p
∆p Pressure differential for U calculation Pa
c vc
St Strouhal number for peak frequency calculation Dimensionless
p
t Pipe wall thickness m
S
TL Transmission loss dB
TL Transmission loss at ring frequency f dB
fr r
U Vena contracta velocity m/s
vc
W Sound power of noise created by valve flow which W
a
propagates downstream
W Mechanical stream power W
m
x Differential pressure ratio Dimensionless
F
x Differential pressure ratio of incipient cavitation noise with Dimensionless
Fz
5
inlet pressure of 6 × 10 Pa
x Differential pressure ratio corrected for inlet pressure Dimensionless
Fzp1
η Acoustic efficiency factor (turbulent) Dimensionless
turb
Acoustic efficiency factor (cavitating) Dimensionless
η
cav
Acoustic efficiency factor of pipe wall Dimensionless
η
s
3
Density of liquid kg/m
ρ
1
3
ρ Density of air = 1,293 kg/m
a
3
Density of pipe material (= 7 800 for steel) kg/m
ρ
S

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SIST EN 60534-8-4:2016
IEC 60534-8-4:2015 © IEC 2015 – 9 –
Table 1 – Numerical constants N
Flow coefficent
Constant K C
v v

–3 –3
N
4,9 × 10 4,6 × 10
14
N 1 1,17
34

5 Preliminary calculations
5.1 Pressures and pressure ratios
There are several pressures and pressure ratios needed in the noise prediction procedure.
They are given below.
The differential pressure ratio x for liquids depends on the pressure difference p -p and the
F 1 2
difference of the inlet pressure p and the vapour pressure p .
1 v
p − p
1 2
x = (1)
F
p − p
1 v
2
The differential pressure for beginning choked flow is approximately F (p –p ). Some
L 1 v
calculations are based on the following pressure differential:
2
Δp = lower of (p − p ) or F (p − p ) (2)
c 1 2 L 1 v
For low differential pressure ratios, the noise is mainly generated by turbulence. If x exceeds
F
x cavitation noise overlays the turbulent noise. At x = 1, cavitation noise has a second
z F,p1 F
minimum and for x > 1, in the flashing region, there is a very gradual increase in sound level
F
as x increases above x = 1.
F F
5.2 Characteristic presssure ratio x
Fz
The valve specific characteristic pressure ratio x can be measured with dependency on the
Fz
valve travel according to IEC 60534-8-2. It should not be confused with K , the value at which
c
choked flow caused by cavitation starts. It identifies the pressure ratio at which the cavitation
is acoustically detected. The value of x depends on the valve and closure member type and
Fz
the specific flow capacity.
Alternatively, the value of x can be estimated from equations (3), (4), and (5). Calculations
Fz
of hydrodynamic noise based on equation (3), (4) and (5) can create uncertainties as
illustrated in Annex A. Figures 4 to 9 include typical curves of x for different control valve
Fz
5
types. Both equation (3a) and Figures 4 to 9 are based on an inlet pressure of 6 × 10 Pa. If a
different inlet pressure is required, then the x value shall be corrected using equation (5).
Fz
0,90
  (3)
XFz =   for valve types except multihole trims
C
1+ 3 F
d
N34 F
L
1
XFz =  for multihole trims (4)
2
N0 dH
4,5 + 1650
FL
NOTE N is a numerical constant, the values of which account for the specific flow coefficient (K or C ) used.
34 v v

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SIST EN 60534-8-4:2016
– 10 – IEC 60534-8-4:2015 © IEC 2015
5
is obtained by testing at an inlet pressure of 6 × 10 Pa, then the tested value shall
When x
Fz
be corrected for the actual inlet pressure using the following equation and using x in place
Fzp1
of x :
Fz
0,125
5
 
6 x 10
 
x = x
 (5)
Fzp1 Fz
 
p
1
 
5.3 Valve style modifier F
d
The valve style modifier depends on the valve and closure member type and on the flow
coefficient C (see IEC 60534-2-3).
5.4 Jet diameter D
j
The jet diameter D can be predicted as in IEC 60534-8-3 per the following equation:
j
D = N F C F (6)
j 14 d L
5.5 Jet velocity
The vena contracta flow velocity, used in calculating the mechanical power, is determined as
follows:
1 2 ∆p
c
U (7)
=
vc
F ρ
L L
5.6 Mechanical power W
m
The mechanical energy dissipated in the valve orifice is determined from the following
equation:
2 2

m U F
vc L
 (8)
W =
m
2
6 Noise predictions
6.1 Internal sound pressure calculation
from 5.6 converted to valve internal noise and
The portion of the mechanical power W
m
radiated into the downstream pipe is a function of the acoustic efficiency η.
For turbulent conditions defined here where (x ≤ x ):
F Fzp1
W = η W (9)
a turb m
For cavitating conditions defined here where (x < x < 1):
Fzp1 F
 W = (η +η )W (10)
a turb cav m
For turbulent flow due to the relatively low fluid velocity U the valve is consider
...