SIST EN 60534-8-3:2011
(Main)Industrial-process control valves - Part 8-3: Noise considerations - Control valve aerodynamic noise prediction method (IEC 60534-8-3:2010)
Industrial-process control valves - Part 8-3: Noise considerations - Control valve aerodynamic noise prediction method (IEC 60534-8-3:2010)
This Standard 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. 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. 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 FpC exceeds 50 % of the rated flow coefficient. This third edition cancels and replaces the second edition published in 2000. This edition constitutes a technical revision. The significant technical changes with respect to the previous edition are as follows: - predicting noise as a function of frequency; - using laboratory data to determine the acoustical efficiency factor.
Vannes de régulation des processus industriels - Partie 8-3: Considérations sur le bruit - Méthode de prédiction du bruit aérodynamique des vannes de régulation (IEC 60534-8-3:2010)
Vannes de régulation des processus industriels - Partie 8-3: Considérations sur le bruit - Méthode de prévision du bruit aérodynamique des vannes de régulation (CEI 60534-8-3:2010)
La CEI 60534-8-3:2010 établit une méthode théorique pour prévoir le niveau de pression acoustique externe engendré dans une vanne de régulation et dans les raccords adjacents par le débit d'un fluide compressible. Cette méthode ne considère que les régimes monophasiques de gaz et vapeurs secs, et est basée sur la loi des gaz parfaits. On suppose que la tuyauterie aval comprend une longueur droite d'au moins 2 m à partir du point de mesure du bruit. La méthode est applicable aux vannes mono-étagées suivantes: - à soupape (droites et d'équerre), - à papillon, - à obturateur rotatif (excentré, sphérique), - à tournant sphérique, et - aux vannes à cage. Les vannes à tournant sphérique à passage direct, pour lesquelles le produit FpC dépasse 50 % du coefficient de débit assigné, sont spécifiquement exclues. Cette troisième édition annule et remplace la deuxième édition parue en 2000. Cette édition constitue une révision technique. Par rapport à l'édition précédente, les modifications techniques majeures sont les suivantes: - la prédiction du bruit en fonction de la fréquence; - l'utilisation des données de laboratoire pour déterminer le coefficient de rendement acoustique.
Regulacijski ventili za industrijske procese - 8-3. del: Šum - Metoda napovedovanja aerodinamičnega šuma regulacijskega ventila (IEC 60534-8-3:2010)
Ta standard vzpostavlja teoretično metodo za napovedovanje zunanjega nivoja zračnega pritiska, ki se naredi v regulacijskem ventilu in v bližnjih razširjevalcih cevi s pretokom stisljivih tekočin. Ta metoda upošteva samo enofazne suhe pline in hlape in temelji na zakonih popolnega plina. Predvideva se, da je dovodno cevje ravno z dolžino vsaj 2 m od točke, kjer so bile izvedene meritve šuma. Metoda velja za naslednje enostopenjske ventile: – kroglasti (ravni vzorec ali kotni vzorec); – metuljasti – rotacijski ventil z vtičem (ekscentrični, sferični); – krogla in – ventili s prirezanimi kletkami. Izrecno izvzeti so polni kroglasti ventili, kjer produktni FpC presega 50 % ocenjenega koeficienta pretoka. Ta tretja izdaja razveljavlja in nadomešča drugo izdajo, objavljeno leta 2000. Ta izdaja je tehnična revizija. Večje tehnične spremembe glede na prejšnjo izdajo so naslednje: – napovedovanje šuma kot funkcije frekvence; – uporaba laboratorijskih podatkov za določanje faktorjev akustične učinkovitosti.
