ISO 23551-8:2016

INTERNATIONAL ISO
STANDARD 23551-8
First edition
2016-02-01
Safety and control devices for gas
burners and gas-burning appliances —
Particular requirements —
Part 8:
Multifunctional controls
Dispositifs de commande et de sécurité pour les brûleurs et les
appareils à gaz — Exigences particulières —
Partie 8: Equipements multifonctionnels
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
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ii © ISO 2016 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Classes of control. 2
4.1 Classes of controls . 2
4.2 Groups of controls . 2
5 Test conditions . 2
6 Construction . 2
6.101 General . 2
6.102 MFC based on combination of controls . 3
6.102.1 General. 3
6.102.2 Interaction between Controls . 3
7 Performance . 3
7.101 General . 3
7.102 External leak-tightness of MFC . 3
7.103 Mechanical thermostat function . 4
7.104 Internal leak tightness of MFC . 4
7.105 Endurance test for combined functions . 4
8 EMC/electrical requirements . 4
9 Marking, installation and operating instructions . 4
9.1 Marking . 4
9.2 Installation and operating instructions . 4
9.3 Warning notice . 4
Annex AA (normative) Water operated gas valves . 5
Bibliography . 7
Foreword
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The committee responsible for this document is ISO/TC 161, Control and protective devices for gas
and/or oil burners and appliances.
ISO 23551 consists of the following parts, under the general title Safety and control devices for gas
burners and gas-burning appliances — Particular requirements:
— Part 1: Automatic and semi-automatic valves
— Part 2: Pressure regulators
— Part 3: Gas/air ratio controls, pneumatic type
— Part 4: Valve-proving systems for automatic shut-off valves
— Part 5: Manual gas valves
— Part 6: Thermoelectric flame supervision controls
— Part 8: Multifunctional controls
— Part 9: Mechanical gas thermostats
— Part 10: Vent valves
iv © ISO 2016 – All rights reserved

Introduction
This part of ISO 23551 is designed to be used in combination with ISO 23550. Together, they establish
the full requirements as they apply to multifunctional controls. This part of ISO 23551 adapts
ISO 23550, where needed, by stating “with the following modification”, “with the following addition”,
“is replaced by the following” or “is not applicable” in the corresponding clauses. In order to identify
specific requirements that are particular to this part of ISO 23551 that are not already covered by
ISO 23550, this part of ISO 23551 may contain clauses or subclauses that are additional to the structure
of ISO 23550. These clauses are numbered starting from 101 or, in the case of an Annex, are designated
AA, BB, CC, etc.
It has been necessary to take into consideration the differing requirements resulting from practical
experience and installation practices in various regions of the world and to recognize the variation
in basic infrastructure associated with gas and/or oil controls and appliances. This part of ISO 23551
provides a basic framework of requirements that recognize these differences.
INTERNATIONAL STANDARD ISO 23551-8:2016(E)
Safety and control devices for gas burners and gas-burning
appliances — Particular requirements —
Part 8:
Multifunctional controls
1 Scope
This part of ISO 23551 specifies the safety, construction and performance requirements for
multifunctional controls intended for use with gas burners, gas appliances and similar use, hereafter
referred to as “MFC”.
This part of ISO 23551 is applicable to MFC with declared maximum inlet pressures up to, and
including, 50 kPa (500 mbar) of nominal connection sizes up to, and including, DN 150 for use with one
or more fuel gases.
MFC consist of two or more functions, at least one of which is a mechanical control, as specified in the
relevant control standards.
2 Normative references
The following referenced documents, in whole or in part, are normatively referenced in this document
and are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 23550:2011, Safety and control devices for gas burners and gas-burning appliances — General
requirements
ISO 23551-1, Safety and control devices for gas burners and gas-burning appliances — Particular
requirements — Part 1: Automatic and semi-automatic valves
ISO 23551-2, Safety and control devices for gas burners and gas-burning appliances — Particular
requirements — Part 2: Pressure regulators
ISO 23551-3, Safety and control devices for gas burners and gas-burning appliances — Particular
requirements — Part 3: Gas/air ratio controls, pneumatic type
ISO 23551-4, Safety and control devices for gas burners and gas-burnin
...