SIST EN 12102:2008
Air conditioners, liquid chilling packages, heat pumps and dehumidifiers with electrically driven compressors for space heating and cooling - Measurement of airborne noise - Determination of the sound power level
Air conditioners, liquid chilling packages, heat pumps and dehumidifiers with electrically driven compressors for space heating and cooling - Measurement of airborne noise - Determination of the sound power level
This document establishes requirements for determining, in accordance with a standardized procedure, the sound power level emitted into the surrounding air by air-conditioners, heat-pumps, liquid chilling packages with electrically driven compressors when used for space heating and/or cooling, as described by the standards EN 14511 and dehumidifiers as described by the standard EN 810.
It is emphasized that this measurement standard only refers to airborne noise.
This standard applies to factory-made units of either fixed capacity or variable capacity by any means.
It covers:
- packaged units, single split and multisplit systems, except water cooled multisplit systems,
- air-to-air air conditioners which evaporate the condensate on the condenser side,
- chillers, shelters, roof-tops.
- inverters.
In the case of units consisting of several parts, this standard applies only to those designed and supplied as a complete package, except for liquid chilling packages with remote condenser.
This standard does not cover:
- units having their condenser cooled by air and by the evaporation of external additional water,
- heat pumps for sanitary hot water, although some definitions can be applied to these units,
- units using transcritical cycles, e.g. with CO2 as refrigerant,
- installations used for heating and/or cooling of industrial processes.
This standard offers ways to determine the sound power level of units. Some of them are specifically adapted to provide results with low uncertainties, by using laboratory class acoustic methods and highly controlled working conditions. Those measurements are suitable for certification, labelling and marking purposes.
In some cases, the target and/or the environment of the measurements do not allow such precision-class results. This standard also offers ways to assess sound power levels with acceptable accuracy even though acoustic methods and/or working conditions are not laboratory-type, e.g. in situ or quality control measurements. This European Standard gives two classes of measurements and results, according to the test environment:;Class A measurements correspond to controlled working conditions (standard or application rating conditions). It is defined by the respect to the tolerances of Table 2.;Class B measurements correspond to the case where the range defined by the tolerances of Table 2 cannot be fulfilled. In both classes, precision or engineering class acoustic methods should be applied. The choice of the acoustic measurement method is done in accordance with EN ISO 3740 and EN ISO 9614 depending on the type of surrounding acoustic fields (diffuse or free field, enclosed or open space), and the available instrumentation. Whatever the current working conditions, the reference of acoustic standard shall be reported, with explicit mention of its accuracy class.
Klimageräte, Flüssigkeitskühlsätze, Wärmepumpen und Entfeuchter mit elektrisch angetriebenen Verdichtern zur Raumbeheizung und Kühlung - Messung der Luftschalllemissionen - Bestimmung des Schallleistungspegels
Diese Europäische Norm legt Anforderungen fest, nach denen der von Klimageräten, Wärmepumpen, Flüssigkeitskühlsätzen mit elektrisch angetriebenen Verdichtern zur Raumbeheizung und Kühlung nach den Normen der Reihe EN 14511 und Entfeuchtern nach der Norm EN 810 an die umgebende Luft abgegebene Schallleistungspegel nach einem genormten Verfahren ermittelt wird.
Es wird darauf hingewiesen, dass sich diese Messnorm nur auf Luftschallemissionen bezieht.
Diese Norm enthält Verfahren für die Ermittlung des Schallleistungspegels von Geräten. Einige dieser Ver¬fahren sind durch Anwendung akustischer Verfahren im Labor und streng geregelter Arbeitsbedingungen speziell so angepasst, dass die Ergebnisse nur geringe Messunsicherheiten aufweisen. Diese Messungen sind für die Zertifizierung, Etikettierung und Kennzeichnung geeignet.
In einigen Fällen sind aufgrund der Zielsetzung und/oder der Messumgebung Ergebnisse dieser Genauigkeitsklasse nicht möglich. Diese Europäische Norm enthält außerdem Verfahren für eine ausreichend genaue Bewertung von Schallleistungspegeln mit akustischen Verfahren und/oder Arbeitsbedingungen außerhalb des Labors, z. B. vor Ort oder Qualitätskontrollmessungen.
Diese Europäische Norm empfiehlt in Abhängigkeit von der Prüfumgebung 2 Klassen für Messungen und Ergebnisse:
Messungen der Klasse A entsprechen geregelten Arbeitsbedingungen (Norm- oder Betriebs-Nennbedingungen). Klasse A wird begrenzt durch Einhaltung der Grenzabweichungen nach Tabelle 2.