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Vannes de régulation des processus industriels - Partie 8-3: Considérations sur le bruit - Méthode de prédiction du bruit aérodynamique des vannes de régulation (IEC 60534-8-3:2010)Vannes de régulation des processus industriels - Partie 8-3: Considérations sur le bruit - Méthode de prévision du bruit aérodynamique des vannes de régulation (CEI 60534-8-3:2010)Industrial-process control valves - Part 8-3: Noise considerations - Control valve aerodynamic noise prediction method (IEC 60534-8-3:2010)25.040.40Merjenje in krmiljenje industrijskih postopkovIndustrial process measurement and control23.060.40Pressure regulators17.140.20Emisija hrupa naprav in opremeNoise emitted by machines and equipmentICS:Ta slovenski standard je istoveten z:EN 60534-8-3:2011SIST EN 60534-8-3:2011en01-marec-2011SIST EN 60534-8-3:2011SLOVENSKI
STANDARDSIST EN 60534-8-3:20011DGRPHãþD
SIST EN 60534-8-3:2011
EUROPEAN STANDARD EN 60534-8-3 NORME EUROPÉENNE
EUROPÄISCHE NORM January 2011
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2011 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60534-8-3:2011 E
ICS 17.140.20; 23.060.40; 25.040.40 Supersedes EN 60534-8-3:2000
English version
Industrial-process control valves -
Part 8-3: Noise considerations -
Control valve aerodynamic noise prediction method (IEC 60534-8-3:2010)
Vannes de régulation des processus industriels -
Partie 8-3: Considérations sur le bruit -
Méthode de prédiction du bruit aérodynamique des vannes de régulation(CEI 60534-8-3:2010)
Stellventile für die Prozessregelung -
Teil 8-3: Geräuschbetrachtungen -
Berechnungsverfahren zur Vorhersage der aerodynamischen Geräusche von Stellventilen
(IEC 60534-8-3:2010)
This European Standard was approved by CENELEC on 2011-01-01. 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 Central Secretariat 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 Central Secretariat 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
SIST EN 60534-8-3:2011
EN 60534-8-3:2011 - 2 - Foreword The text of document 65B/765/FDIS, future edition 3 of IEC 60534-8-3, prepared by IEC/SC 65B, Devices & process analysis, of IEC TC 65, Industrial-process measurement, control and automation, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 60534-8-3 on
2011-01-01. This European Standard supersedes EN 60534-8-3:2000. The significant technical changes with respect to EN 60534-8-3:2000 are as follows: – predicting noise as a function of frequency; – using laboratory data to determine the acoustical efficiency factor. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. The following dates were fixed: – latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement
(dop)
2011-10-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2014-01-01 Annex ZA has been added by CENELEC. __________ Endorsement notice The text of the International Standard IEC 60534-8-3:2010 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated:
[1] IEC 60534-2-1 NOTE
Harmonized as EN 60534-2-1. [2] IEC 60534-8-1 NOTE
Harmonized as EN 60534-8-1. __________ SIST EN 60534-8-3:2011
- 3 - EN 60534-8-3:2011 Annex ZA
(normative)
Normative references to international publications with their corresponding European publications
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 of the referenced document (including any amendments) applies.
