ISO 21927-2:2006

Smoke and heat control systems — Part 2: Specification for natural smoke and heat exhaust ventilators

ISO 21927-2:2006 specifies requirements and gives test methods for natural smoke- and heat-exhaust ventilators that are intended to be installed in a roof and/or wall as a component of a natural smoke- and heat-exhaust system.

Systèmes de contrôle de fumée et de chaleur — Partie 2: Spécifications pour les dispositifs d'évacuation naturelle des fumées et de la chaleur

General Information

• Status: Withdrawn
• Publication Date: 21-Nov-2006
• Withdrawal Date: 21-Nov-2006
• ICS: 13.220.20 - Fire protection
• Technical Committee: ISO/TC 21/SC 11 - Smoke and heat control systems and components
• Drafting Committee: ISO/TC 21/SC 11 - Smoke and heat control systems and components
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 28-Nov-2018

Relations

• Amended By: ISO 21927-2:2006/Amd 1:2010 - Smoke and heat control systems — Part 2: Specification for natural smoke and heat exhaust ventilators — Amendment 1
• Effective Date: 21-Aug-2021
• Revised: ISO 21927-2:2018 - Smoke and heat control systems — Part 2: Specifications for natural smoke and heat exhaust ventilators
• Effective Date: 19-Mar-2016

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 21927-2

First edition
2006-11-15
Smoke and heat control systems —
Part 2:
Specification for natural smoke and heat
exhaust ventilators
Systèmes de contrôle de fumée et de chaleur —
Partie 2: Spécifications pour les dispositifs d'évacuation naturelle des
fumées et de la chaleur




Reference number
ISO 21927-2:2006(E)
©
ISO 2006

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ISO 21927-2:2006(E)
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ISO 21927-2:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Symbols . 4
5 Design requirements . 5
5.1 Initiation device. 5
5.2 Opening mechanism. 6
5.3 Opening of the ventilator . 6
5.4 Size of the geometric area . 6
5.5 Inputs and outputs (connections). 7
6 General testing procedures . 7
7 Aerodynamic free area of the ventilator. 7
8 Performance requirements and classification. 7
8.1 Reliability . 7
8.2 Opening under load. 8
8.3 Low ambient temperature . 9
8.4 Wind load. 10
8.5 Resistance to heat . 10
9 Evaluation of conformity. 11
9.1 General. 11
9.2 Type testing. 11
9.3 Factory production control (FPC) . 11
10 Marking . 11
11 Installation and maintenance information.12
11.1 Installation information . 12
11.2 Maintenance information . 12
Annex A (normative) General testing procedures . 13
Annex B (normative) Determination of the aerodynamic free area. 14
Annex C (normative) Test method for reliability. 28
Annex D (normative) Test method for opening under load . 29
Annex E (normative) Test method for low ambient temperature . 30
Annex F (normative) Test methods for wind load . 32
Annex G (normative) Test method for heat exposure . 33
Annex H (normative) Direct field of application for SHEVs . 36
Bibliography . 40

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ISO 21927-2:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 21927-2 was prepared by Technical Committee ISO/TC 21, Equipment for fire protection and fire fighting,
Subcommittee SC 11, Smoke and heat control systems and components.
ISO 21927 consists of the following parts, under the general title Smoke and heat control systems:
⎯ Part 1: Specification for smoke barriers
⎯ Part 2: Specification for natural smoke and heat exhaust ventilators
⎯ Part 3: Specification for powered smoke and heat exhaust ventilators
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ISO 21927-2:2006(E)
Introduction
In a fire situation, smoke- and heat-exhaust ventilation systems create and maintain a smoke-free layer above
the floor by removing smoke. They also serve simultaneously to exhaust hot gases released by a fire in the
developing stages. The use of such systems to create smoke-free areas beneath a buoyant layer has become
widespread. Their value in assisting in the evacuation of people from buildings and other construction works,
reducing fire damage and financial loss by preventing smoke damage, facilitating access for fire-fighting by
improving visibility, reducing roof temperatures and retarding the lateral spread of fire is firmly established. For
these benefits to be obtained, it is essential that smoke- and heat-exhaust ventilators operate fully and reliably
whenever called upon to do so during their installed life. A smoke- and heat-exhaust ventilation system
(referred to in this part of ISO 21927 as a SHEVS) is a system of safety equipment intended to perform a
positive role in a fire emergency.
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INTERNATIONAL STANDARD ISO 21927-2:2006(E)

