oSIST prEN 1751:2023
(Main)Ventilation for buildings - Air terminal devices - Aerodynamic testing of damper and valves
Ventilation for buildings - Air terminal devices - Aerodynamic testing of damper and valves
This document specifies methods for the testing and rating of dampers and valves used in air distribution systems with pressure differences up to 2 000 Pa.
The tests incorporated in this document will address:
- leakage past a closed damper or valve (for classification see Annex C);
- casing leakage (for classification see Annex C);
- flow rate/pressure requirement characteristics;
- torque: (see Annex A);
- thermal transmittance: (see Annex B).
The acoustic testing of dampers and valves is not included in this document. The tests specified above apply to the following:
- measurement of leakage past a closed damper or valve;
- measurement of casing leakage;
- determination of flow rate and pressure requirements;
- measurement of torque characteristics (see Annex A);
- measurement of thermal transfer characteristics to determine insulation properties (see Annex B).
NOTE Certain aspects of the dynamic performance of dampers and/or valves are dependent upon the air distribution system to which they are connected and are, therefore, difficult to measure in isolation. Such considerations have led to the omission of these aspects of the dynamic performance measurements from this document. Also, in common with other air distribution components, the results from tests carried out in accordance with this document may not be directly applicable if the damper or valve is situated in an area of non-uniform flow.
Lüftung von Gebäuden - Geräte des Luftverteilungssystems - Aerodynamische Prüfungen von Drossel- und Absperrelementen
Dieses Dokument legt Verfahren zur Prüfung und Bewertung von Drossel- und Absperrelementen fest, die in Luftverteilungssystemen mit Differenzdrücken bis zu 2 000 Pa verwendet werden.
Die in diesem Dokument enthaltenen Prüfungen berücksichtigen:
- Leckage bei einem geschlossenen Drossel- bzw. Absperrelement (Klassifizierung siehe Anhang C);
- Gehäuseleckage (Klassifizierung siehe Anhang C);
- typische Anforderungen an Volumenstrom/Druck;
- Drehmoment (siehe Anhang A);
- Wärmedurchgangskoeffizient (siehe Anhang B).
Die akustische Prüfung von Drossel- und Absperrelementen ist nicht in diesem Dokument enthalten. Die vorstehend festgelegten Prüfungen gelten für Folgendes:
- Messung der Leckage bei einem geschlossenen Drossel- bzw. Absperrelement;
- Messung der Gehäuseleckage;
- Bestimmung der Anforderungen an Volumenstrom und Druck;
- Messung des Drehmomentverlaufs (siehe Anhang A);
- Messung der Wärmeübertragung zur Bestimmung der Wärmedämmungseigenschaften (siehe Anhang B).
ANMERKUNG Bestimmte Aspekte der dynamischen Leistung von Drossel- bzw. Absperrelementen sind abhängig vom Luftverteilungssystem, in das sie eingebunden sind, weshalb es schwierig ist, sie getrennt zu messen. Solche Erwägungen haben dazu geführt, dass diese Aspekte der Messung der dynamischen Leistung nicht in das vorliegende Dokument aufgenommen wurden. Wie auch bei anderen Luftverteilungskomponenten sind die Ergebnisse von Prüfungen nach diesem Dokument möglicherweise nicht direkt anwendbar, wenn das Drossel- bzw. Absperrelement in einem Bereich ungleichmäßiger Strömung angeordnet ist.
Ventilation des bâtiments - Bouches d'air - Essais aérodynamiques des registres et clapets
Le présent document spécifie des méthodes pour l'essai et la classification des registres et des clapets utilisés dans les systèmes de distribution d'air avec des différences de pressions jusqu'à 2 000 Pa.
Les essais faisant partie du présent document portent sur:
- fuite à travers un registre ou un clapet fermé (pour la classification voir l’Annexe C);
- étanchéité de l'enveloppe (pour la classification voir l’Annexe C);
- caractéristiques des exigences débit/pression;
- couple (voir l’Annexe A);
- transmission thermique (voir l’Annexe B).
