EN 60534-8-3:2000

SLOVENSKI STANDARD
01-april-2001
Industrial-prodess control valves - Part 8-3: Noise considerations - Control valve
aerodynamic noise prediction method (IEC 60534-8-3:2000)
Industrial-process control valves -- Part 8-3: Noise considerations - Control valve
aerodynamic noise prediction method
Stellventile für die Prozessregelung -- Teil 8-3: Geräuschbetrachtungen -
Berechnungsverfahren zur Vorhersage der aerodynamischen Geräusche von
Stellventilen
Vannes de régulation des processus industriels -- Partie 8-3: Considérations sur le bruit -
Méthode de prédiction du bruit aérodynamique des vannes de régulation
Ta slovenski standard je istoveten z: EN 60534-8-3:2000
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

NORME CEI
INTERNATIONALE IEC
60534-8-3
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2000-07
Vannes de régulation des processus industriels –
Partie 8-3:
Considérations sur le bruit –
Méthode de prédiction du bruit aérodynamique
des vannes de régulation
Industrial-process control valves –
Part 8-3:
Noise considerations –
Control valve aerodynamic noise prediction method
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XA
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60534-8-3  IEC:2000 – 3 –
CONTENTS
Page
FOREWORD . 5
INTRODUCTION .9
Clause
1 Scope and limitations . 11
2 Normative references . 13
3 Definitions. 13
4 Symbols . 15
5 Valves with standard trim . 21
5.1 Pressures and pressure ratios. 21
5.2 Regime definition . 23
5.3 Preliminary calculations. 25
5.4 Regime I (subsonic flow) . 29
5.5 Regimes II to V (common calculations). 31
5.6 Noise calculations . 35
5.7 Calculation flow chart . 39
6 Valves with noise-reducing trim . 41
6.1 Introduction. 41
6.2 Single stage, multiple flow passage trim . 41
6.3 Single flow path, multistage pressure reduction trim (two or more throttling steps) . 43
6.4 Multipath, multistage trim (two or more passages and two or more stages) . 47
6.5 Valves not included in this standard. 49
7 Valves with higher outlet Mach numbers . 49
7.1 Introduction. 49
7.2 Calculation procedure . 49
Annex A (informative) Calculation examples . 55
Bibliography . 113
Figure 1 – Single stage, multiple flow passage trim . 41
Figure 2 – Single flow path, multistage pressure reduction trim . 43
Figure 3 – Multipath, multistage trim (two or more passages and two or more stages) . 47
Table 1 − Numerical constants N . 27
Table 2 – Typical values of valve style modifier F (full size trim). 27
d
Table 3 – Acoustic power ratio r . 29
w
Table 4 – Frequency factors G and G . 39
x y
60534-8-3  IEC:2000 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL-PROCESS CONTROL VALVES –
Part 8-3: Noise considerations –
Control valve aerodynamic noise prediction method
FOREWORD
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.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60534-8-3 has been prepared by subcommittee 65B: Devices, of
IEC technical committee 65: Industrial-process measurement and control.
This second edition of IEC 60534-8-3 cancels and replaces the first edition published in 1995.
This second edition constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
65B/400/FDIS 65B/407/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 3.

