Modulating control valves of the series MDV are approved by DVGW and certified CE according to the Norm EN 161 to meet requirements in industrial and residential combustion systems.They are particularly suitable for the proportional regulation of gas flows of the first, second and third family and of air. The electric motor is unipolar and bidirectional, with high static and maintaining torque for 3-position-operation. The exact linear rating is achieved by means of particular, patented shutter disks, rotating on the same axis.11 different orifice sizes are available according to the operating conditions.