Pressure regulator made of brass for high pressures and high flow rates. For models with outlet-pressure till 25 Bar, the control system is based on convoluted diaphragm, for a better stability and regulation; for models with output pressures higher than 25 bar, the system is controlled by piston. The balanced shutter keeps the outlet pressure almost constant and independentfrom fluctuation of inlet pressure. Designed for the most critical applications such as big distribution plants and fire-fighting systems.