NOTE
When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
Publication Year Title EN/HD Year
IEC 60534 Series
Industrial-process control valves EN 60534 Series
IEC 60534-1 - Industrial-process control valves -
Part 1: Control valve terminology and general considerations EN 60534-1 -
SIST EN 60534-8-3:2011
SIST EN 60534-8-3:2011
IEC 60534-8-3 Edition 3.0 2010-11 INTERNATIONAL STANDARD NORME INTERNATIONALE Industrial-process control valves –
Part 8-3: Noise considerations – Control valve aerodynamic noise prediction method
Vannes de régulation des processus industriels –
Partie 8-3: Considérations sur le bruit – Méthode de prédiction du bruit aérodynamique des vannes de régulation
INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE X ICS 17.140.20; 23.060.40; 25.040.40 PRICE CODECODE PRIXISBN 978-2-88912-241-7
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale ® SIST EN 60534-8-3:2011
– 2 – 60534-8-3 ã IEC:2010 CONTENTS FOREWORD . 4 INTRODUCTION . 6 1 Scope . 7 2 Normative references . 7 3 Terms and definitions . 8 4 Symbols . 9 5 Valves with standard trim . 12 5.1 Pressures and pressure ratios. 12 5.2 Regime definition . 13 5.3 Preliminary calculations . 14 5.3.1 Valve style modifier Fd. 14 5.3.2 Jet diameter Dj . 14 5.3.3 Inlet fluid density r1 . 14 5.4 Internal noise calculations . 15 5.4.1 Calculations common to all regimes . 15 5.4.2 Regime dependent calculations . 16 5.4.3 Downstream calculations . 18 5.4.4 Valve internal sound pressure calculation at pipe wall . 19 5.5 Pipe transmission loss calculation. 20 5.6 External sound pressure calculation . 21 5.7 Calculation flow chart . 22 6 Valves with special trim design . 22 6.1 General . 22 6.2 Single stage, multiple flow passage trim . 22 6.3 Single flow path, multistage pressure reduction trim (two or more throttling steps) . 23 6.4 Multipath, multistage trim (two or more passages and two or more stages) . 25 7 Valves with higher outlet Mach numbers . 27 7.1 General . 27 7.2 Calculation procedure . 27 8 Valves with experimentally determined acoustical efficiency factors . 28 9 Combination of noise produced by a control valve with downstream installed two or more fixed area stages . 29 Annex A (informative)
Calculation examples . 31 Bibliography . 46
Figure 1 – Single stage, multiple flow passage trim . 23 Figure 2 – Single flow path, multistage pressure reduction trim . 24 Figure 3 – Multipath, multistage trim (two or more passages and two or more stages) . 26 Figure 4 – Control valve with downstream installed two fixed area stages . 30
Table 1 – Numerical constants N . 15 Table 2 – Typical values of valve style modifier Fd (full size trim) . 15 Table 3 – Overview of regime dependent equations . 17 SIST EN 60534-8-3:2011
60534-8-3 ã IEC:2010 – 3 – Table 4 – Typical values of Ah and Stp . 18 Table 5 – Indexed frequency bands . 19 Table 6 – Frequency factors Gx (f) and Gy (f) . 21 Table 7 – “A” weighting factor at frequency fi . 22
SIST EN 60534-8-3:2011
– 4 – 60534-8-3 ã IEC:2010 INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
INDUSTRIAL-PROCESS CONTROL VALVES –
Part 8-3: Noise considerations –
Control valve aerodynamic noise prediction method
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 60534-8-3 has been prepared by subcommittee 65B: Measurements and control devices, of IEC technical committee 65: Industrial-process measurement, control and automation. This third edition cancels and replaces the second edition published in 2000. This edition constitutes a technical revision.
The significant technical changes with respect to the previous edition are as follows:
ö predicting noise as a function of frequency; ö using laboratory data to determine the acoustical efficiency factor.
SIST EN 60534-8-3:2011
60534-8-3 ã IEC:2010 – 5 – The text of this standard is based on the following documents: FDIS Report on voting 65B/765/FDIS 65B/780/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 the parts of the 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 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.
SIST EN 60534-8-3:2011
– 6 – 60534-8-3 ã IEC:2010 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 standard offers a method to establish this value. The equations in this standard 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.
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 (see IEC 60534-8-1). The current edition has increased the level of confidence of the calculation. In some cases the results of the previous editions were more conservative. 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 ïC showed good agreement with the calculated values. A rigorous analysis of the transmission loss equations is beyond the scope of this standard. The method considers the interaction between the sound waves existing in the pipe fluid and the first coincidence frequency in the pipe wall. In addition, 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. Examples of 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.
