Ventilation for buildings - Measurement of air flows on site - methods

This standard applies to measurement of airflows on site. It provides the technician with a description of the methods,
their protocols, and tables for noting measured and calculated values so that the necessary measurements are
performed within the margins of stipulated method uncertainties.
Note : The duct traverse method in this standard is an alternative method to the duct traverse method of ISO 3966 and
EN12599. It defines errors due to the simplified approach and describes also other methods of measurements.

Lüftung von Gebäuden - Luftvolumenstrommessung in Lüftungssystemen - Verfahren

Diese Norm gilt für die Messung von Luftvolumenströmen in Lüftungssystemen. Sie bietet dem Techniker eine Beschreibung der Verfahren, deren Protokolle sowie Tabellen zum Protokollieren der gemessenen und berechneten Werte, so dass die erforderlichen Messungen innerhalb der für das Verfahren vorgeschriebenen Toleranzen durch¬geführt werden.
ANMERKUNG   Das in dieser Norm verwendete Messverfahren über den Querschnitt der Luftleitung ist ein alternatives Verfahren zu dem Luftleitungsquerschnitts-Verfahren von ISO 3966 und EN 12599. Es werden Fehler infolge des vereinfachten Ansatzes definiert und außerdem weitere Messverfahren beschrieben.

Systèmes de ventilation pour les bâtiments - Mesurages de débit d'air dans les systèmes de ventilation - Méthodes

La présente norme s’applique à la mesure des écoulements d'air sur site. Elle fournit au technicien une description des méthodes, de leurs protocoles et des tableaux utilisés pour noter les valeurs mesurées et calculées, de sorte que les mesures nécessaires soient effectuées dans les marges d'incertitude de la méthode stipulée.
NOTE   La méthode du plan transversal du conduit dans la présente norme est une variante de la même méthode décrite dans les normes ISO 3966 et EN 12599. Elle définit des erreurs dues à l'approche simplifiée et décrit également d'autres méthodes de mesure.

Prezračevanje stavb - Meritve pretoka zraka v sistemu ventilacije - Metode

General Information

Status
Not Published
Current Stage
4098 - Decision to abandon - Enquiry
Due Date
09-Mar-2012
Completion Date
09-Mar-2012

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SLOVENSKI STANDARD
oSIST prEN 16211:2011
01-marec-2011
3UH]UDþHYDQMHVWDYE0HULWYHSUHWRND]UDNDYVLVWHPXYHQWLODFLMH0HWRGH
Ventilation for buildings - Measurement of air flows on site - methods
Lüftung von Gebäuden - Luftvolumenstrommessung in Lüftungssystemen - Verfahren

Systèmes de ventilation pour les bâtiments - Mesurages de débit d'air dans les systèmes

de ventilation - Méthodes
Ta slovenski standard je istoveten z: prEN 16211
ICS:
91.140.30 3UH]UDþHYDOQLLQNOLPDWVNL Ventilation and air-
VLVWHPL conditioning
oSIST prEN 16211:2011 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 16211:2011
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oSIST prEN 16211:2011
EUROPEAN STANDARD
DRAFT
prEN 16211
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2010
ICS 17.120.10; 91.140.30
English Version
Ventilation for buildings - Measurement of air flows on site -
methods

Systèmes de ventilation pour les bâtiments - Mesurages de Lüftung von Gebäuden - Luftvolumenstrommessung in

débit d'air dans les systèmes de ventilation - Méthodes Lüftungssystemen - Verfahren

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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland 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
Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16211:2010: E

worldwide for CEN national Members.
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oSIST prEN 16211:2011
prEN 16211:2010 (E)
Contents Page

Introduction ........................................................................................................................................................ 4

Foreword ............................................................................................................................................................. 5

1 Scope ...................................................................................................................................................... 5

2 Normative references ........................................................................................................................... 5

3 Terms and definitions ........................................................................................................................... 6

4 Symbols (and abbreviated terms) ....................................................................................................... 8

5 Preparation of measurement ............................................................................................................... 9

5.1 Factors influencing measurements..................................................................................................... 9

