ISO 23553-1:2022 pdf download – Safety and control devices for oil burners and oil-burning appliances — Particular requirements — Part 1: Automatic and semi-automatic valves. 3.4 group 1 control controls (3.2) with connection sizes up to and including DN 25, for use in an appliance where they are not subjected to bending stresses imposed by installation pipe work or in an installation if used with rigid adjacent supports Note 1 to entry: In Canada, Japan and the USA, group 1 controls are not used. 3.5 group 2 control controls (3.2) for use in any situation, either internal or external to...