Mechanical structures for electrical and electronic equipment - Aisle containment for IT cabinets - Part 2: Details of air flow, air separation and air cooling requirements

IEC 62966-2:2020 is dedicated to aisle containment techniques for information technology (IT) equipment typically used in data centres, describes the quantification of its air tightness, in particular the air loss ratio that describes the content of the volumetric flow not used for cooling the IT equipment. This ratio provides an index of efficiency, being inversely proportional to efficiency (the lower this ratio, the higher the efficiency). This document provides methods to measure an aisle containment air leakage rate and defines a classification system for aisle containment leakage.
This document defines:
- the measurement of the air leakage of the individual components of an aisle containment;
- a method for calculating the air leakage of an aisle containment based on its individual components;
- a method for calculating the air leakage rate of an aisle containment in relation to the utilised IT equipment;
- a classification system for aisle containment leakage.

Structures mécaniques pour équipements électriques et électroniques - Confinement d’allées pour les baies informatiques - Partie 2: Détails des exigences relatives au flux d’air, à la séparation des flux d’air et au refroidissement par air

IEC 62966-2:2020 est dédiée aux techniques de confinement pour les équipements informatiques typiquement utilisés dans les centres de données, décrit la quantification de leur étanchéité, et plus particulièrement le taux de fuite d’air, qui définit le débit volumique qui ne sert pas à refroidir les équipements informatiques. Ce taux constitue un indice de rendement, fonctionnant à proportionnalité inverse (plus le taux diminue, plus le rendement augmente). Le présent document donne des méthodes pour mesurer le taux de fuite d’air d’un confinement, et définit un système de classification des fuites du confinement.
Le présent document définit:
- la mesure des fuites d’air des composants individuels d’un confinement;
- une méthode de calcul des fuites d’air d’un confinement, basée sur ses composants individuels;
- une méthode de calcul du taux de fuite d’air d’un confinement, en fonction des équipements informatiques utilisés;
- un système de classification des fuites du confinement.

General Information

Status
Published
Publication Date
14-Jul-2020
Current Stage
PPUB - Publication issued
Completion Date
15-Jul-2020
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IEC 62966-2
Edition 1.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Mechanical structures for electrical and electronic equipment – Aisle
containment for it cabinets –
Part 2: Details of air flow, air separation and air cooling requirements
Structures mécaniques pour équipements électriques et électroniques –
Confinement d’allées pour les baies informatiques –

Partie 2: Détails des exigences relatives au flux d’air, à la séparation des flux

d’air et au refroidissement par air
IEC 62966-2:2020-07(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 62966-2
Edition 1.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Mechanical structures for electrical and electronic equipment – Aisle
containment for it cabinets –
Part 2: Details of air flow, air separation and air cooling requirements
Structures mécaniques pour équipements électriques et électroniques –
Confinement d’allées pour les baies informatiques –

Partie 2: Détails des exigences relatives au flux d’air, à la séparation des flux

d’air et au refroidissement par air
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.240 ISBN 978-2-8322-8510-7

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 62966-2:2020 © IEC 2020
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms and definitions ...................................................................................................... 7

4 Determination of the air leak rate ..................................................................................... 9

4.1 Determination of the air leak rate of the individual components of an aisle

containment ............................................................................................................ 9

4.2 Components and system characteristic curves ...................................................... 10

4.2.1 General ......................................................................................................... 10

4.2.2 Equipment requirements ................................................................................ 11

4.3 Measurement procedure ....................................................................................... 11

4.3.1 Measurement conditions ................................................................................ 11

4.3.2 Preparing the elements of the test housing for measurement ......................... 11

4.3.3 Measurement of the air leak rate ................................................................... 13

4.4 Test report ............................................................................................................ 14

4.5 Measurement precision ......................................................................................... 14

5 Air leakage rate of the aisle containment – Creation of an overall system

characteristic curve for the aisle containment ................................................................ 15