5.2 Sources of errors and uncertainties ................................................................................................. 10

5.2.1 Gross errors ......................................................................................................................................... 10

5.2.2 Systematic errors ................................................................................................................................ 10

5.2.3 Calibration ............................................................................................................................................ 11

5.2.4 Uncertainties ........................................................................................................................................ 12

5.3 Measurement requirement ................................................................................................................. 12

5.3.1 Measurements using a manometer ................................................................................................... 12

5.3.2 Measurements using an anemometer ............................................................................................... 13

5.3.3 Measurements using Pitot static tube .............................................................................................. 13

5.3.4 Mean value calculation of measurement signal ............................................................................... 13

6 Measurement uncertainty ................................................................................................................... 13

6.1 Standard instrument uncertainty, u ................................................................................................. 13

6.2 Standard method uncertainty, u ....................................................................................................... 14

6.3 Standard reading uncertainty, u ....................................................................................................... 14

6.4 Expanded measurement uncertainty, U ......................................................................................... 14

7 Methods for measurement of air flows in ducts – ID-methods ...................................................... 15

7.1 Point velocity measurements using a Pitot static tube – method ID 1 .......................................... 15

7.1.1 Method description ............................................................................................................................. 15

7.1.2 Preparations to be made at the site of measurement ..................................................................... 17

7.1.3 Measurement procedure .................................................................................................................... 21

7.1.4 Corrections of measured values ....................................................................................................... 22

7.1.5 Standard method uncertainty ............................................................................................................ 24

7.2 Point velocity measurements using a hot wire anemometer – method ID 2 ................................ 24

7.2.1 M ethod .................................................................................................................................................. 24

7.2.2 Equipment ............................................................................................................................................ 24

7.2.3 Measuring procedure .......................................................................................................................... 24

7.2.4 Correction of measured values ......................................................................................................... 24

7.2.5 Standard Method uncertainty ............................................................................................................ 25

7.3 Fixed devices for flow measurement – method ID 3 ....................................................................... 25

7.3.1 Method description ............................................................................................................................. 25

7.3.2 Preparations of mesurements ........................................................................................................... 26

7.3.3 Measurement procedure .................................................................................................................... 26

7.3.4 Correction of measured values ......................................................................................................... 26

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7.3.5 Standard method uncertainty ............................................................................................................ 26

7.4 Tracer gas measurement – method ID 4 ........................................................................................... 27

7.4.1 Method description ............................................................................................................................. 27

7.4.2 Equipment ............................................................................................................................................ 28

7.4.3 Calculation of air flow ......................................................................................................................... 29

7.4.4 Standard measurement uncertainty .................................................................................................. 30

7.4.5 Conditions for homogeneous mixing of tracer gas ........................................................................ 30

8 Methods for Supply ATDs (air terminal devices) – ST-methods .................................................... 32

8.1 Measurement of reference pressure – method ST 1 ....................................................................... 33

8.1.1 Equipment ............................................................................................................................................ 34

8.1.2 Correction of measured values ......................................................................................................... 34

8.1.3 Standard method uncertainty ............................................................................................................ 35

8.2 The Bag Method – method ST 2 ........................................................................................................ 35

8.2.1 Limitations ........................................................................................................................................... 36

8.2.2 Equipment ............................................................................................................................................ 36

8.2.3 Preparation .......................................................................................................................................... 36

8.2.4 Measurement ....................................................................................................................................... 36

8.2.5 Correction of measured values ......................................................................................................... 36

8.2.6 Standard method uncertainty ............................................................................................................ 36

8.3 Measurements with flow hood – method ST 3 ................................................................................. 37

8.3.1 Introduction ......................................................................................................................................... 37

8.3.2 Equipment ............................................................................................................................................ 37

8.3.3 Correction of measured values ......................................................................................................... 39

8.3.4 Standard method uncertainty ............................................................................................................ 40

9 Methods for Extract ATDs (air terminal devices) – ET-methods ................................................... 40

9.1 Measurement of reference pressure at extract ATD – method ET 1 .............................................. 41

9.1.1 Limitations ........................................................................................................................................... 42

9.1.2 Equipment ............................................................................................................................................ 42