60534-8-3  IEC:2000 – 7 –
Annex A is for information only.
The committee has decided that the contents of this publication will remain unchanged until 2007.
At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
60534-8-3  IEC:2000 – 9 –
INTRODUCTION
The mechanical stream power, as well as acoustical efficiency factors, are calculated for
various flow regimes. These acoustical efficiency factors give the proportion of the mechanical
stream power which is converted into internal sound power.
This method also provides for the calculation of the internal sound pressure and the peak
frequency for this sound pressure, which is of special importance in the calculation of the pipe
transmission loss.
At present, a common requirement by valve users is the knowledge of the sound pressure level
outside the pipe, typically 1 m downstream of the valve or expander and 1 m from the pipe wall.
This part of IEC 60534 offers a method to establish this value.
The equations in this part of IEC 60534 make use of the valve sizing factors as used in
IEC 60534-1 and IEC 60534-2-1.
In the usual control valve, little noise travels through the wall of the valve. The noise of interest
is only that which travels downstream of the valve and inside of the pipe and then escapes
through the wall of the pipe to be measured typically at 1 m downstream of the valve body and
1 m away from the outer pipe wall.
Secondary noise sources may be created where the gas exits the valve outlet at higher Mach
numbers. This method allows for the estimation of these additional sound levels which can then
be added logarithmically to the sound levels created within the valve. See clauses 5 and 6 for
Mach numbers up to 0,3 and clause 7 for Mach numbers greater than 0,3.
Although this prediction method cannot guarantee actual results in the field, it yields calculated
predictions within 5 dB(A) for the majority of noise data from tests under laboratory conditions
(reference IEC 60534-8-1).
The bulk of the test data used to validate the method was generated using air at moderate
pressures and temperatures; however, it is believed that the method is generally applicable to
other gases and vapours and at higher pressures. Uncertainties become greater as the fluid
behaves less perfectly for extreme temperatures and for downstream pressures far different
from atmospheric, or near the critical point. The equations include terms which account for fluid
density and the ratio of specific heat.
NOTE Laboratory air tests conducted with up to 1 830 kPa (18,3 bar) upstream pressure and up to 1 600 kPa
(16,0 bar) downstream pressure and steam tests up to 225 °C showed good agreement with the calculated values.
The transmission loss equations are based on a rigorous analysis of the interaction between
the sound waves existing in the pipe and the many coincidence frequencies in the pipe wall.
The wide tolerances in pipe wall thickness allowed in commercial pipe severely limit the value
of the very complicated mathematical approach required for a rigorous analysis; therefore, a
simplified method is used.
Example calculations are given in annex A.
This method is based on the IEC standards listed in clause 2 and the references given in the
bibliography.
60534-8-3  IEC:2000 – 11 –
INDUSTRIAL-PROCESS CONTROL VALVES –
Part 8-3: Noise considerations –
Control valve aerodynamic noise prediction method
1 Scope and limitations
This part of IEC 60534 establishes a theoretical method to predict the external sound-pressure
level generated in a control valve and within adjacent pipe expanders by the flow of
compressible fluids.
This method considers only single-phase dry gases and vapours and is based on the perfect
gas laws.
This standard addresses only the noise generated by aerodynamic processes in valves and in
the connected piping. It does not consider any noise generated by reflections, mechanical
vibrations, unstable flow patterns and other unpredictable behaviour.
It is assumed that the downstream piping is straight for a length of at least 2 m from the point
where the noise measurement is made.
This method is valid only for steel and steel alloy pipes (see equations (38) and (40) in 5.6).
The method is applicable to the following single-stage valves: globe (straight pattern and angle
pattern), butterfly, rotary plug (eccentric, spherical), ball, and valves with cage trims.
Specifically excluded are the full bore ball valves where the product F C exceeds 50 % of the
p
rated flow coefficient.
For limitations on special low noise trims not covered by this standard, see 6.5. When the
Mach number in the valve outlet exceeds 0,3 for standard trim or 0,2 for low noise trim, the
procedure in clause 7 is used.
The Mach number limits in this standard are as follows:
Mach number limit
Mach number location Clause 7
Clause 5 Clause 6
High Mach number
Standard trim Noise-reducing trim
applications
No limit No limit No limit
Freely expanded jet M
j
Valve outlet M 0,3 0,2 1,0
o
Downstream reducer inlet M Not applicable Not applicable 1,0
r
Downstream pipe M 0,3 0,2 0,8
60534-8-3  IEC:2000 – 13 –
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 60534. For dated references, subsequent amendments
to, or revisions of, any of these publications do not apply. However, parties to agreements
based on this part of IEC 60534 are encouraged to investigate the possibility of applying the
most recent editions of the normative documents indicated below. For undated references, the
latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
IEC 60534 (all parts), Industrial-process control valves
IEC 60534-1, Industrial-process control valves − Part 1: Control valve terminology and general
considerations
3 Definitions
For the purpose of this part of IEC 60534, all of the definitions given in the IEC 60534 series
apply, as well as the following:
3.1
acoustical efficiency
ratio of the stream power converted into sound power to the stream power of the mass flow
3.2
external coincidence frequency
frequency at which the external acoustic wavespeed is equal to the bending wavespeed in a
plate of equal thickness to the pipe wall
3.3
internal coincidence frequency
lowest frequency at which the acoustic and structural axial wave numbers are equal for a given
circumferential mode, thus resulting in the minimum transmission loss
3.4
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