Les essais acoustiques des registres et des clapets ne font pas partie du présent document. Les essais spécifiés ci-dessus s'appliquent à ce qui suit:
- mesurage de la fuite à travers un registre ou un clapet fermé;
- mesurage de l'étanchéité de l'enveloppe;
- détermination des exigences de débit et pression;
- mesurage des caractéristiques de couple (voir l’Annexe A);
- mesurage des caractéristiques de transfert thermique afin de déterminer les propriétés d'isolation (voir l’Annexe B).
NOTE Certains aspects des performances dynamiques des registres et/ou des clapets sont dépendants du système de distribution d'air auquel ils sont raccordés et sont, par conséquent, difficiles à mesurer isolément. De telles considérations ont amené à omettre ces aspects de mesurage de la performance dynamique du présent document. De plus, comme pour d'autres composants de distribution d'air, les résultats d'essai effectués conformément au présent document peuvent ne pas être directement applicables si le registre ou le clapet est placé dans une zone d'écoulement non uniforme.
Prezračevanje stavb - Naprave za dovod in odvod zraka - Aerodinamično preskušanje dušilnikov in loput
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN 1751:2023
01-marec-2023
Nadomešča:
SIST EN 1751:2014
Prezračevanje stavb - Naprave za dovod in odvod zraka - Aerodinamično
preskušanje dušilnikov in loput
Ventilation for buildings - Air terminal devices - Aerodynamic testing of damper and
valves
Lüftung von Gebäuden - Geräte des Luftverteilungssystems - Aerodynamische
Prüfungen von Drossel- und Absperrelementen
Ventilation des bâtiments - Bouches d'air - Essais aérodynamiques des registres et
clapets
Ta slovenski standard je istoveten z: prEN 1751
ICS:
91.140.30 Prezračevalni in klimatski Ventilation and air-
sistemi conditioning systems
oSIST prEN 1751:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 1751:2023
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oSIST prEN 1751:2023
DRAFT
EUROPEAN STANDARD
prEN 1751
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2023
ICS 91.140.30 Will supersede EN 1751:2014
English Version
Ventilation for buildings - Air terminal devices -
Aerodynamic testing of damper and valves
Ventilation des bâtiments - Bouches d'air - Essais Lüftung von Gebäuden - Geräte des
aérodynamiques des registres et clapets Luftverteilungssystems - Aerodynamische Prüfungen
von Drossel- und Absperrelementen
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 156.
If this draft becomes a European Standard, CEN 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.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1751:2023 E
worldwide for CEN national Members.
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prEN 1751:2023 (E)
Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms, definitions, symbols and suffixes . 6
3.1 Terms and definitions . 6
3.2 Symbols . 6
3.3 Suffixes . 7
4 Instrumentation . 7
4.1 Air flow rate measurement . 7
4.2 Pressure measurement. 8
4.3 Temperature measurement . 9
5 Leakage tests . 9
5.1 General. 9
5.2 Damper and valve leakage. 9
5.3 Casing leakage . 9
6 Flow rate and pressure tests. 10
6.1 Ducted method . 10
6.2 Chamber method . 11
6.2.1 General. 11
6.2.2 Size relationship . 11
6.2.3 Tests . 12
6.3 Calculations and report . 12
Annex A (informative) Mechanical testing of dampers and valves . 20
A.1 Scope . 20
A.2 Instrumentation: Torque measurement . 20
A.3 Pressure test to determine limiting value for structural stability . 20
A.4 Torque tests to determine the torque required to operate the damper or valve and the
limiting value to avoid structural damage . 21
A.4.1 Torque required to operate damper . 21
A.4.2 Maximum permitted torque . 21
Annex B (informative) Thermal transmittance through dampers and valves . 24
B.1 Introduction . 24
B.2 Scope . 24
B.3 Thermal loss test using a substitution method . 24
Annex C (normative) Classification of a damper or valve leakage . 27
C.1 Scope . 27
C.2 Leakage through closed blade(s) . 27
C.3 Casing leakage . 28
Annex D (informative) Effect of duct configuration on pressure loss coefficient . 31
D.1 General. 31
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D.2 Application of correction factor . 32
Annex E (informative) Correction of air flow rate according to ambient conditions . 33
E.1 Calculation on airflow correction under reference conditions – examples . 33
Bibliography . 35
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European foreword
This document (prEN 1751:2023) has been prepared by Technical Committee CEN/TC 156 “Air terminal
devices”, the secretariat of which is held by BSI.