9.1.3 Correction of measured values ......................................................................................................... 42

9.1.4 Standard method uncertainty ............................................................................................................ 42

9.2 Measurement using a flow hood – method ET 2 ............................................................................. 43

9.2.1 Introduction ......................................................................................................................................... 43

9.2.2 Equipment ............................................................................................................................................ 44

9.2.3 Measurements ..................................................................................................................................... 45

9.2.4 Correction of measured values ......................................................................................................... 45

9.2.5 Standard method uncertainty ............................................................................................................ 46

Annex A (normative) Uncertainties ................................................................................................................. 47

Bibliography ..................................................................................................................................................... 50

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oSIST prEN 16211:2011
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Introduction

The construction, function and maintenance of ventilation installations are of great importance for the perception of the

interior climate of a building by those who work or live there. Since it is already clear that many buildings today have

problems with their interior climate and air quality, it is essential to use reliable methods to check that the installation is

functioning as intended. The result of an inspection can have large financial implications if the installation is not

passed. It is thus vital that the inspector bases his judgement on measurement methods which are reliable and have

small, known measurement uncertainties. The construction, function and maintenance of the installation also have a

large impact on the annual running costs of the plant. It is for this reason necessary to pay close attention to these

functions of the installation.

Measurement methods which are both correct and easy to use are developed and standardised to enable the

commissioning and operational monitoring of air processing installations. Interior climate and air quality can often be

improved considerably if the heating and ventilation system is managed in a way that ensures good functioning in the

long term. It is thus important that the installation is designed at the planning stage to allow measurement and

monitoring to be performed using established and approved methods.
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oSIST prEN 16211:2011
prEN 16211:2010 (E)
Foreword

This document (prEN 16211:2010) has been prepared by Technical Committee CEN/TC 156 “Ventilation

for buildings”, the secretariat of which is held by BSI.
This document is currently submitted to the CEN Enquiry.
This document is currently submitted to fill with appropriate information.

Measurement methods which are both correct and easy to use are developed and standardised to enable

the commissioning and operational monitoring of air processing installations. Interior climate and air quality

can often be improved considerably if the heating and ventilation system is managed in a way that ensures

good functioning in the long term. It is thus important that the installation is designed at the planning stage

to allow measurement and monitoring to be performed using established and approved methods.

1 Scope

This standard applies to measurement of airflows on site. It provides the technician with a description of

the methods, their protocols, and tables for noting measured and calculated values so that the necessary

measurements are performed within the margins of stipulated method uncertainties.

Note : The duct traverse method in this standard is an alternative method to the duct traverse method of

ISO 3966 and EN12599. It defines errors due to the simplified approach and describes also other methods

of measurements.
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)

EN12599 Ventilation for buildings - Test procedures and measuring methods for handing over

installed ventilation and air conditioning systems

EN14277 Ventilation for buildings – Air terminal devices – Methods for airflow measurement by

calibrated sensors in or close to ATD/Plenum boxes

ISO 3966, Measurement of fluid flow in closed conduits. Velocity area method using Pitot static tubes.

ISO 5167-1, Measurement of fluid flow by means of pressure differential devices. Part 1: Orifice plates,

nozzles and Venturi tubes inserted in circular cross-section conduits running full.

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
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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 5167-4 Measurement of fluid flow by means of pressure differential devices inserted in circular

cross-section conduits running full-Part 4: Venturi tubes

ISO 5221, Air distribution and air diffusion. Rules to methods of measuring air flow rate in an air-

handling duct.

ISO 4053-1, Measurement of gas flow in conduits -- Tracer methods -- Part 1: General

VIM :/ JCGM see reference – International Vocabulary of Metrology – basic and general concepts and

associated terms (VIM°) – 3 edition, Jan 2008-04-03
ENV 13005 Guide to the expression of uncertainty of measurement
3 Terms and definitions

For the purposes of this European Standard, the following terms and definitions apply:

3.1 Hydraulic diameter

The hydraulic diameter is the diameter of a circular duct which would have the same linear pressure drop, and is

defined by the following formula:
D = 4 ⋅ A/O m eq.3-2
where
A = the cross sectional area of the duct, m
O = the circumference of the duct or perimeter, m
For a rectangular duct this becomes:
D = 2 ⋅ L1 ⋅ L2 / (L1+ L2) m eq. 3-3
where L1 and L2 are the sides of the duct.
For a circular duct this becomes:
D = D m eq. 3-4
where
D = duct diameter, m
3.2 Flow disturbances
Flow disturbances result in velocity profiles in ducts that are non symmetrical.

