This part of ISO23551 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 ISO23551 is applicable to MFC with declared maximum inlet pressures up to, and including, 50kPa (500mbar) of nominal connection sizes up to, and including, DN150 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.This part of ISO23551 is also applicable to:water operated gas valves (see Annex AA); andOSDs according to Annex BB.