SIST EN 60534-8-3:2011
60534-8-3 ã IEC:2010 – 7 – INDUSTRIAL-PROCESS CONTROL VALVES –
Part 8-3: Noise considerations –
Control valve aerodynamic noise prediction method
1 Scope 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 from external surfaces or internally by pipe fittings, 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 (21) and (23) in 5.5). 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 FpC exceeds 50 % of the rated flow coefficient. For limitations on special low noise trims not covered by this standard, see Clause 8. 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 location Mach number limit Clause 5 Standard trim Clause 6 Noise-reducing trim Clause 7 High Mach number applications Freely expanded jet Mj No limit No limit No limit Valve outlet Mo 0,3 0,2 1,0 Downstream reducer inlet Mr Not applicable Not applicable 1,0 Downstream pipe M2 0,3 0,2 0,8 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 of the referenced document (including any amendments) applies.
SIST EN 60534-8-3:2011
– 8 – 60534-8-3 ã IEC:2010 IEC 60534 (all parts), Industrial-process control valves IEC 60534-1, Industrial-process control valves - Part 1: Control valve terminology and general considerations 3 Terms and definitions For the purposes of this document, all of the terms and definitions given in the IEC 60534 series and the following apply: 3.1
acoustical efficiency h ratio of the stream power converted into sound power propagating downstream to the stream power of the mass flow 3.2
external coincidence frequency fg 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 fo lowest frequency at which the internal 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 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 fp frequency at which the internal sound pressure is maximum 3.7
valve style modifier Fd 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 SIST EN 60534-8-3:2011
60534-8-3 ã IEC:2010 – 9 – 4 Symbols Symbol Description Unit A Area of a single flow passage m2 Ah Valve correction factor for acoustical efficiency
(see Table 4) Dimensionless An Total flow area of last stage of multistage trim with n stages at given travel m2 C Flow coefficient (Kv and Cv) Various (see IEC 60534-1) ca External speed of sound (dry air at standard conditions = 343 m/s) m/s Cn Flow coefficient for last stage of multistage trim with n stages Various (see IEC 60534-1) cs Speed of sound of the pipe (for steel = 5 000 m/s) m/s cvc Speed of sound in the vena contracta at subsonic flow conditions m/s cvcc Speed of sound in the vena contracta at critical flow conditions m/s c2 Speed of sound at downstream conditions m/s D Valve outlet diameter m d Diameter of a flow passage (for other than circular, use dH) m dH Hydraulic diameter of a single flow passage m di Smaller of valve outlet or expander inlet internal diameters m Di Internal downstream pipe diameter m Dj Jet diameter at the vena contracta m do Diameter of a circular orifice, the area of which equals the sum of areas of all flow passages at a given travel m Fd Valve style modifier Dimensionless FL Liquid pressure recovery factor of a valve without attached fittings (see Note 4) Dimensionless FLn Liquid pressure recovery factor of last stage of low noise trim Dimensionless FLP Combined liquid pressure recovery factor and piping geometry factor of a control valve with attached fittings (see Note 4) Dimensionless Fp Piping geometry factor Dimensionless fg External coincidence frequency Hz fo Internal coincidence pipe frequency Hz fp Generated peak frequency Hz fpR Generated peak frequency in valve outlet or reduced diameter of expander Hz fr Ring frequency Hz fs Structural loss factor reference frequency = 1 Hz Hz SIST EN 60534-8-3:2011
– 10 – 60534-8-3 ã IEC:2010 Symbol Description Unit Gx, Gy Frequency factors (see Table 4) Dimensionless I Length of a radial flow passage m lw Wetted perimeter of a single flow passage m Lg Correction for Mach number dB (ref po) Lpe,1m (f) Frequency-dependent external sound-pressure level 1 m from pipe wall dB(ref po) LpAe,1m A-weighted overall sound-pressure level 1 m from pipe wall dB(A) (ref po) Lpi Overall Internal sound-pressure level at pipe wall