Smoke and heat control systems —
Part 2:
Specification for natural smoke and heat exhaust ventilators
1 Scope
This part of ISO 21927 specifies requirements and gives test methods for natural smoke- and heat-exhaust
ventilators that are intended to be installed in a roof and/or wall as a component of a natural smoke- and heat-
exhaust system.
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.
ISO 6182-1, Fire protection — Automatic sprinkler systems — Part 1: Requirements and test methods for
sprinklers
ISO 7240-7, Fire detection and alarm systems — Part 7: Point-type smoke detectors using scattered light,
transmitted light or ionization
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13943 and the following apply.
3.1
aerodynamic free area
product of the geometric area multiplied by the coefficient of discharge
3.2
ambient
properties of the surroundings
3.3
automatic activation
initiation of operation without direct human intervention
3.4
aspect ratio
ratio of length to width
3.5
automatic natural smoke- and heat-exhaust ventilator
smoke- and heat-exhaust ventilator that is designed to open automatically after the outbreak of fire if called
upon to do so
NOTE Automatic natural smoke- and heat-exhaust ventilators can also be fitted with a manual control or release
device.
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ISO 21927-2:2006(E)
3.6
coefficient of discharge
C
v
ratio of actual flow rate, measured under specified conditions, to the theoretical flow rate, through the
ventilator, as defined in Annex B
NOTE 1 The coefficient takes into account any obstructions in the ventilator, such as controls, louvers and vanes, and
the effect of external side winds.
NOTE 2 Also called aerodynamic efficiency.
3.7
dual-purpose ventilator
smoke- and heat-exhaust ventilator that has provision to allow its use for comfort (i.e. day-to-day) ventilation
3.8
exhaust ventilator
device for the movement of gases out of the construction works
3.9
fire-open position
configuration of the ventilator specified by its designer to be achieved and sustained while venting smoke and
heat
3.10
gas container
vessel containing gas in a compressed form, the energy of which, when released, opens the ventilator
3.11
geometric area
A
v
area of the opening through a ventilator, measured in the plane defined by the surface of the construction
works, where it contacts the structure of the ventilator
NOTE No reduction is made for controls, louvers or other obstructions.
3.12
initiation device
device that activates the operating mechanism of the component (e.g. of a damper or a ventilator) on receipt
of information from a fire detection system or thermal device
3.13
manual operation
initiation of the operation of a smoke- and heat-exhaust ventilator by a human action (e.g. pressing a button,
or pulling a handle)
NOTE A sequence of automatic actions in the operation of a smoke- and heat-exhaust ventilator started by the initial
human action is regarded as manual operation for the purposes of this part of ISO 21927.
3.14
manually opened natural smoke- and heat-exhaust ventilator
natural smoke- and heat-exhaust ventilator that can be opened only by a manual control or release device
3.15
mass flux
total mass of gases crossing a specified boundary per unit time
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ISO 21927-2:2006(E)
3.16
natural ventilation
ventilation caused by buoyancy forces due to differences in density of the gases because of temperature
differences
3.17
opening mechanism
mechanical device that operates the ventilator to the fire-open position
3.18
opening time
period between the information to open being received by the ventilators and achieving the fire-open position
of the ventilator
3.19
projection area
cross-sectional area of the natural smoke- and heat-exhaust ventilator in its fire-open position above the plane
of the roof, at a right angle to the side-wind flow
3.20
range of natural smoke- and heat-exhaust ventilators
ventilators of various sizes having the same method of construction and the identical number and type of
opening devices
3.21
smoke- and heat-control system
arrangement of components installed in a construction works to limit the effects of smoke and heat from a fire
3.22
smoke- and heat-exhaust system
smoke and heat control system that exhausts smoke and heat from a fire in a construction works or part of a
construction works
3.23
smoke- and heat-exhaust ventilation system
SHEVS
components jointly selected to exhaust smoke and heat in order to establish a buoyant layer of warm gases
above cooler and cleaner air
3.24
smoke- and heat-exhaust ventilator
SHEV
device specially designed to move smoke and hot gases out of a construction works under conditions of fire
3.25
thermal device
temperature-sensitive device that responds to initiate a subsequent action
3.26
throat area
smallest cross-sectional area of the flow path through the ventilator
3.27
ventilator
device for enabling the movement of gases into or out of the construction works
3.28
wind-sensitive control system
control system designed to control two or more banks of ventilators on separate elevations so that only the
ventilators not subject to positive wind pressures open in case of fire
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ISO 21927-2:2006(E)
3.29
wall
external building surface with an inclination of more than 60° relative to the horizontal
3.30
roof
external building surface with inclination of 60° or less relative to the horizontal
NOTE Shed roofs, independent of inclination angle, are considered to be part of roofs.
4 Symbols
Symbol Definition Unit
A any number used in the classifications
2
A aerodynamic free area, expressed in square meters (m )
a
2
A nozzle exit area (for open jet facilities), expressed in square meters (m )
n
2
A projection area of the ventilator for the side-wind flow, expressed in square meters (m )
pr
2
A horizontal cross-section area of the settling chamber, expressed in square meters (m )
sc
2
A geometric area of the ventilator, expressed in square meters (m )
v
B width of the open hole of the settling chamber, expressed in meters (m)
B width of nozzle exit area in open jet facilities, expressed in meters (m)
n
B maximum width of the ventilator in the fire-open position, expressed in meters above (m)
v
the upper surface of the settling chamber
C coefficient of discharge, dimensionless _
v
C coefficient of discharge without side-wind influence, dimensionless _
v0
C coefficient of discharge with side-wind influence, dimensionless _
vw
H height of nozzle exit area in open jet facilities, expressed in meters (m)
n
H maximum height of the ventilator in the fire-open position above the upper surface of (m)
v
the settling chamber, expressed in meters
L length of the open hole of the settling chamber, expressed in meters (m)