Messungen der Klasse B können den durch die Grenzabweichungen in Tabelle 2 vorgegebenen Bereich nicht einhalten.
Bei beiden Klassen sollten akustische Verfahren der Genauigkeitsklasse 1 oder der Genauigkeitsklasse 2 angewendet werden. Die Wahl des akustischen Verfahrens erfolgt nach EN ISO 3740 sowie der Normenreihe EN ISO 9614 in Abhängigkeit der umgebenden Schallfelder (diffuses oder freies Schallfeld, geschlossener oder offener Raum) und den zur Verfügung stehenden Messgeräten.
Climatiseurs, groupes refroidisseurs de liquide, pompes à chaleur et déshumidificateurs avec compresseur entraîné par moteur électrique pour le chauffage et la réfrigération - Mesure de bruit aérien émis - Détermination du niveau de puissance acoustique
La présente Norme européenne établit les exigences de détermination, suivant un mode opératoire normalisé,
du niveau de puissance acoustique émis dans l’air environnant par les climatiseurs, pompes à chaleur ou
groupes refroidisseurs de liquide avec compresseur entraîné par moteur électrique, lorsqu’ils sont utilisés
pour le chauffage et/ou la réfrigération d’un espace, incluant les systèmes multi-split à condensation par eau
comme décrit par l’EN 14511, et par les déshumidificateurs comme décrits par l’EN 810.
Il est souligné que la présente norme de mesure se réfère uniquement au bruit aérien.
La présente Norme européenne propose des moyens de déterminer le niveau de puissance acoustique des
appareils. Certains sont spécifiquement adaptés pour fournir des résultats de faible incertitude, en utilisant
des méthodes acoustiques de laboratoire et des conditions de travail très contrôlées. Ces mesurages
conviennent dans un but de certification, d’étiquetage et de marquage.
Dans certains cas, l’objectif et/ou l’environnement des mesurages ne permettent pas d’obtenir des méthodes
d’une telle classe de précision. La présente Norme européenne propose aussi des moyens d’évaluer les
niveaux de puissance acoustique avec une exactitude acceptable bien que les méthodes acoustiques et/ou
les conditions de travail ne soient pas celles de laboratoire, par exemple in situ ou lors de mesurages de
contrôle qualité.
La présente Norme européenne propose deux classes de mesure et les résultats obtenus, selon
l’environnement de l’essai :
- les mesurages de classe A correspondent aux conditions de travail contrôlées (conditions de
performance nominale ou d’application). Elles sont définies par le respect des tolérances du Tableau 2 ;
- les mesurages de classe B correspondent aux cas où les tolérances du Tableau 2 ne peuvent pas être
respectées.
Klimatske naprave, enote za tekočinsko hlajenje, toplotne črpalke in razvlaževalniki z električnimi kompresorji za ogrevanje ali hlajenje prostora - Merjenje hrupa v zraku - Določanje ravni zvočne moči
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Klimageräte, Flüssigkeitskühlsätze, Wärmepumpen und Entfeuchter mit elektrisch angetriebenen Verdichtern zur Raumbeheizung und Kühlung - Messung der Luftschalllemissionen - Bestimmung des SchallleistungspegelsClimatiseurs, groupes refroidisseurs de liquide, pompes à chaleur et déshumidificateurs avec compresseur entraîné par moteur électrique pour le chauffage et la réfrigération - Mesure de bruit aérien émis - Détermination du niveau de puissance acoustiqueAir conditioners, liquid chilling packages, heat pumps and dehumidifiers with electrically driven compressors for space heating and cooling - Measurement of airborne noise - Determination of the sound power level27.080Heat pumps91.140.30VLVWHPLVentilation and air-conditioning17.140.20Emisija hrupa naprav in opremeNoise emitted by machines and equipment23.120QDSUDYHVentilators. Fans. Air-conditionersICS:Ta slovenski standard je istoveten z:EN 12102:2008SIST EN 12102:2008en,fr,de01-september-2008SIST EN 12102:2008SLOVENSKI
STANDARDSIST ENV 12102:20011DGRPHãþD
SIST EN 12102:2008
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 12102May 2008ICS 91.140.30; 17.140.20Supersedes ENV 12102:1996