Note : flow seldom has a symmetrical appearance except after long straight sections. The symmetry is often disturbed

by varying resistance, for example after a bend, an area decrease or an area increase. The velocity profile will also

become disturbed by a damper, T-piece as well as before and after a fan.
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3.3 Air density, ρ

The density of dry air varies with air pressure and temperature according to the following formula:

B 273
ρ =1,293⋅ ⋅ kg/m eq. 3-5
1013 273 +ϑ
where
B = barometric pressure, h Pa (hPa). (Normal air pressure is 1013 hPa)
ϑ= air temperature, °C

Note: The relative humidity of the air (RH) has very little influence on the density of air at room

temperature. The density of air at 20°C and 1013 hPa which is saturated with water vapour is only approx.

1% less than equivalent dry air.

In a low-pressure system it is hardly necessary to consider the influence of static pressure on air

density. In a high-pressure system, however, it can be necessary. The calculation is then performed as

follows:
B +0,01⋅ p 273
ρ =1,293⋅ ⋅ eq. 3-6
1013 273 +ϑ
where
p = static overpressure in the duct, Pa
ϑ = air temperature in °C
3.4 Dynamic pressure, p
ρ ⋅u
p = Pa eq. 3-7
where
ρ = air density, kg/m
u = air velocity, m/s
3.5 Corrections for air density, ρ

When presenting a measured flow or velocity, it should be stated if it is real flow or standardised flow that is

presented. Below in this section it is described how to convert between standardised and real velocity. The

same conversion is valid for air flow.

The method describes how to compensate and correct the air flow to real flow, that is real flow (real

velocity). The volume of air is as it is at present temperature and barometric pressure. Real flow is not the

same as standardised flow. Standardised flow is used to present the air flow by recalculating the air

volume into standard condition of 1013 hPa and 20°C (68°F). Standardised flow can directly be interpreted

as a mass flow. The reason to use real flow is that the fan approximately transports the same real air flow

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irrespective of the air density. The amount of standardised flow will change with air density. Even though

the dimensioning air flow is made by using ρ = 1.20 kg/m at the fan inlet, the measured velocity is

comparable if the flow is presented as real flow. Providing that the other parameters are identical,

correction of real flow is only necessary if the density at the time of measuring, ρ , deviates from the

density at the fan intake, ρ .

No corrections for air density are required during the proportional balancing of terminals and branch ducts

providing that the entire installation is balanced under the same running conditions. For this reason,

heaters in terminals and branch ducts, for example, must be switched off.

The instrument in use may measure real or standardised flow or the instrument requires calibration

conditions to display correctly. Compensate accordingly, especially when used at other conditions than

calibration condition or standard conditions of 1013 hPa and 20°C. The barometric pressure will decrease

with altitude and also vary with weather. Temperature can also vary especially when the house is not

conditioned.

To calculate from measured (real) velocity or air flow to standard velocity or air flow use the following

formula:
v = v ⋅ ρ / ρ m/s eq. 3-8
s m m s
where:
v = standard velocity, m/s
v = measured (real) velocity, m/s
ρ = density at time of measurement, kg/m
ρ = standard densityρ = 1,2 kg/m