m mass flow rate entering the settling chamber, expressed in kilograms per second (kg/s)
ing
p ambient pressure, expressed in pascals (Pa)
amb
p wind-stagnation pressure, expressed in pascals (Pa)
d
p internal static pressure, expressed in pascals (Pa)
int
p internal static pressure without side wind, expressed in pascals (Pa)
int, v0
p internal static pressure with side wind, expressed in pascals (Pa)
int, vw

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ISO 21927-2:2006(E)
T temperature, expressed in degrees Celsius (°C)
∆T temperature difference, expressed in Kelvin (K)
V side-wind velocity, expressed in meters per second (m/s)
∞
V mean velocity of the settling chamber, expressed in meters per second (m/s)
m, sc
V mean nozzle velocity, expressed in meters per second (m/s)
n
V local velocities in plane above settling chamber, see Figure B.6, expressed in (m/s)
sc
meters per second
W snow load, expressed in pascals (Pa)
s
W wind load, expressed in pascals (Pa)
w
W design wind load, expressed in pascals (Pa)
wd
α opening angle of the ventilator, expressed in degrees °
β angle of attack, expressed in degrees °
β incidence angle at which the smallest value of C obtained with side wind occurs, °
crit vw
expressed in degrees
θ angle of installation of ventilators on a roof, expressed in degrees °
∆p pressure difference, expressed in pascals (Pa)
∆p reference-pressure difference between the static pressure in the settling chamber (Pa)
v0
and the ambient pressure without side wind, expressed in pascals
∆p reference-pressure difference between the static pressure in the settling chamber (Pa)
vw
and the ambient pressure with side wind, expressed in pascals
∆p pressure difference between the static pressure in the settling chamber and the (Pa)
int
ambient pressure, expressed in pascals
3
ρ density of air, expressed in kilograms per cubic meter (kg/m )
air
5 Design requirements
5.1 Initiation device
5.1.1 General
To ensure that the natural smoke and heat ventilator opens in the event of a fire, it shall be fitted with an
automatic initiation device.
Each ventilator shall be fitted with one or more of the following automatic initiation devices:
a) thermal initiation device;
b) initiation device activated by an electrical signal from a remote source, e.g. a smoke and heat detector
system, the interruption of electrical supply or a manually actuated “fire override” switch;
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ISO 21927-2:2006(E)
c) pneumatic initiation device, e.g. a pneumatic signal or a loss of compressed air;
d) initiation device able to respond to other types of release signal.
The response behaviour of thermal automatic initiation devices shall comply with the requirements of
ISO 6182-1. Smoke detectors shall comply with the requirements of ISO 7240-7. In addition, a manually
operated initiation device may be fitted.
A pneumatic non-fail-safe SHEV, which does not open automatically on loss of power, shall have at least a
thermal device and one power source that is mounted directly in the SHEV, unless the required control panel
monitors the lines to the SHEV and indicates a failure.
In some specific design cases where it is suitable that the ventilator shall be only manually initiated, the
ventilator may be installed without an automatic initiation device.
5.1.2 Thermal initiation device
Any thermal initiation or release device shall be within the ventilator and shall be exposed to the hot gas
entering the closed ventilator.
There are two exceptions to this requirement, where an automatic thermal initiation or release device shall not
be fitted to the ventilator:
a) if the ventilators are installed as wall-mounted ventilators;
NOTE Adverse wind conditions can cause a ventilator, which has been opened by the automatic initiation
device, to let in air and not remove heat and smoke.
b) in specific design cases where it is suitable that the ventilators are only manually initiated.
5.2 Opening mechanism
5.2.1 General
The ventilator shall be provided with an opening mechanism with energy within the ventilator, e.g. gas
containers, spring systems, electrical power supply and/or with an external energy source. For the external
links, the manufacturer shall specify the operating requirements for the initiation device and the opening
mechanism, e.g. voltage, energy.
5.2.2 Integral gas containers
Any gas container forming an integral part of the ventilator shall be equipped with a pressure-release device to
prevent an explosion if the container overheats.
5.3 Opening of the ventilator
For on-site testing purposes, there are two types of ventilators:
a) type A, which are able to be opened into their fire-open position;