6 Determination of the air leak rate – Determination of the air leak rate of the overall

system in operation, including the IT equipment ............................................................ 15

Annex A (informative) Aisle containments according to operation mode ............................... 17

A.1 Allocation of the aisle containments according to operation mode ......................... 17

A.1.1 General ......................................................................................................... 17

A.1.2 Types of climate control ................................................................................. 17

A.1.3 Closed-circuit climate control ......................................................................... 17

A.1.4 In-line climate control .................................................................................... 17

A.2 Cold aisle containment .......................................................................................... 18

A.2.1 Principle of the cold aisle containment ........................................................... 18

A.2.2 Objective of the cold aisle .............................................................................. 18

A.2.3 Climate control .............................................................................................. 18

A.3 Hot aisle containment ........................................................................................... 18

A.3.1 Principle of the hot aisle containment ............................................................ 18

A.3.2 Objective of the hot aisle ............................................................................... 19

A.3.3 Climate control .............................................................................................. 19

A.4 Cold and hot aisle containment ............................................................................. 19

A.4.1 Principle of the cold and hot aisle containment .............................................. 19

A.4.2 Objective of the cold aisle in a cold and hot aisle containment ....................... 20

A.4.3 Climate control .............................................................................................. 20

Annex B (informative) Thermodynamic variables within aisle containments .......................... 21

B.1 Air pressure .......................................................................................................... 21

B.1.1 General ......................................................................................................... 21

B.1.2 Minimum differential pressure ........................................................................ 21

B.1.3 Overpressure in hot aisle containments ......................................................... 21

B.1.4 Negative pressure in hot aisle containments .................................................. 21

B.1.5 Overpressure in cold aisle containments ........................................................ 21

B.1.6 Negative pressure in cold aisle containments ................................................ 21

---------------------- Page: 4 ----------------------
IEC 62966-2:2020 © IEC 2020 – 3 –

B.2 Directions of flow .................................................................................................. 22

B.2.1 Directions of flow "from the front to the back" ................................................ 22

B.2.2 Direction of flow "to the side" ......................................................................... 22

B.3 Flow velocities ...................................................................................................... 22

B.3.1 Closed-circuit climate control ......................................................................... 22

B.3.2 In-line climate control .................................................................................... 22

B.3.3 Design of the aisle containments ................................................................... 22

B.4 Temperatures and humidity ................................................................................... 23

B.4.1 General ......................................................................................................... 23

B.4.2 Temperatures ................................................................................................ 23

B.4.3 Humidity ........................................................................................................ 23

Bibliography .......................................................................................................................... 24

Figure 1 – Example of the components – Roof ........................................................................ 9

Figure 2 – Example of the components – Door ...................................................................... 10

Figure 3 – Example of the components – Enclosures ............................................................ 10

Figure 4 – Sealing the installation level ................................................................................. 12

Figure 5 – Example of a connecting design to the neighbouring enclosure ............................ 12

Figure 6 – Example of a connecting design to the roof .......................................................... 13

Figure 7 – Example of a connecting design to the end door .................................................. 13

Figure 8 – Example of component and system characteristic curves ..................................... 14

Figure 9 – Example of a hydraulic addition of individual characteristic curves ....................... 15

Figure 10 – Classification of aisle containment by class factors ............................................ 16

Figure A.1 – Example of an in-line climate control ................................................................. 17

Figure A.2 – Example of a cold aisle containment ................................................................. 18

Figure A.3 – Example of a hot aisle containment ................................................................... 19

Figure A.4 – Example of a cold and hot aisle containment .................................................... 20

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– 4 – IEC 62966-2:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MECHANICAL STRUCTURES FOR
ELECTRICAL AND ELECTRONIC EQUIPMENT –
AISLE CONTAINMENT FOR IT CABINETS –
Part 2: Details of air flow, air separation and air cooling requirements
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,

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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with

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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