This document is currently submitted to the CEN Enquiry.
This document supersedes EN 1751:2014.
In comparison with the previous edition EN 1751:2014, the following technical modifications have been
made:
— Annex C Classification of a damper or valve leakage;
— Closed blade leakage now has the addition of equations for the calculation of classification levels and
an improved graph;
— Case leakage now has equations for classification which are based on ductwork leakage classes in
EN 16798-3:2017, Table19 taking a reference case length of 1 m and also an improved graph.
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).
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1 Scope
This document specifies methods for the testing and rating of dampers and valves used in air distribution
systems with pressure differences up to 2 000 Pa.
The tests incorporated in this document will address:
— leakage past a closed damper or valve (for classification see Annex C);
— casing leakage (for classification see Annex C);
— flow rate/pressure requirement characteristics;
— torque: (see Annex A);
— thermal transmittance: (see Annex B).
The acoustic testing of dampers and valves is not included in this document. The tests specified above
apply to the following:
— measurement of leakage past a closed damper or valve;
— measurement of casing leakage;
— determination of flow rate and pressure requirements;
— measurement of torque characteristics (see Annex A);
— measurement of thermal transfer characteristics to determine insulation properties (see Annex B).
NOTE Certain aspects of the dynamic performance of dampers and/or valves are dependent upon the air
distribution system to which they are connected and are, therefore, difficult to measure in isolation. Such
considerations have led to the omission of these aspects of the dynamic performance measurements from this
document. Also, in common with other air distribution components, the results from tests carried out in accordance
with this document may not be directly applicable if the damper or valve is situated in an area of non-uniform flow.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
CEN/TS 17153, Ventilation for buildings — Correction of air flow rate according to ambient conditions
EN 12792, Ventilation for buildings — Symbols, terminology and graphical symbols
EN 16798-3:2017, Energy performance of buildings — Ventilation for buildings — Part 3: For non-
residential buildings — Performance requirements for ventilation and room-conditioning systems (Modules
M5-1, M5-4)
EN ISO 5167-1, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 1: General principles and requirements (ISO 5167-1)
EN ISO 5167-2, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 2: Orifice plates (ISO 5167-2)
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EN ISO 5167-3, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 3: Nozzles and Venturi nozzles (ISO 5167-3
EN ISO 5167-4, Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full — Part 4: Venturi tubes (ISO 5167-4)
3 Terms, definitions, symbols and suffixes
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12792 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp/ui
3.2 Symbols
The symbols used in this document are given in Table 1.
Table 1 — Symbols
Symbol Quantity Unit
A Internal cross-sectional area of duct 2
m
C Coefficient of discharge -
D
D Equivalent hydraulic diameter m
e
4 A
Circular ducts:
π
2ab
Square/Rectangular ducts:
ab+
p Absolute pressure Pa
p Atmospheric pressure Pa
a
p 2 Pa
d Velocity pressure 1/2 ρ v
p Stagnation or absolute total pressure Pa
t
p Static gauge pressure (p - p ) Pa
s a
Δp Pressure difference across the damper or valve under test Pa
s
Δp Flow meter differential pressure Pa
Δp Conventional total pressure difference for an air density of Pa
t
−3
1,2 kg⋅m at the inlet to the damper or valve under test
q Volume rate of air flow at the flow meter −1
v l⋅s
q Leakage volume rate of air flow −1
vL
l⋅s
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Symbol Quantity Unit
q Closed blade air leakage factor, volume rate of air flow per unit duct −1 −2
vLBA
l⋅s ⋅m
cross-sectional area
q Case air leakage factor, volume rate of air flow per reference −1 −2
vLCA
l⋅s ⋅m
casing area (which is taken as a perimeter of the damper
multiplied by an equivalent length of 1 m)
v Velocity −1
m⋅s
s Position of damper setting %, α or m
T Torque N⋅m
U Thermal transmittance coefficient −1 −2
W⋅K ⋅m
q Temperature °C
ρ Air density -3
kg⋅m
ξ Pressure loss coefficient -
3.3 Suffixes
The following suffixes shall be used with the symbols given in Table 1.