b) type B, which are able to be opened into their fire-open position and closed remotely.
5.4 Size of the geometric area
The size and form of the geometric area shall be such that it complies with the limitation set by the test
apparatus available for the heat exposure test.
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ISO 21927-2:2006(E)
The side length shall not exceed 2,5 m and the aspect ratio of the geometric area shall not exceed 5:1 when
using the simple assessment procedure to determine the aerodynamic free area; see Clause B.1.
NOTE As of the publication date of this part of ISO 21927, maximum dimensions of the test apparatus for the heat
exposure test are in the range of 3 m.
For ventilators larger than the largest ventilator tested in accordance with Annex G, an assessment of the heat
exposure effect shall be made by the testing station to ensure that the performance is not negatively affected.
5.5 Inputs and outputs (connections)
The SHEV shall be equipped with inputs and/or output that allow its connection with the control panel and
power supplies.
6 General testing procedures
For type approval testing, tests shall be carried out in the sequence specified in Clause A.1.
For each test, a test report shall be prepared in accordance with Clause A.2.
Some of the tests mentioned may be omitted when type testing a new product belonging to a product range
that has been tested if only detail changes have been made.
The use of additional functions to smoke ventilation (e.g. daily ventilation) and/or add-ons to the SHEVs are
permitted if they do not negatively alter the performance of the SHEV.
7 Aerodynamic free area of the ventilator
The aerodynamic free area of the ventilator shall be determined in accordance with Annex B.
For roof-mounted ventilators, the aerodynamic free area is written A .
a Roof
For wall-mounted ventilators, the aerodynamic free area is written A .
a Wall
8 Performance requirements and classification
8.1 Reliability
8.1.1 Reliability classification
The ventilator shall be classified as one of the following:
a) Re A;
b) Re 50;
c) Re 1 000.
The designation A, 50 and 1 000 represents the number of openings into the fire-open position and closing
under no applied load in accordance with Annex C.
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ISO 21927-2:2006(E)
8.1.2 Reliability performance
The ventilator shall open, reach its fire-open position not more than 60 s after actuation without damage and
remain in position without an external energy supply (until reset).
8.1.3 Dual purpose ventilator
If the ventilator is a dual purpose ventilator, it shall open to its normal comfort position when tested under no
load 10 000 times in accordance with Annex C prior to testing the same ventilator under 8.1.1 and 8.1.2.
8.2 Opening under load
8.2.1 Loads
8.2.1.1 Snow-load classification
The ventilator shall be classified as one of the following:
a) SL 0;
b) SL 125;
c) SL 250;
d) SL 500;
e) SL 1 000;
f) SL A.
The designations 0, 125, 250, 500, 1 000 and “A” represent the test snow load, expressed in pascals, applied
when the ventilator is tested in accordance with Annex D.
NOTE A ventilator classified SL 0 can be installed in accordance with the manufacturer’s instructions with a minimum
angle of installation > 45° from the horizontal (combining roof pitch and vent pitch (see Figure 1), except where the snow is
prevented from slipping from the ventilator, e.g. by wind deflectors.
Except for SL 0 for ventilators fitted with deflectors, the snow-load classification should not be less than
SL = 2 000 d, where d is the depth of snow, expressed in metres, that can be contained within the confines of
the deflectors.
8.2.1.2 Load due to side-wind simulation
To simulate the side-wind influence, the ventilator shall be subjected to the most unfavourable wind direction
to a side wind of 10 m/s velocity when tested in accordance with Annex D.
This test does not apply for wall-mounted SHEVs.
8.2.2 Performance under load
The ventilator shall open, reach its fire-open position not more than 60 s after actuation and remain in position
without an external energy supply (until reset), when tested under the snow load appropriate to its
classification and under the specified side wind in accordance with Annex D.
For ventilators fitted with wind deflectors, the deflectors shall be at least 80 mm from the nearest part of the
ventilator and they shall not be fitted in such a way to encourage snow or ice to collect to the detriment of the
operation of the ventilator.
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ISO 21927-2:2006(E)
It is recommended that louver-type ventilators be classified not less than SL 500 when used in sub-zero
conditions.
This test does not apply for wall-mounted SHEVs.