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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 62966-2 has been prepared by subcommittee 48D: Mechanical

structures for electrical and electronic equipment, of IEC technical committee 48: Electrical

connectors and mechanical structures for electrical and electronic equipment.
The text of this International Standard is based on the following documents:
FDIS Report on voting
48D/722/FDIS 48D/727/RVD

Full information on the voting for the approval of this International Standard can be found in the

report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

---------------------- Page: 6 ----------------------
IEC 62966-2:2020 © IEC 2020 – 5 –

A list of all parts in the IEC 62966 series, published under the general title Mechanical structures

for electrical and electronic equipment – Aisle containment for it cabinets, can be found on the

IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct understanding

of its contents. Users should therefore print this document using a colour printer.

---------------------- Page: 7 ----------------------
– 6 – IEC 62966-2:2020 © IEC 2020
INTRODUCTION

Cabinets of the IEC 60297 and IEC 60917 standard series are used as enclosures of electronic

and electrical equipment in many different fields of application. A wide field of application is

represented by enclosures equipped with electronic information technology (IT) equipment.

They are frequently set up in large numbers in server rooms and data centres. During their

operation, the electronic equipment installed generates a considerable amount of heat that will

be removed from the equipment by means of cooling air. Precise adjustment of the supply air

temperature and a sufficient cooling air flow are indispensable prerequisites for the fail-safe

operation of equipment in information technology.

It is a common practice to set up cabinets in rows. The server cabinets along the rows are

usually arranged in such a way that surfaces with cold supply air inlets face each other across

an aisle, and surfaces with hot exhaust air outlets also face each other across an aisle. This

row configuration is generally known as hot aisle/cold aisle configuration. Moreover, air is

supplied and discharged exclusively via the front and rear panels of the server cabinets, which

are frequently perforated doors. It is assumed that inside the IT equipment, the cooling air is

moved in a horizontal direction, taking it in at the front and discharging it at the rear.

This part of IEC 62966 specifies the quantification of the air separation, in particular the air leak

rate that describes the content of the volumetric flow not used for cooling in the aisle

containment for information technology (IT) cabinets. The objective of this document is to

stipulate properties and requirements of aisle containment ensuring cost effective installation,

energy-efficient and user-friendly operation of IT equipment in data centres server rooms.

The fan pressurization method (overpressure at the system and elements) is used to categorize

the air tightness of the aisle containment. In doing so, it is used to quantify the air tightness, in

order to compare aisle containments with regard to the air tightness. It is also useful for finding

leaks, or to determine the improvement due to improving the air tightness. The fan

pressurization method cannot measure the air leak rate, but serves as a basis for determining

the air leak rate by calculation. The method can be used to determine air leak rates of the aisle

containment at low-pressure and overpressure on the inside compared with the surroundings.

Thus, this allows a categorization of the elements of an aisle containment – the enclosure – to

be determined.

For this purpose, aisle containment is dismantled into typical individual elements, for example

enclosures, doors and roof covers. The corresponding characteristic curves of these

components are recorded separately and added to the system characteristic curve of the aisle

containment.

The quality of the resulting aisle containment is then classified using a differential pressure

measurement.

The IEC 62966 series, Mechanical structures for electrical and electronic equipment – Aisle

containment for IT cabinets, is subdivided into the following parts:
• IEC 62966-1: Dimensions and mechanical requirements
• IEC 62966-2: Details of air flow, air separation and air cooling requirements

• IEC 62966-3: Aspects of operational safety of IT equipment and users of aisle containment

IEC 62966-1 defines geometric dimensions and mechanical properties ensuring undisturbed,

energy-efficient and user-friendly operation of the data centre.

IEC 62966-2 provides the methods and process to get the aisle containment air leakage and

define the classification (evaluation) system on the aisle containment air leakage, for designers

and users of aisle containments for IT cabinets based on the IEC 60297 and IEC 60917 series.

