The 5801 series is a self-operated reducer for steam, gas and neutral liquids proportional to balance of forces with external pressure intake.

The fluid passes through the valve body which causes a pressure drop, the reduced pressure is transmitted to the adjustment head, through the pressure intake, this force produced opposes the force of the pre-set spring. This creates a balance of forces which keeps the shutter in a certain position. By varying the flow rate, the valve assumes a new equilibrium position.