Key
1 ventilator
2 roof
Figure 1 — Combined roof pitch and vent pitch angle > 45° from the horizontal
8.3 Low ambient temperature
8.3.1 Classification
The ventilator shall be classified as one of the following:
a) T(− 25);
b) T(− 15);
c) T(− 05);
d) T(00);
e) T A.
The designations 25, 15, 05 and “A” represent the number of °C below zero at which the ventilator is tested in
accordance with Annex E. T(00) ventilators are regarded as suitable only for use in construction works where
the temperature is above 0 °C.
8.3.2 Performance at low temperature
When tested in accordance with Annex E, the opening mechanism of a classified ventilator, except those
classified as T(00) (see 8.3.1), shall operate in a manner corresponding to the load-versus-stroke correlation
of the same opening mechanism when it is built-in and tested under ambient temperature. It shall reach the
stroke that corresponds to the fire-open position of the ventilator in not more than 60 s.
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ISO 21927-2:2006(E)
8.4 Wind load
8.4.1 Wind-load classification
The ventilator shall be classified as one of the following:
a) WL 1 500;
b) WL 3 000;
c) WL A.
The designations 1 500, 3 000 and “A” represent the test wind-suction load, expressed in pascals, applied
when the ventilator is tested in accordance with Annex F.
8.4.2 Performance under wind load
The ventilator shall not open under the wind load appropriate to its classification, and shall not suffer
permanent deformation when tested in accordance with Annex F; following this test, it shall open into the
fire-open position within 60 s of actuation.
8.4.3 Resistance to wind-induced vibration
If wind deflectors form an integral part of the ventilator, their natural frequency of vibration shall be higher than
10 Hz with a logarithmic decrement of damping greater than 0,1 when tested in accordance with F.4.2.
8.5 Resistance to heat
8.5.1 Classification
The ventilator shall be classified as given under a) and/or
...