60534-8-3  IEC:2000 – 15 –
3.5
independent flow passage
flow passage where the exiting flow is not affected by the exiting flow from adjacent flow
passages
3.6
peak frequency
frequency at which the internal sound pressure is maximum
3.7
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 Area of a single flow passage m
A Total flow area of last stage of multistage trim with n stages m
n
at given travel
C Flow coefficient (K and C ) Various
v v
(see IEC 60534-1)
C Flow coefficient for last stage of multistage trim with n stages Various
n
(see IEC 60534-1)
c Speed of sound in the vena contracta at subsonic m/s
vc
flow conditions
c Speed of sound in the vena contracta at critical flow conditions m/s
vcc
c Speed of sound at downstream conditions m/s
D Valve outlet diameter m
d Diameter of a flow passage (for other than circular, use d)m
H
d Hydraulic diameter of a single flow passage m
H
d Smaller of valve outlet or expander inlet internal diameters m
i
D Internal downstream pipe diameter m
i
D Jet diameter at the vena contracta m
j
d Diameter of a circular orifice, the area of which equals m
o
the sum of areas of all flow passages at a given travel
F Valve style modifier Dimensionless
d
F Liquid pressure recovery factor of a valve without attached Dimensionless
L
fittings (see note 4)
F Liquid pressure recovery factor of last stage Dimensionless
Ln
of low noise trim
F Combined liquid pressure recovery factor and piping Dimensionless
LP
geometry factor of a control valve with attached fittings
(see note 4)
60534-8-3  IEC:2000 – 17 –
F Piping geometry factor Dimensionless
p
f External coincidence frequency Hz
g
f Internal coincidence pipe frequency Hz
o
f Generated peak frequency Hz
p
f Generated peak frequency in valve outlet or reduced Hz
pR
diameter of expander
f Ring frequency Hz
r
G , G Frequency factors (see table 4) Dimensionless
x y
I Length of a radial flow passage m
l Wetted perimeter of a single flow passage m
w
L A-weighted sound-pressure level 1 m from pipe wall, dB(A) (ref P )
peR o
caused by pipe expander-induced gas turbulence
L Correction for Mach number dB (ref P )
g o
L A-weighted sound-pressure level external of pipe dB(A) (ref P )
pAe o
L A-weighted sound-pressure level 1 m from pipe wall dB(A) (ref P )
o
pAe,1m
L Internal sound-pressure level at pipe wall (see 5.6) dB (ref P )
pi o
L Internal sound-pressure level in downstream pipe (see 7.2) dB (ref P )
piR o
L Combined A-weighted sound-pressure level 1 m from dB(A) (ref P )
pS o
pipe wall, caused by valve trim and expander
L Total internal sound power level dB (ref W )
wi o
M Molecular mass of flowing fluid kg/kmol
M Freely expanded jet Mach number in regimes II to IV Dimensionless
j
M Freely expanded jet Mach number of last stage in Dimensionless
jn
multistage valve with n stages
M Freely expanded jet Mach number in regime V Dimensionless
j5
M Mach number at valve outlet Dimensionless
o
M Mach number in the entrance to expander Dimensionless
R
M Mach number at the vena contracta Dimensionless
vc
M Mach number in downstream pipe Dimensionless
Mass flow rate kg/sm
m Mass flow rate at sonic velocity kg/s
s
N Numerical constants (see table 1) Various
N Number of independent and identical flow passages Dimensionless
o
in valve trim
p Actual atmospheric pressure outside pipe Pa (see note 3)
a
60534-8-3  IEC:2000 – 19 –
p Absolute stagnation pressure at last stage of multistage Pa
n
valve with n stages
–5
p Pa
Reference sound pressure = 2 × 10 (see note 5)
o
p Standard atmospheric pressure (see note 1) Pa
s
p Absolute vena contracta pressure at subsonic Pa
vc
flow conditions
p Absolute vena contracta pressure at critical flow conditions Pa
vcc
p Valve inlet absolute pressure Pa
p Valve outlet absolute pressure Pa
p Valve outlet absolute pressure at break point Pa
2B
p Valve outlet absolute pressure at critical flow conditions Pa
2C
p Valve outlet absolute pressure where region of constant Pa
2CE
acoustical efficiency begins
R Universal gas constant = 8 314 J/kmol × K
r Acoustic power ratio (see table 3) Dimensionless
w
T Inlet absolute temperature at last stage of multistage valve K
n
with n stages
T Vena contracta absolute temperature at subsonic K
vc
flow conditions
T Vena contracta absolute temperature at critical K
vcc
flow conditions
T Inlet absolute temperature K
T Outlet absolute temperature K
TL Transmission loss dB
TL Transmission loss in downstream pipe dB
R
t Pipe wall thickness m
p
U Gas velocity in downstream pipe m/s
p
U Gas velocity in the inlet of expander m/s
R
U Vena contracta velocity at subsonic flow conditions m/s
vc
W Sound power W
a
W Sound power in valve outlet or reduced diameter of expander W
aR
W Stream power of mass flow W
m
W Stream power of mass flow in valve outlet or reduced W
mR
diameter of expander
W Stream power of mass flow rate at sonic velocity W
ms
–12
W Reference sound power = 10 (see note 5) W
o
Recovery correction factor Dimensionless
α
Contraction coefficient for valve outlet or expander inlet Dimensionless
β
γ Specific heat ratio Dimensionless