English VersionAir conditioners, liquid chilling packages, heat pumps anddehumidifiers with electrically driven compressors for spaceheating and cooling - Measurement of airbone noise -Determination of the sound power levelClimatiseurs, groupes refroidisseurs de liquide, pompes àchaleur et déshumidificateurs avec compresseur entraînépar moteur électrique pour le chauffage et la réfrigération -Mesure de bruit aérien émis - Détermination du niveau depuissance acoustiqueKlimageräte, Flüssigkeitskühlsätze, Wärmepumpen undEntfeuchter mit elektrisch angetriebenen Verdichtern zurRaumbeheizung und Kühlung - Messung derLuftschalllemissionen - Bestimmung desSchallleistungspegelsThis European Standard was approved by CEN on 21 March 2008.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2008 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12102:2008: ESIST EN 12102:2008
EN 12102:2008 (E) 2 Contents Page Foreword.4 1 Scope.5 2 Normative references.6 3 Definitions and symbols.7 3.1 General.7 3.2 Symbols.7 3.2.1 Non ducted units.7 3.2.2 Ducted units.7 3.3 Standard operating conditions.7 4 Measuring instruments.8 5 Operation of the unit.9 6 Installation.11 6.1 General points.11 6.2 Ducted units.11 6.2.1 Installation.11 6.2.2 Duct end correction.11 6.2.3 Bend correction.12 6.2.4 Pressure and airflow measurements.13 6.2.5 Casing radiated test.14 6.3 Wall mounted.14 6.4 Ceiling Mounted.14 6.5 Window-type.14 6.6 Multisplits.14 6.7 Single ducts.14 6.7.1 Casing radiated test:.14 6.7.2 Ducted outlet.15 7 Acoustic measurement methods.15 7.1 Frequency range.15 7.2 To choose a method.15 7.2.1 General.15 7.2.2 Available test facilities.15 7.2.3 Target of measurement.16 7.3 Reverberation room methods.16 7.3.1 General.16 7.3.2 Non ducted units.16 7.3.3 Ducted units.17 7.4 Installation of the free field over a reflecting plane method.17 7.4.1 General.17 7.4.2 Reference surface.17 7.4.3 Measuring surface.18 8 Uncertainty of measurement results.20 9 Test report.20 9.1 General.20 9.2 Unit specification.20 9.3 Operating conditions, installation and environmental conditions.20 9.4 Measurement instruments.20 9.5 Measured values and results.21 SIST EN 12102:2008
EN 12102:2008 (E) 3 Annex A (normative)
Energy labelling application.22 A.1 General.22 A.2 Test procedure.22 A.3 Tolerances permitted on declared values.22 Annex B (normative)
Specific measurement for variable capacity units.23 B.1 General requirements.23 B.2 Test mode.23 B.3 Measurements process.23 Bibliography.24
SIST EN 12102:2008
EN 12102:2008 (E) 4 Foreword This document (EN 12102:2008) has been prepared by Technical Committee CEN/TC 113 “Heat pumps and air conditioning units”, the secretariat of which is held by AENOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2008, and conflicting national standards shall be withdrawn at the latest by November 2008. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. This document supersedes ENV 12102:1996. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s). According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. SIST EN 12102:2008
EN 12102:2008 (E) 5
1 Scope This European Standard establishes requirements for determining, in accordance with a standardized procedure, the sound power level emitted into the surrounding air by air conditioners, heat pumps, liquid chilling packages with electrically driven compressors when used for space heating and/or cooling, including water cooled multisplit systems, as described in EN 14511 and dehumidifiers as described in EN 810. It is emphasized that this measurement standard only refers to airborne noise.
This European Standard offers ways to determine the sound power level of units. Some of them are specifically adapted to provide results with low uncertainties, by using laboratory class acoustic methods and highly controlled working conditions. Those measurements are suitable for certification, labelling and marking purposes.
In some cases, the target and/or the environment of the measurements do not allow such precision-class methods. This European Standard also offers ways to assess sound power levels with acceptable accuracy even though acoustic methods and/or working conditions are not laboratory-type, e.g. in situ or quality control measurements. This European Standard gives two classes of measurements and results, according to the test environment:
- Class A measurements correspond to controlled working conditions (standard or application rating conditions). It is defined by the respect to the tolerances of Table 2. - Class B measurements correspond to the case where the range defined by the tolerances of Table 2 cannot be fulfilled.