1 is the inlet of the damper or valve under test;
2 is the outlet of the damper or valve under test;
u is the measuring point upstream of the flow meter;
n is the value at a selected point of the flow rate/static pressure curve.
4 Instrumentation
4.1 Air flow rate measurement
4.1.1 The air flow rate shall be measured using instruments in accordance with EN ISO 5167-1,
EN ISO 5167-2, EN ISO 5167-3 and EN ISO 5167-4, or other instruments which have equivalent
calibrated performance.
4.1.2 Air flow meters shall have a minimum calibration accuracy of ± 2,5 % over the whole range.
NOTE If necessary, flow meters can be calibrated in situ by means of the Pitot static tube traverse technique
described in ISO 3966.
4.1.3 Flow meters shall be checked at intervals as appropriate but not exceeding 12 months. This check
can take the form of one of the following:
— a dimensional check for all flow meters not requiring calibration;
— a calibration over their full range using the original method employed for the initial calibration of
meters calibrated in situ;
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— a check against a flow meter which is compliant with flow meter specifications according to
EN ISO 5167-1, EN ISO 5167-2, EN ISO 5167-3 or EN ISO 5167-4 as appropriate.
4.1.4 Leakage air flow meters shall have a minimum indicated accuracy according to the ranges in
Table 2.
Table 2 — Accuracy of leakage air flow meters
−1 Accuracy of
Range l⋅s
measurement
Up to and including −1
± 0,000 9 l⋅s
0,018
More than 0,018 ± 5 %
NOTE Alternatively, other devices such as variable area, flow-rate meters or integrating air flow meters of the
positive displacement type can be used if calibrated in accordance with 4.1.3 c).
4.2 Pressure measurement
4.2.1 Pressure in the duct shall be measured by means of a liquid-filled calibrated manometer or any
other device conforming to 4.2.2.
4.2.2 The resolution shall not be greater than the characteristics listed for the accompanying range of
manometers, given in Table 3.
Table 3 — Resolution for the ranges of manometers
Range Resolutio
n
Pa
Pa
Up to and including 0,1
50
From 50 to 250 1
From 250 to 500 5,0
Above 500 25,0
4.2.3 The measured value of differential pressure should be greater than 10 % of the range of the
measurement device used.
EXAMPLE With a micromanometer with a range from 0 to 1000 Pa the minimum differential pressure to be
measured is 100 Pa.
4.2.4 The uncertainty of calibration standards shall be:
— for instruments with a measuring range up to 100 Pa, equal or better than ± 0,5 Pa; and
— for instruments with a measuring range over 100 Pa, equal or better than ± 0,5 % of reading.
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4.3 Temperature measurement
Measurement of temperatures shall be conducted, for example, by means of mercury-in-glass
thermometers, resistance thermometers or thermo-couples. Instruments shall have a resolution better
than 0,5 K and be calibrated to an accuracy of ± 0,25 K.
5 Leakage tests
5.1 General
Damper leakage performance could vary depending on whether the damper is subjected to positive or
negative pressure. The manufacturer shall specify the pressure conditions for test.
5.2 Damper and valve leakage
5.2.1 Measurements of damper and/or valve leakage in the shut-off position shall be made under
conditions of actual operation with the damper or valve closed against the maximum recommended static
pressure conditions. Since small flow rates still exist during the closing of the damper and valve condition,
the method used to measure these small flow rates will introduce a high-pressure loss when the damper
or valve is open. This precludes a high-pressure difference in the inlet duct until the damper or valve
approaches the closed position.
As the valve is closed and the flow rate decreases, the inlet static pressure difference will increase to
approximately the recommended inlet pressure.