60534-8-3  IEC:2000 – 21 –
Acoustical efficiency factor (see note 2) Dimensionless
η
Density of fluid at p and T kg/m
ρ
1 1
ρ Density of fluid at p and T kg/m
2 2 2
ρ Density of fluid at last stage of multistage valve kg/m
n
with n stages at p and T
n n
Φ Relative flow coefficient Dimensionless
Subscripts
e Denotes external
i Denotes internal
n Denotes last stage of trim
R Denotes conditions in downstream pipe or pipe expander
NOTE 1 Standard atmospheric pressure is 101,325 kPa or 1,01325 bar.
NOTE 2 Subscripts 1, 2, 3, 4 and 5 denote regimes I, II, III, IV and V respectively.
2 5
NOTE 3 1 bar = 10 kPa = 10 Pa.
NOTE 4 For the purpose of calculating the vena contracta pressure, and therefore velocity, in this standard,
pressure recovery for gases is assumed to be identical to that of liquids.
NOTE 5 Sound power and sound pressure are customarily expressed using the logarithmic scale known as the
decibel scale. This scale relates the quantity logarithmically to some standard reference. This standard reference is
–5 –12
2 × 10 Pa for sound pressure and 10 W for sound power.
5 Valves with standard trim
5.1 Pressures and pressure ratios
There are several pressures and pressure ratios needed in the noise prediction procedure.
They are given below.
The vena contracta is the region of maximum velocity and minimum pressure. This minimum
pressure, which cannot be less than zero absolute, is calculated as follows:
pp−
pp=− (1)
vc 1
F
L
NOTE 1 This equation is the definition of F for subsonic conditions.
L
NOTE 2 When the valve has attached fittings, replace F with F /F .
L LP p
F vena contracta vena contracta
NOTE 3 The factor is needed in the calculation of the pressure. The pressure is
L
then used to calculate the velocity, which is needed to determine the acoustical efficiency factor.
At critical flow conditions, the pressure in the vena contracta is calculated as follows:
γ /()γ −1
 
p = p   (2)
vcc 1
 
γ + 1
 
60534-8-3  IEC:2000 – 23 –
The critical downstream pressure where sonic flow in the vena contracta begins is calculated
from the following equation:
()
p = p − F p − p (3)
2C 1 L 1 vcc
NOTE 4 When the valve has attached fittings, replace F with F /F .
L LP p
The correction factor α is the ratio of two pressure ratios:
a) the ratio of inlet pressure to outlet pressure at critical flow conditions;
b) the ratio of inlet pressure to vena contracta pressure at critical flow conditions.
It is defined as follows:
 
p
 
 
p
p
 2C 
vcc
α ≡ =
(4)
p
 
p
2C
 
 
p
 vcc 
The point at which the shock cell-turbulent interaction mechanism (regime IV) begins to
dominate the noise spectrum over the turbulent-shear mechanism (regime III) is known as the
break point. See 5.2 for a description of these regimes. The downstream pressure at the break
point is calculated as follows:
γ /(γ −1)
p  
p =    (5)
2B
 
α γ
 
The downstream pressure at which the region of constant acoustical efficiency (regime V)
begins is calculated as follows:
p
p = (6)
2CE
22 α
5.2 Regime definition
A control valve controls flow by converting potential (pressure) energy into turbulence. Noise in
a control valve results from the conversion of a small portion of this energy into sound. Most of
the energy is converted into heat.
The different regimes of noise generation are the result of differing sonic phenomena or
reactions between molecules in the gas and the sonic shock cells. In regime I, flow is subsonic
and the gas is partially recompressed, thus the involvement of the factor F . Noise generation
L
in this regime is predominantly dipole.
In regime II, sonic flow exists with interaction between shock cells and with turbulent choked
flow mixing. Recompression decreases as the limit of regime II is approached.
In regime III, no isentropic recompression exists. The flow is supersonic, and the turbulent
flow-shear mechanism dominates.