In both classes, precision or engineering class acoustic methods should be applied. The choice of the acoustic measurement method is done in accordance with EN ISO 3740 and EN ISO 9614 depending on the type of surrounding acoustic fields (diffuse or free field, enclosed or open space), and the available instrumentation. Whatever the current working conditions, the reference of acoustic standard shall be reported, with explicit mention of its accuracy class. NOTE 1 The use of EN ISO 3746 and EN ISO 3747 as survey grade methods are not recommended due to the high level of uncertainties. Their use is only allowed for non controlled environments. Three methods for determining the sound power levels are specified in order to avoid unduly restricting existing facilities and experience.
- the first methodology is based on reverberation room measurement (see EN ISO 3741, EN ISO 3743 and EN ISO 3747 in some favourable cases when the engineering grade can be fulfilled);
- the second method is based on measurements in an essentially free field over a reflecting plane (see EN ISO 3744 and EN ISO 3745);
- the third method is based on sound intensity measurement (see EN ISO 9614) in preferably free field environment. NOTE 2 The references in this European Standard to EN ISO 3743 should be understood as EN ISO 3743-1 or EN ISO 3743-2 as well. The necessity to regulate the test conditions obviously leads to recommend test methods implemented in acoustically designed (enclosed) spaces, such as EN ISO 3741, EN ISO 3743, EN ISO 3745 and also EN ISO 9614 when implemented in enclosed space.
SIST EN 12102:2008
EN 12102:2008 (E) 6 The open spaces should be covered only in specific cases, e.g. when the size or the power of the unit under test cannot be managed by standard test rooms. Suitable test methods are EN ISO 3744 and EN ISO 9614.
NOTE 3 Intensity measurement methods are quite robust and are well suited for tests to be done in environments without or with a light acoustic treatment (the better the acoustic treatment, the easier the implementation). 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. EN 810:1997, Dehumidifiers with electrically driven compressors - Rating tests, marking, operational requirements and technical data sheet EN 14511-1:2007, Air conditioners, liquid chilling packages and heat pumps with electrically driven compressors for space heating and cooling – Part 1: Terms and definitions EN 14511-2, Air conditioners, liquid chilling packages and heat pumps with electrically driven compressors for space heating and cooling – Part 2: Test conditions EN 14511-3:2007, Air conditioners, liquid chilling packages and heat pumps with electrically driven compressors for space heating and cooling – Part 3: Test methods EN 14511-4, Air conditioners, liquid chilling packages and heat pumps with electrically driven compressors for space heating and cooling – Part 4: Requirements EN ISO 3740, Acoustics - Determination of sound power levels of noise sources - Guidelines for the use of basic standards (ISO 3740:2000) EN ISO 3741, Acoustics - Determination of sound power levels of noise sources using sound pressure - Precision methods for reverberation rooms (ISO 3741:1999) EN ISO 3743-1, Acoustics - Determination of sound power levels of noise sources - Engineering methods for small, movable sources in reverberant fields - Part 1: Comparison method for hard-walled test rooms (ISO 3743-1:1994) EN ISO 3743-2, Acoustics - Determination of sound power levels of noise sources using sound pressure - Engineering methods for small, movable sources in reverberant fields - Part 2: Methods for special reverberation test rooms (ISO 3743-2:1994) EN ISO 3744, Acoustics - Determination of sound power levels of noise sources using sound pressure - Engineering method in an essentially free field over a reflecting plane (ISO 3744:1994) EN ISO 3745, Acoustics - Determination of sound power levels of noise sources using sound pressure - Precision methods for anechoic and semi-anechoic rooms (ISO 3745:2003) EN ISO 3746, Acoustics - Determination of sound power levels of noise sources using sound pressure -Survey method using an enveloping measurement surface over a reflecting plane (ISO 3746:1995) EN ISO 3747, Acoustics - Determination of sound power levels of noise sources using sound pressure -Comparison method for use in situ (ISO 3747:2000) EN ISO 9614-1, Acoustics - Determination of sound power levels of noise sources using sound intensity - Part 1: Measurement at discrete points (ISO 9614-1:1993) SIST EN 12102:2008
EN 12102:2008 (E) 7 EN ISO 9614-2, Acoustics - Determination of sound power levels of noise sources using sound intensity - Part 2: Measurement by scanning (ISO 9614-2:1996) EN ISO 9614-3, Acoustics - Determination of sound power levels of noise sources using sound intensity - Part 3: Precision method for measurement by scanning (ISO 9614-3:2002) 3 Definitions and symbols 3.1 General The definitions and symbols given in EN 14511-1:2007 and EN 810:1997 apply. The definitions and symbols of the acoustic standards given in Clause 2 apply. The required value, sound power level, expressed in dB, is denoted by LW, defined by: ⋅=oWWLw10log10