IEC 62966-3 deals with aspects of safely operating IT equipment in aisle containment, with

respect to special fire-protection and fire-fighting issues. It also describes the nature of the

doors for access to the aisle containment and possible access control.
---------------------- Page: 8 ----------------------
IEC 62966-2:2020 © IEC 2020 – 7 –
MECHANICAL STRUCTURES FOR
ELECTRICAL AND ELECTRONIC EQUIPMENT –
AISLE CONTAINMENT FOR IT CABINETS –
Part 2: Details of air flow, air separation and air cooling requirements
1 Scope

This part of IEC 62966, dedicated to aisle containment techniques for information technology

(IT) equipment typically used in data centres, describes the quantification of its air tightness, in

particular the air loss ratio that describes the content of the volumetric flow not used for cooling

the IT equipment. This ratio provides an index of efficiency, being inversely proportional to

efficiency (the lower this ratio, the higher the efficiency). This document provides methods to

measure an aisle containment air leakage rate and defines a classification system for aisle

containment leakage.
This document defines:

a) the measurement of the air leakage of the individual components of an aisle containment;

b) a method for calculating the air leakage of an aisle containment based on its individual

components;

c) a method for calculating the air leakage rate of an aisle containment in relation to the utilised

IT equipment;
d) a classification system for aisle containment leakage.
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.

IEC 62966-1, Mechanical structures for electrical and electronic equipment – Aisle containment

for IT equipment – Part 1: Dimensions and mechanical requirements

ISO 9972, Thermal performance of buildings – Determination of air permeability of buildings –

Fan pressurization method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
air leak rate

ratio of the volumetric air flow not used for cooling to the total volumetric air flow

---------------------- Page: 9 ----------------------
– 8 – IEC 62966-2:2020 © IEC 2020
3.2
aisle containment

boundary that separates the inner volume from the surroundings, usually comprising the base

(floor), access doors or end-piece on the front side, roof elements and containment doors of

the enclosure (cabinet), that contain the IT equipment
3.3
base

area bounded by the doors of the opposite-facing bayed enclosure

(cabinet) suites and the aisle doors or walls
3.4
doors

end piece of an aisle containment on both ends or on one end that

ensures access to the inside of the aisle containment
3.5
roof elements

upper construction of the aisle containment as an upper end piece

3.6
enclosure

server and network cabinets that accommodate IT equipment

3.7
inner volume

volumes of the aisle containment limited by doors, roof elements,

bases and enclosures
3.8
IT equipment

all (active) components that are installed in an enclosure

3.9
supply air

cooling air before entering the IT equipment and other IT related supporting systems, whose

temperature is suitable to absorb the heat flow from the equipment
3.10
supply air temperature
temperature of the supply air to the enclosures.
3.11
exhaust air
heated supply air after exiting the IT equipment that has absorbed the heat flow
3.12
exhaust air temperature
temperature of the exhaust air from the enclosures of an isle containment
3.13
cold aisle

area in front of the enclosures of an aisle containment that is supplied with the supply air

3.14
hot aisle

area behind the enclosures of an aisle containment into which the exhaust air flows

---------------------- Page: 10 ----------------------
IEC 62966-2:2020 © IEC 2020 – 9 –
3.15
operation point

work point of the overall system at a specified time, set via the selected operating parameters

3.16
design point
operating parameters that are used as a basis for correct operation
3.17
air flow unit

equipment unit fitted in an aisle containment able to provide for example through air conditioning

or forced ventilation, the supply of cooling air mass to the entire aisle containment

4 Determination of the air leak rate
4.1 Determination of the air leak rate of the individual components of an aisle
containment

The following description is used to determine the air leak rate of the individual components of

an aisle containment. The same method shall be used for special design adaptations.

The individual components are measured on a test rig. A component characteristic curve is

recorded (pressure drop ∆p versus volumetric air flow). The system characteristic curve is

generated by grouping all of the component characteristic curves.

The quality of the technically correct installation of the entire aisle containment has a decisive

influence on the air leak rate. For this reason, all interfaces of the individual components shall

be made air tight
...

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