60534-8-3  IEC:2000 – 25 –
In regime IV, the shock cell structure diminishes as a Mach disk is formed. The dominant
mechanism is shock cell-turbulent flow interaction.
In regime V, there is constant acoustical efficiency; a further decrease in p will result in no
increase in noise.
For a given set of operating conditions, the regime is determined as follows:
Regime I If p ≥ p
2 2C
Regime II If p > p ≥ p
2C 2 vcc
Regime III If p > p ≥ p
vcc 2 2B
≥
Regime IV If p > p p
2B 2 2CE
Regime V If p > p
2CE 2
5.3 Preliminary calculations
5.3.1 Valve style modifier F
d
In the case of multistage valves, F applies only to the last stage.
d
The valve style modifier can be calculated by
d
H
F = (7a)
d
d
o
The hydraulic diameter d of a single flow passage is determined by the following equation:
H
4 A
d = (7b)
H
l
w
The equivalent circular diameter d of the total flow area is given as follows:
o
4NA
o
= (7c)
d
o
π
Typical values of F are given in table 2.
d
5.3.2 Jet diameter D
j
The jet diameter is given by the following equation:
D = N F C F (8)
j 14 d L
NOTE 1 N is a numerical constant, the values of which account for the specific flow coefficient (K or C ) used.
14 v v
Values of the constant may be obtained from table 1.
C C
NOTE 2 Use the required , not the valve rated value of .
NOTE 3 When the valve has attached fittings, replace F with F /F .
L LP p
60534-8-3  IEC:2000 – 27 –
5.3.3 Acoustic power ratio r
w
The acoustic power ratio represents the portion of sound power radiated into the downstream
pipe. Factors for various valves and fittings are given in table 3.
Table 1 − Numerical constants N
Flow coefficient
Constant
K C
v v
–3 –3
N 4,9 × 10 4,6 × 10
4 4
N
4,23 × 10 4,89 × 10
NOTE Unlisted numerical constants are not used in this standard.
Table 2 – Typical values of valve style modifier F (full size trim)
d
Relative flow coefficient ΦΦ
Valve type Flow direction
0,10 0,20 0,40 0,60 0,80 1,00
Globe, parabolic plug To open 0,10 0,15 0,25 0,31 0,39 0,46
To close 0,20 0,30 0,50 0,60 0,80 1,00
Globe, 3 V-port plug Either* 0,29 0,40 0,42 0,43 0,45 0,48
Globe, 4 V-port plug Either* 0,25 0,35 0,36 0,37 0,39 0,41
Globe, 6 V-port plug Either* 0,17 0,23 0,24 0,26 0,28 0,30
Globe, 60 equal diameter hole drilled cage Either* 0,40 0,29 0,20 0,17 0,14 0,13
Globe, 120 equal diameter hole drilled
Either* 0,29 0,20 0,14 0,12 0,10 0,09
cage
Butterfly, swing-through (centered shaft),
Either 0,26 0,34 0,42 0,50 0,53 0,57
to 70
°
Either 0,08 0,10 0,15 0,20 0,24 0,30
Butterfly, fluted vane, to 70°
Either 0,50
Butterfly 60° flat disk
Eccentric rotary plug Either 0,12 0,18 0,22 0,30 0,36 0,42
Segmented ball 90° Either 0,60 0,65 0,70 0,75 0,78 0,98
NOTE These values are typical only; actual values are stated by the manufacturer.
* Limited p − p in flow to close direction.
1 2
60534-8-3  IEC:2000 – 29 –
Table 3 – Acoustic power ratio r
w
Valve or fitting r
w
Globe, parabolic plug 0,25
Globe, 3 V-port plug 0,25
Globe, 4 V-port plug 0,25
Globe, 6 V-port plug 0,25
Globe, 60 equal diameter hole drilled cage 0,25
Globe, 120 equal diameter hole drilled cage 0,25
Butterfly, swing-through (centered shaft), to 70° 0,5
Butterfly, fluted vane, to 70° 0,5
Butterfly, 60° flat disk 0,5
Eccentric rotary plug 0,25
Segmented ball 90° 0,25
Expanders 1
5.4 Regime I (subsonic flow)
The velocity of the gas in the vena contracta is given by the following equation:
(γ −1) / γ
 
 
 γ  p p
vc 1
 
U = 2  1−  
(9)
vc
 
 
γ − 1  p  ρ
   1  1
 
The stream power of the mass flow is calculated as follows:
mU()
vc
W = (10)
m
The temperature in the vena contracta for subsonic flow is calculated from the following
equation:
(γ −1) / γ
 p 
vc
 