where W is the sound power and W0 is the reference sound power = 1 pW (10-12 W) 3.2 Symbols 3.2.1 Non ducted units The suffix "i" denotes the indoor side of units and "o" the outdoor ones. LWi : sound power level radiated by the indoor side. LWo : sound power level radiated by the outdoor side. 3.2.2 Ducted units For ducted unit, the attended value is the sound power level travelling into the duct. It is assessed from the sound power level radiated by the air outlet opening of the duct, corrected by the "duct end correction" factor E (cf. 6.2.2). The suffix "d" denotes the "in duct" sound power level. LWd = sound power level travelling into the (discharge or suction) duct. For the case of a ducted indoor side of a split unit: LWdi = sound power level travelling into the (discharge or suction) duct of indoor unit. For the case of a ducted unit on the outdoor side: LWdo = sound power travelling into the (discharge or suction) duct of outdoor unit. The sound radiated by the casing does not require any specific suffix. Use the same symbols as in 3.2.1 to specify which unit is concerned, indoor or outdoor side. 3.3 Standard operating conditions The "standard operating conditions" are defined as the conditions for the operating points of the unit in accordance with the relevant parts of EN 14511 series and EN 810. The definitions given in these European Standards also apply. SIST EN 12102:2008
EN 12102:2008 (E) 8 4 Measuring instruments The instruments used for measuring and evaluation shall comply with the requirements of the standards appropriate to the test method used, from acoustic and capacity points of view. To respect Class A measurements, the instruments necessary to control the working conditions shall fulfil the requirements of Table 1. Table 1 — Uncertainties of measurement for indicated values Measured quantity Unit Uncertainty of measurement Liquid
- temperature inlet/outlet
- volume flow
°C m3/s
± 0,3 K ± 3 %
Air
- dry bulb temperature
- wet bulb temperature
- static pressure difference
- volume flow
°C °C
Pa
m³/s
± 0,5 K ± 0,8 K
± 8 Pa (∆p ≤ 100 Pa) ± 8 % (∆p > 100 Pa) ± 10 % Refrigerant
- pressure at compressor outlet
- temperature
kPa °C
± 3 % ± 1 K Concentration
- heat transfer medium
%
± 6 % Electrical quantities
- voltage
V
± 1 % Rotation speed
min-1 ± 1 %
NOTE 1 Wet bulb temperature measurement involves the generation of air flow around a wet thermometer which may generate unwanted noise in the sound power measurement. It is then recommended to preferably determine relative humidity or dew point instead. NOTE 2 Suitable windshields are recommended to be fitted on microphones if they have to be affected by air velocity (above about 2 m/s) which may be produced by the appliance to be tested or by the laboratory facilities. Adjustment should be made to the measured sound pressure levels to compensate for any alteration in the sensitivity of shielded microphones. Above 10 m/s, windshields are usually not efficient enough and care must be taken to reduce the air velocity (by changing the location of microphones) or to change the type of windshields. NOTE 3 For intensity probes, windshields are recommended to be fitted on the probe if they have to be affected by air velocity because they are much more sensitive to that parameter. For instance, the maximum air velocity admitted by EN ISO 9614-1 is 2 m/s. SIST EN 12102:2008
EN 12102:2008 (E) 9 5 Operation of the unit NOTE 1 The case of inverter devices is treated in Annex B. As a general rule, the sound power level is dependent on the operating conditions of the unit. Sound measurements are to be carried out at the standard operating rating conditions. The unit shall be installed and connected for the test as recommended by the manufacturer in its installation and operation manual according to EN 14511 series. The accessories provided by option (for example heating element) shall not be included in the test. Steady state conditions of operation of the appliance are considered obtained and maintained when all the measured quantities remain constant, with respect of the tolerances given in Table 2. The noise measurement shall be started no sooner than 30 minutes of operation under steady state conditions of the appliance. These steady state conditions shall be maintained during the sound pressure (or intensity) measurements that may require from 30 s (multichannel analyzer) to sometimes several hours (free fieldmethods). This requires the continuous recording of the meaningful data. The uncertainties of each measurement shall not exceed the values specified in Table 1. SIST EN 12102:2008
EN 12102:2008 (E) 10
Table 2 —
Permissible deviations from set values
Measured quantity Permissible deviation of the arithmetic mean values from set values Permissible deviations of individual measured values from set values Liquid
- inlet temperature
- ∆ T
- volume flow
± 1 K ± 1 K ± 5 %
± 1,5 K ± 1,5 K ± 10 %
Air
-inlet temperature (dry bulb or wet bulb)
- HR
- rpm of fan
± 2 K a ± 10 % ± 3 %
± 3 K ± 15 % ± 6 %
Airflow
- Static pressure difference
- Airflowb
-
± 5 %
± 8 Pa for ∆P ≤ 100 Pa ± 10 % otherwise ± 10 % Refrigerant
- Liquid temperature
- Saturated vapour/bubble point temperature
± 3 K ± 1,5 K
± 5 K ± 2,5 K
Voltage ± 4 % ± 4 % a Care must be taken with controlled outdoor fan speed units. Unless a specific procedure for fixing the frequency of the compressor’s side fan is specified in the manufacturer's manuals bundled with the unit, the test shall be performed at maximum fan speed obtained with the unit running within the standard rating temperature conditions plus tolerances. b If the rating flow has been measured during a previous test, for instance, during a capacity measurement.
