ISO/TC 161/WG 3 - Controls

ISO 23551-4:2018 specifies safety, constructional and performance requirements of valve-proving systems (VPS), intended for use with gas burners and gas-burning appliances. It also describes the test procedures for checking compliance with these requirements and provides information necessary for the purchaser and user. ISO 23551-4:2018 is applicable to all types of VPS which are used for the automatic detection of leakage in a gas burner section having at least two valves designed in accordance with ISO 23551‑1 and which give a signal if the leakage of one of the valves exceeds the detection limit. ISO 23551-4:2018 is applicable to VPS with a maximum working pressure up to and including 500 kPa for use in systems using fuel gases. ISO 23551-4:2018 is not applicable to VPSs for use in explosive atmospheres. NOTE Provisions for production control are not part of the ISO 23551 series.

ISO 23550:2018 specifies safety, construction, performance and testing requirements for controls for gas burners and gas burning appliances for use with natural gas, manufactured gas or liquefied petroleum gas (LPG). ISO 23550:2018 applies to controls for use at maximum operating pressures up to and including 500 kPa. This document provides the general requirements that are intended to be the basis for the specific control standards found in the ISO 23551 and ISO 23552 series. These include the following: - automatic and semi-automatic gas valves; - gas thermoelectric flame supervision controls; - gas and oil /air ratio controls; - gas pressure regulators; - manual gas valves; - mechanical gas thermostats; - multifunctional gas controls; - air and gas pressure-sensing devices; - gas vent valves; - gas valve-proving systems. ISO 23550:2018 covers type testing only. ISO 23550:2018 is also applicable to Gas Quick Connectors (GQC) for use inside appliances with connections up to, and including DN 25, and a maximum operating pressure up to and including 100 kPa. GQCs include: - tube to tube connections; - tube to control connections; and - tube to fitting connections. ISO 23550:2018 does not apply to mechanical controls for use with liquid fuels. It is also not applicable to corrosive and waste gases.

ISO 23551-10:2016 specifies the safety, design, construction and performance requirements and testing for automatic vent valves (hereafter referred to as "valves") for use with gas burners, gas appliances burning one or more gaseous fuels. It is applicable to valves with declared maximum inlet pressures up to and including 500 kPa (5 bar) of nominal connection sizes up to and including DN 100 (4"). It is applicable to - normally open valves, - electrically operated valves and to valves actuated by fluids where the control valves for these fluids are actuated electrically, but not to any external devices for switching the control signal or actuating energy, and - valves fitted with open position indicator switches. It is not applicable to - valves for burners and appliances using renewables and/or waste gases (i.e. gases having corrosive characteristics), In case valves are in contact with renewables and/or waste gases, it is recommend to use ISO 23551-10:2016 only if explicit information is provided and relevant test methods and requirements are specified. - valves for appliances intended to be installed in the open air and exposed to the outdoor environment, - valves that are connected directly to mains pipe-work or to a container that maintains a standard distribution pressure, and - valves suitable with oil. It is applicable to type testing only.

ISO 23551-1:2012 specifies safety, constructional and performance requirements and testing of automatic and semi-automatic shut-off valves for gas burners, gas appliances and appliances of similar use. It applies to normally closed valves, valves being mounted upstream to gas burners and gas appliances, valves with declared maximum working pressures up to and including 500 kPa, for use on burners or in appliances using fuel gases as natural gas, manufactured gas or liquefied petroleum gas (LPG), valves directly or indirectly actuated, electrically or by mechanical means, valves actuated by hydraulic or pneumatic means, valves where the flow rate is controlled by external electrical signals, either in discrete steps or propor­tional to the applied signal, and valves fitted with closed position indicator switches. ISO 23551-1:2012 covers type testing only.