5.2.2 The damper or valve shall be cycled 10 times between the fully open and fully closed positions of
the actuator at the start of each test (before starting the fan of the air supply system) concluding with the
damper or valve in the fully closed position.
NOTE In all cases in the closed position, the damper drive is subject to a torque rating recommended by the
manufacturer.
5.2.3 The damper or valve under test shall be connected to a test installation similar to that shown in
Figure 1a) or Figure 1b). A suitable air supply shall be connected to the duct. In both cases, care shall be
taken to ensure that duct joints are sealed to manufacturer’s instructions.
5.2.4 The supply air pressure shall be increased to the maximum recommended inlet pressure
difference in accordance with the appropriate classification from Figure C.1 and Figure C.2. The damper
or valve is then modulated to the open position, without any additional adjustment of the supply air
system flow rate, and then returned to the closed position either manually or by the means provided by
the manufacturer. The supply air pressure shall be adjusted as the damper or valve nears closure, to
maintain the recommended inlet static gauge pressure difference within ± 5 %. The above process is to
ensure that the closed condition is as representative as possible of typical operation with airflow present.
NOTE The air flow measuring device for leakage measurement may have to be disconnected in the above
process to avoid any potential damage to the device for measuring low air rates.
5.2.5 Report the damper or valve air leakage factor as a function of test pressure difference in the closed
position. Also include classification (see Annex C).
5.3 Casing leakage
5.3.1 The test installation shall be similar to that shown in Figure 2 a) or Figure 2 b). The damper or
valve casing outlet shall be sealed according to the instructions of the manufacturer. The damper or valve
shall be set to the open position.
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5.3.2 The test of the casing shall be carried out by subjecting the casing to its maximum recommended
pressure in accordance with 5.2.4. The pressure shall be maintained for 60 s before the measurement of
leakage commences.
5.3.3 Report the test results as casing air leakage factor as a function of test pressure. Also include
classification (see Annex C).
6 Flow rate and pressure tests
6.1 Ducted method
6.1.1 This method applies for dampers or valves mounted within a duct.
6.1.2 The damper or valve under test shall be mounted in a system comprising of a fan, a means of
controlling air flow rate, a flow rate measuring system and test ducts (see Figure 3).
6.1.3 The test ducts shall have cross-sectional dimensions equal to the nominal size of the unit under
test or to the manufacturer's instructions. The upstream test duct shall be straight for a minimum length
of 5D . The downstream test duct shall be straight for a minimum length of 5D or 2 m, whichever is
e1 e2
the greatest.
6.1.4 Flow straighteners shall be fitted in the upstream test duct at a position 3D from the connection
e1
to the damper or valve under test or, alternatively a straight duct shall be used without a flow
straightener.
6.1.5 The velocity profile near the upstream connection to the damper or valve under test shall be
uniform to 10 % of the mean value over the test duct cross-section, excluding the area within 15 mm of
the duct walls. Carry out a velocity survey at ten equally spaced intervals along a pair of mutually
perpendicular axis to confirm that the velocity profile is within these limits. Wire mesh screens located
no closer than 2,5D to the upstream connection to the damper or valve under test can, if necessary, be
e1
incorporated to achieve a suitably uniform velocity profile.
6.1.6 The upstream duct static gauge pressure (p ) shall be measured by means of four static pressure
s1
tappings 1,5D from the upstream connection to the damper or valve under test. For a rectangular duct,
e1
these pressure taps shall be at the centre of each side and, for a circular duct, equally spaced around the
circumference. Connect the pressure taps to form a piezometric ring. Alternatively, use a single Pitot
static probe.
6.1.7 The air temperature shall be measured at the flow meter and at a position 2,5D upstream of
e1
the damper or valve under test, and, during the test the temperature variation at the same station shall
not be greater than 3 K.
