This Standard describes the normative requirements for applications and installations of safety devices to protect static pressure equipment. The information contained in this Standard assumes single-phase flow of the fluid discharged from the safety device. JIS B 8227 provides guidance specific to two-phase flow conditions.

Equipment connected together in a system by piping of adequate capacity, which is free from potential blockages and does not contain any valve that can isolate any part, can be considered to be a safety system for the application of pressure relief.

This Standard does not deal with other safety devices, such as safety related monitoring, control and regulation devices and other limiting devices allowed by some national regulations.

NOTE 1 National regulations described in this Standard indicate the High Pressure Gas Safety Act, the Electricity Business Act, the Gas Business Act and the Industrial Safety and Health Act in Japan.

NOTE 2 The International Standard corresponding to this Standard and the symbol of degree of correspondence are as follows.

ISO 4126-9:2008 Safety devices for protection against excessive pressure— Part 9: Application and installation of safety devices excluding standalone bursting disc safety devices (MOD)

In addition, symbols which denote the degree of correspondence in the contents between the relevant International Standards and JIS are IDT (identical), MOD (modified), and NEQ (not equivalent) according to ISO/IEC Guide 21-1.

This Standard is not applicable to pilot operated safety valvesm or those safety valves used for pressure vessels for refrigeration.

This is a product standard, and is not applicable to applications of safety valves.

Note 1) Pressure requirements in this Standard are given in either absolute pressure or gauge pressure, whichever is appropriate for the particular requirement.

Absoute pressure are given in Pa, with the indication :(absolute)” attached are given in Pa with the indication “(gauge)” attached after it.

NOTE The International Standards corresponding to this Standard and the symbol of degree of correspondence are as follows.

ISO 4126-1: 2013 Safety devices for protection against excessive pressurePart 1: Safety valves and Amendment 1: 2016

ISO 4126-7: 2013 Safety devices for protection against excessive pressurePart 7: Common data and Amendment 1: 2016 (Overall evaluation: MOD)

In addition, symbols which denote the degree of correspondence in the contents between the relevant International Standard and JIS are IDT (identical), MOD (modified), and NEQ (not equivalent) according to ISO/ lEC Guide 21-1.

However, the following are not included:

a) those used for the purpose of releasing the pressure of liquid;

b) those which are for use at set pressure under 0.1 MPa or over 42.9 MPa;

c) those of special construction, such as those intended for vehicles;

d) those intended for pressure regulation, such as unloaders;

e) those less than 15 mm in seat diameter.

NOTE: The International Standards corresponding to this Standard and the symbol of degree of correspondence are as follows:

ISO 4126-1: 2004 Safety devices for protection against excessive pressure- Part 1: Safety valves

ISO 4126-7: 2004 Safety devices for protection against excessive pressure- Part 7: Common data

(Overall evaluation: MOD)

The symbols which denote the degree of correspondence in the contents between the relevant International Standards and JIS are IDT (identical), MOD (modified), and NEQ (not equivalent) according to ISO/ lEC Guide 21.

L'ISO 4126-9:2008 décrit les exigences normatives pour l'application et l'installation des dispositifs de sécurité pour la protection des équipements soumis à une pression statique. Les informations contenues dans l'ISO 4126-9:2008 présument que le fluide déchargé par le dispositif de sécurité ait un débit monophasique. Pour des conditions de débit diphasique (liquide/gaz), se référer à l'ISO 4126-10 pour des conseils spécifiques à ces conditions.

Les équipements raccordés les uns aux autres dans un système par des tuyauteries de débit adéquat, exempts de blocages potentiels et ne comprenant pas d'appareil de robinetterie susceptible d'isoler une partie quelconque peuvent être considérés comme des systèmes de sécurité eu égard à l'utilisation pour la décharge de pression.

L'ISO 4126-9:2008 ne traite pas des autres dispositifs de sécurité tels que les dispositifs de surveillance et de commande reliés à la sécurité et autres dispositifs de limitation qui sont autorisés par certaines réglementations nationales.