Modelling and Testing an Innovative Combined Hydraulic Valve for High-Pressure Washing

In this paper the main design features of an innovative combined hydraulic valve for high-pressure washing applications have been investigated by means of numerical modelling and experimental testing. This particular type of hydraulic component is obtained joining together a relief and a bypass valve. When the washing system is activated, the relief valve limits the maximum admitted working pressure while, when the washing system is switched off, the bypass valve unloads the hydraulic circuit and a direct connection with the drain ambient is quickly established. First of all, a very detailed lumped and distributed numerical model of the combined valve has been developed, with particular care devoted to the coupling between all the mechanical internal components (piston with holes, bushing and related springs) and to the valve body inner hydraulic connections. Then, the predictive capability of this lumped and distributed numerical model has been verified by means of a numerical versus experimental comparison, performed for a wide range of operating conditions (inlet pressure and volumetric flow rate) and geometrical parameters (sealing gaps, springs' stiffness and nozzle size). Finally, the previously validated numerical model has been applied in order to identify reliable design solutions for typical washing conditions, characterized by fluid pressure values spanning in the range between 50 to 280 bar and inlet volumetric flow rates comprised between 10 and 40 l/min.