Note that heating or cooling devices in the duct between the fan and the place of measurement must be

switched off while measuring air flow, q or air velocity, v .
m m
4 Symbols (and abbreviated terms)
The following symbols are used in the report.
Symbol Description SI Unit Symbol Description SI Unit
t Time s n Revolutions r.p.m.
α Quotient of measured and - Perimeter m
planned air flow
P Power W
Efficiency -
3 p
Pressure Pa
kg/m
Density
p Dynamic pressure Pa
p Planned pressure Pa
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p Static pressure
s Pa
A Area p Total pressure Pa
a,b p Measured pressure
Dimensions of length, e.g. u Pa
height of a duct
∆p Differential pressure Pa
hPa
Barometric pressure
Differential commissioning
∆p Pa
ppm i
C Contaminant concentration pressure
ppm
Air flow /s, l/s
Initial concentration q m
ppm
i 3
Tracer gas concentration in Corrected air flow m /s, l/s
s stationary condition
m /s, l/s
q Planned air flow
m p
Diameter
Trace gas flow m /s, l/s
m s
Hydraulic diameter
m /s, l/s
q Total air flow
- t
Flow factor
Measured air flow m /s, l/s
mm u
Smaller dimension of a
Temperature °C
mm ϑ
L rectangular duct
Temperature
T K
Larger dimension of a
rectangular duct
Temperature difference
∆ϑ, ∆T °C, K
Std Instrument uncertainty
Volume
Std Method uncertainty
Air velocity
m/s
Std Reading uncertainty
Air velocity in duct centre
m/s
Standard measurement
Corrected velocity
m/s
uncertainty
Air velocity, mean value
m/s
Expanded measurement
uncertainty
5 Preparation of measurement
5.1 Factors influencing measurements

The measurement methods which are to be used must have known and small method uncertainties. The requirements

for method uncertainties must be to some extent related to the requirement for flow tolerances.

There are many factors which affect the measurement results and which must be checked in connection with

measuring. Examples of these are:

‰ Calibration equipment, which must be regularly compared with a traceable norm (calibration unit).

‰ Calibrated measurement instruments.
‰ Calibration intervals.
‰ Examination of instruments’ long term stability.
‰ Instruments’ temperature or density compensation.
‰ Random instrument uncertainties.
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‰ Random reading uncertainties.
‰ Variations in the measured quantity.
‰ Measurement methods adapted to different installation cases.
‰ Deviations when measuring from calibrated installation cases.
‰ Random uncertainties in measurement methods.
‰ Measurement methods’ influence on the flow rate.
‰ Variations in the exterior climate.
‰ Air flow stability.
5.2 Sources of errors and uncertainties

The result of numerical work is influenced by many types of error. Certain sources of error are difficult to

manipulate, others can be reduced or even eliminated.

Errors in given data input may be the result of measurements which have been affected by system errors

or temporary disturbances. Errors in measurement data can be divided into:
• Gross errors
• Systematic errors
• Uncertainties
5.2.1 Gross errors

Gross errors should not be allowed but they may happen by accident as a result of the human factor. The risk of

gross errors arising can be reduced by suitable design of working

conditions and working routines. Stress, tiredness and poor lighting are common reasons for gross errors.

Checks should be planned, either of the end result before it is approved or of the work in

progress, to prevent large amounts of work being repeated as a result of an early error.

Incorrect magnitude of measured values or insufficient regularity can often be discovered

at an early stage. It is also possible to make a check on the likelihood of many results by

examining associations between them. Time taken on designing working conditions and

verification measures is time well spent.
5.2.2 Systematic errors

According to the definition, systematic errors occur if the individual measurement values deviate in the same direction

from the “true” value or if they vary in a regular fashion.

The result of measurements where systematic errors occur may appear as in Figure 1.

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prEN 16211:2010 (E)
Key
1 Measured
2 True value
3 Systematic error
X Time
Figure 1: Explanation of systematic error

The circles represent measured numbers which lie randomly spread around the true value and which according to the

definition are thus free from systematic errors.

The crosses represent results of measurements where the measured numbers lie too high, for example as a result of

an uncalibrated measuring instrument being used. This error can easily be rectified by calibrating the instrument and

determining a correction.
The following applies to a correction:
Correction = (true value) – (read value)
(Read value) + (correction) = estimate of true value
Estimates of true values are also often called measured values.
5.2.3 Calibration

Calibration is a part of the determination of the systematic errors of an instrument, which allows the understanding of

the calibration uncertainty, to eventually set up the instrument or correct the measurements, and by

...

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