dB (ref po) Lpi (f) Frequency-dependent internal sound-pressure level at pipe wall dB (ref po) LpiR Overall Internal sound-pressure level at pipe wall for noise created by outlet flow in expander dB (ref po) LpiR (f) Frequency-dependent internal sound-pressure level at pipe wall for noise created by outlet flow in expander dB (ref po) LpiS (f) Combined
internal frequency-dependent sound-pressure at the pipe wall, caused by the valve trim and expander dB (ref po) Lwi Total internal sound power level dB (ref Wo) M Molecular mass of flowing fluid kg/kmol Mj Freely expanded jet Mach number in regimes II to IV Dimensionless Mjn Freely expanded jet Mach number of last stage in multistage valve with n stages Dimensionless Mj5 Freely expanded jet Mach number in regime V Dimensionless Mo Mach number at valve outlet Dimensionless MR Mach number in the entrance to expander Dimensionless Mvc Mach number at the vena contracta Dimensionless M2 Mach number in downstream pipe Dimensionless &m Mass flow rate kg/s N Numerical constants (see Table 1) Various no Number of independent and identical flow passages in valve trim Dimensionless pa Actual atmospheric pressure outside pipe Pa (see Note 3) pn Absolute stagnation pressure at inlet of the last stage of multistage valve with n stages Pa po Reference sound pressure = 2 ´ 10–5 (see Note 5) Pa ps Standard atmospheric pressure (see Note 1) Pa pvc Absolute vena contracta pressure at subsonic flow conditions Pa p1 Valve inlet absolute pressure Pa p2 Valve outlet absolute pressure Pa R Universal gas constant = 8 314 J/kmol ´ K St Strouhal number for peak frequency calculation (see Table 4) Dimensionless SIST EN 60534-8-3:2011
60534-8-3 ã IEC:2010 – 11 – Symbol Description Unit Tn Inlet absolute temperature at last stage of multistage valve with n stages K Tvc Vena contracta absolute temperature at subsonic flow conditions K Tvcc Vena contracta absolute temperature at critical flow conditions K T1 Inlet absolute temperature K T2 Outlet absolute temperature K TL(f) Frequency-dependent transmission loss
dB ts Pipe wall thickness m Up Gas velocity in downstream pipe m/s UR Gas velocity in the inlet of diameter expander m/s Wa Sound power for noise crated by valve flow and propagating downstream W WaR Sound power for noise generated by the outlet flow and propagating downstream W Wm Stream power of mass flow W Wms Stream power of mass flow rate at sonic velocity W WmR Converted stream power in the expander
W Wo Reference sound power = 10–12 (see Note 5) W x Differential pressure ratio
Dimensionless xvcc Vena contracta differential pressure ratio at critical flow conditions Dimensionless xB Differential pressure ratio at break point Dimensionless xC Differential pressure ratio at critical flow conditions Dimensionless xCE Differential pressure ratio where region of constant acoustical efficiency begins Dimensionless a Recovery correction factor Dimensionless b Contraction coefficient for valve outlet or expander inlet Dimensionless g Specific heat ratio Dimensionless aLA(f) A-Weighting correction based on frequency dB aTL Damping factor for transmission loss dB h Acoustical efficiency factor for noise created by valve flow (see Note 2) Dimensionless hR Acoustical efficiency factor for noise created by outlet flow in expander Dimensionless hs(f) Frequency-dependent structural loss factor Dimensionless r1 Density of fluid at p1 and T1 kg/m3 r2 Density of fluid at p2 and T2 kg/m3 rn Density of fluid at last stage of multistage valve with n stages at pn and Tn kg/m3 rs Density of the pipe
kg/m3 F Relative flow coefficient Dimensionless SIST EN 60534-8-3:2011
– 12 – 60534-8-3 ã IEC:2010 Symbol Description Unit
Subscripts
e Denotes external
i Denotes internal or used as an index for the frequency band number
n Denotes last stage of trim
p Denotes peak
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. NOTE 3 1 bar = 102 kPa = 105 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 2 ´ 10–5 Pa for sound pressure and 10–12 W for sound power. 5 Valves with standard trim 5.1 Pressures and pressure ratios There are several pressures and
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.