T = T (11)
vc 1
 
p
 1 
In the vena contracta, the speed of sound is calculated as follows:
γ R T
vc
c = (12)
vc
M
The Mach number in the vena contracta is calculated using the following equation:
U
vc
M = (13)
vc
c
vc
60534-8-3  IEC:2000 – 31 –
For regime I, the acoustical efficiency factor is calculated as follows:
3,6
−4
η = ( 1 × 10 ) M (14)
1 vc
Thus, the sound power generated in regime I and radiated into the downstream pipe is
=  (15)
W η r W F
a 1 w m L
NOTE When the valve has attached fittings, replace F with F /F .
L LP p
Although not required for this method, the total internal sound power level is calculated as
follows:
W
a
L = 10 log (16)
wi 10
W
o
To calculate pipe internal sound power, subtract 6 dB from L .
wi
The peak frequency of the generated noise is calculated from the following equation:
0,2 U
vc
= (17)
f
p
D
j
5.5 Regimes II to V (common calculations)
The following calculations are common for regimes II through V, which are at sonic velocity or
above.
For sonic (or critical) flow, the temperature is given by
vena contracta
2 T
T = (18)
vcc
γ + 1
The velocity of sound in the vena contracta is calculated using the following equation:
γ R T
vcc
c = (19)
vcc
M
Stream power is then calculated as follows:
m c
vcc
W = (20)
ms
Although not required for this method, the internal sound power level is calculated using
equation (16) and equations (23), (26), (28) or (32).

60534-8-3  IEC:2000 – 33 –
In the freely expanding jet, the Mach number is calculated from the following equation for
regimes II through IV:
()γ −1 / γ
 
 
2 p
 
  − 1
M = (21)
j
 
γ − 1  α p 
 2 
 
5.5.1 Regime II
The acoustical efficiency factor for regime II is calculated from the following equation:
−4 6,6 F
L
η =() 1 × 10 M (22)
2 j
NOTE When the valve has attached fittings, replace F with F /F .
L LP p
The sound power generated in regime II and radiated into the downstream pipe is calculated as
follows:
 p − p 
1 2
 
W = η r W (23)
a 2 w ms
 
p − p
1 vcc
 
The peak frequency is then determined as follows:
0,2Mc
j vcc
= (24)
f
p
D
j
5.5.2 Regime III
In regime III, the acoustical efficiency factor is calculated as follows:
−4 6,6 F
L
()
η = 1 × 10 M (25)
3 j
NOTE When the valve has attached fittings, replace F with F /F .
L LP p
The sound power generated in regime III and radiated into the downstream pipe is given by the
following equation:
W = η r W (26)
a 3 w ms
The peak frequency is calculated from equation (24).
5.5.3 Regime IV
The acoustical efficiency factor in regime IV is calculated as follows:
 
M
6,6 F
j L
−4  
() ()
η = 1 × 10  2 (27)
 
 2 
 
NOTE When the valve has attached fittings, replace F with F /F .
L LP p
60534-8-3  IEC:2000 – 35 –
The sound power generated in regime IV and radiated into the downstream pipe is then
calculated from the following equation:
W = η r W (28)
a 4 w ms
The peak frequency for regime IV is then determined as follows:
0,35 c
vcc
(29)
f =
p
1,25DM −1
jj
5.5.4 Regime V
In this regime, the jet Mach number is calculated from the following equation:
()/
γ −1 γ
M = [] ()22 − 1 (30)
j5
γ − 1
The constant acoustical efficiency factor is determined as follows:
 
 
M 2
j5
 
−4   6,6 F
L
()
η = 1 × 10 2 (31)
 
 
 
 
 
 
NOTE When the valve has attached fittings, replace F with F /F .
L LP p
Then, the sound power generated in regime V and radiated into the downstream pipe is
calculated as follows:
W = η r W (32)
a 5 w ms
The peak frequency for regime V is calculated from equation (29) using M instead of M .
j5 j
5.6 Noise calculations
The downstream mass density is calculated from the following equation:
 
p
 
ρ = ρ (33)
2 1
 
p
 1 
The downstream temperature T may be determined by using thermodynamic isenthalpic
relationships, provided that the necessary fluid properties are known. However, if the fluid
properties are not known, T may be taken as approximately equal to T .
2 1
From the following equation, the downstream sonic velocity can be calculated:
γ
R T
c = (34)
M
60534-8-3  IEC:2000 – 37 –
The Mach number at the valve outlet is calculated using equation (35).
4 m
M = (35)
o
π D ρ c
2 2
NOTE 1 M should not exceed 0,3. If M exceeds 0,3, then accuracy cannot be maintained, and the procedure in
o o
clause 7 should be used.
To calculate the internal sound-pressure level referenced to P , the following equation is used:
o
 
() 3,2 × 10 W ρ c
a 2 2
L = 10 log   (36)
pi 10
 D 
 i 
The transmission loss across the pipe wall is calculated as follows:
 
 
   
 
c G p
−7 2 x a
 
TL = 10 log ()7,6 × 10   (37)
 
 
 
t f p
 
 p p ρ c  s 
 
2 2
 
+ 1
 
 
415 G
y

  
 
NOTE 2 G and G are defined in table 4.
x y
NOTE 3 The ratio p /p is a correction for local barometric pressure.
a s
NOTE 4 The transmission loss model is based on an internal frequency distribution of 6 dB/octave.
The frequencies f , f and f are calculated from the following equations:
r o g
5 000
f = (38)
r
π D
i
f c
 
r 2
f =   (39)
o  
4 343
 
3 ()343
f = (40)
g
π t()5 000
p
NOTE 5 In equations (39) and (40), the constant 343 is the speed of sound in air in metres per second (m/s).
NOTE 6 In equations (38) and (40), the constant 5 000 is the nominal speed of sound in the pipe wall in metres
per second (m/s) for steel.
NOTE 7 Note that the minimum transmission loss occurs at the first pipe coincidence frequency.