6.1.8 The damper or valve shall be set in its fully open position and tests shall be carried out as follows:
— use a minimum of five air flow rates distributed evenly throughout the total flow range, and choose
the lowest air flow rate so that the test duct static pressure is not less than 10 Pa;
— remove the damper or valve from the test installation and connect the upstream test duct directly to
the downstream test duct. Repeat the procedure in 6.1.8 at five air flow rates covering the same flow
rate range used in 6.1.8.
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6.1.9 If required, repeat the procedure described in 6.1.8 with the damper or valve in any position other
than open.
6.1.10 Record the data in accordance with Table 4.
Table 4 — Flow rate and pressure test data
Symbol Quantity Unit Uncertainty of
measurement
p Inlet duct static gauge pressure Pa 3 %
s1(a)
with the damper or valve
installed
p Inlet duct static gauge pressure Pa 3 %
s1(b)
with the damper or valve
removed
p Atmospheric pressure Pa 1 %
a
θ Air temperature at inlet to °C 3 %
1
the damper or valve under
test
a Flow meter differential pressure Pa 3 %
Δp
p Static gauge pressure Pa 3 %
su
immediately upstream of the
flow meter
θ Air temperature °C 3 %
u
immediately upstream of
the flow meter
S Position of damper setting %, α or m 2°
CEN/TS 17153 should be used to correct measured airflow rate to standard
conditions.
a
Or the appropriate parameter which relates to q ·
v
6.2 Chamber method
6.2.1 General
This method applies for dampers and valves with free inlets and discharge.
6.2.2 Size relationship
The size relationship of the test apparatus setup for determining the flow rate and static pressure
differential of the device under test shall be limited to the following:
— the chamber cross-sectional area shall be at least 7 times the internal cross-sectional area of duct (A)
of the device being tested;
— other dimensions shall respect indications of Figure 4.
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6.2.3 Tests
6.2.3.1 Pressure differences according to the test chamber method are a statement of the pressure
difference required to accelerate the air to a given velocity and overcome any entrance (exit) losses due
to the blockage and entrance (exit) conditions.
6.2.3.2 Use a minimum of five air flow rates distributed evenly throughout the total flow range and
choose the lowest air flow rate so that the test duct static pressure is not less than 10 Pa.
6.2.3.3 If required, repeat the procedure described in 6.2.3.2 with the damper or valve in any position
other than open.
6.2.3.4 Record the data given in accordance with Table 5.
Table 5 — Flow rate and pressure test data
Symbol Quantity Unit
Δp Pressure difference across the damper or valve under test Pa
s
p Atmospheric pressure Pa
a
θ Air temperature at inlet to the damper or valve under test °C
1
a Flow meter differential pressure Pa
Δp
p Static gauge pressure immediately upstream of the flow meter Pa
su
θ Air temperature immediately upstream of the flow meter °C
u
S Position of damper setting %, α or m
a
Or the appropriate parameter which relates to q
v·
6.3 Calculations and report
The main characteristic of a damper within the meaning of this standard is the pressure loss coefficient
for the open setting. Furthermore, the throttling effect at different angular positions and installation types
is important for planning. The measurement of different angular positions is described in 6.1 and 6.2.
Annex D gives reference values for the influence of the installation types.
Pressure drop characteristics depend on the type of construction. If different sizes of one type are
geometrically similar, only one average size needs to be investigated.
6.3.1 The volume air flow rate at the flow meter (q ) shall be determined for each test. If there are
v
significant differences in the air temperature and static pressure between the flow meter and the damper
or valve under test, such that the air density ratio is less than 0,98 or greater than 1,02, the correction
regarding CEN/TS 17153 shall be applied – see Annex E
6.3.2 Having measured values of p and p and determined corresponding values of q in
s1(a) s1(b) v1
accordance with 6.3.1, plot the following functions on a linear graph:
2
pqvs (1)
( )
v1
s1 a
( )
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2
pqvs (2)
( )
s1 b v1
( )
Using graphical and/or calculation methods, determine the best straight line through the plotted points
ensuring you pass through zero (see Figure 5a). If isolated points fall outside ± 5 % of the differential
pressure band about the best mean line, repeat the tests at the relevant flow rates to check validity of test
data. If, in the case with the damper fitted, groups of points f
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