The name system 13 stands for a modular system of solenoid coils, armature systems, solenoid operators and solenoid valves. The diameter of the armatures of all valve components is approximately 13 mm. This value is the major characteristic of this type series. The components’ efficiency has been increased to the optimum in years of simulation, construction and practical testing. Since the diameter of the armature is a major determining factor, its selection is of great technical importance.