60534-8-3  IEC:2000 – 39 –
Table 4 – Frequency factors G and G
x y
f < f
f ≥ f
p o
p o
2 / 3
f
 
p
 
4 G = for f < f
2 / 3
x p r
 
f
   
f f
p
o r
 
 
 
G =
x
 
 
f f
 r  o
 
G = 1 for f ≥ f
x p r
   f 
f
p
o
   
G = for f < f G = for f < f
y o g y p g
   
f f
g g
   
G = 1 for f ≥ f G = 1 for f ≥ f
y o g y p g
The downstream pipe velocity correction is approximately:
 
L = 16 log   (41)
g 10
 
1− M
 2 
where
4 m
M = (42)
π D ρ c
i 2 2
NOTE 8 For calculating L , M is limited to 0,3.
g 2
The A-weighted sound-pressure level that is radiated at the outside diameter of the pipe is
determined as follows:
L = 5 + L + TL + L (43)
pAe pi g
NOTE 9 In equation (43), the first term of 5 dB is an average correction that accounts for all of the frequency
peaks.
Finally, the A-weighted sound-pressure level at a distance of 1 m from the pipe wall is
calculated as follows:
D + 2t + 2
i p
L = L − 10 log   (44)
pAe,1m pAe 10
D + 2t
 i p 
 
5.7 Calculation flow chart
The following flow chart provides a logical sequence for using the above equations to calculate
the sound-pressure level.
60534-8-3  IEC:2000 – 41 –
Start with subclauses 5.1, 5.2 and 5.3.
If regime I, then subclauses 5.4 and 5.6.
If regime II, then subclauses 5.5, 5.5.1 and 5.6.
If regime III, then subclauses 5.5, 5.5.2 and 5.6.
If regime IV, then subclauses 5.5, 5.5.3 and 5.6.
If regime V, then subclauses 5.5, 5.5.4 and 5.6.
NOTE See annex A for calculation examples.
6 Valves with noise-reducing trim
6.1 Introduction
This clause is applicable to valves with noise-reducing trim. Although it uses much of the
procedure from clause 5, it is placed in a separate clause of this standard, because these trims
need special consideration.
6.2 Single stage, multiple flow passage trim
For valves with single stage, multiple flow passage trim (see figure 1 for one example of many
effective noise reducing trims), the procedure in clause 5 shall be used, except as noted below.
d
l
Valve plug
Drilled cage
IEC  625/2000
NOTE This is one example of many effective noise-reducing trims.
Figure 1 – Single stage, multiple flow passage trim

60534-8-3  IEC:2000 – 43 –
All flow passages shall have the same hydraulic diameter, and the distance between them shall
be sufficient to prevent jet interaction.
Although the valve style modifier is the same as in clause 5, an example of its application is
given below:
Example:
Assume a trim with 48 exposed rectangular passages which have a width of 0,010 m and a
height of 0,002 m. The area A of each passage is 0,010 × 0,002 = 0,000 02 m . The wetted
perimeter l = (2 × 0,010) + (2 × 0,002) = 0,024 m; d = 0,035 m, and d = 0,0033, which yields
w o H
F = 0,0033/0,035 = 0,094.
d
The jet diameter D is calculated as follows:
j
[]
D = N ⋅ F C 0,9 − 0,06()l/ d (45)
j 14 d
NOTE 1 F has been replaced by [0,9 – 0,06(l/d)] in the expression for D , and l/d has a maximum value of 4.
Ln j
The result of using [0,9 – 0,06(l/d)] instead of F is a general increase in the transmission loss
Ln
in regimes I, II and III by up to 5 dB.
The Mach number at the valve outlet is calculated using equation (35).
NOTE 2 For pressure ratios p /p > 4, equation (7a), which is used to calculate F , is only applicable when the wall
1 2 d
distance between passages exceeds 0,7 d. It also loses its validity if the Mach number M at the valve outlet exceeds 0,2.
o
6.3 Single flow path, multistage pressure reduction trim (two or more throttling steps)
For single flow path, multistage valves (see figure 2 for one example of many effective noise-
reducing trims), the procedure of clause 5 shall be used, except as noted below.
Seat ring
Valve plug
IEC  626/2000
NOTE This is one example of many effective noise-reducing trims.
Figure 2 – Single flow path, multistage pressure reduction trim