NOTE 2 For units tested in enclosed space, care should be taken to the airflow of the unit (m³/h) which would preferably not exceed 60 times the volume of the room (m³). This upper limit indicates the microphones can be submitted to excessive air velocity. In addition, it is recommended to check the air speed through the microphone path(s) or at the different microphone positions to ensure negligible influence of air speed over the microphone(s). The set value for the relative humidity shall be calculated from the dry and wet bulb temperatures given in EN 14511 series and from the atmospheric pressure measured during the test. In the case of heat pumps with air as the heat transfer medium, the evaporator shall be free of ice during the measurement. However, sound measurements are sometimes not possible due to coil frosting and stationary time running requirement. SIST EN 12102:2008
EN 12102:2008 (E) 11 6 Installation 6.1 General points The unit should be installed and connected up for the test as recommended by the manufacturer in its installation and operation instruction manual. In case of split or ducted units, care must be taken to ensure that transmission of structure-borne sound via ducts and piping systems is minimized. The test shall be performed with anti-vibratory pads if supplied by the manufacturer, otherwise make the unit level using small wooden wedges. 6.2 Ducted units 6.2.1 Installation For units which are to be connected with ducts, it is recommended to use straight ducts, without bend. The length of the ducts will depend on the dimensions of the unit, but should be as short as possible. If a bend cannot be avoided, only one soft bend without guide vanes is permissible in each duct.
The ducts shall not radiate noise capable of disturbing the measurements. In some cases (e.g. discharge noise), the use of standard metal duct is sufficient to avoid a parasite radiation. But in case of measurements of radiated noise of the casing for a ducted unit (e.g. in reverberation room), the radiation of duct should be as low as possible to avoid perturbation of the sound pressure under measurement. In that case, the ducts may be made of materials ensuring a good insulation against airborne transmission and having an acoustically reflecting outer layer.
NOTE It is permitted to change the shape of the duct, e.g. a rectangular outlet followed by a circular duct. In that case, the areas should be the same at ± 10% and the change of shape should be as smooth as possible. This can be helpful because the circular ducts present a better sound insulation in the low frequency range than the rectangular ones.
Any soundproofing lining inside the ducts is prohibited. An external lining can be installed to limit the radiation. The best device is an additional uncoupled covering. The shape of the duct should fit the shape of inlet/outlet of the unit, and only one duct is allowed by inlet/outlet. It is recommended to insert a weak connection between the duct and the unit.
As no in-duct measurement is allowed, the measurement shall be carried out at the duct opening (inlet/outlet sound level), which should be preferably mounted flush to the wall (or to the reflecting plane).
The final sound power level results shall be given taking into account the corrections explained in 6.2.2. 6.2.2 Duct end correction The acoustic energy travelling into the duct is not fully transferred to the surrounding space at the outlet (or inlet), because of the sudden change of acoustical impedance. For the low frequency range (large wavelength), a part of energy is reflected due to the change of section. To get the in-duct sound power level, it is then necessary to add a duct end correction factor E (dB) to the sound power level measured at the outlet (or inlet) of the duct. This correction depends on the equivalent diameter of the duct and on the frequency. The equivalent diameter D (m) is the diameter corresponding to the cross-sectional area A
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