60534-8-3  IEC:2000 – 45 –
NOTE 1 All calculations in 6.3 are applicable to the last stage.
The flow coefficient C shall be used in place of C. It is applicable to the last stage of the
n
multistage trim. When values of C are not available from the valve manufacturer, the following
n
relationship shall be used:
CN= A (46)
n16 n
NOTE 2 N is a numerical constant, the value of which accounts for the specific flow coefficient (K or C ) used.
16 v v
Values of the constants may be obtained from table 1.
The stagnation pressure p at the last stage shall be used in place of p , and the density ρ
n 1 n
shall be used in place of ρ . These values are determined using the following equations as
appropriate:
NOTE 3 If p /p ≥ 2, then first assume that p /p < 2 and calculate p from equation (47a). If the calculated
1 2 n 2 n
p ≥ 2 p , then calculate p from equation (47b) and continue with the procedure.
n 2 n
If p /p ≥ 2 and p /p < 2:
1 2 n 2
 p C 
 
p = + p (47a)
n 2
 
1,155 C
 n 
If p /p ≥ 2 and p /p ≥ 2:
1 2 n 2
 
C
 
p = p (47b)
n 1
 
C
 n 
If p /p < 2:
1 2
 C 
2 2 2
 ()
p = p − p + p (47c)
n 1 2 2
 
C
 n 
 p 
n
 
ρ = ρ (48)
n 1
 
p
 1 
The jet diameter for the last stage used in the equations for the peak frequency is determined
from the following equation:
D = N F C F (49)
j 14 d n L
NOTE 4 For this equation, use F of the last stage.
d
Finally, the A-weighted sound pressure level that is radiated at the outside diameter of the pipe
is determined from the following equation:
 P 
 
L = 5 + L + 10 log  + TL + L (50)
pAe pi 10 g
 
P
 n 
NOTE 5 The noise contribution of the last stage is given by L . The term 10 log (p p ) includes the sound
pi 10 1/ n
pressure level caused by the pressure reductions of the other stages.

60534-8-3  IEC:2000 – 47 –
6.4 Multipath, multistage trim (two or more passages and two or more stages)
NOTE 1 This subclause covers only linear travel valves.
NOTE 2 All calculations in 6.4 are applicable to the last stage.
For multipath, multistage trim (see figure 3 for one example of many effective noise-reducing
trims), the procedure of clause 5 shall be used, except as noted below.
Valve
plug
IEC  627/2000
NOTE This is one example of many effective noise-reducing trims.
Figure 3 – Multipath, multistage trim (two or more passages and two or more stages)
All flow passages shall have the same hydraulic diameter, and the distance between them shall
be sufficient to prevent jet interaction. The flow area of each stage shall increase between inlet
and outlet.
The vena contracta pressure p shall be calculated using F instead of F in equation (1).
vc Ln L
The flow coefficient per equation (46) shall be used in place of ; the stagnation pressure
C C
n
p of the last stage per equation (47) shall be used in place of p ; and the density ρ per
n 1 n
equation (48) shall be used in place of ρ .
The jet Mach number is calculated from the following equation:
U
vc
M = (51)
jn
c
vc
where the velocity U in the last stage is determined from equation (9) using p in place of p
vc n 1
and using ρ in place of ρ .
n 1
60534-8-3  IEC:2000 – 49 –
The peak frequency f is calculated from equation (52) using the jet diameter D for the last
p j
stage from equation (49):
0,2 M c
jn vc
= (52)
f
p
D
j
Finally, the A-weighted sound-pressure level L is calculated using equation (50).
pAe
M
NOTE 3 The method of 6.4 is not accurate if the Mach number at the valve outlet exceeds 0,2. For calculation
o
of M , see equation (35). At a Mach number of 0,3, errors may exceed 5 dB. Refer to clause 7 for the procedure for
o
higher Mach numbers.
NOTE 4 See annex A for a calculation example.
6.5 Valves not included in this standard
Low noise trims other than those in clause 6 are not covered by this standard. The method of
this standard may be used for these trims, provided the manufacturer supplies values to justify
additional changes in sound-pressure level as a function of travel and/or valve-pressure ratio in
addition to the sound-pressure level obtained using the applicable subclauses of clause 5 of
this standard.
7 Valves with higher outlet Mach numbers
7.1 Introduction
This clause provides a method for predicting sound pressure levels
...